Similar to #11246, the destination controller was complaning above
trying to register dupe metrics for the api cache gauges, when a given
target cluster got re-linked. This change unregisters the gauges for the
target cluster when said cluster is removed.
Supersedes #11252
Adds support for remote discovery to the destination controller.
When the destination controller gets a `Get` request for a Service with the `multicluster.linkerd.io/remote-discovery` label, this is an indication that the destination controller should discover the endpoints for this service from a remote cluster. The destination controller will look for a remote cluster which has been linked to it (using the `linkerd multicluster link` command) with that name. It will look at the `multicluster.linkerd.io/remote-discovery` label for the service name to look up in that cluster. It then streams back the endpoint data for that remote service.
Since we now have multiple client-go informers for the same resource types (one for the local cluster and one for each linked remote cluster) we add a `cluster` label onto the prometheus metrics for the informers and EndpointWatchers to ensure that each of these components' metrics are correctly tracked and don't overwrite each other.
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Signed-off-by: Alex Leong <alex@buoyant.io>
There were a few improvements we could have made to a recent change that
added a ClusterStore concept to the destination service. This PR
introduces the small improvements:
* Sync dynamically created clients in separate go routines
* Refactor metadata API creation
* Remove redundant check in cluster_store_test
* Create a new runtime schema every time a fake metadata API client is
created to avoid racey behaviour.
Signed-off-by: Matei David <matei@buoyant.io>
Currently, the control plane does not support indexing and discovering resources across cluster boundaries. In a multicluster set-up, it is desirable to have access to endpoint data (and by extension, any configuration associated with that endpoint) to support pod-to-pod communication. Linkerd's destination service should be extended to support reading discovery information from multiple sources (i.e. API Servers).
This change introduces an `EndpointsWatcher` cache. On creation, the cache registers a pair of event handlers:
* One handler to read `multicluster` secrets that embed kubeconfig files. For each such secret, the cache creates a corresponding `EndpointsWatcher` to read remote discovery information.
* Another handle to evict entries from the cache when a `multicluster` secret is deleted.
Additionally, a set of tests have been added that assert the behaviour of the cache when secrets are created and/or deleted. The cache will be used by the destination service to do look-ups for services that belong to another cluster, and that are running in a "remote discovery" mode.
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Signed-off-by: Matei David <matei@buoyant.io>
* Use metadata API in the proxy and tap injectors
Part of #9485
This adds a new `MetadataAPI` similar to the current `k8s.API` hosting informers, but backed by k8s' `metadatainformer` shared informers, which retrieves only the objects metadata, resulting in less memory consumption by its clients. Currently this is only implemented for the proxy and tap injectors. Usage by the destination controller will be implemented as a follow-up.
## Existing API enhancements
Shared objects and logic required by API and MetadataAPI have been moved to the new `k8s.go`, `api_resource.go` and `prometheus.go` files. That includes the `isValidRSParent()` function whose arg is now more generic.
## Unit tests
`/controller/k8s/api_test.go` now also instantiates a MetadataAPI, used in the augmented `TestGetObjects()` and `TestGetOwnerKindAndName()` tests. The `resources` struct was introduced to capture the common fields among tests and simplify `newMockAPI()`'s signature.
## Other Changes
The injector no longer watches for Pods. It only requires watching workloads that own resources (and also watch namespaces), so Pod is not required.
## Testing Memory Consumption
Install linkerd, inject emojivoto and check the injector memory consumption with `kubectl -n linkerd top pod linkerd-proxy-injector-xxx`. It'll start consuming about 16Mi. Then ramp up emojivoto's `voting` deployment replicas to 2000. After 5 minutes memory will stabilize around 32Mi using the current branch. Using the latest edge, it'll stabilize around 110Mi.
Alejandro Pedraza
Alex Leong
Matei David