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dev-guide: clarify concepts in local_cluster doc

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Radhika Puthiyetath
2017-06-19 15:58:45 -07:00
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Documentation/dev-guide/local_cluster.md
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# Set up a local cluster # Set up a local cluster
For testing and development deployments, the quickest and easiest way is to set up a local cluster. For a production deployment, refer to the [clustering][clustering] section. For testing and development deployments, the quickest and easiest way is to configure a local cluster. For a production deployment, refer to the [clustering][clustering] section.
## Local standalone cluster ## Local standalone cluster
Deploying an etcd cluster as a standalone cluster is straightforward. Start it with just one command: ### Starting a cluster
Run the following to deploy an etcd cluster as a standalone cluster:
``` ```
$ ./etcd $ ./etcd
... ...
``` ```
The started etcd member listens on `localhost:2379` for client requests. 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.
To interact with the started cluster by using etcdctl: The running etcd member listens on `localhost:2379` for client requests.
### Interacting with the cluster
Use `etcdctl` to interact with the running cluster:
1. Configure the environment to have `ETCDCTL_API=3` so `etcdctl` uses the etcd API version 3 instead of defaulting to version 2.
``` ```
# use API version 3 # use API version 3
$ export ETCDCTL_API=3 $ export ETCDCTL_API=3
```
2. Store an example key-value pair in the cluster:
```
$ ./etcdctl put foo bar $ ./etcdctl put foo bar
OK OK
```
If OK is printed, storing key-value pair is successful.
3. Retrieve the value of `foo`:
```
$ ./etcdctl get foo $ ./etcdctl get foo
bar bar
``` ```
If `bar` is returned, interaction with the etcd cluster is working as expected.
## Local multi-member cluster ## Local multi-member cluster
A `Procfile` at the base of this git repo is provided to easily set up a local multi-member cluster. To start a multi-member cluster go to the root of an etcd source tree and run: ### 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:
``` ```
# install goreman program to control Profile-based applications.
$ go get github.com/mattn/goreman $ go get github.com/mattn/goreman
$ goreman -f Procfile start
...
``` ```
The started members listen on `localhost:2379`, `localhost:22379`, and `localhost:32379` for client requests respectively. 2. Start a cluster with `goreman` using etcd's stock Procfile:
To interact with the started cluster by using etcdctl: ```
$ 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. Configure the environment to have `ETCDCTL_API=3` so `etcdctl` uses the etcd API version 3 instead of defaulting to version 2.
``` ```
# use API version 3 # use API version 3
$ export ETCDCTL_API=3 $ export ETCDCTL_API=3
```
2. Print the list of members:
```
$ etcdctl --write-out=table --endpoints=localhost:2379 member list $ 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 | | ID | STATUS | NAME | PEER ADDRS | CLIENT ADDRS |
+------------------+---------+--------+------------------------+------------------------+ +------------------+---------+--------+------------------------+------------------------+
@ -53,38 +92,72 @@ $ etcdctl --write-out=table --endpoints=localhost:2379 member list
| 91bc3c398fb3c146 | started | infra2 | http://127.0.0.1:22380 | http://127.0.0.1:22379 | | 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 | | fd422379fda50e48 | started | infra3 | http://127.0.0.1:32380 | http://127.0.0.1:32379 |
+------------------+---------+--------+------------------------+------------------------+ +------------------+---------+--------+------------------------+------------------------+
```
3. Store an example key-value pair in the cluster:
```
$ etcdctl put foo bar $ etcdctl put foo bar
OK OK
``` ```
To exercise etcd's fault tolerance, kill a member: 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 # kill etcd2
$ goreman run stop etcd2 $ goreman run stop etcd2
```
3. Store a key:
```
$ etcdctl put key hello $ etcdctl put key hello
OK OK
```
4. Retrieve the key that is stored in the previous step:
```
$ etcdctl get key $ etcdctl get key
hello hello
```
# try to get key from the killed member 5. Retrieve a key from the stopped member:
```
$ etcdctl --endpoints=localhost:22379 get key $ etcdctl --endpoints=localhost:22379 get key
2016/04/18 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" ```
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 Error: grpc: timed out trying to connect
```
6. Restart the stopped member:
# restart the killed member ```
$ goreman run restart etcd2 $ goreman run restart etcd2
```
# get the key from restarted member 7. Get the key from the restarted member:
```
$ etcdctl --endpoints=localhost:22379 get key $ etcdctl --endpoints=localhost:22379 get key
hello hello
``` ```
To learn more about interacting with etcd, read [interacting with etcd section][interacting]. 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][interacting].
[interacting]: ./interacting_v3.md [interacting]: ./interacting_v3.md
[clustering]: ../op-guide/clustering.md [clustering]: ../op-guide/clustering.md