The grpc resolver implementation is fed from changes to the
router.Router. Within the router there is a map of various areas storing
the addressing information for servers in those areas. All map entries
are of the WAN variety except a single special entry for the LAN.
Addressing information in the LAN "area" are local addresses intended
for use when making a client-to-server or server-to-server request.
The client agent correctly updates this LAN area when receiving lan serf
events, so by extension the grpc resolver works fine in that scenario.
The server agent only initially populates a single entry in the LAN area
(for itself) on startup, and then never mutates that area map again.
For normal RPCs a different structure is used for LAN routing.
Additionally when selecting a server to contact in the local datacenter
it will randomly select addresses from either the LAN or WAN addressed
entries in the map.
Unfortunately this means that the grpc resolver stack as it exists on
server agents is either broken or only accidentally functions by having
servers dial each other over the WAN-accessible address. If the operator
disables the serf wan port completely likely this incidental functioning
would break.
This PR enforces that local requests for servers (both for stale reads
or leader forwarded requests) exclusively use the LAN "area" information
and also fixes it so that servers keep that area up to date in the
router.
A test for the grpc resolver logic was added, as well as a higher level
full-stack test to ensure the externally perceived bug does not return.
Registering gRPC balancers is thread-unsafe because they are stored in a
global map variable that is accessed without holding a lock. Therefore,
it's expected that balancers are registered _once_ at the beginning of
your program (e.g. in a package `init` function) and certainly not after
you've started dialing connections, etc.
> NOTE: this function must only be called during initialization time
> (i.e. in an init() function), and is not thread-safe.
While this is fine for us in production, it's challenging for tests that
spin up multiple agents in-memory. We currently register a balancer per-
agent which holds agent-specific state that cannot safely be shared.
This commit introduces our own registry that _is_ thread-safe, and
implements the Builder interface such that we can call gRPC's `Register`
method once, on start-up. It uses the same pattern as our resolver
registry where we use the dial target's host (aka "authority"), which is
unique per-agent, to determine which builder to use.
Protobuf Refactoring for Multi-Module Cleanliness
This commit includes the following:
Moves all packages that were within proto/ to proto/private
Rewrites imports to account for the packages being moved
Adds in buf.work.yaml to enable buf workspaces
Names the proto-public buf module so that we can override the Go package imports within proto/buf.yaml
Bumps the buf version dependency to 1.14.0 (I was trying out the version to see if it would get around an issue - it didn't but it also doesn't break things and it seemed best to keep up with the toolchain changes)
Why:
In the future we will need to consume other protobuf dependencies such as the Google HTTP annotations for openapi generation or grpc-gateway usage.
There were some recent changes to have our own ratelimiting annotations.
The two combined were not working when I was trying to use them together (attempting to rebase another branch)
Buf workspaces should be the solution to the problem
Buf workspaces means that each module will have generated Go code that embeds proto file names relative to the proto dir and not the top level repo root.
This resulted in proto file name conflicts in the Go global protobuf type registry.
The solution to that was to add in a private/ directory into the path within the proto/ directory.
That then required rewriting all the imports.
Is this safe?
AFAICT yes
The gRPC wire protocol doesn't seem to care about the proto file names (although the Go grpc code does tack on the proto file name as Metadata in the ServiceDesc)
Other than imports, there were no changes to any generated code as a result of this.
This is the OSS portion of enterprise PR 3822.
Adds a custom gRPC balancer that replicates the router's server cycling
behavior. Also enables automatic retries for RESOURCE_EXHAUSTED errors,
which we now get for free.
Allow for some message duplication in subscription events during assertions.
I'm pretty sure the subscriptions machinery allows for messages to occasionally
be duplicated instead of dropping them, as a once-and-only-once queue is a pipe
dream and you have to pick one of the other two options.
Previously, public referred to gRPC services that are both exposed on
the dedicated gRPC port and have their definitions in the proto-public
directory (so were considered usable by 3rd parties). Whereas private
referred to services on the multiplexed server port that are only usable
by agents and other servers.
Now, we're splitting these definitions, such that external/internal
refers to the port and public/private refers to whether they can be used
by 3rd parties.
This is necessary because the peering replication API needs to be
exposed on the dedicated port, but is not (yet) suitable for use by 3rd
parties.
This is the OSS portion of enterprise PR 2056.
This commit provides server-local implementations of the proxycfg.ConfigEntry
and proxycfg.ConfigEntryList interfaces, that source data from streaming events.
It makes use of the LocalMaterializer type introduced for peering replication,
adding the necessary support for authorization.
It also adds support for "wildcard" subscriptions (within a topic) to the event
publisher, as this is needed to fetch service-resolvers for all services when
configuring mesh gateways.
Currently, events will be emitted for just the ingress-gateway, service-resolver,
and mesh config entry types, as these are the only entries required by proxycfg
— the events will be emitted on topics named IngressGateway, ServiceResolver,
and MeshConfig topics respectively.
Though these events will only be consumed "locally" for now, they can also be
consumed via the gRPC endpoint (confirmed using grpcurl) so using them from
client agents should be a case of swapping the LocalMaterializer for an
RPCMaterializer.
Introduces the capability to configure TLS differently for Consul's
listeners/ports (i.e. HTTPS, gRPC, and the internal multiplexed RPC
port) which is useful in scenarios where you may want the HTTPS or
gRPC interfaces to present a certificate signed by a well-known/public
CA, rather than the certificate used for internal communication which
must have a SAN in the form `server.<dc>.consul`.
TestSubscribeBackend_IntegrationWithServer_DeliversAllMessages has been
flaking a few times. This commit cleans up the test a bit, and improves
the failure output.
I don't believe this actually fixes the flake, but I'm not able to
reproduce it reliably.
The failure appears to be that the event with Port=0 is being sent in
both the snapshot and as the first event after the EndOfSnapshot event.
Hopefully the improved logging will show us if these are really
duplicate events, or actually different events with different indexes.
tlsutil.Config already presents an excellent structure for this
configuration. Copying the runtime config fields to agent/consul.Config
makes code harder to trace, and provides no advantage.
Instead of copying the fields around, use the tlsutil.Config struct
directly instead.
This is one small step in removing the many layers of duplicate
configuration.
We have seen test flakes caused by 'concurrent map read and map write', and the race detector
reports the problem as well (prevent us from running some tests with -race).
The root of the problem is the grpc expects resolvers to be registered at init time
before any requests are made, but we were using a separate resolver for each test.
This commit introduces a resolver registry. The registry is registered as the single
resolver for the consul scheme. Each test uses the Authority section of the target
(instead of the scheme) to identify the resolver that should be used for the test.
The scheme is used for lookup, which is why it can no longer be used as the unique
key.
This allows us to use a lock around the map of resolvers, preventing the data race.
