@@ Line 1: / Line 1: @@
+Docker is a service for creating and managing linux containers.
+Containers are the application layer of an OS and whatever software you're trying to run.
+The container itself contains the code to be run along with the environment.
+Anything which needs state is mounted as a volume to the container.
 ==Installation==
 ===Ubuntu===
 [https://docs.docker.com/install/linux/docker-ce/ubuntu/#install-docker-engine---community-1 Reference]
+{{hidden | Install Script |
 <syntaxhighlight lang="bash">
+# Uninstall old docker
+sudo apt-get remove docker docker-engine docker.io containerd runc
 # Update repos
 sudo apt update
@@ Line 29: / Line 37: @@
 sudo apt-get install docker-ce docker-ce-cli containerd.io
 </syntaxhighlight>
+}}
+===Windows===
+* Upgrade Windows to 2004 or newer
+* Install and enable WSL2
+* Install Docker Desktop
 ==Guides==
 [https://docs.docker.com/get-started/ Get Started]
-==Usage==
+==Dockerfile==
+How to write a dockerfile
+==CLI Usage==
 ===Images===
+For the most part, you don't need to worry about images as <code>docker run</code> and <code>docker-compose</code> will download and build images for you as needed.
 <syntaxhighlight lang="bash">
+# List images.
+docker image ls
+# Prune unused images.
+docker image prune -a
+# Copy image.
+docker tag $SOURCE $TARGET
+docker push $TARGET
 </syntaxhighlight>
+;Notes
+* Pruning with <code>docker system prune</code> will also delete images.
+* Omitting <code>-a</code> will only prune dangling (untagged) images.
 ===Containers===
@@ Line 44: / Line 75: @@
 </syntaxhighlight>
-===Windows===
+===Run===
+<pre>
+docker run <container>
+</pre>
+* <code>-p hostport:containerport</code> to do port forwarding
+** To restrict listing to localhost use <code>-p 127.0.0.1:80:80</code>
+* <code>-it</code> to be interactive with a pseudo-tty
+===stats===
+[https://docs.docker.com/engine/reference/commandline/stats/ docker stats]
+Returns information about container cpu usage, memory usage, network usage, and disk usage.
+==Networking==
+The default mode for networking is bridge. You should leave this for most of your containers.
+===bridge===
+In bridge mode, the docker service acts as a NAT and gives each container a separate local IP along with the docker host.
+On linux, you can type <code>ip a</code> to see the ip address of the <code>docker0</code> network interface.
+On my server, it is <code>172.17.0.1/16</code>.
+To access services running on the host (such as MySQL or Postgres), you will need to make these services listen on this network interface and allow it through your firewall. I suggest using [https://github.com/qoomon/docker-host qoomon/docker-host] which can redirect network traffic to the host.
+When using docker-compose, services can access each other using their service name as the hostname. However, the port needs to be exposed in the compose file.
+===host===
+In this mode, docker processes have full access to your network. This can cause port conflicts if you are not careful.
+Furthermore, your docker service will have full access to your localhost. I do not recommend using this mode for most things.
+==GPUs==
+See [https://docs.docker.com/config/containers/resource_constraints/#gpu docker guide]
+===Setup===
+# Go to [https://nvidia.github.io/nvidia-container-runtime/ nvidia-container-runtime] and add the repo
+# Install <code>nvidia-container-runtime</code>
+===Run===
+Add <code>--gpus all</code> to your docker run command.
+===compose===
+See [https://github.com/docker/compose/issues/6691 issue].
+<pre>
+    deploy:
+      resources:
+        reservations:
+          devices:
+            - driver: nvidia
+              count: 1
+              capabilities: [gpu]
+</pre>
+==Windows==
 Notes on using docker with windows
-====Git bash paths====
+===Git bash paths===
 [https://github.com/docker/toolbox/issues/673 Reference]<br>
 When mounting paths using git bash, you need to prepend a <code>/</code> to <code>$(pwd)</code><br>
+==docker-compose==
+Docker compose allows you to specify multiple docker services into a single <code>docker-compose.yml</code> file and run them all together.
+You can also use it to setup docker commands instead of listing options in a shell script.
+<pre>
+# Create a folder for your service and cd into it
+# Make the docker-compose file.
+# Run (i.e. build, create, and start)
+docker-compose up -d
+# Stop
+docker-compose down
+# Upgrade
+docker-compose pull # Optional, reduces downtime
+docker-compose up --force-recreate --build -d
+docker image prune -f
+</pre>
+* Note that <code>docker-compose restart</code> will just restart existing containers. It will not recreate them.
+[https://docs.docker.com/compose/compose-file/compose-file-v3/ Compose file reference]
+===Compose file===
+See [https://docs.docker.com/compose/compose-file/compose-file-v3/ Compose file specification].
+Previously, the Compose file (<code>docker-compose.yml</code>) required a version. Version 2 and version 3 had different options and not all options from version 2 were available in version 3. However, as of docker-compose v1.27+, you should no longer specify a version and options from both versions are supported.
+{{hidden | Example docker-compose.yml |
+<syntaxhighlight lang="yaml">
+services:
+  web:
+    image: registry.gitlab.davidl.me/dli7319/davidl_me:latest
+    restart: unless-stopped
+</syntaxhighlight>
+}}
+==Accessing the Host==
+Sometimes you may have services running on the host which you want to access from a container.<br>
+See [https://github.com/qoomon/docker-host docker-host] for a container which can access the host.<br>
+Add the following to your docker compose to expose port 8201 to other containers:
+<syntaxhighlight lang="yaml">
+  docker-host:
+    image: qoomon/docker-host
+    cap_add:
+      - NET_ADMIN
+      - NET_RAW
+</syntaxhighlight>
+* You do not need to add <code>expose</code>.
+By default, networks are allocated with ip ranges:
+* 172.17.0.0/12 with size /16
+* 192.168.0.0/16 with size /20
+If you want this to be more consistent, you can change it as follows:
+Set the following in <code>/etc/docker/daemon.json</code>:
+<syntaxhighlight lang="json">
+{
+  "default-address-pools":[
+    {"base":"172.16.0.0/12","size":24}
+  ]
+}
+</syntaxhighlight>
+Then restart your docker: <code>sudo systemctl restart docker</code> and prune networks <code>docker network prune</code>.<br>
+Next, in your firewall, allow connections to your localhost from 172.16.0.0/12.
+<pre>
+ufw allow from 172.16.0.0/12 to any comment "from_docker"
+</pre>
+==Registries==
+The official Docker registry is [https://hub.docker.com/ Docker Hub].<br>
+However, [https://www.docker.com/increase-rate-limits/ Docker Hug has rate limits] of 100 pulls per 6 hours.<br>
+Alternative public registries:
+* [https://gallery.ecr.aws/ AWS ECR Gallery] has a mirror for all official docker containers.
+==Caching==
+If you want your builds to be fast on CICD, you have to setup [https://docs.docker.com/build/cache/ caching].
+In particular you should:
+* Enable [https://docs.docker.com/build/buildkit/ buildkit] by setting the environment variable <code>DOCKER_BUILDKIT=1</code>
+* Use <code>--cache-from</code> in your build.
+* Setup external caching, e.g. with <code>--build-arg BUILDKIT_INLINE_CACHE=1</code>.
+** Use <code>--arg BUILDKIT_INLINE_CACHE=1</code> if using <code>docker buildx build</code>.
+* For multistage builds, cache each stage in your container registry.
+;Resources
+* https://michalwojcik.com.pl/2021/01/21/using-cache-in-multi-stage-builds-in-gitlab-ci-docker/
+* https://testdriven.io/blog/faster-ci-builds-with-docker-cache/#multi-stage-builds
+==Useful Services==
+* [https://containrrr.dev/watchtower/ https://containrrr.dev/watchtower/] is a tool which will automatically update your docker containers when new images are published. It also has an http endpoint to trigger checks manually e.g. from CI/CD.
+==My Images==
+I have a few custom container images below:
+* [https://github.com/dli7319/docker-anki-server ghcr.io/dli7319/docker-anki-server:main]
+* [https://github.com/dli7319/docker-nextcloud ghcr.io/dli7319/docker-nextcloud:main]
+* [https://github.com/dli7319/docker-mediawiki ghcr.io/dli7319/docker-mediawiki:main]
+==Resources==
+* [https://www.youtube.com/watch?v=fqMOX6JJhGo freeCodeCamp.org Docker Tutorial for Beginners Video]

Docker (software): Difference between revisions