health

package health

The health package handles internal healthchecks for the agents, that allow to check every asynchronous component is running as intended.

For more information on the context, see the agent-healthcheck.md proposal.

How to add a component?

• First, you need to register, by calling health.Register with a user-visible name. You will receive a *health.Handle to keep. As soon as Register is called, you need to start reading the channel to be considered healthy.

• In your main goroutine, you need to read from the handle.C channel, at least every 15 seconds. This is accomplished by using a select statement in your main goroutine. If the channel is full (after two tries), your component will be considered unhealthy, which might result in the agent getting killed by the system.

• If your component is stopping, it should call handle.Deregister() before stopping. It will then be removed from the healthcheck system.

Where should I tick?

It depends on your component lifecycle, but the check's purpose is to check that your component is able to process new input and act accordingly. For components that read input from a channel, you should read the channel from this logic.

This is usually hightly unprobable, but it's exactly the scope of this system: be able to detect if a component is frozen because of a bug / race condition. This is usually the only kind of issue that could be solved by the agent restarting.