Docker
Contents
Docker
Remote Docker Engine (aka containers running on a remote host)
docker -H=remote-docker-engine:2375 run nginx
Training
https://www.youtube.com/watch?v=fqMOX6JJhGo https://www.freecodecamp.org/ https://www.youtube.com/channel/UC8butISFwT-Wl7EV0hUK0BQ https://kodekloud.com/p/docker-labs
Containers
List running containers
docker ps
List all containers
docker ps -a
Run a container
docker run [image] [command] -d detached -i interactive -t terminal (usually -it) -e VAR=value (environment variables) -v VOLUME_NAME:/container/mount/point --entrypoint=sleep [image] [attribute] --name name --network network_name --link real_container_name:target_name (adds entries to /etc/hosts) <-- Depreciated
run:version (using a tag)
Stop a container
docker stop [name]/[id]
Port mapping
-p (host/external):(container/internal)
Directory mapping
-v /host/dir:/container/dir
Inspect (returns json)
docker inspect [container]
Images
List images
docker image ls
Remove image (must have no containers attached)
docker rmi [image]
Repository
Docker Hub
Assumes docker.io
image: nginx/nginx account/image <-- if nginx is specified it uses that as the username/account name also
Private Registry
docker login private-registry.io docker run private-registry.io/apps/internal-app
Deploy Private Registry
docker run -d -p 5000:5000 --name registry registry:2 docker image tag my-image localhost:5000/my-image docker push localhost:5000/my-image docker pull localhost:5000/my-image
Dockerfile
Contains Instructions or Arguments
CMD can be as per cli or in json format
CMD command param1 CMD ["command","param1"]
FROM ubuntu:18.04 COPY . /app ADD root/bashrc /root/.bashrc ENV HOME /root WORKDIR /root RUN make /app CMD python /app/app.py
Build
docker build [path/Dockerfilefolder] -t name:tag
Create a Ubuntu container that sleeps for 5 seconds before exiting Dockerfile
From Ubuntu CMD sleep 5
docker build -t ubuntu-sleeper . docker run ubuntu-sleeper
Dockerfile
From Ubuntu ENTRYPOINT ["sleep"] CMD ["5"] (becomes the default)
docker build -t ubuntu-sleeper . docker run ubuntu-sleeper 10
Networks
docker network ls
Containers can resolve containers by name in the same network (internal dns server 127.0.0.11)
Create a network
docker network create --driver bridge --subnet 182.18.0.0/16 custom-isolated-network
Bridge
Internal network common to all docker containers in 172.17.0.0/24 network
None
Containers are isolated. Containers are not connected to any network
Host
Container runs directly on the host network.
Storage
Default storage
/var/lib/docker
Create volume
docker volume create data_volume (generated /var/lib/docker/volumes/data_volume
Use Volume
docker run --mount data_volume:/var/lib/mysql mysql
Bind Mounting (with new syntax)
docker run --mount type=bind,source=/host/data/mysql,target=/var/lib/mysql mysql
Compose
Yaml - run multiple containers together on a single Docker Host.
docker compose up
/blah/application/docker-compose.yml
version: 2
services:
db:
environment:
POSTGRES_PASSWORD: mysecretpassword
image: postgres
wordpress:
image: wordpress
links:
- db
ports:
- 8085:80
version: '3.0'
replace image with build (and path) to use local built images
Start
docker-compose up
Versions of docker-compose files (supports all)
- Version 1 - can not specify order or networks (all bridge and then links)
- Version 2 - starts with services: at the start, and version: 2 (all in bridge network, no need to use links), also has depends on feature
- version 3 - supports docker swarm
version: 2
services:
redis:
image: redis
...
neworks:
- back-end
vote:
image: voting-app
networks:
- front-end
- back-end
networks:
front-end:
back-end:
Engine - Resources - cgroups
Control Groups
docker run --cpus=.5 ubuntu <-- limit to max 50% docker run --memory=100m ubuntu <-- limit to 100MB
Docker Swarm
H/A and distribution across multiple hosts Swarm Manager 1 --> n Workers (Nodes)
