Forum: Cfengine Help
Subject: Re: Running a command just once.
Author: ro
Link to topic: https://cfengine.com/forum/read.php?3,21797,21846#msg-21846
Hi Chad,
I'm facing this issue as well. I'm a strong supporter of idempotency, but at
the same time I have requirements that the community version of Cfengine just
can't satisfy because it can't check the states that the various services are
in (i.e. setting up an initial LDAP DIT, creating certain basic Kerberos users
that reside in LDAP, setting up MySQL and PostgreSQL databases
andsoonandsoforth).
So what I'm using are "firstrun" classes. Since the above services are just
specific to very few servers, I take the burden and append the various firstrun
classes by hand upon first install:
cf-agent -D FIRSTRUN_LDAP_INITIALIZE
In my Cfengine config I then have:
bundle agent LDAPBaseFirstrun {
vars:
FIRSTRUN_LDAP_INITIALIZE::
"cmd_ldap_schema_cosine" string => "/usr/bin/ldapadd -Y
EXTERNAL -H ldapi:/// -f /etc/ldap/schema/cosine.ldif";
commands:
FIRSTRUN_LDAP_INITIALIZE::
"$(cmd_ldap_schema_cosine)",
contain => setuid_sh("root"),
classes =>
if_repaired("repaired_LDAPBaseFirstrun");
reports:
repaired_LDAPBaseFirstrun:: "Repaired promise LDAPBaseFirstrun";
}
In your case, this would take the logic of 'when' the script is to be run out
of the script itself and put it in Cfengine.
Another possibility would be to let Cfengine create a flag file and check upon
it on every execution:
bundle agent LDAPBaseFirstrun {
vars:
LDAP::
"flag_file" string =>
"/root/LDAPBaseFirstrun.executed";
"cmd_ldap_schema_cosine" string => "/usr/bin/ldapadd -Y
EXTERNAL -H ldapi:/// -f /etc/ldap/schema/cosine.ldif";
classes:
LDAP::
"flag_file_exists"
expression => fileexists("$(flag_file)");
files:
repaired_LDAPBaseFirstrun::
"$(flag_file)"
create => true;
commands:
!flag_file_exists::
"$(cmd_ldap_schema_cosine)",
contain => setuid_sh("root"),
classes =>
if_repaired("repaired_LDAPBaseFirstrun");
reports:
repaired_LDAPBaseFirstrun:: "Repaired promise LDAPBaseFirstrun";
}
Or, as mark suggests, deleting the script itself, which isn't possible, if the
command is executed by Cfengine itself, as in the above example.
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