# How to ## Install Docker Community Edition ( DockerCE ) ``` sudo apt remove docker docker-engine docker.io containerd runc ; \ sudo apt install ca-certificates curl gnupg lsb-release ; \ curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null sudo apt update ; \ sudo apt-get install docker-ce docker-ce-cli containerd.io docker-compose-plugin sudo groupadd docker ; \ sudo usermod -aG docker $USER ; \ newgrp docker # Optional sudo chown "$USER":"$USER" /home/"$USER"/.docker -R ; \ sudo chmod g+rwx "$HOME/.docker" -R sudo systemctl enable docker.service ; \ sudo systemctl enable containerd.service sudo gpasswd -a $USER docker ``` ## Uninstall Docker ``` sudo apt-get remove docker docker-engine docker.io containerd runc sudo apt-get purge docker-ce docker-ce-cli containerd.io sudo rm -rf /var/lib/docker ``` ## Remove all non-used docker containers ``` docker system prune ``` ## Removing "\" images ``` docker rmi $(docker images -f "dangling=true" -q) ``` ## Show real-time logs from the initialized container ``` docker logs -f container-name ``` ## Size of container ``` docker ps --size ``` ## Get running containers ### Name ``` docker ps -f status=running --format "{{.Names}}" ``` ### JSON ``` docker ps -f status=running --format "{{json .}}" ``` ## Show online/offline containers ``` #!/bin/sh list_of_containers="container1 container2container3" containers=`docker ps -f status=running --format "{{.Names}}"` for container in $list_of_containers do if echo $containers |grep -q $container then echo "$container online " else echo "$container offline" #exit 1 fi done exit 0 ``` ## Create temporary containers ``` docker run -it --rm --name my-frontend-build -v "$PWD":/home/node/app -w /home/node/app node:13-alpine sh -c "npm run build" ``` ## Docker Service Providers DNS ``` nmcli dev show | grep IP4.DNS ``` ## Specify DNS servers for Docker ``` sudo nano /etc/docker/daemon.json { "dns": ["8.8.8.8", "8.8.4.4"] } sudo service docker restart ``` ## [Set Memory limit](https://www.baeldung.com/ops/docker-memory-limit) ### Memory For instance, let's limit the memory that the container can use to 512 megabytes. **To constrain memory, we need to use the *****m***** parameter:** ``` $ docker run -m 512m nginx ``` We can also set a soft limit called a reservation. It's activated when docker detects low memory on the host machine: ``` $ docker run -m 512m --memory-reservation=256m nginx ``` ### CPU By default, access to the computing power of the host machine is unlimited. **We can set the CPUs limit using the *****cpus***** parameter.** For example, let's constrain our container to use at most two CPUs: ``` $ docker run --cpus=2 nginx ``` We can also specify the priority of CPU allocation. The default is 1024, higher numbers are higher priority: ``` $ docker run --cpus=2 --cpu-shares=2000 nginx ``` Similar to the memory reservation, CPU shares play the main role when computing power is scarce and needs to be divided between competing processes.
### Setting Memory Limit With the docker-compose File We can achieve similar results using [*docker-compose*](https://www.baeldung.com/docker-compose) files. Mind that the format and possibilities will vary between versions of *docker-compose*.
#### Versions 3 and Newer With *docker swarm* Let's give the Nginx service limit of half of CPU and 512 megabytes of memory, and reservation of a quarter of CPU and 128 megabytes of memory. **We need to create “*****deploy*****” and then “*****resources*****” segments in our service configuration**: ``` services: service: image: nginx deploy: resources: limits: cpus: 0.50 memory: 512M reservations: cpus: 0.25 memory: 128M ``` **To take advantage of the *****deploy***** segment in a docker-compose file, we need to use the** [***docker stack***](https://docs.docker.com/engine/reference/commandline/stack_deploy/) **command.** To deploy a stack to the swarm, we run the *deploy* command: ``` $ docker stack deploy --compose-file docker-compose.yml bael_stack ``` #### Version 2 With *docker-compose* In older versions of *docker-compose,* we can put resource limits on the same level as the service's main properties. They also have slightly different naming: ``` service: image: nginx mem_limit: 512m mem_reservation: 128M cpus: 0.5 ports: - "80:80" ``` To create configured containers, we need to run the *docker-compose* command: ``` $ docker-compose up ``` ### Verifying Resources Usage After we set the limits, we can verify them using the *docker stats* command: ``` $ docker stats CONTAINER ID NAME CPU % MEM USAGE / LIMIT MEM % NET I/O BLOCK I/O PIDS 8ad2f2c17078 bael_stack_service.1.jz2ks49finy61kiq1r12da73k 0.00% 2.578MiB / 512MiB 0.50% 936B / 0B 0B / 0B 2 ``` ## MACOS ### Set Bridge IP (docker bip) ``` cd ~/Library/Containers/com.docker.docker/Data/database/com.docker.driver.amd64-linux echo '{"experimental": false,"debug":"true","bip":"172.18.19.1/24"}' > etc/docker/daemon.js ``` ## [How to change the Docker default subnet IP address](https://support.getjoan.com/hc/en-us/articles/360008889859-How-to-change-the-Docker-default-subnet-IP-address) If the Docker Engine default bridge network is conflicting with your internal network hosts access, you can change the default Docker subnet by following these steps: 1. First, you need to delete your old containers ``` sudo docker-compose stop ``` 2. Next, change the subnet IP inside "/etc/docker/daemon.json", by using this command: ``` sudo vim /etc/docker/daemon.json ``` 3. Type in the Netmask IP. With the following structure. Please keep in mind that the IP used here is an example: ``` { "default-address-pools": [ {"base":"10.10.0.0/16","size":24} ] } ``` 4. Restart the Docker Daemon by using this command: ``` sudo service docker restart ``` 5. Create a new VSS container and postgres with the following command: ``` sudo docker-compose up -d ``` And that’s it! ## Docker unable to access from VPN ### Linux * Check your subnet IP [here](https://vinnyfs89.gitbook.io/knowledge/technology/programming/dev-ops/docker/how-to#how-to-change-the-docker-default-subnet-ip-address) * Reset your networks to set correct subnet ip ``` docker network prune ``` #### Using Docker Compose + OpenVPN Set the content below inside your docker-compose file: ``` networks: default: driver: bridge ipam: config: - subnet: 10.10.1.0/24 ``` ### Windows * Set a "default-address-pool" ![](https://2560416838-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-MG5LE_2YTMyt4-SQf6m%2F-MTvIUvjN_CkjwBqZjHz%2F-MTvJUQV9wwvt2dIMhBB%2Fimage.png?alt=media\&token=8baac82b-0ff8-4be6-afee-7b42d3d63137) * Set a subnet network inside the `docker-compose` file ![](https://2560416838-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-MG5LE_2YTMyt4-SQf6m%2F-MTvIUvjN_CkjwBqZjHz%2F-MTvJwDYMuKzRmVUk5n5%2Fimage.png?alt=media\&token=85898816-5926-4f8f-bfc9-b94b7c605578)