Docker Course Labs

Lab Solution

My solution is here:

Copy it to the main folder so the config paths are correct, and the app will work:

cp labs/troubleshooting/lab/solution.yml labs/troubleshooting/

docker-compose -f labs/troubleshooting/solution.yml up -d

Use the app at http://localhost:8090

Validation failures

  1. The image name is incorrect for the web component. You'll see a manifest unknown error.

  2. Not enough CPUs - the web application request 25 CPUs, which is a typo - it should be 2.5. Unless you have a mega powerful machine, Docker can't allocate enough CPUs to create the container.

Startup failures

  1. Incorrect entrypoint for the API. It's specifying the command to run but dontet is a typo. You'll see executable file not found in $PATH - it should be dotnet.

  2. Duplicate port mapping - both the web app and API are trying to publish port 8089. You'll see port is already allocated - the web app should be publishing to port 8090.

Runtime failures

  1. The API container exits after starting. Check the logs and you'll see the application was not found. The volume mount is incorrect - it's loading the config folder into the /app folder, which overwrites the contents from the image so there is no application binary. The volume target should be /app/config.

Networking failures

  1. Try using the website and you'll get the RNG service unavailable! error. The web container logs show you the app is using the correct URL, but if you run nslookup the API container can't be found. The spec uses two different networks, so the containers aren't connected - the web container needs to attach to the app-net network.