This PR refactors xds_client to support multiples watches. Those watches can be for the same type and same resource_name.
There's upper level `Client` and lower level `v2client`. Before this change, all logic was in `v2client`, and `Client` was a thin wrapper.
This PR moves some of the functionality from `v2client` to `Client`. New layers:
- Upper level `Client`
- keeps a list of watchers
- provides method `func WatchXXX() (cancel func())`
- has `WatchService()` which involves `LDS` and `RDS`
- handles resources from the xDS responses and dispatch to the watchers
- including multiple watchers for the same resource_name
- keeps cache
- and checks cache for new watches
- Lower level `v2client`
- is a dumb client that
- manages ADS stream
- sends a new xDS request when add/remove watch
- parses xDS responses
- It doesn't call watchers, but forwards all parsed results to upper Client
- handles ACK/NACK
- supports `addWatch(type, name)` and `removeWatch(type, name)`
- instead of `func watchCDS() func()`, which is now moved up to upper `Client`
Also includes other changes:
- Corresponding test changes (some tests for `v2client` were moved to `Client`)
- Method and type renaming
- CDS/EDS -> Cluster/Endpoints
- callback functions all accept updates as non-pointers
- More logs in xds bootstrap/resolver/cds/eds
- Bootstrap file content/error
- Request/response on ADS stream
- Actions by client/resolver/balancer
- Content of updates
- Logs prefixed with component name and id
- `[xds-bootstrap]`
- `[xds-client <address>]`
- `[cds-lb <address>]`
- `[eds-lb <address>]`
We are using some sane defaults for now:
KeepaliveTime: 5 minutes
KeepaliveTimeout: 20 seconds
PermitWithoutStream: false
This does differ with the defaults used internally, but we are OK with
it, because it is more important to have a reasonable value here than
having one that works for all deployments or even making this
configurable through the bootstrap file.
This PR removes the xds_client implementation from eds balancer, and replaces it with a xds_client wrapper. (The xds_client wrapper has very similar API as the old xds_client implementation, so the change in the eds balancer is minimal).
The eds balancer currently doesn't look for xds_client from attributes, and always creates a new xds_client. The attributes change will be done in a following up change.
* Add a helper to the fakexds package to return a ClientConn talking to
the fake server.
* Tests will make use of this ClientConn wherever required, or they will
directly pass the fake server's address as the balancerName to the
xdsclient.New() function, thus exercising that code path as well.
* Add grpc.WithTimeout to list in vet.sh
Easwar Swaminathan