Allow a health/ping request to be identified by User-Agent (#567)

* Add an option to allow health checks based on User-Agent.

* Formatting fix

* Rename field and avoid unnecessary interface.

* Skip the redirect fix so it can be put into a different PR.

* Add CHANGELOG entry

* Adding a couple tests for the PingUserAgent option.

logging_handler_test.go

@@ -5,11 +5,14 @@ import (
 	"fmt"
 	"net/http"
 	"net/http/httptest"
+	"net/url"
 	"strings"
 	"testing"
 	"time"
 
+	"github.com/oauth2-proxy/oauth2-proxy/pkg/apis/options"
 	"github.com/oauth2-proxy/oauth2-proxy/pkg/logger"
+	"github.com/oauth2-proxy/oauth2-proxy/pkg/validation"
 )
 
 func TestLoggingHandler_ServeHTTP(t *testing.T) {
@@ -67,3 +70,59 @@ func TestLoggingHandler_ServeHTTP(t *testing.T) {
 		}
 	}
 }
+
+func TestLoggingHandler_PingUserAgent(t *testing.T) {
+	tests := []struct {
+		ExpectedLogMessage string
+		Path               string
+		SilencePingLogging bool
+		WithUserAgent      string
+	}{
+		{"444\n", "/foo", true, "Blah"},
+		{"444\n", "/foo", false, "Blah"},
+		{"", "/ping", true, "Blah"},
+		{"200\n", "/ping", false, "Blah"},
+		{"", "/ping", true, "PingMe!"},
+		{"", "/ping", false, "PingMe!"},
+		{"", "/foo", true, "PingMe!"},
+		{"", "/foo", false, "PingMe!"},
+	}
+
+	for idx, test := range tests {
+		t.Run(fmt.Sprintf("%d", idx), func(t *testing.T) {
+			opts := options.NewOptions()
+			opts.PingUserAgent = "PingMe!"
+			opts.SkipAuthRegex = []string{"/foo"}
+			opts.Upstreams = []string{"static://444/foo"}
+			opts.Logging.SilencePing = test.SilencePingLogging
+			if test.SilencePingLogging {
+				opts.Logging.ExcludePaths = []string{"/ping"}
+			}
+			opts.RawRedirectURL = "localhost"
+			validation.Validate(opts)
+
+			p := NewOAuthProxy(opts, func(email string) bool {
+				return true
+			})
+			p.provider = NewTestProvider(&url.URL{Host: "localhost"}, "")
+
+			buf := bytes.NewBuffer(nil)
+			logger.SetOutput(buf)
+			logger.SetReqEnabled(true)
+			logger.SetReqTemplate("{{.StatusCode}}")
+
+			r, _ := http.NewRequest("GET", test.Path, nil)
+			if test.WithUserAgent != "" {
+				r.Header.Set("User-Agent", test.WithUserAgent)
+			}
+
+			h := LoggingHandler(p)
+			h.ServeHTTP(httptest.NewRecorder(), r)
+
+			actual := buf.String()
+			if !strings.Contains(actual, test.ExpectedLogMessage) {
+				t.Errorf("Log message was\n%s\ninstead of matching \n%s", actual, test.ExpectedLogMessage)
+			}
+		})
+	}
+}