This commit is trying to DRY up the initiation of the gRPC client in
each command:
It renames the function to CLI instead of GRPC as it actually set up a
CLI client, not a generic grpc client
It also moves the configuration of address, timeout (which is now
consistent) and api to use Viper, allowing users to set it via env vars
and configuration file
This commit changes the way CLI and grpc-gateway communicates with the
gRPC backend to socket, instead of localhost. Unauthenticated access now
goes on the socket, while the network interface will require API key (in
the future).
This commit sets up the API and gRPC endpoints and adds authentication
to them. Currently there is no actual authentication implemented but it
has been prepared for API keys.
In addition, there is a allow put in place for gRPC traffic over
localhost. This has two purposes:
1. grpc-gateway, which is the base of the API, connects to the gRPC
service over localhost.
2. We do not want to break current "on server" behaviour which allows
users to use the cli on the server without any fuzz
This commit moves the TLS configuration into a seperate function.
It also wires up the gRPC interface and prepares handing the API
endpoints to the grpc gateway.
This commit adds some Prometheus metrics to /metrics in headscale.
It will add the standard go metrics, some automatic gin metrics and some
initial headscale specific ones.
Some of them has been added to aid debugging #97 (loop bug)
In the future, we can use the metrics to get rid of the sleep in the
integration tests by checking that our expected number of nodes has been
registered:
```
headscale_machine_registrations_total
```
