Improve Proxy Protocol docs/configuration parsing

[sidewinder12s]

Feature Request:
Improve the documentation/parsing of proxy_protocol_authorized_addrs listener configuration options. The parsing is not very friendly and the documentation just says the field is a string, leaving you guessing how to input multiple IPs which is completely expected if your putting in IPs of a load balancer. I would have expected it to be an array. The fact you need to separate the addresses with a comma isn't documented either.

Environment:

• Vault Version: v0.9.3
• Operating System/Architecture: docker/ubuntu/amd64

Vault Config File:
Within the listener config:

proxy_protocol_behavior = "allow_authorized"
proxy_protocol_authorized_addrs = ""10.15.163.13:8200, 10.15.163.12:8200""

Startup Log Output:

{\"line\":\"\u001b[0;31mError initializing listener of type tcp: failed parsing proxy_protocol_authorized_addrs: error parsing authorized address: Unable to convert \\"  10.15.163.12:8200\\" to an IPv4 or IPv6 address, or a UNIX Socket\u001b[0m\",\"source\":\"stdout\",\"tag\":\"vault:0.9.3/container_name/9882051d8d99\"},\"time\":\"1520029773.110934\",\"host\":\"host.com\"}

Expected Behavior:
Vault should have started up.

Actual Behavior:
Vault failed to start

Steps to Reproduce:
Add a proxy_protocol_authorized_addrs field with 2 addresses and a space between the 2 to the listener config.

proxy_protocol_authorized_addrs = ""10.15.163.13:8200, 10.15.163.12:8200""

References:
Removing the space between the 2 addresses fixes this however that doesn't seem to be documented anywhere.

proxy_protocol_authorized_addrs = ""10.15.163.13:8200,10.15.163.12:8200""

[shelby-moore]

It's also strange that with proxy_protocol_behavior = "use_always" you need to specify proxy_protocol_authorized_addrs, which will cause Vault to not start up if it is an empty string. It would be preferable to not require proxy_protocol_authorized_addrs at all in this case, or at least allow it to be an empty string.

[jefferai]

I would have expected it to be an array.

You can use an array or a comma-separated string, both work.

It's also strange that with proxy_protocol_behavior = "use_always" you need to specify proxy_protocol_authorized_addrs, which will cause Vault to not start up if it is an empty string

This could probably be changed, please file an issue for it or submit a PR.

[jefferai]

Closed by #4528