docker-cheatsheet

Reference: https://github.com/wsargent/docker-cheat-sheet
Youtube Tutorial: Docker Tutorial for Beginners
Qwiklab Walkthrough: Introduction to Docker

Image

Images are just templates for docker containers.

docker build creates image from Dockerfile.

docker build .                  (random name, default tag)
docker build node-app .         (default tag)
docker build -t node-app:0.1 .

The -t is to name and tag an image with the name:tag syntax. The name of the image is node-app and the tag is 0.1. If you don't specify a tag, the tag will default to latest. Same image tagged with different names have same image ID.
The . means current directory so you need to run this command from within the directory that has the Dockerfile.

docker rmi removes an image.

docker rmi node-app:0.1             (use -f to force the deletion)
docker rmi $(docker images -aq)     (remove remaining images)

Child images should be removed before parent images can be removed.

docker images shows all images.
docker commit creates image from a container, pausing it temporarily if it is running.
docker tag tags an image to a name (local or registry).

Container

Your basic isolated Docker process.

docker run creates and starts a container in one operation.

docker run hello-world
docker run --name my-container node-app:v0.1
docker run -p 4000:80 node-app:0.1

docker run -it node-app:0.1                     (if it's python program, will open a python shell)
docker run -it node-app:0.1 bash                (run image, bash into the environment, can see all files)
docker exec -it my-container bash               (create a new bash session in the container )

The --name names the container. Otherwise it will randomly generate a container name.
The -p instructs Docker to map the host's port 4000 to the container's port 80.
The -d flag makes the container run in the background (not tied to the terminal's session).

The -it allocates a pseudo-TTY connected to the container’s stdin, creating an interactive bash shell in the container.
The docker exec -it [container_id] bash will create a new Bash session in the container.
Bash ran in the WORKDIR directory (/app) specified in the Dockerfile.

docker rm deletes a container.

docker rm my-container               
docker rm $(docker ps -aq)           (remove all containers)

docker stop stops a running container.

docker stop my-container
docker stop $(docker ps -q)          (stop all containers)

docker ps shows running containers, use -a to show all running and stopped containers.
docker create creates a container but does not start it.
docker start starts a container so it is running.

Registry

A Docker registry stores Docker images. Docker Hub is a public registry that anyone can use, and Docker is configured to look for images on Docker Hub by default.

docker login to login to a registry, use --username or -u to specify username.
docker logout to logout from a registry.
docker pull pulls an image from registry. If no tag is provided, Docker Engine uses the :latest tag as a default.
docker push pushes an image to the registry from local machine.

Example: Pull an official image

These commands pull the debian:latest and debian:jessie images from Docker Hub.

$ docker pull debian
$ docker pull debian:jessie

debian:jessie image shares layers with debian:latest. Pulling debian:jessie only pulls its metadata, but not its layers.
Also they have the same image ID because they are the same image tagged with different names.

Example: Push an image to a registry

First save the new image by finding the container ID (using docker container ls) and then committing it to a new image name.

$ docker container commit c16378f943fe rhel-httpd:latest

Now, push the image to the registry using the image ID. In this example the registry is on host named registry-host and listening on port 5000. To do this, tag the image with the host name or IP address, and the port of the registry:

$ docker image tag rhel-httpd:latest registry-host:5000/myadmin/rhel-httpd:latest
$ docker image push registry-host:5000/myadmin/rhel-httpd:latest

Running docker images, you should see both rhel-httpd and registry-host:5000/myadmin/rhel-httpd listed.

Example: Push/Pull to/from Docker Hub

Push to Docker Hub
Create a new repository on DockerHub.
Login to DockerHub via docker login on your local computer.
Tag your image with hostname and tag-name. Push it to using format yueyang0115/[repo-name]:[tag-name].

docker tag my-app:v1 yueyang0115/dukeproj:v1
docker push yueyang0115/dukeproj:v1

Pull from Docker Hub

docker pull yueyang0115/dukeproj:v1

Example: Push/Pull an image to/from Google Container Registry

To push images, tag the images with a registry name using format [hostname]/[project-id]/[image]:[tag].
You can find your project ID by running gcloud config list project.

docker tag node-app:0.2 gcr.io/[project-id]/node-app:0.2
docker push gcr.io/[project-id]/node-app:0.2

To pull an image from gcr and run it

docker pull gcr.io/[project-id]/node-app:0.2
docker run -p 4000:80 -d gcr.io/[project-id]/node-app:0.2

Example: Push/Pull an image to/from Amazon Elastic Container Registry

Open Amazon ECR console and create a repository. Click on "view push commands" to see the instruction.

yueyang0115 / docker-cheatsheet