Archive for the ‘hudson’ Category

Improved svn post-commit hook for hudson

Wednesday, March 24th, 2010

Hudson’s wiki entry about the Subversion plugin explains how to setup a post-commit svn hook so commits trigger the hudson builds without the need of hudson to constantly poll the repository.

The proposed post-commit hook implementation is good, but what happens when the svn server does not respond is that the commit takes place but the hook blocks for ever. This can be confusing and annoying.

The svn server may not be able to respond because it may be down or can’t be reached. In any case, and as the Fallacies of Distributed Computing explain, the network is unreliable, so a better approach is to add a timeout and retries setting on the command which attempts to notify svn:

UUID=`svnlook uuid $REPOS`
/usr/bin/wget \
  --timeout=2 \
  --tries=2 \
  --header "Content-Type:text/plain;charset=UTF-8" \
  --post-data "`svnlook changed --revision $REV $REPOS`" \
  --output-document "-" \

Wget will now fail if after 2 seconds the svn server hasn’t responded, and will try that twice. After that the user will get an error message but the commit will have been done.