This field only accepts IP addresses; it is an error to use
a DNS name with it.
The sources helper was swallowing the helpful part of the context
about the issue with that field.
This commit ensures that we do surface it.
The purpose is to provide a deeper, offline validation pass
of the policy configuration, prior to deploying and making it
live.
The system behavior changes when in `--validate` mode:
* Listeners, spool and spawned tasks will be silently skipped;
the parameters will be validated but the primary functions
of those things will be skipped silently.
* After triggering the `init` event, an additional new `validate_config`
event (which can be registered multiple times) will be triggered
to allow lua modules to perform extended validation.
* A module can either raise an error via `error` to immediately report
a problem, or instead call a new, preferred, `kumo.validation_failed()`
function to flag validation as failed but allow additional validation
to be performed and summarized all together.
* Once the `validate_config` event returns, the process will terminate
with either exit code 0 for a successful validation, or non-zero
to indicate that something failed.
Validation errors are reported in a human readable form.
This commit adds validate_config event handlers for the following
helper modules:
* `shaping` - any warnings reported by the underlying rust code
will be reported here and cause validation to fail. This is
functionally equivalent to using the `validate-shaping` binary,
except that it will automatically be passed the set of shaping
files defined by your `init.lua`
If the `sources` helper is also configured, the list of sources
referenced by the shaping config will be cross-checked against
the sources data to confirm that all possible sources are defined.
* `sources` - each listed source and pool will be validated by
calling `kumo.make_egress_source` or `kumo.make_egress_pool`
respectively.
Pool membership will be validated to confirm that every
listed pool is defined in the sources data.
* `queues` - each domain and tenant that references an egress_pool
will be cross-checked with the `sources` helper, if the sources
helper has been configured.
It is now an error to attempt to setup any of the above helpers
more than once.
refs: https://github.com/KumoCorp/kumomta/issues/211
Wez Furlong