Health check a server with 'nohup $(cmd) &'

While working on a project with [EdgeDB] and [FastAPI], I wanted to perform health checks against the FastAPI server in the GitHub CI. This would notify me about the working state of the application. The idea is to: - Run the server in the background. - Run the commands against the server that'll denote that the app is in a working state. - Perform cleanup. - Exit with code 0 if the check is successful, else exit with code 1. The following shell script demonstrates a similar workflow with a Python HTTP server. This script: - Runs a Python web server in the background. - Makes an HTTP request against the server and checks if it returns HTTP 200 (OK). If the request fails or the server isn't ready then waits for a second and makes the request again, and keeps retrying for the next 20 times before giving up. - Performs cleanups and kills the Python processes. - Exit with code 0 if the request is successful, else exit with code 1. The nohup before the python3 -m http.server 5000 makes sure that the SIGHUP signal can't reach the server and shut down the process. The ampersand & after the command runs the process in the background. Afterward, the script starts making requests to the http://localhost:5000/ URL in a loop. If the server returns HTTP 200, the health check is considered successful. This will break the loop and the script will be terminated with exit 0 status. If the server doesn't return HTTP 200 or isn't ready yet, the script will keep retrying 20 times with a 1 second interval between each subsequent request before giving up. A failed health check will cause the script to terminate with exit 1 status. Further reading - [Difference between nohup and ampersand] [edgedb]: https://www.edgedb.com/ [fastapi]: https://fastapi.tiangolo.com/ [difference between nohup and ampersand]: https://stackoverflow.com/questions/15595374/whats-the-difference-between-nohup-and-ampersand