ivanitch/docker-compose.md

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Docker Guides

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docker-compose.md

Docker Compose

Docker compose is a tool that is used for defining and running multi-container Docker apps in an easy way. It provides docker-compose.yml configuration file that can be used to bring up an app and the suite of services it depends on with just one command.

docker-compose up - start all services from docker-compose.yml
docker-compose up db - start only service db
docker-compose up --build - rebuild all images and run containers
docker-compose -f docker-compose.prod.yml up - start all services from docker-compose.prod.yml
docker-compose build db - rebuild db service
docker-compose down
docker-compose down --remove-orphans - remove containers for services not defined in the Compose file.
docker-compose down -v - shutdown containers, remove volumes. Docker stores volumes at /var/lib/docker/volumes
docker-compose logs db | less - show logs of db container
docker-compose ps - show running app's containers
docker-compose exec fpm bash - connect to running fpm container and start bash console in it
docker-compose exec db mysql -u root -ppassword - connect to running db container and start mysql console
docker-compose run --rm php-cli sh - run php-cli container, start sh console. --rm - Docker also removes the anonymous volumes associated with the container when the container is removed.
docker-compose rm db - remove db container
docker-compose rm -fv - remove all containers with volumes
docker-compose config - show docker-compose.yml content after the substitution step has been performed

Proxy settings for Docker

If you see an error:

docker-compose up
Pulling db (mysql:)...
ERROR: Get https://registry-1.docker.io/v2/: Proxy Authentication Required

you should configure your Docker's proxy settings (see stackoverflow).

Create file /etc/systemd/system/docker.service.d/http-proxy.conf:

[Service]
Environment="HTTP_PROXY=http://kenny:[email protected]:3118"
Environment="HTTPS_PROXY=http://kenny:[email protected]:3118"
Environment="NO_PROXY=localhost,127.0.0.1,localaddress,.localdomain.com"

Reload docker:

sudo service docker restart

Check if it works:

docker pull busybox

Compose CLI environment variables

We can create .env file and define there env variables.

COMPOSE_PROJECT_NAME=myapp - Sets the project name. This value is prepended along with the service name to the container on start up. For example, if your project name is myapp and it includes two services db and web, then Compose starts containers named myapp_db_1 and myapp_web_1 respectively.

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docker_commands.md

Docker Commands

Installation

We can install Docker using official bash script.

curl -fsSL https://get.docker.com -o get-docker.sh
sudo sh get-docker.sh

System

docker system prune - clean up any resources - images, containers, volumes, and networks — that are dangling (not associated with a container)
docker system prune -a - remove ALL stopped containers, unused networks, abandoned images, build cache

Containers

They are created from Docker Images and run the actual app.

docker run busybox echo 123 - find image, load up the container, run a provided command
docker run --rm busybox - flag --rm: remove container when it exits
docker run -it busybox sh - flag --it: attach us to an interactive tty in the container
docker run --name hello -it busybox sh - param --name hello sets name hello for created container
docker run -p 8000:80 nginx - flag -p: publish a container's port to the host
docker run --net foo-network foo-container - flag --net: set network for container
docker run --rm -it -v $(pwd):/app php:8 bash - create volume for current dir
docker ps - list running containers
docker ps -a - list all containers
docker volume ls - list all volumes
docker start foo-container - start container
docker stop foo-container - stop container
docker rm foo-container - remove container
docker kill foo-container - kill container
docker container ls - list contaners
docker container ls -a - list all containers
docker container prune - remove all stopped containers
docker port foo-container - show exposed ports
docker container logs foo-container - see logs of the container
docker exec -it foo-container sh - run console into container
docker logs -f foo-container - show logs of container. Docker's log location: /var/lib/docker/containers/
docker stats - show statistics for running containers
docker stats foo-container - show CPU, Memory Usage, Net, Block I/O of container

Images

They are blueprints of our app which form the basis of containers.

docker build -t kenny/nginx:2.0 . - build an image with repo name kenny/nginx and tag 2.0
docker image ls - list images
docker image prune - remove all dangling images (not used by containers)
docker rmi -f foo-image-name - remove image, -f - forced mode
docker save nginx > nginx.tar - save image to .tar archive. Size: 121Mb
docker save nginx:latest | gzip > nginx.tar.gz - save image to .tar.gz archive. Size: 50Mb
docker load < ./nginx.tar.gz - load image from .tar.gz or .tar archive

Network

docker network ls - list docker's networks
docker network inspect bridge - inspect bridge network of docker
docker network create foo-network - create new bridge network
docker network rm foo-network - remove network
docker network prune - remove all custom networks not used by at least one container

By default, docker creates networks in these pools:

172.17.0.0/16 - 172.31.0.0/16
192.168.0.0/20 - 192.168.240.0/20

These IP addresses may conflict with server's IP address. You may lose SSH connection trying to docker-compose up. In this case create file /etc/docker/daemon.json:

{
  "default-address-pools" : [
    {
      "base" : "172.31.0.0/16",
      "size" : 24
    }
  ]
}

In these case created networks will have Subnet: 172.31.1.0/24, 172.31.2.0/24, .., 172.31.255.0/24.

Useful commands

Copy config from working container

docker run -d httpd:2.4
docker ps
docker cp [ID of container]:/usr/local/apache2/conf/httpd.conf ./httpd.conf

docker-compose run php bash
docker ps # See Container ID
docker cp 164b0441bb1c:/usr/local/etc/php/php.ini-development ./

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docker_swarm.md

Docker Swarm

docker node ls - show virtual machines in the cluster
docker service ls - show services in cluster
docker node inspect jenkins - show detail info for node
docker node update jenkins --label-add db - add label db for node jenkins
docker service ps site_api-php - show replicas' info for one serivce

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dockerfile.md

Dockerfile

Example 1

# base image
FROM python:3-onbuild

# This port the container should expose
EXPOSE 5000

# Tell the container which command it should run when it's started
CMD ['python', './app.py']

Example 2

FROM nginx:latest

ADD ./nginx/default.conf /etc/nginx/conf.d/default.conf
WORKDIR /var/www/frontend

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errors.md

Docker Errors

ERROR: network site_default is ambiguous

docker network ls
docker network rm e2d790be0302