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--- lwc:docker [2026/01/24 14:34] – John Harrison
+++ lwc:docker [2026/03/01 10:34] (current) – John Harrison
@@ Line 17: / Line 17: @@
   * copy files from docker container: ''docker cp container_id:/foot.txt foo.txt''
   * prune unneeded files (save disk space): ''sudo docker system prune -a -f''
+===== Docker Maintenance =====
+  * ''docker system df'': show overall space usage by category
+  * ''docker inspect $(docker ps -q) | grep -A 10 Mounts'': see what volume goes with what container
+  * ''docker inspect CONTAINER_NAME --format '{{range .Mounts}}{{.Name}} -> {{.Destination}}{{println}}{{end}}' '': list what volume is associated with the container
+  * ''docker ps'': list docker containers
+  *
+===== Housekeeping =====
+  * When removing a service use ''docker compose down -v'' instead of ''docker compose down.''
+    *  The ''-v'' removes the associated volumes at the same time.
+  * When updating images, after pulling and restarting, run ''docker image prune'' to remove the dangling images
+  * ''docker ps -a'': see all containers, even the ones that are stopped
+  *
+==== Watchtower ====
+  * Watchtower is a container which auto updates Docker containers
+  * It will only update containers with updates that have the same tag
+    * to always get the latest version use the tag ''latest''
+    * you can check which images have which tags with ''docker images''
+      * some images might have ''latest'' but not be base images so they won't be updated
+  * check the logs: ''docker logs watchtower''
+  * if you want Watchtower to skip trying to update an image add to ''docker-compose.yml''
+<code>
+ services:
+  db:
+    # label the image as each image gets its own label
+    image: mariadb:latest # an example
+    labels:
+      - "com.centurylinklabs.watchtower.enable=false" # ADD THIS LINE
+</code>
+  * run watchtower immediately: ''docker run --rm -v /var/run/docker.sock:/var/run/docker.sock containrrr/watchtower --run-once''
+===== Basic Operations =====
+  * ''docker run'': run container
+    * use the ''-d'' flag for "detach" i.e. run in background
+    * use the ''-p'' flag to forward the port i.e. ''-p 9000:80'' maps port 80 in the container to 9000 on the host
+    * user the ''--name'' flag to name the container (otherwise it's auto generated)
+  * ''docker stop <ID>''
+  * ''docker logs <ID>''
+  * ''docker start <ID>'': restart a container
+  * ''docker build <DIR_WHERE_Dockerfile_IS_LOCATED>'': build the image
+    * ''-t'': add name and tag. Ex: ''docker build -t node-app:1.0 .''
+===== Docker Registry =====
+  * Docker Hub is the default registry and it is the biggest public registry
+  * you can store a private or public registry on Docker Hub
+  * Each application gets its on repo in the registry
+===== creating a Dockerfile =====
+  * All dockerfiles start with a parent image or "base image"
+  * define the base image with ''FROM''
+  * copy files into the container: ''COPY''
+    * example: ''COPY package.json /app/''
+  * set the working directory: ''WORKDIR''
+    * example: ''WORKDIR /app''
+  * next come the dependencies: ''RUN <dependencies here>''
+    * example: ''RUN npm install''
+  * for the last command in the docker file i.e. start the process: ''CMD''
+    * example: ''CMD ["node", "server.js"]''