Improve the Nginx auth_request example (#2278)

* The `X-Forwarded-Uri` was required to bypass authentication

- Fix the `skip_auth_routes` option not working in Nginx

* Add tests for allowed requests with proxied `X-Forwarded-Uri` header

* Avoid nginx startup failure: host not found in upstream "oauth2-proxy"

* The `--reverse-proxy` option is required for nginx

* Update the change logs

* Use the authOnlyPath constant

* Remove the unused header `X-Scheme`

CHANGELOG.md

@@ -13,6 +13,7 @@
 - [#2237](https://github.com/oauth2-proxy/oauth2-proxy/pull/2237) adds an option to append CA certificates (@emsixteeen)
 - [#2128](https://github.com/oauth2-proxy/oauth2-proxy/pull/2128) Update dependencies (@vllvll)
 - [#2274](https://github.com/oauth2-proxy/oauth2-proxy/pull/2274) Upgrade golang.org/x/net to v0.17.0 (@pierluigilenoci)
+- [#2278](https://github.com/oauth2-proxy/oauth2-proxy/pull/2278) Improve the Nginx auth_request example (@akunzai)
 - [#2282](https://github.com/oauth2-proxy/oauth2-proxy/pull/2282) Fixed checking Google Groups membership using Google Application Credentials (@kvanzuijlen)
 - [#2183](https://github.com/oauth2-proxy/oauth2-proxy/pull/2183) Allowing relative redirect url though an option
 - [#1866](https://github.com/oauth2-proxy/oauth2-proxy/pull/1866) Add support for unix socker as upstream (@babs)

contrib/local-environment/docker-compose-nginx.yaml

@@ -31,6 +31,7 @@ services:
   nginx:
     container_name: nginx
     image: nginx:1.18
+    restart: unless-stopped
     ports:
       - 80:80/tcp
     hostname: nginx

contrib/local-environment/nginx.conf

@@ -38,6 +38,7 @@ server {
     # Make sure the OAuth2 Proxy knows where the original request came from.
     proxy_set_header Host       $host;
     proxy_set_header X-Real-IP  $remote_addr;
+    proxy_set_header X-Forwarded-Uri $request_uri;
 
     proxy_pass http://oauth2-proxy:4180/;
   }
@@ -78,6 +79,7 @@ server {
     # Make sure the OAuth2 Proxy knows where the original request came from.
     proxy_set_header Host       $host;
     proxy_set_header X-Real-IP  $remote_addr;
+    proxy_set_header X-Forwarded-Uri $request_uri;
 
     proxy_pass http://oauth2-proxy:4180/;
   }

contrib/local-environment/oauth2-proxy-nginx.cfg

@@ -10,3 +10,5 @@ cookie_secure="false"
 redirect_url="http://oauth2-proxy.oauth2-proxy.localhost/oauth2/callback"
 cookie_domains=".oauth2-proxy.localhost" # Required so cookie can be read on all subdomains.
 whitelist_domains=".oauth2-proxy.localhost" # Required to allow redirection back to original requested target.
+# Enables the use of `X-Forwarded-*` headers to determine request correctly
+reverse_proxy="true"

docs/docs/configuration/overview.md

@@ -339,6 +339,8 @@ Available variables for standard logging:
 
 ## Configuring for use with the Nginx `auth_request` directive
 
+**This option requires `--reverse-proxy` option to be set.**
+
 The [Nginx `auth_request` directive](http://nginx.org/en/docs/http/ngx_http_auth_request_module.html) allows Nginx to authenticate requests via the oauth2-proxy's `/auth` endpoint, which only returns a 202 Accepted response or a 401 Unauthorized response without proxying the request through. For example:
 
 ```nginx
@@ -351,7 +353,6 @@ server {
     proxy_pass       http://127.0.0.1:4180;
     proxy_set_header Host                    $host;
     proxy_set_header X-Real-IP               $remote_addr;
-    proxy_set_header X-Scheme                $scheme;
     proxy_set_header X-Auth-Request-Redirect $request_uri;
     # or, if you are handling multiple domains:
     # proxy_set_header X-Auth-Request-Redirect $scheme://$host$request_uri;
@@ -360,7 +361,7 @@ server {
     proxy_pass       http://127.0.0.1:4180;
     proxy_set_header Host             $host;
     proxy_set_header X-Real-IP        $remote_addr;
-    proxy_set_header X-Scheme         $scheme;
+    proxy_set_header X-Forwarded-Uri  $request_uri;
     # nginx auth_request includes headers but not body
     proxy_set_header Content-Length   "";
     proxy_pass_request_body           off;

docs/docs/configuration/tls.md

@@ -63,7 +63,6 @@ There are two recommended configurations:
             proxy_pass http://127.0.0.1:4180;
             proxy_set_header Host $host;
             proxy_set_header X-Real-IP $remote_addr;
-            proxy_set_header X-Scheme $scheme;
             proxy_connect_timeout 1;
             proxy_send_timeout 30;
             proxy_read_timeout 30;

oauthproxy_test.go

@@ -2632,6 +2632,104 @@ func TestAllowedRequest(t *testing.T) {
 	}
 }
 
+func TestAllowedRequestWithForwardedUriHeader(t *testing.T) {
+	upstreamServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+	}))
+	t.Cleanup(upstreamServer.Close)
+
+	opts := baseTestOptions()
+	opts.ReverseProxy = true
+	opts.UpstreamServers = options.UpstreamConfig{
+		Upstreams: []options.Upstream{
+			{
+				ID:   upstreamServer.URL,
+				Path: "/",
+				URI:  upstreamServer.URL,
+			},
+		},
+	}
+	opts.SkipAuthRegex = []string{
+		"^/skip/auth/regex$",
+	}
+	opts.SkipAuthRoutes = []string{
+		"GET=^/skip/auth/routes/get",
+	}
+	err := validation.Validate(opts)
+	assert.NoError(t, err)
+	proxy, err := NewOAuthProxy(opts, func(_ string) bool { return true })
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	testCases := []struct {
+		name    string
+		method  string
+		url     string
+		allowed bool
+	}{
+		{
+			name:    "Regex GET allowed",
+			method:  "GET",
+			url:     "/skip/auth/regex",
+			allowed: true,
+		},
+		{
+			name:    "Regex POST allowed ",
+			method:  "POST",
+			url:     "/skip/auth/regex",
+			allowed: true,
+		},
+		{
+			name:    "Regex denied",
+			method:  "GET",
+			url:     "/wrong/denied",
+			allowed: false,
+		},
+		{
+			name:    "Route allowed",
+			method:  "GET",
+			url:     "/skip/auth/routes/get",
+			allowed: true,
+		},
+		{
+			name:    "Route denied with wrong method",
+			method:  "PATCH",
+			url:     "/skip/auth/routes/get",
+			allowed: false,
+		},
+		{
+			name:    "Route denied with wrong path",
+			method:  "GET",
+			url:     "/skip/auth/routes/wrong/path",
+			allowed: false,
+		},
+		{
+			name:    "Route denied with wrong path and method",
+			method:  "POST",
+			url:     "/skip/auth/routes/wrong/path",
+			allowed: false,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			req, err := http.NewRequest(tc.method, opts.ProxyPrefix+authOnlyPath, nil)
+			req.Header.Set("X-Forwarded-Uri", tc.url)
+			assert.NoError(t, err)
+
+			rw := httptest.NewRecorder()
+			proxy.ServeHTTP(rw, req)
+
+			if tc.allowed {
+				assert.Equal(t, 202, rw.Code)
+			} else {
+				assert.Equal(t, 401, rw.Code)
+			}
+		})
+	}
+}
+
 func TestAllowedRequestNegateWithoutMethod(t *testing.T) {
 	upstreamServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(200)