---

Alias: ["docker"]
Tag: ["Computer", "Server", "Container"]
Date: 2021-09-19
DocType: "Personal"
Hierarchy: "NonRoot"
TimeStamp:
location: [51.514678599999996, -0.18378583926867909]
CollapseMetaTable: Yes

---

Parent:: [[Selfhosting]], [[Server Alias]], [[Server Tools]]

---

 ^Top

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```button
name Save
type command
action Save current file
id Save
```
^button-dockerSave

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# Configuring docker

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

&emsp;

```toc
style: number
```

&emsp;

---

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### Installation
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#### 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
~~~
```

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#### Configuring user permissions
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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
~~~
```

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#### 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–compose --version
~~~
```

&emsp;

---

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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:

```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.

&emsp;

#### 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
~~~
```

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#### Maintaining containers
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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.

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#### 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.

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#### Update environment variables
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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
~~~
```

&emsp;

---

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### Basic commands
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#### List containers

```ad-command
~~~bash
docker container ls
~~~
```

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#### Execute commands in container

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

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