> For the complete documentation index, see [llms.txt](https://yingzehou.gitbook.io/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://yingzehou.gitbook.io/docs/anaplanintern/docker.md). # Docker Tool for running app in isolated environment ## Container Abstraction at the app layer that packages **code** and **dependencies** together. Multiple containers can run on **SAME** machine, each as an **ISOLATED** process * A running instance of an Image ## Virtual Machines Abstraction of physical hardware-->turn one server into many. Full copy of OS, app, and libraries; Takes up huge space and slow to boot ## Docker Image * Template for creating an environment * Snapshot * Has everything need to run app (OS, Software, App code) ## General Process 1. Pull official Images from Docker Hub: `docker pull nginx` and check all Images`: docker images` 2. Run a container in Image: `docker run -d -p 8080:80 nginx:latest;` "latest" is the TAG and needed 3. Check all containers running: `docker container ls` 4. Remove container: `docker rm [ID/NAME]` / `docker rm $(docker ps -aq)` / `docker rm -f $(docker ps -aq)` ## Exposing Port * The container is running with a port of 80 * Host issue request of localhost:8080 mapped to PORT 80 in container --> run -p 8080:80 when running the container * Open up browser and go to localhost:8080 to get the container's application's page * Multiple hosts to one port: `-p 8080:80 -p 3000:80` ## Naming Container * `docker run --name website -d -p 3000:80 -p 8080:80 nginx:latest` Specify the name, easier to identify and stop ## Volumes Allow sharing of data, files, and folders * Hosts and container form Volumes * Create file locally: website/index.html (website is a folder) * `docker run --name website -v $(pwd):/usr/share/nginx/html:ro -d -p 8080:80 nginx:latest.` In this way, we serve the container with our local file (ro Read Only flag can be removed in order to write into container) * `docker exec -it website bash`. In this way, we will be inside the container. Go to usr/share/nginx/html to make changes, and these changes will be on local machine as well ## Share Volumes Between Containers * `docker run --name website-copy --volumes-from website -d -p 8081:80 nginx:latest.` In this way, we use the data from website container to serve the website-copy container. ## DockerFile Create our own images {% embed url="" %} * Create a file called "Dockerfile" in the root directory of project ```docker FROM nginx:latest ADD . /usr/share/nginx/html ``` * `docker build --tag website:latest .` (. stands for current directory, this is where to look for a Dockerfile) * Can use node.js and express framework to make a simple backend server ```docker FROM node:latest WORKDIR /app ADD . . RUN npm install CMD node index.js ``` * Go into your local node.js app folder: `docker build --tag user-api:latest .` * `docker run --name user-api -d -p 3000:3000 user-api:latest` This runs the container ### .dockerignore ```docker node_modules Dockerfile .git folder/** ``` ## Layer and Cache Use cache to boost performance: A source file change shouldn't trigger all things to rebuild ```docker FROM node:latest WORKDIR /app ADD package*.json ./ RUN npm install ADD . . CMD node index.js ``` In this way, adding package.json & package-lock.json into the container is using cache since these two files are not changing. ## Reduce Image Size Use **ALPINE**; Supported tags for official images `docker pull node:lts-alpine` --> smaller size and faster Tags, Versioning, and Tagging: * Allow control image version * Avoid breaking changes (Not always using the latest version) * Safe Have control over the tags + version: `docker pull node:8-alpine` instead of `docker pull node:alpine` ### How to correctly Tag images `docker tag website:latest website:1` Tag from latest to 1, so that tag 1 contains current version. If do another `docker tag website:latest website:2`, tag 2 will be pointing to the latest one, and changes in the latest version will not reflect in tag 1 ## Docker Registries * Server application that can store and distribute Docker images. Store images in a server host instead of our local host * Used in CD/CI Pipeline * Running our applications by uploading container from local to registry. Host have images --> Have a docker registry --> push images from host to docker registry Private/Public Registry ### Create Docker Hub Repo 1. Create Repo from Docker Hub website (Similar to Github) 2. `docker push user/website:tagname` to push new tag to the repo ## Inspect and Logs `docker logs [containerID]` to show all logs `docker logs -f [containerID]` to follow the log and see real-time updates when new logs happen `docker inspect [containerID]` to inspect detailed information of this container