jenkins image - Strange behaviour when setting up plugins

[henrist]

It seems plugins are not always installed (updated) when putting them in plugins.txt.

Reproduce:

• Let plugins.txt contain only mailer:1.15
• Use this script:

set -e
n=jenkins-test

docker build -t cantara/jenkins .

while true; do
    docker stop $n || true
    docker rm $n || true
    docker rm jenkins-data || true

    sleep 10

    docker create -v /var/jenkins_home --name jenkins-data cantara/jenkins
    docker run -d -p 8080:8080 --volumes-from jenkins-data --name $n cantara/jenkins

    sleep 40
done

• Open http://localhost:8080/pluginManager/installed after each time new container is run.
• Expected result: Plugin mailer is in version 1.15.
• Actual result: Plugin mailer is sometimes version 1.11 (original version) and sometimes 1.15 from plugins.txt override.