docker : list containers in a specific network

 

List containers in a precise 

$ docker network ls
NETWORK ID     NAME                               DRIVER    SCOPE
f732a9b3c5a1   bridge                             bridge    local
7ec614323767   host                               host      local
...

docker network inspect     -f '{{ range $key, $value := .Containers }}{{printf "%s: %s\n" $key .Name}}{{ end }}' <NETWORK NAME>
<ID> <Name>

Caddy + xcaddy within a docker container

Start Caddy within a docker container and add a plugin.

https://caddyserver.com/docs/modules/security

./docker-compose.yml

version: '3.4'
networks:
  monitor-net:
    driver: bridge
volumes:
    caddy_data: {}
services:
  caddy:
    # cf. https://github.com/caddyserver/caddy/releases
    # image: caddy:2.5.0
    build:
      context: ./caddy/ # where to look for the Dockerfile
      dockerfile: Dockerfile # actual name of the Dockerfile
      args:
        image_ref: caddy:2.5.0
    container_name: caddy
    ports:
      - "80:80"
      - "443:443"
    volumes:
      - ./caddy:/etc/caddy
      - caddy_data:/data
    env_file:
      ./.env
    restart: unless-stopped
    networks:
      - monitor-net
    labels:
      org.label-schema.group: "monitoring"

image_ref: caddy:2.5.0 # image reference used twice in the Dockerfile, once with ${image_ref}-builder, once directly

./caddy/Dockerfile :

ARG image_ref
FROM ${image_ref}-builder AS caddy-build
RUN xcaddy build --with github.com/greenpau/caddy-security
FROM ${image_ref}
COPY --from=caddy-build /usr/bin/caddy /usr/bin/caddy

Caddyfile must exist (content not relevant here):

./caddy/Caddyfile

command :

docker-compose  up --build caddy

Linux cleaning tips (systemd, apt/ubuntu, docker)

 (evolutive article where I store what's been useful to me to clean space on linux servers I'm using)

Note : my current servers are running Ubuntu.

OS / SystemD : purge logs bigger than ...

Only keep 10M of each log files handle through syslog

sudo journalctl --vacuum-size 10M

OS / apt : remove remnants

Remove automatically all unused packages Remove automatically installed packages not needed anymore (i.e. packages that were installed as dependencies of packages that have now been removed or aren't requiring this dependency anymore)

apt options :

•   autoremove - Remove automatically all unused packages
•   clean - Erase downloaded archive files
•   autoclean - Erase old downloaded archive files

sudo apt-get clean autoremove autoclean

Docker : remove logs older than ...

Only keep the last 1000h of docker containers logs

sudo docker image prune --all --filter "until=1000h" -f

Docker : remove remnants

Be careful ! If your docker environments are not running they might be deleted by some of the following commands !

Remove unused volumes, containers, images, networks, etc.

sudo docker system prune -f 

sudo docker system prune -a --volumes

kill processes from docker-compose "container_name"

Context : 

follwing a project-name change -> renaming the directory-name/docker-compose.yml the processes that were started by docker-compose were duplicated.

From the new project :

*  impossible to see them.

From docker ps : no process listed

From OS perspective ps aux : process present.

Test 1 : kill them all !

 Step 1 : identify them

ps aux | grep $(echo "$(grep container_name docker-compose.yml | grep -v '#' | awk '{printf("%s\\|", $2)}')grep")

Step 2 : kill -9 them all

ps aux | grep $(echo "$(grep container_name docker-compose.yml | grep -v '#' | awk '{printf("%s\\|", $2)}')grep") | awk '{print $2}' | xargs sudo kill -9

-> result : when restarting docker, they're back :-( 

Test 2 : stop docker + docker-compose start

apparently working, but I lost my container's content...

Docker : thiner images

(from  GitLab Commit at KubeCon : One Layer Builds (Docker Not Included), by Jason Plum https://gitlab.com/WarheadsSE and Will Christensen)

* use FROM Scratch, instead of FROM <distro> 

 * Explore each layer of a docker image

https://github.com/wagoodman/dive 

* use Buildah : http://buildah.io/ "A tool that facilitates building OCI container images."

•     https://developers.redhat.com/blog/2021/01/11/getting-started-with-buildah
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