Docker Commands, Help & Tips
Show commands & management commands
$ docker
Docker version info
$ docker version
Show info like number of containers, etc
$ docker info
WORKING WITH CONTAINERS
Create an run a container in foreground
$ docker container run -it -p 80:80 nginx
Create an run a container in background
$ docker container run -d -p 80:80 nginx
Shorthand
$ docker container run -d -p 80:80 nginx
Naming Containers
$ docker container run -d -p 80:80 --name nginx-server nginx
TIP: WHAT RUN DID
- Looked for image called nginx in image cache
- If not found in cache, it looks to the default image repo on Dockerhub
- Pulled it down (latest version), stored in the image cache
- Started it in a new container
- We specified to take port 80- on the host and forward to port 80 on the container
- We could do "$ docker container run --publish 8000:80 --detach nginx" to use port 8000
- We can specify versions like "nginx:1.09"
List running containers
$ docker container ls
OR
$ docker ps
List all containers (Even if not running)
$ docker container ls -a
Stop container
$ docker container stop [ID]
Stop all running containers
$ docker stop $(docker ps -aq)
Remove container (Can not remove running containers, must stop first)
$ docker container rm [ID]
To remove a running container use force(-f)
$ docker container rm -f [ID]
Remove multiple containers
$ docker container rm [ID] [ID] [ID]
Remove all containers
$ docker rm $(docker ps -aq)
Get logs (Use name or ID)
$ docker container logs [NAME]
List processes running in container
$ docker container top [NAME]
TIP: ABOUT CONTAINERS
Docker containers are often compared to virtual machines but they are actually just processes running on your host os. In Windows/Mac, Docker runs in a mini-VM so to see the processes youll need to connect directly to that. On Linux however you can run "ps aux" and see the processes directly
IMAGE COMMANDS
List the images we have pulled
$ docker image ls
We can also just pull down images
$ docker pull [IMAGE]
Remove image
$ docker image rm [IMAGE]
Remove all images
$ docker rmi $(docker images -a -q)
TIP: ABOUT IMAGES
- Images are app bianaries and dependencies with meta data about the image data and how to run the image
- Images are no a complete OS. No kernel, kernel modules (drivers)
- Host provides the kernel, big difference between VM
Some sample container creation
NGINX:
$ docker container run -d -p 80:80 --name nginx nginx (-p 80:80 is optional as it runs on 80 by default)
APACHE:
$ docker container run -d -p 8080:80 --name apache httpd
MONGODB:
$ docker container run -d -p 27017:27017 --name mongo mongo
MYSQL:
$ docker container run -d -p 3306:3306 --name mysql --env MYSQL_ROOT_PASSWORD=123456 mysql
CONTAINER INFO
View info on container
$ docker container inspect [NAME]
Specific property (--format)
$ docker container inspect --format '{{ .NetworkSettings.IPAddress }}' [NAME]
Performance stats (cpu, mem, network, disk, etc)
$ docker container stats [NAME]
ACCESSING CONTAINERS
Create new nginx container and bash into
$ docker container run -it --name [NAME] nginx bash
- i = interactive Keep STDIN open if not attached
- t = tty - Open prompt
For Git Bash, use "winpty"
$ winpty docker container run -it --name [NAME] nginx bash
Run/Create Ubuntu container
$ docker container run -it --name ubuntu ubuntu
(no bash because ubuntu uses bash by default)
You can also make it so when you exit the container does not stay by using the -rm flag
$ docker container run --rm -it --name [NAME] ubuntu
Access an already created container, start with -ai
$ docker container start -ai ubuntu
Use exec to edit config, etc
$ docker container exec -it mysql bash
Alpine is a very small Linux distro good for docker
$ docker container run -it alpine sh
(use sh because it does not include bash)
(alpine uses apk for its package manager - can install bash if you want)
NETWORKING
"bridge" or "docker0" is the default network
Get port
$ docker container port [NAME]
List networks
$ docker network ls
Inspect network
$ docker network inspect [NETWORK_NAME]
("bridge" is default)
Create network
$ docker network create [NETWORK_NAME]
Create container on network
$ docker container run -d --name [NAME] --network [NETWORK_NAME] nginx
Connect existing container to network
$ docker network connect [NETWORK_NAME] [CONTAINER_NAME]
Disconnect container from network
$ docker network disconnect [NETWORK_NAME] [CONTAINER_NAME]
Detach network from container
$ docker network disconnect
IMAGE TAGGING & PUSHING TO DOCKERHUB
tags are labels that point ot an image ID
$ docker image ls
Youll see that each image has a tag
Retag existing image
$ docker image tag nginx btraversy/nginx
Upload to dockerhub
$ docker image push bradtraversy/nginx
If denied, do
$ docker login
Add tag to new image
$ docker image tag bradtraversy/nginx bradtraversy/nginx:testing
DOCKERFILE PARTS
- FROM - The os used. Common is alpine, debian, ubuntu
- ENV - Environment variables
- RUN - Run commands/shell scripts, etc
- EXPOSE - Ports to expose
- CMD - Final command run when you launch a new container from image
- WORKDIR - Sets working directory (also could use 'RUN cd /some/path')
- COPY # Copies files from host to container
Build image from dockerfile (reponame can be whatever)
From the same directory as Dockerfile
$ docker image build -t [REPONAME] .
TIP: CACHE & ORDER
- If you re-run the build, it will be quick because everythging is cached.
- If you change one line and re-run, that line and everything after will not be cached
- Keep things that change the most toward the bottom of the Dockerfile
EXTENDING DOCKERFILE
Custom Dockerfile for html paqge with nginx
FROM nginx:latest # Extends nginx so everything included in that image is included here
WORKDIR /usr/share/nginx/html
COPY index.html index.html
Build image from Dockerfile
$ docker image build -t nginx-website
Running it
$ docker container run -p 80:80 --rm nginx-website
Tag and push to Dockerhub
$ docker image tag nginx-website:latest btraversy/nginx-website:latest
$ docker image push bradtraversy/nginx-website
VOLUMES
Volume - Makes special location outside of container UFS. Used for databases
Bind Mount -Link container path to host path
Check volumes
$ docker volume ls
Cleanup unused volumes
$ docker volume prune
Pull down mysql image to test
$ docker pull mysql
Inspect and see volume
$ docker image inspect mysql
Run container
$ docker container run -d --name mysql -e MYSQL_ALLOW_EMPTY_PASSWORD=True mysql
Inspect and see volume in container
$ docker container inspect mysql
TIP: Mounts
- You will also see the volume under mounts
- Container gets its own uniqe location on the host to store that data
- Source: xxx is where it lives on the host
Check volumes
$ docker volume ls
There is no way to tell volumes apart for instance with 2 mysql containers, so we used named volumes
Named volumes (Add -v command)(the name here is mysql-db which could be anything)
$ docker container run -d --name mysql -e MYSQL_ALLOW_EMPTY_PASSWORD=True -v mysql-db:/var/lib/mysql mysql
Inspect new named volume
docker volume inspect mysql-db
BIND MOUNTS
- Can not use in Dockerfile, specified at run time (uses -v as well)
- ... run -v /Users/brad/stuff:/path/container (mac/linux)
- ... run -v //c/Users/brad/stuff:/path/container (windows)
TIP: Instead of typing out local path, for working directory use $(pwd):/path/container - On windows may not work unless you are in your users folder
Run and be able to edit index.html file (local dir should have the Dockerfile and the index.html)
$ docker container run -p 80:80 -v $(pwd):/usr/share/nginx/html nginx
Go into the container and check
$ docker container exec -it nginx bash
$ cd /usr/share/nginx/html
$ ls -al
You could create a file in the container and it will exiost on the host as well
$ touch test.txt
DOCKER COMPOSE
- Configure relationships between containers
- Save our docker container run settings in easy to read file
- 2 Parts: YAML File (docker.compose.yml) + CLI tool (docker-compose)
1. docker.compose.yml - Describes solutions for
- containers
- networks
- volumes
2. docker-compose CLI - used for local dev/test automation with YAML files
Sample compose file (From Bret Fishers course)
version: '2'
# same as
# docker run -p 80:4000 -v $(pwd):/site bretfisher/jekyll-serve
services:
jekyll:
image: bretfisher/jekyll-serve
volumes:
- .:/site
ports:
- '80:4000'
To run
docker-compose up
You can run in background with
docker-compose up -d
To cleanup
docker-compose down