- Write a small nodejs app that uses a mongo database for some CRUD operations.
- The homepage (/) will show a list of users available in your database in a tabular format.
- The homepage will also have a form through which we can write some information (First Name, Last Name, Email Address, Mobile Number) about the user in the database.
- In the table showing the information of the users, there will be two buttons for each row.
- The “Edit” button will allow us to edit the existing information of the user.
- The “Delete” button can delete the user from the database.
- Once the nodejs application is ready and functional, write a Dockerfile for building the image for the application.
- After that, write a docker-compose file which will allow us to use the application.
Most frontend frameworks won't pass all environment variables to browser runtime. Only variables with specific name format (e.g. prefix by REACT_APP_ for react) will be passed.
COPY ./src . copies the contents of ./src (not the folder itself) to workdir. In most cases, you want to do COPY ./src ./src. (https://stackoverflow.com/a/30316600)
If volume mounting file, ensure that it exists in both sides, otherwise docker create a directory instead of a file (https://stackoverflow.com/a/64821508)
User USER root in Dockerfile unless default user (from base) is root.
To access host machine's ports from container, add the following in docker-compose.yml (non-compose containers run using docker run automatically get this):
extra_hosts:
- "host.docker.internal:host-gateway"
# Access host machine's localhost using host.docker.internalPass environment variables to docker run command: https://stackoverflow.com/a/46547817
SERVER_HOST has to be 0.0.0.0 to listen to requests from outside container.
Docker logs are line-buffered. So if a command prints without newline, you may not be able to see it in docker logs. For same reason, can't see progress bars of pip install.
From inside a container process, docker's stdout can be accessed by /proc/1/fd/1 and stderr can be accessed by /proc/1/fd/2. So, for seeing output of a cron, use * * * * * printf "[$(date -Iseconds)]\t$(curl -s polling:8090)\n" > /proc/1/fd/1 2>/proc/1/fd/2. % has to be escaped in crontab`.
You can create overlapping local to remote mounts: https://stackoverflow.com/questions/50238503/overlapping-bind-mounts-and-permissions-in-docker-on-linux
To prevent docker with background processes from shutting down, add CMD tail -f /dev/null.
Use alias compose-up="docker-compose pull && docker-compose up -d --build --remove-orphans". Without pull, latest tagged image may not actually be latest and without --build, compose will use your previous built image even if your Dockerfile has changed.
Also use alias docker-ps='docker ps --format "table {{.Names}}\t{{.RunningFor}}\t{{.Status}}\t{{.Ports}}"'
At each step, docker build doesn't use cache if any of the workdir files or previous steps have changed since last build. Use RUN --mount=type=cache,target=/root/.cache for dependency installation commands to persist dependency caches across builds.
https://docs.docker.com/compose/compose-file/#extension && https://www.educative.io/blog/advanced-yaml-syntax-cheatsheet && https://docs.docker.com/build/building/secrets/
If you just need to change the entrypoint from an image, directly do it in docker-compose using command: instead of creating a separate Dockerfile.
Connect multiple compose projects using https://docs.docker.com/compose/compose-file/06-networks/#external , connect remote compose project's network using https://code.visualstudio.com/docs/containers/ssh (docker context create my-remote-docker-machine --docker "host=ssh://username@host:port"). :caution: Caution Don't forget to revert the docker context to default. As long as you're in a remote machine's docker context, all mappings (port / volume) will work in the remote machine's context. This is often a deal-breaker as it can't support hot-reloading.