Documentation/op-guide: document grpcproxy sync

Signed-off-by: Gyu-Ho Lee <gyuhox@gmail.com>
This commit is contained in:
Gyu-Ho Lee 2017-02-27 17:11:30 -08:00
parent 095407df58
commit 4d69d9663b

View File

@ -98,3 +98,73 @@ $ ETCDCTL_API=3 ./etcdctl --endpoints=127.0.0.1:2379 get foo
foo
bar
```
## Client endpoint synchronization and name resolution
The proxy supports registering its endpoints for discovery by writing to a user-defined endpoint. This serves two purposes. First, it allows clients to synchronize their endpoints against a set of proxy endpoints for high availability. Second, it is an endpoint provider for etcd [gRPC naming][dev-guide/grpc_naming.md].
Register proxy(s) by providing a user-defined prefix:
```bash
$ etcd grpc-proxy start --endpoints=localhost:2379 \
--listen-addr=127.0.0.1:23790 \
--advertise-client-url=127.0.0.1:23790 \
--resolver-prefix="___grpc_proxy_endpoint" \
--resolver-ttl=60
$ etcd grpc-proxy start --endpoints=localhost:2379 \
--listen-addr=127.0.0.1:23791 \
--advertise-client-url=127.0.0.1:23791 \
--resolver-prefix="___grpc_proxy_endpoint" \
--resolver-ttl=60
```
The proxy will list all its members for member list:
```bash
ETCDCTL_API=3 ./bin/etcdctl --endpoints=http://localhost:23790 member list --write-out table
+----+---------+--------------------------------+------------+-----------------+
| ID | STATUS | NAME | PEER ADDRS | CLIENT ADDRS |
+----+---------+--------------------------------+------------+-----------------+
| 0 | started | Gyu-Hos-MBP.sfo.coreos.systems | | 127.0.0.1:23791 |
| 0 | started | Gyu-Hos-MBP.sfo.coreos.systems | | 127.0.0.1:23790 |
+----+---------+--------------------------------+------------+-----------------+
```
This lets clients automatically discover proxy endpoints through Sync:
```go
cli, err := clientv3.New(clientv3.Config{
Endpoints: []string{"http://localhost:23790"},
})
if err != nil {
log.Fatal(err)
}
defer cli.Close()
// fetch registered grpc-proxy endpoints
if err := cli.Sync(context.Background()); err != nil {
log.Fatal(err)
}
```
Note that if a proxy is configured without a resolver prefix,
```bash
$ etcd grpc-proxy start --endpoints=localhost:2379 \
--listen-addr=127.0.0.1:23792 \
--advertise-client-url=127.0.0.1:23792
```
the member list API to the grpc-proxy returns its own `advertise-client-url`:
```bash
ETCDCTL_API=3 ./bin/etcdctl --endpoints=http://localhost:23792 member list --write-out table
+----+---------+--------------------------------+------------+-----------------+
| ID | STATUS | NAME | PEER ADDRS | CLIENT ADDRS |
+----+---------+--------------------------------+------------+-----------------+
| 0 | started | Gyu-Hos-MBP.sfo.coreos.systems | | 127.0.0.1:23792 |
+----+---------+--------------------------------+------------+-----------------+
```