This repository is to experiment docker's HEALTHCHECK feature. You can (and should) configure HEALTHCHECK for your app. Docker will periodically run these checks and can take action if a container becomes unhealthy.
It contains a small web app written in Go that exposes /health endpoint. It has a small API, that can change its health status.
/sabotagewill make it respond with 500./timeoutwill make it respond after 20s./recoverwill return it back to healthy state, with 200 response code.
From Docker docs -
The HEALTHCHECK instruction has two forms:
HEALTHCHECK [OPTIONS] CMD command (check container health by running a command inside the container)
HEALTHCHECK NONE (disable any healthcheck inherited from the base image)
The HEALTHCHECK instruction tells Docker how to test a container to check that it is still working. This can detect cases such as a web server that is stuck in an infinite loop and unable to handle new connections, even though the server process is still running.
When a container has a healthcheck specified, it has a health status in addition to its normal status. This status is initially starting. Whenever a health check passes, it becomes healthy (whatever state it was previously in). After a certain number of consecutive failures, it becomes unhealthy.
The options that can appear before CMD are:
--interval=DURATION (default: 30s)
--timeout=DURATION (default: 30s)
--start-period=DURATION (default: 0s)
--retries=N (default: 3)
-
Clone the repo and build the image:
docker build . -t go-healthchecker -
Bring up the container, wait until it gets healthy.
- To change the healthcheck response, connect to the container and update its status
