Jenkins agent.jar when running agents in Kubernetes?

dev-samples · February 19, 2022, 9:00pm

I am running Jenkins in Kuberntes using the k8s plugin (for some reason I cannot post links in the forum)

I have created some podTemplates and a few containers based on maven and gradle docker images.

I keep reading about the jenkins agent.jar that should be started from the agents (again I have a link to an official jenkins blog but I am not allowed to post links

But currently I just use gradle:jdk11 for my build agents and I don’t see that containing any agent.jar.

Is the agent.jar only relevant/needed when running jenkins controller/agents in a non-k8s environment?

MarkEWaite · February 20, 2022, 2:18am

Good question. The kubernetes plugin usage section says:

The Kubernetes plugin allocates Jenkins agents in Kubernetes pods. Within these pods, there is always one special container jnlp that is running the Jenkins agent.

The container jnlp is used by the Kubernetes plugin to run the Jenkins agent.jar.

dev-samples · February 20, 2022, 10:50am

Ok but from that page - that I am not allowed to link to (quite frustrating):

jenkins/agent is the new name of the old jenkins/slave image, starting from 4.3-2
jenkins/inbound-agent is the new name of the jenkins/jnlp-slave image, starting from 4.3-2

so its two different images. I get that the jnlp container is needed but I don’t really see any reason why the jenkins/agent container is needed?

MarkEWaite · February 20, 2022, 11:50pm

As far as I can tell, history more than anything. We’ve considered combining the agent repository, inbound agent repository, and ssh agent repository into a single repository. The jenkins/agent image is used as the basis for jenkins/inbound-agent. I believe it is also used as the basis for other images.

dev-samples · February 21, 2022, 9:28am

Got it. Looking that the jenkins/agent dockerfile:

github.com

jenkinsci/docker-agent/blob/d636967c67aa27bb749cbf316d8a7b4cb46761fd/11/alpine/Dockerfile

# The MIT License
#
#  Copyright (c) 2015-2020, CloudBees, Inc. and other Jenkins contributors
#
#  Permission is hereby granted, free of charge, to any person obtaining a copy
#  of this software and associated documentation files (the "Software"), to deal
#  in the Software without restriction, including without limitation the rights
#  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
#  copies of the Software, and to permit persons to whom the Software is
#  furnished to do so, subject to the following conditions:
#
#  The above copyright notice and this permission notice shall be included in
#  all copies or substantial portions of the Software.
#
#  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
#  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
#  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
#  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
#  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
#  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

This file has been truncated. show original

it seems its basically setting up a JDK and the jenkins uid/gid.

And then the jenkins/inbound-agent

github.com

jenkinsci/docker-inbound-agent/blob/93c202459561b673356586355805d748f0d24881/11/alpine/Dockerfile

# The MIT License
#
#  Copyright (c) 2015-2020, CloudBees, Inc.
#
#  Permission is hereby granted, free of charge, to any person obtaining a copy
#  of this software and associated documentation files (the "Software"), to deal
#  in the Software without restriction, including without limitation the rights
#  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
#  copies of the Software, and to permit persons to whom the Software is
#  furnished to do so, subject to the following conditions:
#
#  The above copyright notice and this permission notice shall be included in
#  all copies or substantial portions of the Software.
#
#  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
#  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
#  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
#  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
#  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
#  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

This file has been truncated. show original

use jenkins/agent as base image - getting the same uid/gid as the jenkins/agent.

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Jenkins agent.jar when running agents in Kubernetes?

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