With this step, you’ll install Docker to let you run containers, and Portainer for easy web-based management of those containers. You should have already completed the Provision Storage and Install Ansible and System Updates steps. If not, make sure to go back and do that first.
By the end of this step you will have:
You can’t skip Docker installation. It forms the foundation nearly all of the applications use to run. Technically, you could skip Portainer and use the docker-compose command-line tool instead.
A Docker container is a bit like a virtual machine, but it’s a virtual machine without its own kernel. It shares the kernel with the underlying operating system. In the case of the Raspberry Pi OS, it’s Linux running on ARM-based hardware.
The best part about Docker containers is that there are thousands of pre-built ones available at Docker Hub. Just pull one down, do a little configuration, and go.
Installation of Docker is done by running the Ansible playbook called install-docker.yml Just download the file to the Pi or copy the contents from the web into a text file. Then run the playbook with the command, ansible-playbook install-docker.yml. The playbook will install Docker and also Docker Compose.
Installation looks like this:
pi@mypi:~/cloudpi $ ansible-playbook install-docker.yml
PLAY [Install Docker Community Edition] *****************************************
TASK [Gathering Facts] **********************************************************
ok: [localhost]
TASK [Installing apt key for official repository] *******************************
changed: [localhost]
TASK [Adding official repository] ***********************************************
changed: [localhost]
TASK [Installing Docker] ********************************************************
changed: [localhost]
TASK [Installing Docker Compose] ************************************************
changed: [localhost]
TASK [Adding pi user to docker group] *******************************************
changed: [localhost]
TASK [Starting Docker] **********************************************************
ok: [localhost]
PLAY RECAP **********************************************************************
localhost : ok=7 changed=5 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
A note about the docker group
Any users running docker commands from command prompt will need to use sudo unless they are in the docker group. The Ansible playbook takes care of adding the pi user to the docker group, though you will need to log out and back in for the changes to take effect. Any other users will need to be added to the group manually or preface all docker commands with sudo.
Portainer provides a nice web front-end to the Docker system. You can plug any valid docker-compose.yml file into it’s Stacks feature and have an application running within a matter of minutes. Portainer also offers advanced features like LDAP integration for user account and Git integration for docker-compose files.
Portainer itself is a containerized application. Obviously, you can’t use Portainer to deploy Portainer. So for this one instance, docker-compose is used. Here’s the procedure:
docker-compose up -d.It should look like this when deployed:
pi@raspberrypi:~/cloudpi/portainer $ docker-compose up -d
Creating network "portainer_default" with the default driver
Creating volume "portainer_data" with default driver
Creating portainer ... done
If all goes well, wait a bit and open a web browser for your Raspberry Pi on port 9000. (e.g. http://mypi.home:9000 or http://192.168.0.42:9000) You should see the Portainer logo and fields to set up administrative credentials. Set up your admin user and password and you’ll be logged in.
If you see a bunch of errors generated by Python, log out and log back into the Pi and run the groups command to make sure you’re part of the docker group. If, not, you can use sudo docker-compose up -d.
Explore Portainer on your own or check out the docs on their web site.
If you ran the playbook for the Nginx test web server, you should be able to locate it on Portainer’s Containers page. The test instance won’t be needed anymore, so go ahead and exercise your Portainer skills by stopping and removing the container.
With Docker and Portainer running, you’re ready to start deploying applications. The first task is to deploy Nginx again, but this time it will be a configuration that goes beyond just displaying a Welcome page.
You think you can drive accurately in confined spaces until someone puts something like a shipping container in the way… —Chris Harris