{"id":450,"date":"2011-04-03T09:45:57","date_gmt":"2011-04-03T08:45:57","guid":{"rendered":"http:\/\/www.streppone.it\/cosimo\/blog\/2011\/04\/a-command-line-tool-for-debian-to-purge-varnish-objects\/"},"modified":"2011-04-03T09:45:57","modified_gmt":"2011-04-03T08:45:57","slug":"a-command-line-tool-for-debian-to-purge-varnish-objects","status":"publish","type":"post","link":"https:\/\/www.streppone.it\/cosimo\/blog\/2011\/04\/a-command-line-tool-for-debian-to-purge-varnish-objects\/","title":{"rendered":"A command line tool for Debian to purge Varnish objects"},"content":{"rendered":"

I've been using varnish<\/a> mostly on Debian systems. I found the reload-vcl<\/code> script included in Debian to be useful.<\/p>\n

The reload-vcl<\/code> script<\/h3>\n

It's part of the standard varnish debian package<\/a>. It uses the system defaults in \/etc\/defaults\/varnish<\/code>, so it knows how to correctly invoke the varnishadm<\/code> utility to perform administrative commands. As the name implies, it reloads the default VCL file using the vcl.load<\/code> and vcl.use<\/code> commands, checking that every step succeeds properly before continuing so it's safe to use. It loads the new VCL file and labels it automatically with a unique id.<\/p>\n

Something analogous but regarding the purge functionality could have been useful, so I looked at the source code for reload-vcl<\/code>. Most of it deals with loading of \/etc\/defaults\/varnish<\/code> and various sanity checks. I reused that bit to make another script, to control cache purging<\/strong>.<\/p>\n

The purge-cache script<\/h3>\n

Here's the full source code. Below there's a link to download the latest version from github.<\/p>\n

\r\n#!\/bin\/sh\r\n\r\n# purge-cache: Script to purge varnish cache. Defaults are defined in\r\n# \/etc\/default\/varnish.\r\n#\r\n# Cosimo <cosimo@cpan.org>\r\n# Based on reload-vcl, by Stig Sandbeck Mathisen <ssm at debian dot org>\r\n\r\n# Settings\r\ndefaults=\/etc\/default\/varnish\r\n\r\n# Paths\r\nvarnishadm=\/usr\/bin\/varnishadm\r\ndate=\/bin\/date \r\ntempfile=\/bin\/tempfile\r\n\r\n# Messages\r\n# msg_no_varnishadm: varnishadm\r\nmsg_no_varnishadm="Error: Cannot execute %sn"\r\nmsg_no_management="Error: $DAEMON_OPTS must contain '-T hostname:port'n"\r\n# msg_defaults_not_readable: defaults\r\nmsg_defaults_not_readable="Error: %s is not readablen"\r\n# msg_defaults_not_there: defaults\r\nmsg_defaults_not_there="Error: %s does not existn"\r\nmsg_usage="Usage: $0 [-h][-q][-u <url>|-r <regex>|-a]nt-htdisplay helpnt-qtbe quietnt-utpurge by exact (relative) url (ex.: \/en\/products\/)nt-rtpurge objects with URL matching a regex (ex.: ^\/blogs\/)nt-atpurge all objects from cachen"\r\nmsg_purge_failed="Error: purge command failedn"\r\n# msg_purge_url: url\r\nmsg_purge_url="Purging objects by exact url: %sn"\r\n# msg_purge_regex: regex\r\nmsg_purge_regex="Purging objects with URL matching regex: %sn"\r\nmsg_purge_all="Purging all cachen"\r\nmsg_purge_ok="Purge command successfuln"\r\n\r\n# Load defaults file\r\nif [ -f "$defaults" ]\r\nthen\r\n    if [ -r "$defaults" ]\r\n    then\r\n        . "$defaults"\r\n    else\r\n        printf >&2 "$msg_defaults_not_readable" $defaults\r\n        exit 1 \r\n    fi\r\nelse\r\n    printf >&2 "$msg_defaults_not_there" $defaults\r\n    exit 1\r\nfi\r\n\r\n# parse command line arguments\r\nwhile getopts hqu:r:a flag\r\ndo\r\n    case $flag in\r\n        h)\r\n            printf >&2 "$msg_usage"\r\n            exit 0\r\n            ;; \r\n        u)\r\n            purge_method=url\r\n        url="$OPTARG"\r\n            ;; \r\n        r)\r\n            purge_method=regex\r\n        regex="$OPTARG"\r\n            ;; \r\n        a)\r\n            purge_method=all\r\n            ;; \r\n        q)\r\n            quiet=1\r\n            ;; \r\n        *)\r\n            printf >&2 "$msg_usagen"\r\n            exit 1\r\n            ;; \r\n    esac\r\ndone\r\n\r\n# Parse $DAEMON_OPTS (options must be kept in sync with varnishd).\r\n# Extract the -f and the -T option, and (try to) ensure that the\r\n# management interface is on the form hostname:address\r\nOPTIND=1\r\nwhile getopts a:b:dFf:g:h:l:n:P:p:s:T:t:u:Vw: flag $DAEMON_OPTS\r\ndo\r\n    case $flag in\r\n        f)\r\n            if [ -f "$OPTARG" ]; then\r\n                vcl_file="$OPTARG"\r\n            fi \r\n            ;; \r\n        T)\r\n            if [ -n "$OPTARG" -a "$OPTARG" != "${OPTARG%%:*}" ]\r\n                then\r\n                mgmt_interface="$OPTARG"\r\n            fi  \r\n            ;;  \r\n    esac\r\ndone\r\n\r\n# Sanity checks \r\nif [ ! -x "$varnishadm" ]\r\nthen\r\n    printf >&2 "$msg_no_varnishadm" $varnishadm\r\n    exit 1\r\nfi\r\n\r\nif [ -z "$mgmt_interface" ]\r\nthen\r\n    printf >&2 "$msg_no_management"\r\n    exit 1\r\nfi\r\n\r\nlogfile=$($tempfile)\r\npurge_command="vcl.list"\r\n\r\n# Now run the purge command against the admin interface\r\nif [[ $purge_method = "url" ]]\r\nthen\r\n        purge_command="purge req.url == $url"\r\n        printf >&2 "$msg_purge_url" $url | grep -v "^$" > $logfile\r\nelse\r\n    if [[ $purge_method = "regex" ]]\r\n    then\r\n        purge_command="purge.url $regex"\r\n        printf >&2 "$msg_purge_regex" $regex | grep -v "^$" > $logfile\r\n    else\r\n        if [[ $purge_method = "all" ]]\r\n        then\r\n            purge_command="purge.url ."\r\n            printf >&2 "$msg_purge_all" | grep -v "^$" > $logfile\r\n        fi\r\n    fi\r\nfi\r\n\r\n# For some reason, using:\r\n#\r\n#   fi | grep -v "^$" > $logfile\r\n#\r\n# results in purge_command assignment being wiped out\r\n# at the end of the block??\r\n\r\nif [ -z "$purge_command" ]\r\nthen\r\n    printf >&2 "$msg_usagen"\r\n    exit 1\r\nfi\r\n\r\n# echo "cmd: $varnishadm -T $mgmt_interface $purge_command"\r\n\r\nif $varnishadm -T $mgmt_interface $purge_command\r\nthen\r\n    printf >&2 "$msg_purge_ok"\r\nelse\r\n    printf >&2 "$msg_purge_failed"\r\n    exitstatus=1\r\nfi | grep -v "^$" > $logfile\r\n\r\n# Blather\r\nif [ -z "${quiet}" -o -n "$exitstatus" ]\r\nthen\r\n    cat >&2 $logfile\r\nfi\r\n\r\n# Cleanup\r\nrm -f $logfile  \r\nexit $exitstatus\r\n<\/code><\/pre>\n
You can control how objects are purged from the cache with 3 options:<\/p>\n