The new proxy has changed its configuration as follows:
- `LISTENER` urls are now `LISTEN_ADDR` addresses;
- `CONTROL_URL` is now `DESTINATION_SVC_ADDR`;
- `*_NAMESPACE` vars are no longer needed;
- The `PROXY_ID` is now the `DESTINATION_CONTEXT`;
- The "metrics" port is now the "admin" port, since it serves more than
just metrics;
- A readiness probe now checks a dedicated /ready endpoint eagerly.
Identity injection is **NOT** configured by this branch.
It's sometimes helpful to spotcheck proxy metrics from a specific pod,
but doing so with kubectl requires a few steps.
Introduce a new `linkerd metrics` command. When given a pod name and
namespace, returns a dump of the proxy's /metrics endpoint.
Also modify the k8s.portforward module to accept initialized k8s config
and client objects, to enable testing.
Fixes#2350.
Signed-off-by: Andrew Seigner <siggy@buoyant.io>