Don't use $proxy_protocol var which may be undefined.

[pmahoney-raise]

I'm on AWS with an nginx-ingress-controller behind an ELB (created by a kubernetes Service of type LoadBalancer). I set the following annotations:

      annotations:
        service.beta.kubernetes.io/aws-load-balancer-backend-protocol: "http"
        service.beta.kubernetes.io/aws-load-balancer-proxy-protocol: ""

which disable proxy protocol and enable http backend protocol, which cause the ELB to set X-Forwarded-For and X-Forwarded-Proto headers when communicating with the backend (nginx in this case).

And I have this annotation on the nginx-ingress-controller:

      use-proxy-protocol: "false"

However, the X-Forwarded-For header is not being passed along by nginx to its upstream services. This is because when the X-Forwarded-Proto is set to "https", the nginx config on line 128 sets $pass_access_scheme to "https", which in turn results in $the_x_forwarded_for being set to $proxy_protocol_addr on line 140.

Because I'm not using proxy protocol, $proxy_protocol_addr is unset. However, when using either proxy protocol or X-Forwarded-For, $remote_addr is set correctly by the real_ip_header directives on lines 24 and 27.

This pull request solves my problem, though I can't say it doesn't break other configurations. My goal with this PR is to document the issue.

See #800 (comment)

[k8s-reviewable]

This change is 

[coveralls]

Coverage remained the same at 44.539% when pulling b916b5f on raisemarketplace:pm/non-proxy-protocol into 9ec862b on kubernetes:master.

[aledbf]

@pmahoney-raise please update to quay.io/aledbf/nginx-ingress-controller:0.148 to check this issue is fixed

[pmahoney-raise]

Yes, it does work. Inspecting the nginx template looks good too. Thanks.

What's the relationship between that version and this codebase?

[aledbf]

The change is in #890. Basically I replaced the map checking if proxy is enabled or not.
(Using maps in nginx is not very flexible)

[aledbf]

Can we close this PR?

[pmahoney-raise]

Fixed in #890