The Cricket Reference Guide

This section is the definitive reference for each and every tag that Cricket knows about. Use this section as a reference when you need to know the exact format for something, or the exact behavior of a certain tag.

File Format

Cricket config files are simple text files arranged into a tree-shaped set of files called a Config Tree. They are processed by a Perl module called This setup would make it possible to use one config tree for Cricket and other clients of At this time, there are no other programs that use the config tree design, but there may be in the future. It was set up this way because the config tree will grow to contain an accurate picture of your network; it makes sense to try to leverage that information to other network administration tools. The overriding philosophy here is duplicated information is bad: it is hard to maintain, and it invites silly mistakes.

The Cricket config tree is 100% incompatible with MRTG configuration files. There are not even any plans to write a converter, though one could probably be written. When you choose to use Cricket, it's a very good idea to approach your config from a fresh perspective, to take maximum advantage of Cricket's features.

The comment character for Cricket is "#". If a "#" is found at the beginning of the line (or is preceded only by whitespace) then the "#" and everything after it will be deleted. Completely blank lines are discarded from the input too.

The fundamental unit of a config file is a chunk. A chunk is made up of one line which begins in column one, and one or more lines which have whitespace before them. In this way, you can continue a long line to another line by simply inserting a newline and some whitespace. When it is glued back together internally, the newline and whitespace are replaced by a space. A chunk should have at least one word (a group of characters that are not whitespace) at the beginning. This word (called the "token" by the code) tells what kind of chunk it is dealing with, and what kind of parser to use. If it is an unknown token, can be told to ignore it. By default, unknown chunks cause a warning, but not a fatal error. Clients of can control this; Cricket chooses to ignore unknown chunks.

Text Parser

This parser is used in cases where free-text is useful, for instance in the HTML dictionary. The first two tokens are parsed out, and they serve as the chunk type, and the key. Everything after these first two tokens is considered the value.

Simple Parser

This parser is used for simple mappings, like the OID mapping. An example of a valid OID line is:

oid	ifInOctets

The format is a token, another token (called the key; ifInOctets in this case), and finally the value. The value can have whitespace in it, but only if it is surrounded by double quotes ("). Embedded quotes are not yet supported.

Tag/Value Parser

This is the most useful, and most commonly used parser. Here's an example of a Tag/Value chunk:

graph   ifInOctets
    color       =   dark-green
    draw-as     =   AREA
    legend      =   "Average bits in"
    y-axis      =   "bits per second"
    scale       =   8,*

Like the others, it parses out two tokens, the chunk type and the key. After this, it parses a series of tag/value pairs separated by whitespace and the equals sign ("="). The values must be surrounded by quotes to embed whitespace, like the Simple Parser. If you repeat a tag, only the second occurrence will be used.


All tokens and keys are case-insensitive. The tags in a tag/value chunk are also case insensitive. The values will have their case preserved when they are used by the system.

Tag names can have numbers, letters, the period symbol, the dash, and the underscore. Avoid using other punctuation, since those symbols are used by Cricket internally.

OID tags are more limited, to conform with the SNMP spec. A tag in an OID dictionary can be made up of numbers and letters. Dashes are not alowed.

Target names should consist of letters, numbers, dashes and underscores. Do not put slashes in them, since they end up being used as parts of filenames.

Inside of double quotes, on the right side of an equals sign, anything goes, with the exception of the double quote itself. There is currently no way to include the double quote in a string.

Avoid choosing names that begin and end with two dashes (like --default--). Criecket uses some names like this internally, and future additions will make use of these names.

The following table shows which tokens are parsed with which parsers:


For some tags, you can put Perl expressions into the value. (inst-names is one such tag) However, double quotes are often useful in Perl expressions. That's problematic, since at present there is no way to put quotes into values. Instead, you should use single quotes. Thus it might look something like this:

inst-names =   "('Port 1 Ethernet', 'Port 2 Ethernet', 
                 'Port 3 FDDI', 'Port 6 FDDI', 
                 'Port 7 Ethernet' , 'Port 9 Ethernet')"

Dictionary Reference

In this section are detailed lists of every tag you will find in every dictionary.

Jump directly to:

The Target Dictionary

For each target known to Cricket, there is a target dictionary. The target dictionary holds all the information needed by Cricket to collect and store variables from a component. The target dictionary is expanded with respect to itself immediately before it is used to collect or display data.


Default value: not set

If this tag exists, and it is set to false, then this target will be skipped when the collector comes across it. This is useful if you no longer want to collect an obsolete target, but you still want it in the config tree so that you can look at it with the grapher.


Default value: not set

If this item is set, it tells Cricket to send the data it collects somewhere else after it is added to the RRD file. The value of this tag is interpreted as a colon separated list of two things. The first is where to send the data. The second item is used on a case-by-case basis. The only place to send data right now is to SNMP traps. To do so, set copy-to to a string like this:

The traps Cricket sends are marked with an enterprise number of "" (which is enterprises.webtv.wtvOps.wtvOpsTraps). Their generic type is 6, and their specific type is 3. The first varbind is the full path to the target, including the target name. The other varbinds are the actual data. The OID's for these varbinds can be ignored. They are not significant.

New copy-to types can only be added by editing the source to the collector. Please send any patches to the Cricket maintainer, so others can use your nifty copy-to method.


Default value: unset

This string is displayed in the description column of the directory selection list, if it is set. If not, the column is simply left blank.


Default value: unset

Hold on tight, this is a weird one. If this is set in the dictionary of the first target displayed in the "Targets that are available" table, then the table will have only one column. This is useful when you have lots of views and don't want to lose the space used by the description column.


Default value: same as target name

You can use this tag to use a more user friendly name for a target for display purposes. If you do not set it, the target name itself will be displayed.


Default value: none

This tag is interpreted by the grapher as a comma-separated list of events to fetch from the events dictionary, and add to the graph in the form of a vertical rule.


Default value: none

This is the SNMP instance number. Cricket only really needs this value to be set correctly if %inst% shows up in the ds-source tag of the datasources you are collecting. If inst is set, Cricket will attempt to evaluate it as a Perl expression.

Note: there's no protection against side-effects from this expression, so to avoid a security problem from an inst like unlink('/etc/motd'); you should make certain your config tree is only writable by you.

The result of evaluating the instance is examined to see whether it is a mapped instance, a scalar, or a vector. If it starts with "map(", it is a mapped instance. The instance mapping algorithm is used to derive an instance number from the rest of the data in the target (see Instance Mapping for more information on this), then the target is processed as though the instance number had been a scalar all along.

If it is a scalar (i.e. inst=1) then it is processed normally. If the instance is a vector (i.e. inst="(0..12)", or inst="(1, 3, 5)") then the target is processed once for each value in the list. The target dictionary is expanded with respect to itself for each instance, so it's possible to embed %inst% into the rrd-datafile tag. In fact, it's critical to add %inst% to some part of the rrd-datafile tag, or else the data will all be stored on top of one another in the same datafile.


Default value: none

When making the instance selector table, Cricket will use names from this tag instead of the instances themselves. If it will be needed, inst-names is eval'ed (just like inst). For each instance in the inst tag, Cricket looks for a corresponding entry in the inst-name vector. If it finds one, it uses that as the instance name, otherwise it defaults to the instance it fetched from the inst tag.


Default-value: unset

This description shows up at the top of a page of graphs, in the "Summary" section. There is more room on this page for a longer description. You can include your own HTML as long as you close all tags that you open. If you don't feel like setting this for every target, set it to %short-desc% in the "--default--" target, and the short description will show up on each graph page for every target which does not have an explicit long description. (Such is the power of the config tree.)


Default-value: none

If this tag exists, then the fetched value for this target will be checked after the RRD is updated. The format of a monitor-thresholds tag is 2 or more fields, colon delimited. Field 1 always contains the datasource associated with the target that you want to monitor, and field 2 specifies what monitor type you wish to apply to the specified datasource, any additional fields are passed to the monitor and are called arguments (field 3 is argument 1). Currently there are 3 supported monitor types: value, hunt, and relation.

Value monitors are the easiest to configure, and allow you to configure high-water/low-water monitoring on a datasource. Argument 1 is the low-water, and argument 2 is the high-water. Example: monitor-thresholds = "myds:value:10:20" would cause Cricket to send a trap if the last value for the datasource "myds" in the RRD file is below 10 or above 20.

Hunt monitors tell Cricket that a given target is the roll over for another target, so that if target 1 is at capacity, then traffic will begin to flow over target 2. This is especially useful to identify premature rollover in a set of modem banks configured to hunt from one to the next. Arguments for hunt monitors are as follows:

  1. The value that must be reached before rollover should occur. Generally this should be slightly less than the maximum capacity of the target.
  2. The name of the target that precedes this target in the huntgroup.
  3. The datasource of the target that should be checked (e.g. connected users)

Example: monitor-thresholds = "myds:hunt:40:pop-1:myds" when placed in the target definition of pop-2, would cause Cricket to send a trap if traffic was seen on pop-2 before pop-1 reached 40 users.

Relation monitors are the most flexible, and allow Cricket to compare the value of the target you are monitoring with any other stored value within Cricket's RRD files. This can be used to compare a target against itself at a previous time (e.g. compare the traffic on a router interface to the traffic a week ago on that same interface), to compare against the same target for a different datasource (e.g. compare the packet rate on a router to the error rate), or to compare a target against a completely seperate target (e.g. compare the traffic on router-1 to the traffic on router-2 to be sure that they are load balancing correctly). Arguments for relation monitors are as follows:

  1. Threshold, this is the difference between the two datasources, it can either be an absolute value, or a percentage (specified by the suffix "pct" as not to conflict with Cricket's variable expansion).
  2. Target, this is the target that is to be compared against. Note that this can be left blank, in which case the target will be compared against itself.
  3. Datasource, this is the datasource that is to be compared against. Note that this too can be left blank, in which case the ds specified in field 1 will be used.
  4. Time, this is the number of seconds to go back in the RRD file that is being fetched from for comparison. Note that data must exist in the RRD file for that exact number of seconds back or the monitor will be skipped.

When a threshold is violated the subroutine named Alarm in is executed. Likewise, when a recovery is detected, the subroutine named Clear is run. At present, these subroutines send an SNMP trap to the address in the target tag trap-address. You could replace these subroutines with ones that send mail, or log to some other alert manager.

Note: Monitoring of vectored instances is not supported. More than one monitor can be placed in a monitor-thresholds tag using a comma as a delimiter.


Default-value: none

If this tag exists, then this target is considered by Cricket to be a multi-target. To the collector, this means that it simply doesn't need to collect anything, and can skip the target. To the grapher, it means this target will aggregate the data from several different targets all onto one set of graphs. It will plot the data from each of the different targets all on the same graph. It assumes that the target-type of each of the specified targets is the same. It works best if the graph dictionary for each datasource does not specify a color (otherwise you'll end up with more than one line with the same color). It enforces only one AREA graph--it will convert the others into LINE2 in order to ensure they can be seen. It does not currently support vector instances. Other than that, the syntax matches that for "targets". This tag can also be used in connection with the mtargets-ops flag to perform Arithematic operations.

Note: This tag will not work with vector instances at this time. If you absolutely need it to work, you'll need to use multiple separate scalar targets to poll the device's ports, and then use the mtargets tag to graph each of the scalar targets.


Default-value: none

This tag is used in connection with the "mtargets" tag. This tag lets you perform arithematic operations on multiple targets. For example, this lets you add multiple targets together and graph the results. This tag must either be set to an RPN notation, or to a short-hand form, like "sum()".

If set to an RPN expression, it should be defined as a comma seperated list of operations, such as "+","-","*","/". This is used as a RPN calculator, operating on the targets listed in the mtargets definition. So, if you list three targets in your mtargets definition, you could define mtargets-ops="+,+", and the result would be a graph of the three targets added together.

If this tag is set to "sum()", the correct number of plusses will be substituted to make a valid RPN expression to sum each of the targets in the mtargets tag.

If this tag is set to "avg()", it will be replaced by the correct RPN expression to calculate the average of the targets in the mtargets tag.

The HTML summary section also has the same set of operations done to the values there. The operations are done to each datasource defined for that target-type. If you have defined a scale for the individual datasource, these operations are done on the scaled values.


Default value: 0

The order tag is used to control the order that targets are displayed. It has nothing to do with the order that they are polled. (Though it might work like that someday.) When the display is laid out by the CGI application, it sorts the targets from the highest order to the lowest order. Targets which have the same order are sorted alphanumerically within their order.


Default value: none

This tag tells Cricket where to put the data it collects, and where to find the data it will graph. Since there are no guarantees about where Cricket will be running from, you should use a full path here. The sample-config ships with a one-size-fits all definition for rrd-datafile in the root Defaults file. Except for special cases, you can probably use it and it will generate the filenames for you automatically.


Default value: none

This tag is used to set the step size (in seconds) for the RRD file when it is first created. This value cannot be changed once the RRD file is created, so if you need to change it in the config tree, then you must remove the RRD file, forcing Cricket to re-create it, to make the change stick. You will, of course, lose all the data you have collected so far. It is critical that the collector runs on each target at least as often as the rrd-polling-interval, otherwise RRD may mark the intervening polling periods as unknown.

RRA's are defined in terms of the fundamental polling-interval of the RRD. Thus, if you chose to adjust the rrd-polling-interval (and then run the collector at a non-standard rate) then you should re-visit the RRA definitions and probably make adjustments to them. A particular example of adjusting rrd-polling-interval would be using Cricket to monitor a 155 Mbit OC3 link. Because an SNMP Counter32 can wrap in under 5 minutes at bandwidths above 100 Mbits, it's critical to fetch the data more often, or else RRD will not be able to correctly detect and process the counter wrap. Hopefully in the next few versions, we will have an example of a part of the config tree optimized for very fast interfaces.


Default value: unset

If this tag is present, it will override the same tag in the datasource dictionary. See the entry on rrd-max there for more information.


Default value: unset

If this tag is present, it will override the same tag in the datasource dictionary. See the entry on rrd-min there for more information.


Default value: unset

This description shows up in the target selection table which the CGI program displays. It is a good idea to keep this description to one line. You can include your own HTML in it as long as you close all tags that you open.


Default value: none

This tag is not directly used by Cricket except when it is doing instance mapping. However, it is convention (as exemplified by the sample-config tree) that this tag should hold the SNMP community string, the hostname, and the port number in the exact form that is required by the snmp:// ds-source specification. Thus, ds-sources can simply start with snmp://%snmp%/, and they will incorporate the current host, port, and community string into the ds-source tag as soon as they are expanded with respect to the current target.

When using instance mapping, the snmp tag is used directly, so it must be present, even if you are using another convention to get the data into the ds-source tags.


Default value: none

If this tag exists, then this target is considered by Cricket to be a multi-target. To the collector, this means that it simply doesn't need to collect anything, and can skip the target. To the grapher, it means this target will aggregate the data from several different targets all onto one report. The syntax is a semi-colon deliminated list of targets. The target definition can either by fully-qualified, which would look like "/router-interfaces/Datacenter1/ds3-1", or unqualified, in which case they are assumed to be in the current directory.

For targets with vector instance definitions, it may also be useful to specify which instance you wish to display. You can do that by putting a colon after the target definition. So, it would look something like this: targets="/switch-ports/switch-1:3;/switch-ports/switch-2:5..7". This would put up instance #3 from switch-1, and instance #5, #6, and #7 from switch-2. Variable expansion is handled in the instance definition section as well.

This functionality assumes that the target-type of each of the specified targets is the same. You also must set a target-type for the multi-target itself. There are some variables which control the presentation of this data, which are also listed in this reference.


Default value: none

This tag sets the text which is displayed above each graph in a "targets" multi-target. It should be an array of the same length as the "targets" array. This value overrides the default presentation, and also overrides the tag targets-short-desc. Syntax would look like: targets-long-desc="('Target1','Target2')"


Default value: none

By default above each graph in a targets multi-target page, the short-desc of each target being displayed is printed above that graph (as well as some other text). This replaces that text with this. It should be an array which matches the "targets" array. The syntax would look the same as for targets-long-desc.


Default value: none

This tag sets the target type for this target. It must be one of the target type names from the targetType dictionary. Cricket uses the targetType to decide which variables to fetch, and how much data to store in the RRD.


Default value: unset

This tag is used to tell where to send SNMP traps when it needs to send one. The format should be community@hostname:port. You can safely leave off community and port. The defaults are "public", and "162", respectively.


Default value: unset

When this tag is set and the target is part of a multitarget which has mtargets-ops set, then data which is unknown will be treated as a 0. This is very useful when trying to create aggregate graphs that sum a set of targets that span different time ranges. By default, places where one target is unknown and the others are known will show on the graph as unknown (blank). In some cases, this can result in no graph appearing at all (when the set of known datapoints are completely disjoint). Set this flag to "true" to avoid this problem.

In addition, the following tags are set automatically by Cricket for your use in other tags in the target dictionary:


Default value: automatically set

The short name of the current target. This does not include the entire path from the config tree root to the target.


Default value: automatically set

The path leading from the base of the config tree to the current target.


Default value: automatically set

The config tree root directory. This is especially useful for creating paths which you want to be relative to the config tree root. For instance, setting rrd-datafile to %auto-base%/../cricket-data/foo.rrd would put the datafile in a directory named cricket-data, next to the base of the config tree.


Default value: automatically set

The name of the current view, as selected using the user interface. This is sometimes useful to incorporate into strings used in the user interface via the HTML dictionary.

The Datasource Dictionary

This dictionary tells Cricket everything it needs to know about individual datasources. A datasource is a single variable about a target which is polled and logged. For instance, a datasource for a router interface would be "inbound bandwidth". A separate datasource definition is needed for each of the other variables that you might want to measure ("outbound bandwidth", for instance).


Default value: unset If this tag is set, the value is incorporated into a key at the bottom of the page of graphs. This is a very good place to put notes about how the value is measured, what uncertainty there is in the measurement, etc. You can put arbitrary HTML into it, as long as you close any tags that you open. If there are no datasources with a description, then no key will be printed. Only datasources with descriptions will be present in the key.


Default value: none

This tag is used to tell Cricket where to fetch the data from. There is a scheme identifier from the beginning until the first colon. Everything after the first colon is defined on a per-scheme basis. The scheme identifier is case-insensitive.

The per-scheme part is expanded with respect to the target dictionary immediately before it is resolved into measurements, making it possible to plug values from the target dictionary into the ds-source at runtime. Likely candidates for this substitution include the SNMP hostname and community string, the instance number (which is appended to table-base OID's), and some or all of the command line for EXEC datasources.

Here's a detailed description of each scheme.

These ds-sources look like this: snmp://community@hostname:port/oid. The hostname part can be either an IP address or a domain name. It will be resolved with gethostbyname() in the latter case. The oid part can include a text label which will be expanded from the OID dictionary.

This ds-source is used to tell Cricket to run a shell command in order to fetch the value or values required for a target. After the exec: scheme identifier comes an integer followed by a colon, followed by a command (including whatever arguments are required for the command). The number chooses a line of output from the command (starting from line 0). For example, say the "vmstat" program on your system prints this when given the "-s" argument:

      350 swap ins
     2982 swap outs
      239 pages swapped in
     3298 pages swapped out
Then the following datasource would fetch the number of pages swapped out:

exec:3:vmstat -s

Note that we allow the text output from the command (i.e. "pages swapped out") to go in to Cricket. As of version 0.64, Cricket ignores everything after the first space or tab. It will attempt to interpret the first sequence of non-space charaters on the line as a floating point number. Since an integer is a degenerate form of a floating point number, they are acceptable. This behavior holds for all ds-sources, actually, but it is most useful for the EXEC type.

If the initial integer is omitted (and there are no colons in the command line to confuse Cricket) then the line number will be assumed to be 0, and the first line of output will be used as the measurement.

This ds-source tells Cricket to read a file and find the results on a certain line of that file. The line is specified using the same syntax as EXEC. For example, say the file /tmp/data has two lines in it, like this:


Then this datasource would always fetch "235" from the file:


Presumably, there would be some other process updating the data file with interesting data from someplace, or else the graph would be a flat line at 235.

This ds-source uses a Perl function to fetch the result. It is not enabled by default, since it requires extra code to be useful, and could be a security vulnerability, if the config tree were not properly protected. To enable it, uncomment the line use func; in collector.

This ds-source uses Perl's eval keyword to evaluate some Perl code at runtime. Usually, this will be a function call to a function you have written yourself and added into collector. A good way to add the code portably is to keep it in it's own file and incorporate it with the require keyword. You will need to be careful to avoid stomping on any data that collector uses, since it will be running your code in it's namespace. This should be fixed someday, if many extensions to Cricket use this interface.

Datasources are batched together and executed with as few network transactions or shell executions are possible. For instance, if you are fetching six datasources from the same hostname, all six datasources will be rolled into one SNMP request. Likewise, if you are fetching 3 different lines from the results of the same command, that command will be run only once.

Schemes are expected to return their data as an array of numbers. If the values are of the form "XXX@YYY", then the measurement XXX will be recorded as being taken at time YYY. The time must be in the form of a Unix time_t, i.e. number of seconds since 1970. Currently, this feature is only supported by the EXEC and FILE schemes. RRD imposes the restriction that data can only be added in strictly ascending time order. Each datasource which has a time in it should have a matching time. If this is not the case, Cricket will log a warning, but use the first time it found in the array.

You might use this feature if you are fetching the data from another data collection system which is operating on a different polling cycle than Cricket. You could use a shell script to fetch the data from the other system, along with the time the data was sampled. Then you could format the result into the "XXX@YYY" format, and print it to standard out for Cricket to read.

New schemes can be added to Cricket with minimal effort. Use the file lib/ as your guide, then add a use statement for your new .pm file to collector.


Default value: GAUGE

The DS type is used by RRD to know how to interpret the numbers fetched from this datasource. There are three possibilities:

The measurement will be directly copied into the RRD datafile without any extra processing. Examples of this type of measurement include readings from thermometers, percent disk space free, etc.

The measurements from COUNTER datasources will be treated like SNMP counters. An SNMP counter increases monotonically until a fixed wrap-around point (usually either 2^31-2 or 2^63-2, depending on the size of the data type). To convert a COUNTER measurement into a rate (for instance, "count of octets" to "octets per second") RRD subtracts the previous value from the current one, and adjusts for any wraparound conditions. Any SNMP variable which is marked with the SNMP "COUNTER" data type should have it's rrd-ds-type set to COUNTER.

DERIVE is like COUNTER, but there is no overflow check, so negative rates are possible. This datasource type would be useful when you have a count of something (which may increase and decrease), and you want to graph the rate of change.

ABSOLUTE is for COUNTERs which get reset upon reading. Some SNMP variables have this property. Using ABSOLUTE instead of COUNTER tells RRD to compute the rate assuming the value is an absolute count of octets (or whatever) during the last polling period.

The datasource type names are case-insensitive. They are passed directly through to RRD when the RRD file is created. If the datasource type is changed later, you must use rrd-tune to apply the change to the underlying RRD file. For more information about them, consult the RRD documentation for the create command.


Default value: 1800 (value is in seconds)

The heartbeat for a datasource is the number of seconds that can pass between updates before the datasource is marked unknown. If this tag is changed after the RRD file has been created, then the rrd-tune tool must be used to apply the changes to the existing RRD's.


Default value: U

This tag is used to set the RRD maximum value parameter. If RRD gets a value higher than this number, it will throw the data away, instead of adding it to the RRA. This can be used to filter bad data, though it could be argued it would be better to simply avoid fetching bad data in the first place. When it is set to "U" (for unknown), RRD does not attempt to check incoming data against an upper bound.

If the tag rrd-max is present in the target dictionary, it will override the value found in the datasource dictionary. This makes is possible to assign different maxima to different targets.

If this value is changed after the underlying RRD file has been created, the rrd-tune script must be used to apply the changes.


Default value: U

Like rrd-max, this tag is passed through to RRD unchanged. It can be used to apply an upper bound to data submitted to RRD.

Also like rrd-max, if rrd-min appears in the target dictionary, it will override the rrd-min in the datasource dictionary.

The TargetType Dictionary

The TargetType dictionary tells Cricket which datasources to gather together for a certain kind of target. Unlike other dictionaries, keys in this one can occur multiple times.

Default value: none

Each ds tag tells Cricket about a variable it will be fetching. The value of the tag must be comma-separated list of known datasource names.


Default value: none

A view is a subset of the datasources that you'd like to display together, apart from the rest of the datasources. The syntax for the value is "view-name: ds ds ...". The view name you choose shows up in the CGI grapher, so you should try to make it descriptive. The space-separated list of datasources after the colon must be datasources that are part of the target type. You can specify several views by separating them by commas.

The Graph Dictionary

The graph dictionary controls how individual variables are displayed when it comes time to graph them. The graph dictionary is structured exactly the same as the datasource dictionary, and in some ways they could be merged. For historical reasons, or architectural reasons (I haven't decided yet...) they remain separate dictionaries.

There are actually two "flavors" of graph dictionary tags; per-datasource and generic. The generic tags relate to the graphs themselves, as opposed to the individual datasources drawn onto the graphs. For instance, the width and height of a graph are configured by generic tags, whereas the color of a datasource is configured by a per-datasource tag. Per-datasource tags are stored in the graph dictionary just as all the tags in the datasource dictionary are stored. Generic tags are stored only in the --default-- dictionary.

Below, the generic tags are listed.


Default value: 200

This tag defines the requested height of the data area of the graph. This value is passed into RRD, which then draws the actual image somewhat bigger, in order to leave room for the margin, the scales, and the legend.


Default value: none

HTML defines image sizing tags that allow the browser to layout the page more efficiently. Using the Cricket's size hints, you can control what image sizing tags Cricket generates in it's HTML output. Most browsers will attempt to scale the image if the size hints passed in via HTML do not match the actual size of the image. The result is a hard-to-read graph that took too long to draw. Thus it is critical that if you choose to use sizing hints to help the browser layout the page, you make them precisely the same as the size of the generated image.

Because RRD pads the image with extra space, it's not possible for Cricket to guess the finished size of the image using the width and height tags. Instead, you need to find this number yourself by measuring an actual image produced by RRD. In Netscape Navigator, you can do this by right clicking on the image, then choosing Open this Image. Once the image is loaded, check the title bar for the actual size of the image.


Default value: "d:w"

What set of graphs are initially displayed. If you tend to be fetching graphs at low bandwidth, you might like to frob this. Setting it to "d", will make Cricket only send you the daily graph, instead of the daily and weekly graphs.


Default value: false

Set this tag to true to enable interlaced image. An interlaced image will appear to "fade in" in most web browsers.


Default value: png (for 4.0+ browsers), gif otherwise

Set this tag to 'gif' to get RRD Tool to create GIFs. The GIFs created by RRD are big and slow, because they do not use patented compression techniques. Cricket will use GIFs if the browser will not support PNG's.


Default value: none

This tag can be used to pass through arguments to the RRD Tool. The most appropriate use for this tag is to send color tags through to the RRD Tool. For instance, to make the canvas that the graph is drawn on appear black, you can set rrd-graph-args to "-c CANVAS#000000". This tag is split on whitespace before it is sent to RRD Tool, so it is not possible at this time to send arguments with embedded whitespace to RRD Tool.


Default value: none

Vertical rules are lines added to the graph by Cricket to help you visually find patterns in the data related to time of day. A vertical rule is placed at each "zero time" which appears on a graph. For an hourly graph, a zero time is midnight. For a daily graph, a zero time is the beginning of the most recent Monday. For a weekly graph, a zero time is the first day of the month. For a monthly graph, a zero time is the first day of the year. At this time, the definition of zero time for a given scale is hardcoded into Cricket's grapher.cgi script.

To enable vertical rules, use the vrule-color tag to choose a color for them. That's all there is to it. If vrule-color is defined, Cricket will automatically add the vertical rules for you.


Default value: 500

Like height, this is the height of the data area of the graph. The actual height of the resulting image will differ.


Default value: none

Like height-hint above, this controls the value used by Cricket for the height tag in its HTML output. See height-hint for more information about how to set this.


Default value: none

Using this tag (and it's opposite, y-min) you can explicitly control the vertical scale of the graph. If you use either y-min or y-max, you disable auto-scaling, and so you must explicitly set both of them. These tags are especially useful when you are graphing some value which should normally be very tightly bounded (for instance between 0 and 1 second), but occasionally jumps far above 1 second. In this case, all variation under one second will be essentially invisible on the graph, unless you set the y-min to 0 and the y-max to 1.

Because the graph dictionary is expanded with respect to the target dictionary, you could say y-max = %specific-y-max%, then set the tag specific-y-max on a per-target basis.

In general, it's a good idea to leave these unset and rely on auto-scaling, unless you have a situation that calls for explicit bounds.


Default value: none

See y-max, above.

The following tags are per-datasource. They can occur in the --default-- dictionary, in which case they are inherited into all subsequent per-datasource dictionaries. However, unlike the generic tags above, they are only ever referenced with respect to a certain datasource.


Default value: none

If this is set to true, then the conversion to SI units will use powers of 2 instead of powers of 10. For instance, if a router is reporting that it's moving 1048576 bits per second through a particular interface, and "bytes" is set to 1 (or "true") then the value will be reported in the HTML summary as 1 Mbit/sec. Without the bytes tag, the value would be reported at 1.04 Mbit/sec, which is slightly misleading. When measuring very large numbers of bytes, the difference can be significant.

The numbers on the veritcal axis of a graph are scaled by powers of 2 if the bytes tag is set to true for any of the datasources on the graph.


Default value: none

Use the color tag to explicitly control the color of the datasource as it appears both on the graph, and in the HTML summary. If this is left unset, then Cricket will automatically choose colors according to the --order-- key in the color dictionary. If you choose to set it, either set it to one of the color names in the color dictionary, or set it to an HTML-style color specification without the pound sign. For instance, to make a datasource's line red, set color to "ff0000".


Default value: ?

This tag tells Cricket how to draw the datasource on the graph. The choices are as follows:

draws a filled-in shape representing the value of the datasource over time.
uses a thin line
uses a medium line
uses a heavy line

Default value: datasource name

Using legend allows you to customize the datasource name which is displayed on the graph's legend, and in the HTML summary. If you don't use a legend tag, the name of the datasource (as specified by the ds tag in the targetType dictionary) will be used.


Default value: 2

You can adjust the number of decimal points in the HTML summary values using the precision tag. The default is two. If you simply want the value displayed to be rounded to the nearest integer, set precision to zero. Alternatively, you can set it to the string "integer".


Default value: none

If scale is set, then the datasource is run through a computation (usually a simple scaling operation) before it it plotted or listed in the HTML summary. The tag is interpreted as a string of operations that will be executed by a Reverse Polish Notation (RPN) calculator, separated by commas. When the expression begins executing, the current value of the datasource is already on the stack. Thus setting scale to "8,*" will multiply the datasource by 8 before plotting it.

The RPN operations available are "+" (plus), "-" (minus), "*" (multiply), "/" (divide), and "LOG" (take the natural logarithm of the top of the stack). Any other token is pushed onto the stack as a number. The top of the stack at the end of the string of operations is taken as the scaled value.

This feature is very useful when plotting bits per second from a router interface. Routers tend to report bandwidth in bytes per second, but humans tend to think about link capacity in bits per second. Using a scale tag of "8,*" can bridge this gap by scaling the bytes per second from the router into bits per second for human use.


Default value: true

This controls the amount of summary data shown on the top of graphs. If set to true, Cricket makes an extra call to RRD Tool to fetch the average and the maximum for the crurrent day of data. If set to false, only the current reading is shown.


Default value: true

Setting this tag to "false" will prevent Cricket from transforming the value printed in the HTML summary into SI units (i.e. 2000 bytes/sec is transformed into 2 kbytes/sec). The scale on the graph, however, will still have the transformation done to it. Set this tag to "false" for items that are not typically counted with SI units, like system load average.

Here are the SI units that are used by Cricket:

a 10e-18 Ato
f 10e-15 Femto
p 10e-12 Pico
n 10e-9 Nano
µ 10e-6 Micro
milli 10e-3 Milli
k 10e3 Kilo
M 10e6 Mega
G 10e9 Giga
T 10e12 Terra
P 10e15 Peta
E 10e18 Exa

Note that on graphs, 'milli' is denoted by 'm'. In the HTML summary, where there is more room, Cricket uses the less ambiguous 'milli'.


Default value: one space

This tag can be used by the extremely fastidious user to control the HTML summary. Usually, one space is exactly what you'd want between the value and the unit specifier of the value. However, for certain units, like the degree sign, no space is called for. In this case, set space to "", the empty string.


Default value: the value of the y-axis tag

In the HTML summary, the units tag is appended after the value of the datasource. If a datasource is collecting bandwidth information, for instance, it would make sense to set y-axis to "bits per second", since there is plenty of room for it. In the legend, where room is more limited, it would be better to set units to "bps", instead of letting it default to "bits per second".


Default value: unset

See y-max in the generic section. If there is a generic y-max, it overrides the per-datasource y-max. If there are multiple per-datasource y-maxes, then the maximum of all of them is used.


Default value: unset

See y-max above.

The Color Dictionary

The color dictionary is used to configure Cricket's auto-color selection system and to map color names to HTML-style color specifications (without the pound sign). Every key, except for the special key --order-- is considered a color name, and should have a color specification. The special key --order-- is used to tell Cricket what order to assign the colors when doing auto-selection.

An HTML-style color specification consists of three hex numbers ranging from 00 to ff. The numbers represent the intensity of the red, green, and blue components of the final color. For an example of a correctly configured color dictionary, see the Defaults file in the root of the sample config tree.

The OID Dictionary

The OID dictionary is a convenient place to put OID's to make the config files more readable. Before any SNMP operation, the user-supplied OID is scanned. Any text parts of the OID that match an entry in the OID dictionary get replaced. Note that this is a separate process from variable expansion, for historical reasons. The keys and values in this table are separated by whitespace. Each entry starts with the keyword "OID".

In keeping with the conventions of ASN.1 and SNMP, OID names are case insensitive, must start with a letter, and can otherwise consist of letters and numbers.

The HTML Dictionary

The HTML dictionary holds components of the UI that is created by the grapher using HTML. Before it is used, the HTML dictionary is expanded with respect to itself.


Default value: any errors generated on this page

Any runtime errors that the grapher finds while attempting to create the page are added to this tag. It is usually referenced in the page-footer.

Note that only errors that Cricket can find while it's running will show up here. Problems finding the Perl interpreter, or parsing grapher.cgi will still show up in the webserver's error log.


Default value: the contents of the VERSION file

This is the complete version string, including the version number and the time it was packaged for release.


Default value: the version number

This is simply the version number from the complete Cricket version string.


Default value: the title

This tag is set by the grapher to the title it expects to use on this page. It is normally referenced in the head tag.


Default value: none

This tag is incorporated into the HTML body tag. This is the perfect place to set a bacground color. It's not useful for much else, unless you want your graphs to play a MIDI file in the background.


Default value: none

This is HTML that will be inserted between the <head> and </head> tags. It can be used to incorporate a cascading style sheet into the Cricket user interface. This would allow you to easily control aspects of the UI design that are hardcoded in the source code.

To incorporate a CSS called "cricket.css", use a head tag like this:

html	head
	<link rel="stylesheet" src="cricket.css" type="text/css">


Default value: none

This is the HTML that will go on the bottom of the page. As Cricket is shipped, it includes a link to the RRD Tool website. Tobias Oetiker, the author of RRD Tool, has respectfully asked frontend authors to feature a link to RRD Tool. Please take into account his wishes as you edit this tag.

The version of page-footer in the sample-config directory refers to a tag called contact, which can be used to put sub-tree specific contact information into the bottom of the page. This is only meant as an example. You might choose to put completely different information at the bottom of the page.


Default value: none

This is the HTML that will go at the top of the page, after the <body> tag, but before the rest of the user interface. As shipped, it illustrates how you might put a company logo on each page.

The Event Dictionary

This dictionary holds information related to events. An event is some point in time which you'd like to mark on graphs so that later, you'll remember why it was that those graphs look the way they do. An event is named, just like a target or a datasource. The event names are used in the target dictionary tag called events. See the entry for that tag for more information.

Each event should have the following tags set:


The color of the event. This should be the name of a color in the color dictionary.


The time the event happened, which controls where on a grpah the vertical rule appears.


This is the text that will show up in the legend on the graph.

The RRA Dictionary

The RRA dictionary holds parameters used by Cricket when it is setting up a new RRD file. These parameters control how much data RRD stores, and on what schedule it consolidates high resolution data into lower resolution data.

The RRA dictionary that ships with Cricket in the sample config tree will rollup and retain data using the same schedule that MRTG 2.x has used for years. This has proven satisfactory for most users. If you change the polling rate from 5 minutes, this dictionary needs to be edited. Likewise, if you want to keep history farther back in time, you'll need to edit these entries.

Because this table is only used when a new RRD is being created, you would need to delete any existing datafile, losing all of the data in it, before a change to the RRA dictionary takes effect.

For more information on the format of these dictionary entries, read the RRD Tool documentation on the "create" command.

Cricket version 1.0.2, released 2000-05-19.

Copyright (C) 1998-2000 Jeff Allen. Cricket is released under the GNU General Public License.