Docker

// Terms
Image:  Operating system image, stored in a repo.  Single file.  A template for an image
Dockerfile: Definition of an image (source code of an image)
Container: Instance of an image
Registry: A repository to push and pull containers (like git)
Microservices: Single process per container
Fat containers: Similar to a virtual machine

// Notes
- Digitalocean guides are a great resource!
- By default, only root can use docker (attach to the docker daemon)
	- If you want non-priv users to use docker, do that through sudo
		OR
	- create a docker group and add them to it
- By default, Docker containers do persist data when stopped, then started/exec'd later
- By default, Docker containers do NOT persist data across "runs" (new containers from image)
	- Use docker data volumes to persist changes
		- See "data volume" containers and "--volumes-from" option when starting a container
	- You can also share data between the host and container
		- See docker run "-v" option
- Docker generates random container names for you if you don't specify a name

// Determine how much space docker is using
docker system df

// Clean up unused base images and shit taking up disk space, especially in /var/lib/docker/overlay2/
docker system prune -a

// Remove all build cache
docker buildx prune --all
docker builder prune --all

// Installing LATEST version of docker on CentOS 7 (not version that comes with CentOS)
https://github.com/NaturalHistoryMuseum/scratchpads2/wiki/Install-Docker-and-Docker-Compose-(Centos-7)

// Installing LATEST docker-compose
curl -L "https://github.com/docker/compose/releases/download/1.23.1/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
chmod +x /usr/local/bin/docker-compose

// Show docker version
docker version

// show all info about the docker environment
docker info

// Search docker registry for any image with name "centos"
docker search centos

// Download latest centos image from the registry
docker pull docker.io/centos

// Download specific tagged centos image
docker pull docker.io/centos:centos7.0.1406

// Push centos 7.0 image with id cc2cf48cc784 to a remote registry
docker tag cc2cf48cc784 gitlabserver.nucleussec.com:8443/root/vulndockerimages/centos7.0
docker push gitlabserver.nucleussec.com:8443/root/vulndockerimages/centos7.0


// See all images that have been downloaded
docker images -a

// Save a docker image to a tarfile
docker save someimage > someimage.tar

// show all running containers
docker ps

// stop a running container
docker stop <container id>

// stop all containers
docker stop $(docker ps -aq)

// restart a container
docker start <container id>

// commit a copy of the container (presumably with changes from the base image) to a new image
docker commit -m "<comment>" -a "<author>" <container id> <new image name>

// remove a stopped docker containers
docker rm <container id>

// remove all containers
docker rm $(docker ps -aq)

// show all docker containers running or stopped
docker ps -a

// show running processes in a container
docker top <container id>

// look at all info on a container
docker inspect <container id>

// Downloads/pulls latest centos (centos:latest) image from docker.io and runs cat command
docker run -it centos cat /etc/redhat-release

// Same thing but automatically clean up the container and remove the file system when the container exits
docker run --rm -it centos cat /etc/redhat-release

// spin up a new container named "mycontainer" from a docker image and get shell inside
docker run -it --name="mycontainer" <image name> /bin/bash

	// mount a host volume/dir
	-v
	// after container runs the command, stop, then delete itself
	--rm

// Get a shell in a running container
docker exec -it <container name> /bin/bash

// Edit a file in a container that doesn't have an editor
docker cp <container>:/path/to/file.ext .
	// copies it to your local machine (to your current directory).
	// Then edit the file locally using your favorite editor, and then:
docker cp file.ext <container>:/path/to/file.ext
	// to replace the old file.

#### Docker Compose ####
# docker-compose up		// in same directory as docker-compose.yml
# docker-compose up -d	// start containers in background (instead of dying when terminal dies)
# docker-compose stop	// in same directory as docker-compose.yml
# docker-compose ps		// show running containers
# docker-compose rm 	// start from scratch