## Motivation
Closes#5016
Depends on linkerd/linkerd2-proxy-api#44
## Solution
A `profileTranslator` exists for each service and now has a new
`fullyQualifiedName` field.
This field is used to set the `FullyQualifiedName` field of
`DestinationProfile`s each time an update is sent.
In the case that no service profile exists for a service, a default
`DestinationProfile` is created and we can use the field to set the correct
name.
In the case that a service profile does exist for a service, we still use this
field to set the name to keep it consistent.
### Example
Install linkerd on a cluster and run the destination server:
```
go run controller/cmd/main.go destination -kubeconfig ~/.kube/config
```
Get the IP of a service. Here, we'll get the ip for `linkerd-identity`:
```
> kubectl get -n linkerd svc/linkerd-identity
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
linkerd-identity ClusterIP 10.43.161.68 <none> 8080/TCP 4h25m
```
Get the profile of `linkerd-identity` from service name or IP and note the
`FullyQualifiedName` field:
```
> go run controller/script/destination-client/main.go -method getProfile -path 10.43.161.68:8080
INFO[0000] fully_qualified_name:"linkerd-identity.linkerd.svc.cluster.local" ..
```
```
> go run controller/script/destination-client/main.go -method getProfile -path linkerd-identity.linkerd.svc.cluster.local
INFO[0000] fully_qualified_name:"linkerd-identity.linkerd.svc.cluster.local" ..
```
Signed-off-by: Kevin Leimkuhler <kevin@kleimkuhler.com>
The openAPIV3Schema validation in the ServiceProfiles CRD is very limited in what it can validate and is obviated by more sophisticated validation done by the validating admission controller. Therefore, we would like to remove the openAPIV3Schema validation to reduce the size and complexity of the CRD object.
To do so, we must also bump the version of the ServiceProfile custom resource from v1alpha1 to v1alpha2. This ensures that when the controller is upgraded, it will attempt to watch the v1alpha2 resource. If it cannot (because, for example, the controller pod started before the ServiceProfile CRD was updated and therefore the v1alpha2 version does not exist) then it will go into a crash loop backoff until it can. This essentially means that the controller will wait for the CRD to be upgraded to include v1alpha2 before it will start.
Bumping the version is necessary because if we did not, it would be possible for the controller to start before the CRD is updated (removing the validation). In this case, when the CRD is edited, the controller will lose its list watch on ServiceProfiles and will stop getting updates.
Signed-off-by: Alex Leong <alex@buoyant.io>
This change implements the DstOverrides feature of the destination profile API (aka traffic splitting).
We add a TrafficSplitWatcher to the destination service which watches for TrafficSplit resources and notifies subscribers about TrafficSplits for services that they are subscribed to. A new TrafficSplitAdaptor then merges the TrafficSplit logic into the DstOverrides field of the destination profile.
Signed-off-by: Alex Leong <alex@buoyant.io>
This is a major refactor of the destination service. The goals of this refactor are to simplify the code for improved maintainability. In particular:
* Remove the "resolver" interfaces. These were a holdover from when our decision tree was more complex about how to handle different kinds of authorities. The current implementation only accepts fully qualified kubernetes service names and thus this was an unnecessary level of indirection.
* Moved the endpoints and profile watchers into their own package for a more clear separation of concerns. These watchers deal only in Kubernetes primitives and are agnostic to how they are used. This allows a cleaner layering when we use them from our gRPC service.
* Renamed the "listener" types to "translator" to make it more clear that the function of these structs is to translate kubernetes updates from the watcher to gRPC messages.
Signed-off-by: Alex Leong <alex@buoyant.io>
Kevin Leimkuhler
Oliver Gould
Alex Leong