rrdcgi - Create web pages containing RRD graphs based on templates

Author

       Tobias Oetiker <tobi@oetiker.ch>

1.7.2                                              2025-03-04                                          RRDCGI(1)

Description

rrdcgi is a sort of very limited script interpreter. Its purpose is to run as a cgi-program and parse a
web page template containing special <RRD:: tags. rrdcgi will interpret and act according to these tags.
In the end it will printout a web page including the necessary CGI headers.

rrdcgi parses the contents of the template in 3 steps. In each step it looks only for a subset of tags.
This allows nesting of tags.

The argument parser uses the same semantics as you are used from your C-shell.

--filter|-f
Assume that rrdcgi is run as a filter and not as a cgi.

Keywords
RRD::CV name
Inserts the CGI variable of the given name.

RRD::CV::QUOTE name
Inserts the CGI variable of the given name but quotes it, ready for use as an argument in another
RRD:: tag. So even when there are spaces in the value of the CGI variable it will still be
considered to be one argument.

RRD::CV::PATH name
Inserts the CGI variable of the given name, quotes it and makes sure it starts neither with a '/'
nor contains '..'. This is to make sure that no problematic pathnames can be introduced through
the CGI interface.

RRD::GETENV variable
Get the value of an environment variable.

<RRD::GETENV REMOTE_USER>

might give you the name of the remote user given you are using some sort of access control on the
directory.

RRD::GOODFOR seconds
Specify the number of seconds this page should remain valid. This will prompt the rrdcgi to
output a Last-Modified, an Expire and if the number of seconds is negative a Refresh header.

RRD::INCLUDE filename
Include the contents of the specified file into the page returned from the cgi.

RRD::SETENV variablevalue
If you want to present your graphs in another time zone than your own, you could use

<RRD::SETENV TZ UTC>

to make sure everything is presented in Universal Time. Note that the values permitted to TZ
depend on your OS.

RRD::SETVAR variablevalue
Analog to SETENV but for local variables.

RRD::GETVAR variable
Analog to GETENV but for local variables.

RRD::TIME::LAST rrd-filestrftime-format
This gets replaced by the last modification time of the selected RRD. The time is
strftime-formatted with the string specified in the second argument.

RRD::TIME::NOW strftime-format
This gets replaced by the current time of day. The time is strftime-formatted with the string
specified in the argument.

Note that if you return : (colons) from your strftime format you may have to escape them using \
if the time is to be used as an argument to a GRAPH command.

RRD::TIME::STRFTIME START|ENDstart-specend-specstrftime-format
This gets replaced by a strftime-formatted time using the format strftime-format on either start-spec or end-spec depending on whether START or END is specified. Both start-spec and end-spec
must be supplied as either could be relative to the other. This is intended to allow pretty
titles on graphs with times that are easier for non RRDtool folks to figure out than "-2weeks".

Note that again, if you return : (colon) from your strftime format, you may have to escape them
using \ if the time is to be used as an argument to a GRAPH command.

RRD::GRAPH rrdgrapharguments
This tag creates the RRD graph defined by its argument and then is replaced by an appropriate
<IMG ... > tag referring to the graph. The --lazy option in RRD graph can be used to make sure
that graphs are only regenerated when they are out of date. The arguments to the RRD::GRAPH tag
work as described in the rrdgraph manual page.

Use the --lazy option in your RRD::GRAPH tags, to reduce the load on your server. This option
makes sure that graphs are only regenerated when the old ones are out of date.

If you do not specify your own --imginfo format, the following will be used:

Note that %s stands for the filename part of the graph generated, all directories given in the
PNG file argument will get dropped.

RRD::PRINT number
If the preceding RRD::GRAPH tag contained any PRINT arguments, then you can access their output
with this tag. The number argument refers to the number of the PRINT argument. The first PRINT
has number 0.

RRD::INTERNAL <var>
This tag gets replaced by an internal var. Currently these vars are known: VERSION, COMPILETIME.
These vars represent the compiled-in values.

Example 1

       The example below creates a web page with a single RRD graph.

        #!/usr/local/bin/rrdcgi
        <HTML>
        <HEAD><TITLE>RRDCGI Demo</TITLE></HEAD>
        <BODY>
        <H1>RRDCGI Example Page</H1>
        <P>
        <RRD::GRAPH demo.png --lazy --title="Temperatures"
                 DEF:cel=demo.rrd:exhaust:AVERAGE
                 LINE2:cel#00a000:"D. Celsius">

        </P>
        </BODY>
        </HTML>

Example 2

       This script is slightly more elaborate, it allows you to run it from a form which sets RRD_NAME. RRD_NAME
       is then used to select which RRD you want to use as source for your graph.

        #!/usr/local/bin/rrdcgi
        <HTML>
        <HEAD><TITLE>RRDCGI Demo</TITLE></HEAD>
        <BODY>
        <H1>RRDCGI Example Page for <RRD::CV RRD_NAME></H1>
        <H2>Selection</H2>
        <FORM><INPUT NAME=RRD_NAME TYPE=RADIO VALUE=roomA> Room A,
              <INPUT NAME=RRD_NAME TYPE=RADIO VALUE=roomB> Room B.
              <INPUT TYPE=SUBMIT></FORM>
        <H2>Graph</H2>
        <P>
        <RRD::GRAPH <RRD::CV::PATH RRD_NAME>.png --lazy
                 --title "Temperatures for "<RRD::CV::QUOTE RRD_NAME>
                 DEF:cel=<RRD::CV::PATH RRD_NAME>.rrd:exhaust:AVERAGE
                 LINE2:cel#00a000:"D. Celsius">

        </P>
        </BODY>
        </HTML>

Example 3

       This example shows how to handle the case where the RRD, graphs and cgi-bins are separate directories

        #!/.../bin/rrdcgi
        <HTML>
        <HEAD><TITLE>RRDCGI Demo</TITLE></HEAD>
        <BODY>
        <H1>RRDCGI test Page</H1>
        <RRD::GRAPH
         /.../web/pngs/testhvt.png
         --imginfo '<IMG SRC=/.../pngs/%s WIDTH=%lu HEIGHT=%lu >'
         --lazy --start -1d --end now
         DEF:http_src=/.../rrds/test.rrd:http_src:AVERAGE
         AREA:http_src#00ff00:http_src
        >
        </BODY>
        </HTML>

       Note 1: Replace /.../ with the relevant directories

       Note 2: The SRC=/.../pngs should be paths from the view of the webserver/browser

Name

       rrdcgi - Create web pages containing RRD graphs based on templates

Synopsis

       "#!/path/to/"rrdcgi [--filter|-f]