Start Dockerized Apps on Boot, on Linux

Wolfram Kriesing - December 24, 2020 - tagged with: #tools #linux #command line #docker #tidbit

I want to get my nextcloud setup to run using docker-compose, and to start with I need a linux machine with docker running at start up. This is task #1, it looks like this blog post has the answers how to do it.

The System

$ lsb_release -a
No LSB modules are available.
Distributor ID:	LinuxMint
Description:	Linux Mint 19.3 Tricia
Release:	19.3
Codename:	tricia

What the heck is lsb_release, never heard of it, and I can't imagine what that term means and how I could even ever remember it, since the abbreviation does not sound intuitive.

The man page says the following:

The lsb_release command provides certain LSB (Linux Standard Base) and distribution-specific information.

Get Latest docker

$ apt upgrade docker.io
Reading package lists... Done
Building dependency tree       
Reading state information... Done
docker.io is already the newest version (19.03.6-0ubuntu1~18.04.2).
Calculating upgrade... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

I have seen newer docker flying around. Mmmh. Will postpone this for now.

See Docker Info from the OS level

Not sure this headline is right and makes sense to others. It does to me (until I know better).

$ service docker status # OR
$ systemctl status docker
● docker.service - Docker Application Container Engine
   Loaded: loaded (/lib/systemd/system/docker.service; enabled; vendor preset: enabled)
   Active: active (running) since Thu 2020-12-24 13:27:29 CET; 2h 14min ago
     Docs: https://docs.docker.com

The two commands above show the running docker service and some info and details.

Make Docker Start on Boot

According to the article above it is "just":

$ sudo systemctl enable --now docker

and you can check that via

$ systemctl is-enabled docker
enabled

which print enabled now. I am not sure if this was not also the case before. Let me reboot and see. ... Works! Cool.

Not Just Text Files?

I learned stuff (which I am afraid I will forget too soon again, that's why it's written here).

What I am really wondering about is, that the Linux philosophy is that all things are stored in pure text files, afaik. Why was this enabling of docker as a service not a simple "add this line in file X"? Maybe it was and I just didn't look in the right place under the hood. Of the entire thing was a bit more complicated than expected and that's why there are scripts that do that for me.

Actually I thought back in the years, when I was doing more of Linux stuff by hand, that I used to manually just enter which deamons to start and that was it. But my memories might fool me.

Just Text Files!

And the answer comes, right the moment after I asked the question and I needed to take the next step in my nextcloud setup.

My next step is to make the nextcloud, which is running in a docker-compose setup start every time the machine boots. So even after a power outage, or whatever on next boot our private cloud will be online again. No need to have me around all the time.

This stackoverflow post explains exactly how to do it. And it is very simple, I am just listing the three step below, refer to the so post to get all the details:

Create a file > /etc/systemd/system/nextcloud.service
Fill in the info, including how to start the service and finally
sudo systemctl enable nextcloud.

Applying my learnings from above, I think I can cehck if it worked.

$ systemctl is-enabled nextcloud.service
enabled

And reboot again. My nextcloud is up and running on machine (re)boot. Yeah.

Here is my service file:

$ cat /etc/systemd/system/nextcloud.service
[Unit]
Description=nextcloud
Requires=docker.service
After=docker.service

[Service]
Restart=always
ExecStart=/usr/bin/docker-compose -f /nextcloud/docker-compose.yml up -d
ExecStop=/usr/bin/docker-compose -f /nextcloud/docker-compose.yml down

[Install]
WantedBy=default.target

And here is the proof that it all works, really:

$ systemctl status nextcloud
● nextcloud.service - nextcloud
   Loaded: loaded (/etc/systemd/system/nextcloud.service; enabled; vendor preset: enabled)
   Active: active (running) since Thu 2020-12-24 16:54:10 CET; 7s ago

Update Docker Images with docker-compose

I had built my nextcloud setup about a year ago, a simple docker-compose build did not update any of the docker images, but I am sure there have been changes to any of the layers, like the DB, the app, the nginx proxy, etc. But why did it not update? I tried

$ docker-compose build db
db uses an image, skipping
$ docker-compose build --no-cache app
app uses an image, skipping

:(
None works.

Because the right one is:

$ docker-compose pull
Pulling db (mariadb:latest)...
latest: Pulling from library/mariadb
...

Oh, and don't just update the nextcloud image and bump multiple major versions, it can't handle it. Do one major version at a time! #justSaying If you try php occ upgrade it will let you know, but it was already to late for me by then.