As of Consul 0.7.0, the peers.json file is only used for recovery
after an outage. The format of this file depends on what the server has
configured for its Raft protocol version. Please see the agent configuration
page at https://www.consul.io/docs/agent/options.html#_raft_protocol for more
details about this parameter.

For Raft protocol version 2 and earlier, this should be formatted as a JSON
array containing the address and port of each Consul server in the cluster, like
this:

[
  "10.1.0.1:8300",
  "10.1.0.2:8300",
  "10.1.0.3:8300"
]

For Raft protocol version 3 and later, this should be formatted as a JSON
array containing the node ID, address:port, and suffrage information of each
Consul server in the cluster, like this:

[
  {
    "id": "adf4238a-882b-9ddc-4a9d-5b6758e4159e",
    "address": "10.1.0.1:8300",
    "non_voter": false
  },
  {
    "id": "8b6dda82-3103-11e7-93ae-92361f002671",
    "address": "10.1.0.2:8300",
    "non_voter": false
  },
  {
    "id": "97e17742-3103-11e7-93ae-92361f002671",
    "address": "10.1.0.3:8300",
    "non_voter": false
  }
]

The "id" field is the node ID of the server. This can be found in the logs when
the server starts up, or in the "node-id" file inside the server's data
directory.

The "address" field is the address and port of the server.

The "non_voter" field controls whether the server is a non-voter, which is used
in some advanced Autopilot configurations, please see
https://www.consul.io/docs/guides/autopilot.html for more information. If
"non_voter" is omitted it will default to false, which is typical for most
clusters.

Under normal operation, the peers.json file will not be present.

When Consul starts for the first time, it will create this peers.info file and
delete any existing peers.json file so that recovery doesn't occur on the first
startup.

Once this peers.info file is present, any peers.json file will be ingested at
startup, and will set the Raft peer configuration manually to recover from an
outage. It's crucial that all servers in the cluster are shut down before
creating the peers.json file, and that all servers receive the same
configuration. Once the peers.json file is successfully ingested and applied, it
will be deleted.

Please see https://www.consul.io/docs/guides/outage.html for more information.