Jenkins: Can't connect to Docker daemon

Question

I am running Jenkins and Docker on a CentOS machine. I have a Jenkins job that pulls a Github repo and builds a Docker image. When I try running the job I get the error:

+ docker build -t myProject . Cannot connect to the Docker daemon. Is the docker daemon running on this host? Build step 'Execute shell' marked build as failure Finished: FAILURE 

This problem occurs even though I have added jenkins to my docker usergroup via sudo usermod -aG docker jenkins and restarted my machine. How do I fix this?

By the way, if try changing the command to sudo docker build -t myProject . I just get the error sudo: sorry, you must have a tty to run sudo

Answer 1

After the installation of Jenkins and Docker. Add jenkins user to dockergroup (like you did)

sudo gpasswd -a jenkins docker 

Edit the following file

vi /usr/lib/systemd/system/docker.service 

And edit this rule to expose the API :

ExecStart=/usr/bin/docker daemon -H unix:// -H tcp://localhost:2375 

Do not create a new line with ExecStart, simply add the commands at the end of the existing line.

Now it's time to reload and restart your Docker daemon

systemctl daemon-reload systemctl restart docker 

Then restart jenkins, you should be able to perform docker commands as jenkins user in your jenkins jobs

sudo service jenkins restart 

Answer 2

I had the same issue with Jenkins.

I did fix it by adding /var/run/docker.sock:/var/run/docker.sock on docker-compose.yml :

  jenkins:   container_name: jenkins   build: "jenkins/"   ports:     - "8080:8080"   environment:     - JAVA_OPTS:-Djava.awt.headless=true   volumes:     - /var/jenkins_home     - /var/run/docker.sock:/var/run/docker.sock