Plugins do not stop properly

[zsoltkacsandi]

Description

Plugins executed via scanner/families/plugins/runner/runner.go do not exit properly in the following scenarios:

• context deadline/cancellation
• a panic occurs
• termination of the scanner process (e.g. getting a SIGINT)

Resulting in zombie processes and stuck plugin containers:

Error response from daemon: Cannot kill container: 1428993dcd5f: container 1428993dcd5f PID 38877 is zombie and can not be killed. Use the --init option when creating containers to run an init inside the container that forwards signals and reaps processes

There are multiple reasons for this behaviour:

• if the parent context is cancelled, the family manager returns and does not wait for the underlying goroutines to finish their execution
• the Stop and Remove functions do not have a separate context, if the context passed from the CLI is cancelled, the cancellation propagates to these functions as well
• panics are not handled

Expected Behavior

Plugins exit gracefully if something happens that deviates from the happy path.
Plugin containers are able to handle OS signals properly.

Steps to Reproduce

1. Run the scanner CLI with a plugin enabled
2. After the plugin has started running, terminate the main process, cause a panic, or cancel the context passed to the plugin runner

Checklist

• I have read the contributing guidelines
• I have verified this does not duplicate an existing issue