![]() This can be accomplished by using nohup and putting the process into the background using &. In other cases, you may want to start up a process and leave it running. For example, if you wanted to run yarn install every time you connected to the container to keep dependencies up to date, you could add the following: "postStartCommand" : "yarn install" Video: Run npm install when a container is created The easiest way to do this is using the postStartCommand property in devcontainer.json. When you are working in a development container, you may want to execute a command or start something each time the container starts. In the real world, there are times when you need to get something working until you can come up with a proper solution.Start a process when the container starts Ideally, your container shouldn’t need any outside tasks. I’ve written service files before for containers when I needed pre and post-tasks before and after the container was created and destroyed. Secondly, all of your Docker services will be within the docker daemon and not scattered throughout the system. Firstly, it doesn’t require you to create a unique service file for each container. The restart policy also reduces complexity in a few different ways. I recommend avoiding this unless you have a good reason to do so.ĭocker’s built-in restart policy has better control of handling when the container should restart. Many posts online outline creating a systemd service file to start Docker containers. The output will include a log to help solve any issues that may be arising. ![]() You can get a more detailed status of the docker service by running the following systemctl command. You can verify that the service has been enabled by checking the enabled status using systemctl. It will likely be a single command you have to run or create a symbolic link. # systemctl enable dockerįor other init systems, you’ll have to research how to enable services. Enable the service within systemd by using the systemctl command. If the Docker daemon doesn’t start automatically, none of your containers will start.ĭepending on your system, the process to enable the Docker daemon will vary. Once you have your containers running with a restart policy, you need to enable the Docker service. The update command can modify multiple containers at the same time. To update an existing container’s restart policy, use docker update with the policy you want. ![]() The majority of my containers use “always” or “unless-stopped.” # docker run -d -restart always The following command will create a container that will always restart. Similar to always, except that when the container is stopped (manually or otherwise), it is not restarted even after Docker daemon restarts. If it is manually stopped, it is restarted only when Docker daemon restarts or the container itself is manually restarted. Restart the container if it exits due to an error, which manifests as a non-zero exit code.Īlways restart the container if it stops. Optionĭo not automatically restart the container. For more details, read the official Docker Restart Policy page. The restart policy flag is -restart and has four different options. You can set the Docker restart policy when creating a container or update an existing container with a new restart policy. The flag also affects the behavior of what happens if you manually stop a container. ![]() The container can automatically start again on erroneous exits or with all exit codes. The behavior is determined by which policy you choose. The restart policy dictates whether the container should restart when it exits. ![]() That should be the end of this post, but I’ll provide more details, examples, and reasons why you want to avoid other methods.ĭocker’s restart policy is a flag you set when you first create a container from an image. Docker’s restart policy is the best way to have containers automatically start when you boot your server or computer. ![]()
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