Add a HEALTHCHECK to an Image

Labs have no container engine, so nothing is built or started: your files are checked by reading them, the way a reviewer or a CI linter would. docker-compose config (to validate Compose files) and hadolint (a Dockerfile linter) are installed.

The service in /home/student/projects/image-resizer sometimes hangs while its process keeps running, so nothing restarts it. It answers GET /healthz on port 8777 with status 200 when it is healthy.

Task

Add a HEALTHCHECK to the Dockerfile that:

• calls http://localhost:8777/healthz with curl, failing on any HTTP error status (curl -f)
• runs every 30 seconds, with a 3-second timeout, marking the container unhealthy after 3 failures in a row
• gives the service 10 seconds to start before failures count