Friday, December 28, 2018

Docker Sample Commands

Below is a cheat sheet for using Docker, a popular containerization platform. It provides a list of commonly used commands to pull images from a registry, retag images, log in to a registry, push images to a registry, list images, delete images, create a Docker container from an image, stop and kill running containers, create overlay networks, list running containers, stop and remove containers, attach to and detach from containers, set containers to read-only, flatten images, check container resource usage, build images from Dockerfiles, use Docker Compose to build, create, and start containers, create and run a container with a mounted volume, copy files to and from containers, and inspect containers. It also includes a Dockerfile sample.

Pull an image from a registry
docker pull alpine:3.4

Retag a local image with a new image name and tag
docker tag alpine:3.4 myrepo/myalpine:3.4

Log in to a registry (the Docker Hub by default)
docker login
Push an image to a registry
docker push myrepo/myalpine:3.4
List all images that are locally stored with the Docker engine
docker images
Delete an image from the local image store
docker rmi alpine:3.4
Create a Docker from image
docker run
--rm #remove container automatically after it exits
-it #connect the container to terminal
--name web #name the container
-p 5000:80 #expose port 5000 externally and map to port 80
-v ~/dev:/code #create a host mapped volume inside the container
alpine:3.4 #the image from which the container is instantiated
/bin/sh #the command to run inside the container
Stop a running container through SIGTERM
docker stop web
Stop a running container through SIGKILL
docker kill web
Create an overlay network and specify a subnet
docker network create --subnet --gateway -d overlay mynet
List the networks
docker network ls
List the running containers
docker ps
List the all running/stopped containers
docker ps -a

Stop a container
docker stop <container­name>

Stop a container (timeout = 1 second)
docker stop t 1 <container­name>
Delete all running and stopped containers
docker rm -f $(docker ps -aq)

Remove all stopped containers
docker rm $(docker ps q f "status=exited”)
Create a new bash process inside the container and connect it to the terminal
docker exec -it web bash
Print the last 100 lines of a container’s lo
docker logs --tail 100 web

Exporting image to an external file
docker save o <filename>.tar [username/]<image­name>[:tag]

Importing and image to an external file
docker load i <filename>.tar 

Inspecting docker image
docker inspect <Container-ID>

Attach to a running container 
docker attach <Container-ID>

Detach from the Container with out killing it ##turn interactive mode to daemon mode
Type Ctrl + p , Ctrl + q

Set the container to be read-only:
docker run --read-only

Flatten an image
ID=$(docker run -d image-name /bin/bash)
docker export $ID | docker import – flat-image-name

To check the CPU, memory, and network I/O usage
docker stats <container>
Build an image from the Dockerfile in the current directory and tag the image
docker build -t myapp:1.0 .

Docker file samples

vi Dockerfile
FROM ubuntu
RUN apt-get update
RUN apt-get install -y nginx
COPY index.html /usr/share/nginx/html/
ENTRYPOINT [“/usr/sbin/nginx”,”-g”,”daemon off;”]
Build new images, create all containers, and start all containers (Compose). (This will not rebuild images if a Dockerfile changes.)
docker-compose up

Build, create, and start all in the background (Compose):
docker-compose up -d

Rebuild all images, create all containers, and start all containers (Compose):
docker-compose up --build

Create a new container for my_service in docker-compose.yml and run the echo command instead of the specified command:
docker-compose run my_service echo "hello"

Run a container with a volume named my_volume mounted at /my/path in the Docker container. (The volume will be created if it doesn't already exist.) 
docker run --mount source=my_volume,target=/my/path my-image
docker run -v my_volume:/my/path my-image

Copy my-file.txt from the host current directory to the /tmp directory in my_container:
docker cp ./my-file.txt my_container:/tmp/my-file.txt

Inspect an container
docker inspect python_web | less 

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