Docker Plugin for Jenkins Pipeline - No user exists for uid 1005

Question

I'm trying to execute an SSH command from inside a Docker container in a Jenkins pipeline. I'm using the CloudBees Docker Pipeline Plugin to spin up the container and execute commands, and the SSH Agent Plugin to manage my SSH keys. Here's a basic version of my Jenkinsfile:

node {
  step([$class: 'WsCleanup'])
  docker.image('node').inside {
    stage('SSH') {
      sshagent (credentials: [ 'MY_KEY_UUID' ]) {
        sh "ssh -vvv -o StrictHostKeyChecking=no ubuntu@example.org uname -a"
      }
    }
  }
}

When the SSH command runs, I get this error:

+ ssh -vvv -o StrictHostKeyChecking=no ubuntu@example.org uname -a
No user exists for uid 1005

Answer 1

I combed through the logs and realized the Docker Pipeline Plugin is automatically telling the container to run with the same user that is logged in on the host by passing a UID as a command line argument:

$ docker run -t -d -u 1005:1005 [...]

I decided to check what users existed in the host and the container by running cat /etc/passwd in each environment. Sure enough, the list of users was different in each. 1005 was the jenkins user on the host machine, but that UID didn't exist in the container. To solve the issue, I mounted /etc/passwd from the host to the container when spinning it up:

node {
  step([$class: 'WsCleanup'])
  docker.image('node').inside('-v /etc/passwd:/etc/passwd') {
    stage('SSH') {
      sshagent (credentials: [ 'MY_KEY_UUID' ]) {
        sh "ssh -vvv -o StrictHostKeyChecking=no ubuntu@example.org uname -a"
      }
    }
  }
}