Sample GRPC
service prepared for embedded devices & IoT where orchestration (like k8s) is not present.
Service is using etcd
implementation of Raft
algorithm (https://github.com/etcd-io/raft).
Prerequisites:
- Go 1.19
- GRPC for Go (check
make install
) - Goreman
Scope:
-
embedded service composed of N nodes
-
each service is using
Raft
consensus algorithm to find the leader -
leader handles basic API operations using
GRPC
Goals:
-
check in details how
Raft
works -
check performance of such service
-
check how resilient such service is and what's the impact of failures on service performance
Design is borrowed from raft example which is based on REST API
and fits GRPC needs perfectly too.
The service consists of three components:
- a raft-backed key-value store,
- a GRPC server
- a raft consensus server based on etcd's raft implementation.
The raft-backed key-value store
is a key-value map that holds all committed key-values.
The store bridges communication between the raft server and the GRPC server.
Key-value updates are issued through the store to the raft server.
The store updates its map once raft reports the updates are committed.
The GRPC server
exposes the current raft consensus by accessing the raft-backed key-value store.
The raft server
participates in consensus with its cluster peers.
When the GRPC server submits a proposal, the raft server transmits the proposal to its peers.
When raft reaches a consensus, the server publishes all committed updates over a commit channel.
In our case, this commit channel is consumed by the key-value store.