The following terms are used within this document to describe the different parts of the Healthchecker:
An execution unit including all needed configuration that returns one of the exit states 0 (SUCCESS), 1 (WARNING), or 2 (ERROR). In case of a warning or error a text string describing the problem can be returned.
A reusable execution unit doing a single kind of check.
Checks are typically implemented using shell scripts or calling a system command like grep.
A set of tests executed together (depending on connected classes) and returning the highest exit state of all included tests.
Each test can be connected to one or more classes. The test is only executed on nodes that belong to one of its connected classes.