Not able to scale jenkins-slave container.

[TheTechOddBug]

Using docker-compose scale jenkins-slave=2 command, the response obtained is:

WARNING: The LDAP_PWD variable is not set. Defaulting to a blank string.
WARNING: The LDAP_FULL_DOMAIN variable is not set. Defaulting to a blank string.
WARNING: The CUSTOM_NETWORK_NAME variable is not set. Defaulting to a blank string.
WARNING: The PROTO variable is not set. Defaulting to a blank string.
WARNING: The TARGET_HOST variable is not set. Defaulting to a blank string.
WARNING: The GERRIT_MYSQL_DATABASE variable is not set. Defaulting to a blank string.
WARNING: The GERRIT_MYSQL_USER variable is not set. Defaulting to a blank string.
WARNING: The GERRIT_MYSQL_PASSWORD variable is not set. Defaulting to a blank string.
WARNING: The PASSWORD_GERRIT variable is not set. Defaulting to a blank string.
WARNING: The PASSWORD_JENKINS variable is not set. Defaulting to a blank string.
WARNING: The INITIAL_ADMIN_USER variable is not set. Defaulting to a blank string.
WARNING: The INITIAL_ADMIN_PASSWORD_PLAIN variable is not set. Defaulting to a blank string.
WARNING: The GERRIT_USER_NAME variable is not set. Defaulting to a blank string.
WARNING: The GERRIT_USER_EMAIL variable is not set. Defaulting to a blank string.
WARNING: The PASSWORD_SQL variable is not set. Defaulting to a blank string.
WARNING: The SONAR_MYSQL_PASSWORD variable is not set. Defaulting to a blank string.
WARNING: The SONAR_MYSQL_USER variable is not set. Defaulting to a blank string.
WARNING: The SONAR_MYSQL_DATABASE variable is not set. Defaulting to a blank string.
WARNING: The SLAVE_EXECUTORS variable is not set. Defaulting to a blank string.
WARNING: The LDAP_DOMAIN variable is not set. Defaulting to a blank string.
WARNING: The JENKINS_PWD variable is not set. Defaulting to a blank string.
WARNING: The INITIAL_ADMIN_PASSWORD variable is not set. Defaulting to a blank string.
WARNING: The GERRIT_PWD variable is not set. Defaulting to a blank string.
WARNING: The SONAR_DB_LOGIN variable is not set. Defaulting to a blank string.
WARNING: The DOCKER_CLIENT_CERT_PATH variable is not set. Defaulting to a blank string.
WARNING: The SONAR_ACCOUNT_LOGIN variable is not set. Defaulting to a blank string.
WARNING: The SONAR_DB_PASSWORD variable is not set. Defaulting to a blank string.
WARNING: The "jenkins-slave" service is using the custom container name "jenkins-slave". Docker requires each container to have a unique name. Remove the custom name to scale the service.
Creating and starting jenkins-slave ... error

ERROR: for jenkins-slave Conflict. The name "/jenkins-slave" is already in use by container 5fcb0ac37729803ea490b70242b1c152a1e6463b9de1111ff30d14896324de17. You have to remove (or rename) that container to be able to reuse that name.

The container for jenkins-slave could not have name in order to let it scale.

[nickdgriffin]

Most of those warnings can be removed by sourcing the environment variable files.

You are correct in saying we can't scale the slave at the moment as it has a container name specified - this is currently needed for the CLI to be able to copy the certificates in when using Docker Machine, but could probably be improved to be more flexible.

That being said, the build-in slave isn't really intended to be used in anger and is mostly there to facilitate the things the Core currently does.