---
Alias: ["docker"]
Tag: ["Computer", "Server", "Container"]
Date: 2021-09-19
DocType: "Personal"
Hierarchy: "NonRoot"
TimeStamp:
location: [51.514678599999996, -0.18378583926867909]
CollapseMetaTable: true
---
Parent:: [[Selfhosting]], [[Server Alias]], [[Server Tools]]
---
^Top
 
```button
name Save
type command
action Save current file
id Save
```
^button-dockerSave
 
# Configuring docker
 
```ad-abstract
title: Summary
collapse: open
This note runs through [docker ](https://docker.com ), a free tool to create containers to run independent applications.
```
 
```toc
style: number
```
 
---
 
### Installation
[[#^Top|TOP]]
 
#### Program installation
1. **Prerequisites**
```ad-command
~~~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**
```ad-command
~~~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**
```ad-command
~~~bash
sudo apt update
sudo apt install docker-ce docker-ce-cli containerd.io
~~~
```
4. **Test install**
```ad-command
~~~bash
sudo systemctl status docker
~~~
```
 
#### Configuring user permissions
[[#^Top|TOP]]
Users with sudo rights need to be added to the 'docker' group for being able to instruct docker:
```ad-command
~~~bash
sudo gpasswd -a (username) docker
sudo newgrp docker
~~~
```
 
```ad-warning
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.
```ad-command
~~~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:
```ad-command
~~~bash
sudo chmod +x /usr/local/bin/docker-compose
~~~
```
Installation can be checked as follows:
```ad-command
~~~bash
sudo docker–
~~~
```
 
---
 
### docker elements
[[#^Top|TOP]]
 
#### 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:
```ad-command
~~~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:
```ad-command
~~~bash
sudo docker-compose up -d
~~~
```
 
#### Maintaining containers
[[#^Top|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:
```ad-code
~~~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:
```ad-path
~/.bashrc
```
The command needs to be run periodically.
Otherwise, use the below sequence in the relevant folder:
```ad-command
~~~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:
```ad-command
~~~bash
docker-compose up -d
~~~
```
From within the container folder.
 
#### Update environment variables
[[#^Top|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**
```ad-command
~~~bash
sudo systemctl stop docker
~~~
```
2. **Edit the json config file**
```ad-path
/var/lib/docker/containers/(container id)/config.v2.json
```
Within the 'Env' declaration, add the requested data field:
```ad-code
~~~bash
"DATA_FIELD=data_value"
~~~
```
3. **Restart docker**
```ad-command
~~~bash
sudo systemctl start docker
~~~
```
 
---
 
### Basic commands
[[#^Top|TOP]]
 
#### List containers
```ad-command
~~~bash
docker container ls
~~~
```
 
#### Execute commands in container
```ad-command
~~~bash
docker exec -it -u (username) (command)
~~~
```
[[#^Top|TOP]]
 
 
