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---
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Alias: ["docker"]
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Tag: ["Computer", "Server", "Container"]
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Date: 2021-09-19
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DocType: "Personal"
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Hierarchy: "NonRoot"
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TimeStamp:
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location: [51.514678599999996, -0.18378583926867909]
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CollapseMetaTable: Yes
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---
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Parent:: [[Selfhosting]], [[Server Alias]], [[Server Tools]]
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---
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```button
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name Save
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type command
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action Save current file
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id Save
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```
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^button-dockerSave
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# Configuring docker
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```ad-abstract
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title: Summary
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collapse: open
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This note runs through [docker](https://docker.com), a free tool to create containers to run independent applications.
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```
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```toc
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style: number
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```
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---
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### Installation
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#### Program installation
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1. **Prerequisites**
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`sudo apt update`
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`sudo apt install curl apt-transport-https ca-certificates software-properties-common`
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If the packages are already installed and to the latest version, the OS will skip.
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2. **Pull the software signature key & image**
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`curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key ad`
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`sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu focal stable" `
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3. **Install docker**
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`sudo apt update`
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`sudo apt install docker-ce docker-ce-cli containerd.io`
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4. **Test install**
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`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:
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`sudo gpasswd -a (username) docker`
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`sudo newgrp docker`
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#### Installing docker-compose
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Docker-compose is a script generatir enabling leaner execution and update of each container. The following commands install the wizard.
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```
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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
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```
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File permissions need to be changed for docker-compose to be executable:
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`sudo chmod +x /usr/local/bin/docker-compose`
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Installation can be checked as follows:
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`sudo docker–compose --version`
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---
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### docker elements
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#### docker network
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In order for docker to work, each container needs an internal IP address. This is defined by an internal docker network as follows:
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```
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sudo docker network create --driver=bridge --subnet=xxx.yyy.zzz.0/24 --gateway=xxx.yyy.zzz.1 dockernet
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```
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x, y, z to be defined by the user.
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#### Creating containers
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Containers are created through docker-compose. Tutorial exist for each application to run in docker. In short:
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1. A directory for the app must be created
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2. A yaml file for docker-compose must be created in the folder
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3. The docker-compose command for initialisation must be run from the folder:
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`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.
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Easiest is to create aliases in the .bashrc of home directory by adding:
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>alias dc-up='sudo docker-compose --compatibility up -d'
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alias dc-update='sudo docker-compose pull && sudo docker-compose --compatibility up -d'
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alias dc-update-all='for d in ./*/ ; do (cd "$d" && dc-update); done'
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To the following file:
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`~/.bashrc`
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The command needs to be run periodically.
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#### Updating containers
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For updating containers, just amend the docker-compose file and run the following command to preserve the mounted data:
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`docker-compose up -d`
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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:
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1. **stop docker**
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`sudo systemctl stop docker`
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2. **Edit the json config file**
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Location: `/var/lib/docker/containers/(container id)/config.v2.json`
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Within the 'Env' declaration, add the requested data field:
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> "DATA_FIELD=data_value"
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3. **Restart docker**
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`sudo systemctl start docker`
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---
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### Basic commands
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#### List containers
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`docker container ls`
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#### Execute commands in container
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`docker exec -it -u (username) (command)`
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  |
