Daemon and application
The daemon is the cluster member. The application is a client of the daemon on the same host.
This is the same split as a local Docker engine: apps do not join the cluster; the daemon does.
text
app A ─┐
app B ─┼─► daemon on this host ─► other daemons (Raft + gRPC)
cli ─┘Daemon
Started with clusdr start. It:
- Votes (or observes) in Raft
- Serves the Runtime API on TCP
- Optionally binds the Unix control socket
- Holds locks, leases, and the membership table in RAM; Raft is the writer
If clusdr init was never run, the process can still start and logs that identity is missing.
Application
Uses clusdr.Local() (Go) or clusdr.local() (Python). It dials CLUSDR_GRPC_ADDR or 127.0.0.1:7947.
It is not a voter. It does not speak Raft. Two processes on one machine share the daemon.
Dial(addr) exists for tests and operators. It is not the default app path.
CLI
clusdr is one binary. Operator commands (members, join, watch, …) dial the Runtime API. Only status looks at the Unix socket.