As part of a project at work, a web application running in Tomcat must periodically pull files form Git. No, it’s not Jenkins. Usually it work a treat but getting it all working on Windows proved to be tricky, and I post the solution here in hopes of saving someone’s mental health.<\/p>\n
Tomcat was running under a service account, user svcacct. In order to present the right identity and host keys, I wrote a simple wrapper to execute ssh with specific keys.<\/p>\n
ssh -o PreferredAuthentications=publickey -o IdentityFile=C:\\Users\\svcacct\\.ssh\\service_acct_pk -o UserKnownHostsFile=C:\\Users\\scvacct\\.ssh\\known_hosts %*\n<\/pre>\nFor Git to use this wrapper, the GIT_SSH<\/strong> environment variable must be set to point to it. Also, the host key was added manually to known_hosts. Tomcat had to be restarted for the new environment variable to take effect.<\/p>\n
But it didn’t work. Git was coughing this into the logs:<\/p>\n
fatal: protocol error: bad line length character:\nc:\n<\/pre>\nAfter much wailing and gnashing of teeth, and setting GIT_TRACE<\/strong> to 1, the problem was determined to be caused by Windows echoing the full path the the ssh executable. Git was trying to parse the output of ls-remote and gagging on the “C:\\Program Files\\” prefix.<\/p>\n
Turning off the echo in the batch file did the trick:<\/p>\n
@echo off\nssh -o PreferredAuthentications=publickey -o IdentityFile=C:\\Users\\wpsadmin\\.ssh\\id_rsa-transformation_svc -o UserKnownHostsFile=C:\\Users\\wpsadmin\\.ssh\\known_hosts %*\n<\/pre>\n