How to override Jenkins' random image tag for a Dockerfile agent in a pipeline

Question

I have a step in my Jenkinsfile that runs using a Dockerfile agent. When jenkins creates the docker image it gives it a random long tag and I'd like to replace that with my own tag. I tried passing the tag using additionalBuildArgs but that gives the docker image an additional tag.

agent {
        dockerfile {
            additionalBuildArgs '-t my-image:latest'
        }
}

Is there a way to stop Jenkins from passing a tag?

Answer 1

The plugin that controls this action is pipeline-model-definition-plugin.

you can see at the plugin's code that the image name is a hash of the project name and the dockerfile path:

def hash = Utils.stringToSHA1("${runWrapper.fullProjectName}\n${script.readFile("${dockerfilePath}")}")
def imgName = "${hash}"

then it takes the additional args and adds them to the image name:

def additionalBuildArgs = describable.getAdditionalBuildArgs() ? " ${describable.additionalBuildArgs}" : ""
script.sh "docker build -t ${imgName}${additionalBuildArgs} -f \"${dockerfilePath}\" \"${describable.getActualDir()}\""

so by using the dockerfile step, it seems that the name would always be a hash.