Simple CD pipeline demo at scale with Jenkins Swarm,Docker Swarm and Goland

Original blog post link

First let's create the jenkins master

docker service create --name jenkins-master \
	-p 50000:50000 \
	-p 80:8080 jenkins

• port 50000 used by all joining slaves created in the next step.
• created as a service so that docker swarm will manage the container and reschedule it if needed.
• /var/jenkins_home is used for all data so in a real deployment this need to be either a mount a folder from the host or use some docker storage driver.

Required plugins

• Pipeline the new Pipeline as Code plugin that allows to specify the steps in a Jenkinsfile
• GitHub plugin to checkout and push to github
• Self-Organizing Swarm Plug-in Modules deploy each Docker swarm node as a jenkins slave
• GitHub Branch Source Plugin scan a github account and automatically create jobs for repos that have a Jenkinsfile in the root directory. It also creates a github webhook so every repo push will trigger a build.

Now let's add some jenkins slaves

first create a secret that will be used by the Jenkins slaves to connect to the master

echo "-master http://10.0.0.101 -password admin -username admin"|docker secret create jenkins-v1 -

• 10.0.0.101 replace it with actual Jenkins master IP
• jenkins-v1 instead of just jenkins so that we can rotate the passwords - Docker docs

On the testing docker swarm

docker service create \
	--mode=global \
	--name jenkins-swarm-agent \
	-e LABELS=docker-test \
	--mount "type=bind,source=/var/run/docker.sock,target=/var/run/docker.sock" \
	--mount "type=bind,source=/tmp/,target=/tmp/" \
	--secret source=jenkins-v1,target=jenkins \
	vipconsult/jenkins-swarm-agent

On the staging docker swarm

docker service create \
	--mode=global \
	--name jenkins-swarm-agent \
	-e LABELS=docker-stage \
	--mount "type=bind,source=/var/run/docker.sock,target=/var/run/docker.sock" \
	--mount "type=bind,source=/tmp/,target=/tmp/" \
	--secret source=jenkins-v1,target=jenkins \
	vipconsult/jenkins-swarm-agent

On the production Docker swarm

docker service create \
	--mode=global \
	--name jenkins-swarm-agent \
	-e LABELS=docker-prod \
	--mount "type=bind,source=/var/run/docker.sock,target=/var/run/docker.sock" \
	--mount "type=bind,source=/tmp/,target=/tmp/" \
	--secret source=jenkins-v1,target=jenkins \
	vipconsult/jenkins-swarm-agent

• vipconsult/jenkins-swarm-agent is simple image that runs the jenkins swarm plugin which connects to a given master using parameters from the Docker secret
• mode=global when we add new nodes to the Docker cluster they will all connect to the jenkins master to serve as slaves
• **mount "type=bind,source=/var/run/docker.sock,target=/var/run/docker.sock" ** we mount the Docker socket so that we can use the Docker client inside a container to start new containers or services directly on the host. This is a better approach than Docker in Docker
• mount "type=bind,source=/tmp/,target=/tmp/" all containers can share files generated by the same Jenkins job
• LABELS=docker-test the jenkins slave label. This is used when you define where to run each pipeline step - the labels need to match the ones used in the Jenkinsfile - node("docker-test") , node("docker-stage") , node("docker-prod")
• secret source=jenkins-v1,target=jenkins using the secret created in the previous step, needs to match a user on the jenkins master

Finally lets start building!

Create a new GitHub Organization job using the Jenkins GUI - this will scan all repositories for a Jenkinsfile in the root directory and add it as a new job.

• Owner this is the github account or organization - vipconsult in this case
• Scan credentials need to add some github credentials - anonymous github api requests are limited and will fail to scan all repositories.
• The Jenkinsfile is set to use credentials with ID "DockerHub" so also need to create those.

Automate the builds with Github Webhooks

Using the Github Webhooks every repo change will trigger a new build.

In my case the jenkins master is behind a router so the webhook was created with my internal IP so I needed to open a firewall port so that the webhook can hit the Jenkins master. Here is a little nifty tool that simplifies the whole process and works even when you don't have access to the router. It uses UPNP protocol to automatically open and map a port to your Jenkins master machine

apt-get install miniupnpc
upnpc -a 10.0.0.101 80 8081 tcp

• 10.0.0.101 Jenkins master internal IP
• 80 Jenkins Master port
• 8081 external port useg by Github webhooks so after this Github can send webhooks using your external ip and the external port like http://216.58.213.78:8081/

Required :) - Fork it and give it a try

Just fork the project and change the docker hub username at the top of the Jenkinsfile.