Obsidian/05.02 Networks/Configuring Docker.md

Alias	Tag	Date	DocType	Hierarchy	TimeStamp	location	CollapseMetaTable
docker	💻 🖥️ Container	2021-09-19	Personal	NonRoot		51.514678599999996 -0.18378583926867909	true

Parent:: Selfhosting, Server Alias, Server Tools

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Configuring docker

 

title: Summary
collapse: open
This note runs through [docker](https://docker.com), a free tool to create containers to run independent applications.

 

style: number

 

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Installation

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Program installation

1. Prerequisites

~~~bash
sudo apt update
sudo apt install curl apt-transport-https ca-certificates software-properties-common
~~~

If the packages are already installed and to the latest version, the OS will skip.

2. Pull the software signature key & image

~~~bash
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key ad
sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu focal stable"
~~~

3. Install docker

~~~bash
sudo apt update
sudo apt install docker-ce docker-ce-cli containerd.io
~~~

4. Test install

~~~bash
sudo systemctl status docker
~~~

 

Configuring user permissions

#^Top Users with sudo rights need to be added to the 'docker' group for being able to instruct docker:

~~~bash
sudo gpasswd -a (username) docker
sudo newgrp docker
~~~

 

title: [[Configuring Docker|docker]] for non root users
[[Configuring Docker|docker]] predominantly works for the root user. In order to let non-root users instruct Docker, users need to be added to the Docker group:

`sudo usermod -aG docker (username)`

Potentially, the Docker group needs to be defined:

`sudo groupadd docker`

 

Installing docker-compose

Docker-compose is a script generatir enabling leaner execution and update of each container. The following commands install the wizard.

~~~bash
sudo curl -L "https://github.com/docker/compose/releases/download/1.29.2/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
~~~

File permissions need to be changed for docker-compose to be executable:

~~~bash
sudo chmod +x /usr/local/bin/docker-compose
~~~

Installation can be checked as follows:

~~~bash
sudo docker–compose --version
~~~

 

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docker elements

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docker network

In order for docker to work, each container needs an internal IP address. This is defined by an internal docker network as follows:

~~~bash
sudo docker network create --driver=bridge --subnet=xxx.yyy.zzz.0/24 --gateway=xxx.yyy.zzz.1 dockernet
~~~

x, y, z to be defined by the user.

 

Creating containers

Containers are created through docker-compose. Tutorial exist for each application to run in docker. In short:

1. A directory for the app must be created
2. A yaml file for docker-compose must be created in the folder
3. The docker-compose command for initialisation must be run from the folder:

~~~bash
sudo docker-compose up -d
~~~

 

Maintaining containers

#^Top Maintaining containers with docker is arduous and easier to do with docker-compose. Easiest is to create aliases in the .bashrc of home directory by adding:

~~~bash
alias dc-up='sudo docker-compose --compatibility up -d'
alias dc-update='sudo docker-compose pull && sudo docker-compose --compatibility up -d'
alias dc-update-all='for d in ./*/ ; do (cd "$d" && dc-update); done'
~~~

To the following file:

~/.bashrc

The command needs to be run periodically.

Otherwise, use the below sequence in the relevant folder:

~~~bash
docker-compose down
docker-compose pull
docker-compose up -d
~~~

 

Updating containers

For updating containers, just amend the docker-compose file and run the following command to preserve the mounted data:

~~~bash
docker-compose up -d
~~~

From within the container folder.

 

Update environment variables

#^Top Docker does not have a standard way to update environment variables, and requires to take down and then re-initialise a container with the appropriate variable fed in the run script. To avoid that, the followong steps can be taken:

1. stop docker

~~~bash
sudo systemctl stop docker
~~~

2. Edit the json config file

/var/lib/docker/containers/(container id)/config.v2.json

Within the 'Env' declaration, add the requested data field:

~~~bash
"DATA_FIELD=data_value"
~~~

3. Restart docker

~~~bash
sudo systemctl start docker
~~~

 

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Basic commands

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List containers

~~~bash
docker container ls
~~~

 

Execute commands in container

~~~bash
docker exec -it -u (username) (command)
~~~

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