Add max-depth to global config

[danthegoodman1]

Is your feature request related to a problem? Please describe.

It would be nice for multi-tenant environmentss to be able to specify a global max-depth such that requests would not be able to cause high latency and demanding DB queries.

Describe the solution you'd like

Adding max-depth as a something the max-depth query param cannot exceed.

Describe alternatives you've considered

None

Additional context

[zepatrik]

Makes sense 👍

[doodlesbykumbi]

Trying to confirm I understand what is meant by

max-depth to global config

Does this mean setting max-depth in the configuration passed to serve, such that the effective max-depth for any given request is the lesser one between the global max-depth vs the request max-depth ?

[danthegoodman1]

Trying to confirm I understand what is meant by

max-depth to global config

Does this mean setting max-depth in the configuration passed to serve, such that the effective max-depth for any given request is the lesser one between the global max-depth vs the request max-depth ?

@doodlesbykumbi yep!

[doodlesbykumbi]

Thanks @danthegoodman1. I follow the gist of this feature request and the motivation. I think the implementation should be straightforward. I wonder though if the idea of "depth" will be semantically consistent across all the things that will make use of this global value. It definitely is consistent between check and expand, just not sure if that will generally be the case. Never-mind, I'm fairly certain it'll be consistent.

[doodlesbykumbi]

So here's my proposal for an implementation

1. Add a serve.read.max-depth key to the config schema. Something like:

{
  "max-depth": {
    "type": "integer",
    "default": 1000,
    "title": "Maximum depth",
    "description": "The maximum depth on all read operations.",
    "minimum": 0,
    "maximum": 65535
  }
}

2. Expose the value in the Config provider through something like

KeyReadMaxDepth = "serve.read.max-depth"
func (k *Config) ReadAPIMaxDepth() int {
	return k.p.Int(KeyReadMaxDepth)
}

3. Consume the value via dependency injection in expand and check (for both gRPC and HTTP):

	// The lesser of the global max-depth and the request max-depth
	maxDepth := h.d.Config().ReadAPIMaxDepth()
	if int(req.MaxDepth) < maxDepth {
		maxDepth = int(req.MaxDepth)
	}

4. Add unit tests to confirm that the lesser value takes precedence (for both gRPC and HTTP).