Containers (docker) #

Containerization and virtualization is the ultimate separation of concerns. The breakdown of complexity and the de-coupling of the system components.

Running a container exposing a port: #

Exposes the container 80 port as a local/host 8080:

docker run -p 8080:80 edpichler/nginx

Entering inside a running docker container #

   docker exec -it e4383e55958d /bin/bash

Listeing all containers: #

docker ps -a

Deleting forcevily all the containers: #

docker rm -f $(docker ps -a -q)

Deleting all images that are not being used by running containers #

The additional filter is to do not delete images downloaded less than 2 days ago.

 docker system prune -a --filter "until=$((2*24))h"

If you want to add on crontab, the -f flag will just prevent of the confirmation prompt be showed during the cron job running:

 docker system prune -af --filter "until=$((2*24))h"

Docker Swarm #

Make a node inactive/active #

It will stops imediatelly all running containers in that node. They will be balanced to other nodes, though (if its configuration allows it).

docker node ls
docker node update --availability drain 15wkcqw42fjzb1aqoavyfkk13
docker node update --availability active 15wkcqw42fjzb1aqoavyfkk13

Update a service #

docker service list

docker service update --force myservice-api --image myname/myimage:latest --update-order start-first --update-failure-action rollback --with-registry-auth  --replicas 1 --env-add FLYWAY_MIGRATE="false"

Kill a service #

docker service list

docker service update --force myservice-api --replicas 0