Table of Contents

• • Local standalone cluster
    • Starting a cluster
    • Interacting with the cluster
  • Local multi-member cluster
    • Starting a cluster
    • Interacting with the cluster
    • Testing fault tolerance

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:

1. Store an example key-value pair in the cluster:

     $ ./etcdctl put foo bar
     OK
   

   If OK is printed, storing key-value pair is successful.

2. 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:

1. Install goreman to control Procfile-based applications:

   $ go get github.com/mattn/goreman
   

2. 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:

1. 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 |
   +------------------+---------+--------+------------------------+------------------------+
   

2. 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.

1. 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.

2. Stop the member:

   # kill etcd2
   $ goreman run stop etcd2
   

3. Store a key:

   $ etcdctl put key hello
   OK
   

4. Retrieve the key that is stored in the previous step:

   $ etcdctl get key
   hello
   

5. 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
   

6. Restart the stopped member:

   $ goreman run restart etcd2
   

7. 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.