How to automatically start docker containers

Posted on May 13, 2020

Recap from our last post, if you open up you database client, DBeaver for instance. You will get the following error.

Database Connection Error

Simply because we have not started docker-compose service hence the postgres container is not up and running.

You may want to start some of your containers at system boot.These are some of the applications that you use frequently and therefore you wish that everytime you are interacting with them, they are up and running!

Containers you may wish to start automatically

PlantUML Server

Docker server container to render code as diagrams or is it vice versa! (Diagrams as Code)

Check the references at the bottom of this post if you want to delve deeper into this subject.

I will use systemd, process manager to automate this.

Step 1: Enable the Docker Service

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$ sudo systemctl enable docker

Then confirm it is up and running sudo systemctl status docker

Step 2: Create the Docker Compose Service File For Our Container

Change directory to the one shown below

$ cd /etc/systemd/system/

While inside that folder create a file. Mine I called it docker-compose-familyDB.service Here is the command

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$ sudo touch docker-compose-familyDB.service

Use vim or Gedit to open that file.

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$ sudo gedit docker-compose-familyDB.service

Then paste the following content and save the file.

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# /etc/systemd/system/docker-compose-familyDB.service

[Unit]
Description=Docker Compose Application familyDB  Service
Requires=docker.service
After=docker.service

[Service]
WorkingDirectory=/home/josphat/Desktop/docker-postgres
ExecStart=/usr/local/bin/docker-compose up
ExecStop=/usr/local/bin/docker-compose down
TimeoutStartSec=0
Restart=on-failure
StartLimitIntervalSec=60
StartLimitBurst=3

[Install]
WantedBy=multi-user.target

Check that the WorkingDirectory path is pointing to the location of your docker-compose.yml file. On our docker-compose.yml file, in the previous post, add the line restart: always meaning our container restarts only when Docker daemon restarts.Here is how our file now looks like.

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version: "3.3"
services:
  database:
    image: postgres:latest # use latest official image
    env_file:
      - database.env # configure postgres
    volumes:
      - database-data:/var/lib/postgresql/data/ # persist data even if cotainer shuts down
    ports:
      - 5432:5432
    restart: always
volumes:
  database-data: # names volumes can be managed easier using docker-compose

Step 3: Activate the Service File

First reload the unit file we created.Run this command everytime you do a modification to your unit file.

$ sudo systemctl daemon-reload

Then activate the service run by typing the following commands

$ sudo systemctl enable docker-compose-familyDB.service

Whenever you want to stop the service, here are the commands

$ sudo systemctl stop docker-compose-familyDB.service
$ sudo systemctl disable docker-compose-familyDB.service

Step 4: Verify your Service is Running

Reboot

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$ reboot

Then after you system is up, Open Dbeaver Client and Verify if the Database Connection Error is displayed, as shown by the screenshot on the top of this post.

If you were able to connect to your database automatically, then your service is up and running, in short, you have automatically started postgres docker container at system reboot. Otherwise you can type the following command to check status of your service and troubleshoot as necessary.

$ sudo systemctl status docker-compose-familyDB.service

TODO:

I will definately remove these references from this post and create another post for Diagram As Code.

References

Although this article is about autostarting docker container, I thought I should list some important reference here for someone who may wish to pursue diagram as code topic later.

If you wish to learn more on this Diagram As Code.Here are a few resources,I found online.