feat: add timeout to did resolver resolve method #2464

dbluhm · 2023-09-06T00:31:34Z

This PR adds a timeout parameter to the DID Resolver interface, defaulting to 30 seconds. Without it, a poorly behaved resolver plugin can "resolve" documents that aren't actually DID Docs and cause ACA-Py to run out of memory.

There's space for additional tuning on the timeout default. Some DID Methods are, in my experience, quite slow (did:btcr and did:ion resolvers can be pretty slow sometimes). 30 seconds might be overly charitable.

burdettadam · 2023-09-06T15:46:15Z

aries_cloudagent/resolver/did_resolver.py

@@ -42,20 +43,28 @@ async def _resolve(
 profile: Profile,
 did: Union[str, DID],
 service_accept: Optional[Sequence[Text]] = None,
+ *,
+ timeout: Optional[int] = None,


why not initialize to 30 instead of None? That would make it more evident that the time-out default is 30 seconds.

Fair question; using the optional enables expression that the timeout wasn't set. Since we call _resolve from two other methods, and we want the timeout to apply to both and we want a default of 30 seconds when the timeout isn't set, we would have to set the default timeout to 30 on both the resolve and resolve_with_metadata methods or else make sure the timeout wasn't included in the call to _resolve. It ends up being cleaner to set the default when timeout is None. But I think there's a middle ground. I'll put a constant on the class that has the default timeout value so it's clearer what it is and how it's used at a glance.