How to package several services in one docker image? - docker

Question

I have a docker compose application, which works fine in local. I would like to create an image from it and upload it to the docker hub in order to pull it from my azure virtual machine without passing all files. Is this possible? How can I do it?
I tried to upload the image I see from docker desktop and then pull it from the VM but the container does not start up.
Here I attach my .yml file. There is only one service at the moment but in the future there will be multiple microservices, this is why I want to use compose.
version: "3.8"
services:
dbmanagement:
build: ./dbmanagement
container_name: dbmanagement
command: python manage.py runserver 0.0.0.0:8000
volumes:
- ./dbmanagement:/dbmandj
ports:
- "8000:8000"
environment:
- POSTGRES_HOST=*******
- POSTGRES_NAME=*******
- POSTGRES_USER=*******
- POSTGRES_PASSWORD=*******
Thank you for your help

Answer 1

The answer is: yes, you can but you should not
According to the Docker official docs:
It is generally recommended that you separate areas of concern by using one service per container
Also check this:
https://stackoverflow.com/a/68593731/3957754
docker-compose is enough
docker-compose exist just for that: Run several services with one click (minimal configurations) and commonly in the same server.
foreground process
In order to works a docker container needs a foreground process. To understand what is this, check the following links. As a extremely summary we can said you that a foreground process is something that when you launch it using the shell, the shell is taken and you can and you cannot enter more commands. You need to press ctrl + c to kill the process and get back your shell.
https://unix.stackexchange.com/questions/175741/what-is-background-and-foreground-processes-in-jobs
https://linuxconfig.org/understanding-foreground-and-background-linux-processes
The "fat" container
Anyway, if you want to join several services or process in one container (previously an image) you can do it with supervisor.
Supervisor could works a our foreground process. Basically you need to register one or many linux processes and then, supervisor will start them.
how to install supervisor
sudo apt-get install supervisor
source: https://gist.github.com/hezhao/bb0bee800531b89d7be1#file-supervisor_cmd-sh
add single config: /etc/supervisor/conf.d/myapp.conf
[program:myapp]
autostart = true
autorestart = true
command = python /home/pi/myapp.py
environment=SECRET_ID="secret_id",SECRET_KEY="secret_key_avoiding_%_chars"
stdout_logfile = /home/pi/stdout.log
stderr_logfile = /home/pi/stderr.log
startretries = 3
user = pi
source: https://gist.github.com/hezhao/bb0bee800531b89d7be1
start it
sudo supervisorctl start myapp
sudo supervisorctl tail myapp
sudo supervisorctl status
In the previous sample, we are used supervisor to start a python process.
multiple process with supervisor
You just need to add more [program] sections to the config file:
[program:php7.2]
command=/usr/sbin/php-fpm7.2-zts
process_name=%(program_name)s
autostart=true
autorestart=true
[program:dropbox]
process_name=%(program_name)s
command=/app/.dropbox-dist/dropboxd
autostart=true
autorestart=true
Here some examples, just like your requirement: several process in one container:
canvas lms : Basically starts 3 process: postgress, redis and a ruby app
https://github.com/harvard-dce/canvas-docker/blob/master/assets/supervisord.conf
ngnix + php + ssh
https://gist.github.com/pollend/b1f275eb7f00744800742ae7ce403048#file-supervisord-conf
nginx + php
https://gist.github.com/lovdianchel/e306b84437bfc12d7d33246d8b4cbfa6#file-supervisor-conf
mysql + redis + mongo + nginx + php
https://gist.github.com/nguyenthanhtung88/c599bfdad0b9088725ceb653304a91e3
Also you could configure a web dashboard:
https://medium.com/coinmonks/when-you-throw-a-web-crawler-to-a-devops-supervisord-562765606f7b
Another samples with docker + supervisor:
https://gist.github.com/chadrien/7db44f6093682bf8320c
https://gist.github.com/damianospark/6a429099a66bfb2139238b1ce3a05d79