A Guide to using Docker and Docker-Compose
Docker is used to run individual containers managed manually by a user. Whereas, Docker-compose does all the container orchestration as specified in the docker-compose.yml. For example, you can configure a container wait for another container to be ready in the dockerfile by specifying
docker-compose.yml
depends_on:
- <container_name>
Note: you need to implement your own retry logic in your applications running inside containers. A container being UP doesn't gurantee that the applications inside its container is ready to respond to requests.
Run a Docker-compose Package
docker-compose up -d
Stop all Running Containers
docker-compose down
Start containers after making changes to the dockerfile to remove used containers
docker-compose up -d --remove-orphans
View all running Containers
docker-compose ps
Execute a command inside a particular container
We will use docker as we are targeting only a single Container. Remember, docker-compose is used for orchestration of multiple containers.
docker exec -it <container_name_or_id> <command>
//it stands for interactive mode
//get access to the bash shell of the container to work with the mysql instance inside the container
docker exec -it mysqlDB /bin/bash
View logs of a container
docker logs <container_name_or_id>
docker logs --tail <no of lines> --follow --timestamps <container_name_or_id>
Volumes Mounting in docker-compose:
You can specify directories in the docker-compose.yml file if you need to mount any directory or file to a container.
volumes:
- ./var/log/gorse:/var/log/gorse
- ./var/lib/gorse:/var/lib/gorse
The syntax is:
volumes:
- <path outside container>:<path inside container>
//can be abolute path or relative paths.
//If you specify a relative path, docker will create directories for it in the current directory
This will mount the directory specified in the <path outside container> to the <path inside container> in the container.
So, if you have a directory that contains files that you want to use inside a particular container, you can specify an absolute path to the directory that you want in the <path outside cotnainer> and then specify where you want it to be mounted in the directory inside the container in <path inside container>.
LIST CONTAINERS
sudo docker container ls -a
LIST IMAGES
sudo docker image ls -a
LIST ALL CONTAINERS (running/stopped):
sudo docker ps -a
REMOVE A CONTAINER:
sudo docker container rm <container-name>
REMOVE A DOCKER IMAGE:
sudo docker image rm <container-name>