> For the complete documentation index, see [llms.txt](https://oviniciusfeitosa.gitbook.io/knowledge/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://oviniciusfeitosa.gitbook.io/knowledge/technology/programming/dev-ops/docker/how-to.md). # 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" ![](/files/-MTvJUQV9wwvt2dIMhBB) * Set a subnet network inside the `docker-compose` file ![](/files/-MTvJwDYMuKzRmVUk5n5) --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://oviniciusfeitosa.gitbook.io/knowledge/technology/programming/dev-ops/docker/how-to.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.