docker-playground
Based on the Pluralsight course Getting Started with Docker by Nigel Poulton.
DOCKER commands
build a new image with tag (-t). maurobertoli is the docker.com account
docker image build -t maurobertoli/gsd:first-ctr .
list of available images
docker image ls
remove an image from local
docker image rm maurobertoli/gsd:first-ctr
list of running containers
docker container ls
get an image from the repo and start it | -d = detached (in background) | --name = the container name
docker container run -d --name web -p 8000:8080 maurobertoli/gsd:first-ctr
stop a containerized app (an app running inside a container) gracefully
docker container stop web
start a containerized app
docker container stop web
remove a containerized app
docker container rm web
force removing a running container
docker container rm web -f
run a container in interactive mode (-it) using alpine linux dist and run the command sh as entrypoint. type exit to exit sh and then exit the container.
docker container run -it --name test alpine sh
press CTRL + P + Q (process quit) to exit the container BUT keeping running it in the background
run a windows container in interactive mode
docker container run -it mcr.microsoft.com/powershell:nanoserver pwsh.exe
DOCKER COMPOSE
Docker compose allows to create multi-container app (many images + network as example)
create all the images needed and start the containers | -d = detached (in background)
docker-compose up -d
shotdown all the containers
docker-compose down
print your resolved application config to the terminal
docker-compose config
DOCKER SWARM
init docker swarm, specify an ip different to the host if needed, and set it as manager. You will get a token and a command to add a service
docker swarm init --advertise-addr=192.168.0.20
add a manager to the same swarm (from another host/machine/ip)
docker swarm join-token manager
add a service to the swarm
docker swarm join --token SWMTKN-1-xxxx...xxx 192.168.0.20:2377
list all nodes in the swarm (managers and workers)
docker node ls
add a worker to a swarm (running from a manager host), this we give a command with a token
docker swarm join-token worker
then run this from the machines that you have to join as a worker
docker swarm join --token SWMTKN-1-xxxx...xxx 192.168.0.20:2377
DOCKER SWARM - manage apps
pre-requisite: swarm initialized
create a service from an existing image. Only existing images can be used.
docker service create --name web -p 8080:8080 --replicas 3 maurobertoli/gsd:first-ctr
list all services in the swarm
docker service ls
list the containers (in this case 3 equal rows for the image) for this host (note: only this machine)
docker container ls
list the containers (in this case 3 equal rows for the image) for this swarm (you will get info about hte node too)
docker service ps web
scale the service called "web" to 10 instances
docker service scale web=4
if you try to force remove some containers, they will be restarted asap
docker container rm xxx-ID-1 xxx-ID-2 -f
remove the service and related containers
docker service rm web
DOCKER SWARM - yml file
we can obtain a stack the same scenario using the declarative way with a yml file (look at the swarm-stack folder).
Note that only existing images in a registry can be used, so you need to specify an image name (instead of build: .)
So just add to an existing docker-compose.yml
image: maurobertoli/gsd:first-ctr
deploy:
replicas: 10Then deploy with (stackname is your stack/application name)
docker stack deploy -c docker-compose.yml stackname
check the stack
docker stack ls
check the services deployed in the stack
docker stack services stackname
check the containers and more info on the stack
docker stack ps stackname
you can edit the yml file and apply the changes (ex. replicas: 5) and re-run the same command
docker stack deploy -c docker-compose.yml stackname
remove the stack and related containers
docker stack rm stackname