One of the benefits of buildpacks is that they are multi-process - an image can have multiple entrypoints for each operational mode.
Let’s see how this works. We will specify a process type that allows a debugger to attach to our application.
To enable running the debug process, we’ll need to have our buildpack define a “process type” for the worker.
We’ll need to create a launch.toml file in the buildpack layers directory:
# ...
cat > "${CNB_LAYERS_DIR}/launch.toml" << EOL
# our web process
[[processes]]
type = "web"
command = ["node", "app.js"]
default = true
# our debug process
[[processes]]
type = "debug"
command = ["node", "--inspect", "app.js"]
EOL
# ...
After building the application, you should then be able to run your new NodeJS debug process:
docker run --rm --entrypoint debug test-node-js-app
and see the debug log output:
Debugger listening on ws://127.0.0.1:9229/