What is the effect of failing a health check in a Docker container?

When a container fails a health check, it indicates that the application inside the container is not functioning as expected. The purpose of health checks is to monitor the state of the running services in the container and determine whether they are responding correctly.

If a container consistently fails its health check, Docker will recognize this issue and take action based on the health check configuration. Specifically, if the health check fails a certain number of times (as defined by the health check parameters), Docker automatically marks the container as unhealthy. When this happens, the container is typically restarted to attempt to recover the application to a healthy state.

This automated response helps maintain the overall reliability and availability of services running in a Docker environment. By ensuring that containers that are not functioning correctly are restarted, Docker helps to minimize downtime and keep the system healthy.

The other options do not accurately represent the behavior of Docker in response to failed health checks. For example, the container does not simply continue running without issues, nor are its resources reallocated in a manner directly tied to health checks, and the image of the container is not rebuilt automatically due to health check failures.