Patroni

Set up a local cluster

Configuring local clusters for testing and development

For testing and development deployments, the quickest and easiest way is to configure a local cluster. For a production deployment, refer to the clustering section.

Local standalone cluster

Starting a cluster

Run the following to deploy an etcd cluster as a standalone cluster:

$ ./etcd
...

If the etcd binary is not present in the current working directory, it might be located either at $GOPATH/bin/etcd or at /usr/local/bin/etcd. Run the command appropriately.

The running etcd member listens on localhost:2379 for client requests.

Interacting with the cluster

Use etcdctl to interact with the running cluster:

Store an example key-value pair in the cluster:
```
  $ ./etcdctl put foo bar
  OK
```
If OK is printed, storing key-value pair is successful.
Retrieve the value of foo:
```
$ ./etcdctl get foo
bar
```
If bar is returned, interaction with the etcd cluster is working as expected.

Local multi-member cluster

Starting a cluster

A Procfile at the base of the etcd git repository is provided to easily configure a local multi-member cluster. To start a multi-member cluster, navigate to the root of the etcd source tree and perform the following:

Install goreman to control Procfile-based applications:
```
$ go install github.com/mattn/goreman@latest
```
Start a cluster with goreman using etcd’s stock Procfile:
```
$ goreman -f Procfile start
```
The members start running. They listen on localhost:2379, localhost:22379, and localhost:32379 respectively for client requests.

Interacting with the cluster

Use etcdctl to interact with the running cluster:

Print the list of members:

$ etcdctl --write-out=table --endpoints=localhost:2379 member list

The list of etcd members are displayed as follows:

+------------------+---------+--------+------------------------+------------------------+
|        ID        | STATUS  |  NAME  |       PEER ADDRS       |      CLIENT ADDRS      |
+------------------+---------+--------+------------------------+------------------------+
| 8211f1d0f64f3269 | started | infra1 | http://127.0.0.1:2380  | http://127.0.0.1:2379  |
| 91bc3c398fb3c146 | started | infra2 | http://127.0.0.1:22380 | http://127.0.0.1:22379 |
| fd422379fda50e48 | started | infra3 | http://127.0.0.1:32380 | http://127.0.0.1:32379 |
+------------------+---------+--------+------------------------+------------------------+

Store an example key-value pair in the cluster:
```
$ etcdctl put foo bar
OK
```
If OK is printed, storing key-value pair is successful.

Testing fault tolerance

To exercise etcd’s fault tolerance, kill a member and attempt to retrieve the key.

Identify the process name of the member to be stopped.

The Procfile lists the properties of the multi-member cluster. For example, consider the member with the process name, etcd2.
Stop the member:
```
# kill etcd2
$ goreman run stop etcd2
```
Store a key:
```
$ etcdctl put key hello
OK
```
Retrieve the key that is stored in the previous step:
```
$ etcdctl get key
hello
```

Retrieve a key from the stopped member:

$ etcdctl --endpoints=localhost:22379 get key

The command should display an error caused by connection failure:

2017/06/18 23:07:35 grpc: Conn.resetTransport failed to create client transport: connection error: desc = "transport: dial tcp 127.0.0.1:22379: getsockopt: connection refused"; Reconnecting to "localhost:22379"
Error:  grpc: timed out trying to connect

Restart the stopped member:
```
$ goreman run restart etcd2
```
Get the key from the restarted member:
```
$ etcdctl --endpoints=localhost:22379 get key
hello
```
Restarting the member re-establish the connection. etcdctl will now be able to retrieve the key successfully. To learn more about interacting with etcd, read interacting with etcd section.

Last modified April 18, 2023: Fix instructions for installing goreman. (964f7ab)