Serf keyring operations write to disk in Consul dev mode

[highlyunavailable]

Server version: Consul v0.7.2
Client version: N/A

Operating system and Environment details

Windows 8.1, development done locally

Description of the Issue (and unexpected/desired result)

I ran into the following issue while implementing the /v1/operator/keyring API for my Consul.NET API - it seems that using the serf keyring calls in dev mode writes to the disk, which breaks testing in new and fun ways.

Expected result: Restarting the server in dev mode deletes all encryption keys except that which is specified in the config file.

Actual result: Serf writes installed encryption keys to a local directory which is preserved in dev mode.

Reproduction steps

I'm running Consul as follows: consul.exe agent -dev -config-file test_config.json and test_config.json contains the following:

{
    "log_level": "TRACE",
    "bind_addr": "127.0.0.1",
    "server": true,
    "bootstrap": true,
    "acl_datacenter": "dc1",
    "acl_master_token": "yep",
    "acl_default_policy": "allow",
    "encrypt": "OSvH5y8K4Lc9qaof5YUpwg=="
}

If I start Consul with the command above and in another prompt run consul.exe keyring -list, I get, as expected:

==> Gathering installed encryption keys...
==> Done!

WAN:
  OSvH5y8K4Lc9qaof5YUpwg== [1/1]

dc1 (LAN):
  OSvH5y8K4Lc9qaof5YUpwg== [1/1]

If I add another one, e.g. consul.exe keyring -install 7a9OTTuJHbTdatQ/pRlw2g== I get, as expected:

==> Installing new gossip encryption key...
==> Done!

However, this creates a ./serf directory with local.keyring and remote.keyring in it.

If I restart the server, which, as a reminder is in Dev mode so it doesn't write to disk or keep state, and then do consul.exe keyring -list I get:

==> Gathering installed encryption keys...
==> Done!

WAN:
  OSvH5y8K4Lc9qaof5YUpwg== [1/1]
  7a9OTTuJHbTdatQ/pRlw2g== [1/1]

dc1 (LAN):
  OSvH5y8K4Lc9qaof5YUpwg== [1/1]
  7a9OTTuJHbTdatQ/pRlw2g== [1/1]

[mckennajones]

@slackpad Since dev mode is not supposed to write to disk at all, should the keyring -install command even be supported in dev mode?

[slackpad]

Yeah that should probably just fail outright in dev mode.