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dty
Asked: 2012-04-24 03:44:02 +0800 CST

Using Augeas to modify Squid configuration

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I'm running squid-deb-proxy and I want to alter the configuration using Puppet/Augeas.

When I try this:

augeas {'squid-deb-proxy.conf':
    lens    => 'Squid.lns',
    incl    => '/etc/squid-deb-proxy/squid-deb-proxy.conf',
    changes => ["set http_port 3129"],
    require => Package['squid-deb-proxy']
}

I get the following error from Puppet:

err: /Stage[main]/Portal::Packages::Squid-deb-proxy/Augeas[squid-deb-proxy.conf]: Could not evaluate: Save failed with return code false

I tried the following with augtool:

augtool> rm /augeas/load/*
rm : /augeas/load/* 867
augtool> set /augeas/load/Squid/lens Squid.lns
augtool> set /augeas/load/Squid/incl /etc/squid-deb-proxy/squid-deb-proxy.conf
augtool> load
augtool> print
/augeas
/augeas/root = "/"
/augeas/context = "/files"
/augeas/variables
/augeas/version = "0.10.0"
/augeas/version/save
/augeas/version/save/mode[1] = "backup"
/augeas/version/save/mode[2] = "newfile"
/augeas/version/save/mode[3] = "noop"
/augeas/version/save/mode[4] = "overwrite"
/augeas/version/defvar
/augeas/version/defvar/expr
/augeas/version/pathx
/augeas/version/pathx/functions
/augeas/version/pathx/functions/count
/augeas/version/pathx/functions/glob
/augeas/version/pathx/functions/label
/augeas/version/pathx/functions/last
/augeas/version/pathx/functions/position
/augeas/version/pathx/functions/regexp
/augeas/save = "overwrite"
/augeas/span = "disable"
/augeas/load
/augeas/load/Squid
/augeas/load/Squid/lens = "Squid.lns"
/augeas/load/Squid/incl = "/etc/squid-deb-proxy/squid-deb-proxy.conf"
/augeas/files
/augeas/files/etc
/augeas/files/etc/squid-deb-proxy
/augeas/files/etc/squid-deb-proxy/squid-deb-proxy.conf
/augeas/files/etc/squid-deb-proxy/squid-deb-proxy.conf/path = "/files/etc/squid-deb-proxy/squid-deb-proxy.conf"
/augeas/files/etc/squid-deb-proxy/squid-deb-proxy.conf/mtime = "1335175492"
/augeas/files/etc/squid-deb-proxy/squid-deb-proxy.conf/lens = "Squid.lns"
/augeas/files/etc/squid-deb-proxy/squid-deb-proxy.conf/lens/info = "/usr/share/augeas/lenses/dist/squid.aug:433.18-.95:"
/augeas/files/etc/squid-deb-proxy/squid-deb-proxy.conf/error = "parse_failed"
/augeas/files/etc/squid-deb-proxy/squid-deb-proxy.conf/error/pos = "1449"
/augeas/files/etc/squid-deb-proxy/squid-deb-proxy.conf/error/line = "42"
/augeas/files/etc/squid-deb-proxy/squid-deb-proxy.conf/error/char = "0"
/augeas/files/etc/squid-deb-proxy/squid-deb-proxy.conf/error/lens = "/usr/share/augeas/lenses/dist/squid.aug:433.18-.95:"
/augeas/files/etc/squid-deb-proxy/squid-deb-proxy.conf/error/message = "Iterated lens matched less than it should"
/files

Which seems to suggest that the lens can't parse the config file. Line 42 of squid-deb-proxy.conf reads:

cache_access_log /var/log/squid-deb-proxy/access.log

And cache_access_log doesn't appear to be listed in /usr/share/augeas/lenses/dist/squid.aug.

So... it appears to me that the Squid lens shipping with Augeas 0.10.0 doesn't cover all of the Squid configuration options. Doesn't this make the lens configurations tremendously brittle? I haven't looked into lenses, but why don't they just define the 'structure' of the file (e.g. "name whitespace value-including-spaces", or "name tabs-only value-list-space-separated", etc.)? It seems a bit strange, and a bit of a maintenance headache, to have to have the lenses know about all of the configuration options.

Have I correctly diagnosed this? And if so, what can I do about it (ideally without having to modify the lens by hand, etc.)

squid puppet configuration configuration-management augeas

1 Answers

  1. Best Answer

    I can confirm that the current lens doesn't support the cache_access_log parameter, and the best thing to do about this indeed is to open a ticket on the Augeas trac.

    Some configuration files are trivial to map, and you can just specify a pattern (such as "key = value"). Others are more tricky, where some entries have a specific syntax, and others have a different one. For example, in the case of the squid lens, http_access or acl entries have a different syntax than the rest of the file. For this reason, it is necessary to list all know keys in the file to map them to the proper parser.

    For such lenses, the best thing to do when a key is missing in the lens is to report it (or even better, to send a patch to the list, it's quite trivial in this case).

    Looking forward to your ticket/patch!

    • 1