Forum: CFEngine Help
Subject: Re: convert class name into a string
Author: sauer
Link to topic: https://cfengine.com/forum/read.php?3,24123,24184#msg-24184
msvob...@linkedin.com Wrote:
-------------------------------------------------------
> Sauer, good suggestion, but allclasses.txt are
> only global classes. Local classes wouldn't work.
Nope - allclasses.txt is kept up-to-date as cf-agent works its way through the
promises. At the end of execution (which is what you see when you look at the
file if cf-agent isn't actively running), you're probably only seeing global
classes because your last bundle probably doesn't define any local classes.
Demonstration time!
$ cat ./classes.cf
#!/var/cfengine/bin/cf-agent -Kf
body common control{ bundlesequence => { "a", "b" }; }
bundle agent a {
classes:
"localclass" or => { "linux", "!linux" };
commands:
"/bin/grep class '$(sys.workdir)/state/allclasses.txt'";
reports:
someotherclass:: "a Some Other Class";
localclass:: "a Local Class";
}
bundle agent b {
classes:
"someotherclass" or => { "linux", "!linux" };
commands:
"/bin/grep class '$(sys.workdir)/state/allclasses.txt'";
reports:
someotherclass:: "b Some Other Class";
localclass:: "b Local Class";
}
$ ./classes.cf
Q: ".../bin/grep class": localclass
I: Last 1 quoted lines were generated by promiser "/bin/grep class
'/home/user/.cfagent/state/allclasses.txt'"
R: a Local Class
Q: ".../bin/grep class": someotherclass
I: Last 1 quoted lines were generated by promiser "/bin/grep class
'/home/user/.cfagent/state/allclasses.txt'"
R: b Some Other Class
$ grep class ~user/.cfagent/state/allclasses.txt
someotherclass
Note how allclasses.txt contains the classes which were in effect when the last
bundle was processed at the end. In each bundle, however, the grep found that
a locally-defined class existed in allclasses.txt. In bundle b, the
locally-defined class from bundle a is also not found.
Something the more attentive reader might note: I had to slightly change the
grep command in bundle b, because cf-agent was initially skipping it as the
same command had already been validated in a previous bundle. That's why the
one in bundle b has an extra space before the filename argument; that's enough
to throw off the "was this validated before" check.
In any event, from this one can infer that it's also possible to use a module
script to parse allclasses.txt and set variables, in the event that the
CFEngine syntax does not allow for easy enough handling of the file / selection
of variable names. Neil could probably write a quick shell/perl script which
looks for a pattern in class names and sets variables from those patterns, for
example. :)
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