Numerous codepaths have emerged that create k8s configs, k8s clients,
and make k8s api requests.
This branch consolidates k8s client creation and APIs. The primary
change migrates most codepaths to call `k8s.NewAPI` to instantiate a
`KubernetesAPI` struct from `pkg`. `KubernetesAPI` implements the
`kubernetes.Interface` (clientset) interface, and also persists a
`client-go` `rest.Config`.
Specific list of changes:
- removes manual GET requests from `k8s.KubernetesAPI`, in favor of
clientsets
- replaces most calls to `k8s.GetConfig`+`kubernetes.NewForConfig` with
a single `k8s.NewAPI`
- introduces a `timeout` param to `k8s.NewAPI`, currently only used by
healthchecks
- removes `NewClientSet` in `controller/k8s/clientset.go` in favor of
`k8s.NewAPI`
- removes `httpClient` and `clientset` from `HealthChecker`, use
`KubernetesAPI` instead
Signed-off-by: Andrew Seigner <siggy@buoyant.io>
The `install` command errors when the deploy target contains an existing
Linkerd deployment. The `upgrade` command is introduced to reinstall or
reconfigure the Linkerd control plane.
Upgrade works as follows:
1. The controller config is fetched from the Kubernetes API. The Public
API is not used, because we need to be able to reinstall the control
plane when the Public API is not available; and we are not concerned
about RBAC restrictions preventing the installer from reading the
config (as we are for inject).
2. The install configuration is read, particularly the flags used during
the last install/upgrade. If these flags were not set again during the
upgrade, the previous values are used as if they were passed this time.
The configuration is updated from the combination of these values,
including the install configuration itself.
Note that some flags, including the linkerd-version, are omitted
since they are stored elsewhere in the configurations and don't make
sense to track as overrides..
3. The issuer secrets are read from the Kubernetes API so that they can
be re-used. There is currently no way to reconfigure issuer
certificates. We will need to create _another_ workflow for
updating these credentials.
4. The install rendering is invoked with values and config fetched from
the cluster, synthesized with the new configuration.
https://github.com/linkerd/linkerd2/pull/2521 introduces an "Identity"
controller, but there is no way to include it in linkerd installation.
This change alters the `install` flow as follows:
- An Identity service is _always_ installed;
- Issuer credentials may be specified via the CLI;
- If no Issuer credentials are provided, they are generated each time `install` is called.
- Proxies are NOT configured to use the identity service.
- It's possible to override the credential generation logic---especially
for tests---via install options that can be configured via the CLI.
This change introduces a new Identity service implementation for the
`io.linkerd.proxy.identity.Identity` gRPC service.
The `pkg/identity` contains a core, abstract implementation of the service
(generic over both the CA and (Kubernetes) Validator interfaces).
`controller/identity` includes a concrete implementation that uses the
Kubernetes TokenReview API to validate serviceaccount tokens when
issuing certificates.
This change does **NOT** alter installation or runtime to include the
identity service. This will be included in a follow-up.
Andrew Seigner
Oliver Gould