Implement Geo proxy routing

By default, a Geo proxy will proxy all requests to the URL returned by
the API endpoint `/api/v4/geo/proxy`.

Certain routes, defined in `GeoLocalRoutes`, can be served locally for
improved performance. Many more local routes will be added later.

workhorse/internal/upstream/routes.go

@@ -337,6 +337,42 @@ func configureRoutes(u *upstream) {
 
 		u.route("", "", defaultUpstream),
 	}
+
+	// Routes which should actually be served locally by a Geo Proxy. If none
+	// matches, then then proxy the request.
+	u.geoLocalRoutes = []routeEntry{
+		// Git and LFS requests
+		//
+		// Note that Geo already redirects pushes, with special terminal output.
+		// Note that excessive secondary lag can cause unexpected behavior since
+		// pulls are performed against a different source of truth. Ideally, we'd
+		// proxy/redirect pulls as well, when the secondary is not up-to-date.
+		//
+		u.route("GET", gitProjectPattern+`info/refs\z`, git.GetInfoRefsHandler(api)),
+		u.route("POST", gitProjectPattern+`git-upload-pack\z`, contentEncodingHandler(git.UploadPack(api)), withMatcher(isContentType("application/x-git-upload-pack-request"))),
+		u.route("POST", gitProjectPattern+`git-receive-pack\z`, contentEncodingHandler(git.ReceivePack(api)), withMatcher(isContentType("application/x-git-receive-pack-request"))),
+		u.route("PUT", gitProjectPattern+`gitlab-lfs/objects/([0-9a-f]{64})/([0-9]+)\z`, lfs.PutStore(api, signingProxy, preparers.lfs), withMatcher(isContentType("application/octet-stream"))),
+
+		// Serve health checks from this Geo secondary
+		u.route("", "^/-/(readiness|liveness)$", static.DeployPage(probeUpstream)),
+		u.route("", "^/-/health$", static.DeployPage(healthUpstream)),
+		u.route("", "^/-/metrics$", defaultUpstream),
+
+		// Authentication routes
+		u.route("", "^/users/(sign_in|sign_out)$", defaultUpstream),
+		u.route("", "^/oauth/geo/(auth|callback|logout)$", defaultUpstream),
+
+		// Admin Area > Geo routes
+		u.route("", "^/admin/geo$", defaultUpstream),
+		u.route("", "^/admin/geo/", defaultUpstream),
+
+		// Geo API routes
+		u.route("", "^/api/v4/geo_nodes", defaultUpstream),
+		u.route("", "^/api/v4/geo_replication", defaultUpstream),
+
+		// Don't define a catch-all route. If a route does not match, then we know
+		// the request should be proxied.
+	}
 }
 
 func createUploadPreparers(cfg config.Config) uploadPreparers {

workhorse/internal/upstream/upstream.go

@@ -9,8 +9,10 @@ package upstream
 import (
 	"fmt"
 	"os"
+	"sync"
 
 	"net/http"
+	"net/url"
 	"strings"
 
 	"github.com/sirupsen/logrus"
@@ -21,6 +23,7 @@ import (
 	"gitlab.com/gitlab-org/gitlab/workhorse/internal/config"
 	"gitlab.com/gitlab-org/gitlab/workhorse/internal/helper"
 	"gitlab.com/gitlab-org/gitlab/workhorse/internal/log"
+	proxypkg "gitlab.com/gitlab-org/gitlab/workhorse/internal/proxy"
 	"gitlab.com/gitlab-org/gitlab/workhorse/internal/rejectmethods"
 	"gitlab.com/gitlab-org/gitlab/workhorse/internal/upload"
 	"gitlab.com/gitlab-org/gitlab/workhorse/internal/upstream/roundtripper"
@@ -41,8 +44,13 @@ type upstream struct {
 	RoundTripper          http.RoundTripper
 	CableRoundTripper     http.RoundTripper
 	APIClient             *apipkg.API
+	geoProxyBackend       *url.URL
+	geoLocalRoutes        []routeEntry
+	geoProxyCableRoute    routeEntry
+	geoProxyRoute         routeEntry
 	accessLogger          *logrus.Logger
 	enableGeoProxyFeature bool
+	mu                    sync.RWMutex
 }
 
 func NewUpstream(cfg config.Config, accessLogger *logrus.Logger) http.Handler {
@@ -119,25 +127,9 @@ func (u *upstream) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	// Look for a matching route
-	var route *routeEntry
+	cleanedPath := prefix.Strip(URIPath)
 
-	if u.enableGeoProxyFeature {
-		geoProxyURL, err := u.APIClient.GetGeoProxyURL()
-
-		if err == nil {
-			log.WithRequest(r).WithFields(log.Fields{"geoProxyURL": geoProxyURL}).Info("Geo Proxy: Set route according to Geo Proxy logic")
-		} else if err != apipkg.ErrNotGeoSecondary {
-			log.WithRequest(r).WithError(err).Error("Geo Proxy: Unable to determine Geo Proxy URL. Falling back to normal routing")
-		}
-	}
-
-	for _, ro := range u.Routes {
-		if ro.isMatch(prefix.Strip(URIPath), r) {
-			route = &ro
-			break
-		}
-	}
+	route := u.findRoute(cleanedPath, r)
 
 	if route == nil {
 		// The protocol spec in git/Documentation/technical/http-protocol.txt
@@ -152,3 +144,65 @@ func (u *upstream) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 	route.handler.ServeHTTP(w, r)
 }
+
+func (u *upstream) findRoute(cleanedPath string, r *http.Request) *routeEntry {
+	if u.enableGeoProxyFeature {
+		if route := u.findGeoProxyRoute(cleanedPath, r); route != nil {
+			return route
+		}
+	}
+
+	for _, ro := range u.Routes {
+		if ro.isMatch(cleanedPath, r) {
+			return &ro
+		}
+	}
+
+	return nil
+}
+
+func (u *upstream) findGeoProxyRoute(cleanedPath string, r *http.Request) *routeEntry {
+	geoProxyURL, err := u.APIClient.GetGeoProxyURL()
+
+	if err == nil {
+		u.setGeoProxyRoutes(geoProxyURL)
+		return u.matchGeoProxyRoute(cleanedPath, r)
+	} else if err != apipkg.ErrNotGeoSecondary {
+		log.WithRequest(r).WithError(err).Error("Geo Proxy: Unable to determine Geo Proxy URL. Falling back to normal routing")
+	}
+
+	return nil
+}
+
+func (u *upstream) matchGeoProxyRoute(cleanedPath string, r *http.Request) *routeEntry {
+	// Some routes are safe to serve from this GitLab instance
+	for _, ro := range u.geoLocalRoutes {
+		if ro.isMatch(cleanedPath, r) {
+			log.WithRequest(r).Debug("Geo Proxy: Handle this request locally")
+			return &ro
+		}
+	}
+
+	log.WithRequest(r).WithFields(log.Fields{"geoProxyBackend": u.geoProxyBackend}).Debug("Geo Proxy: Forward this request")
+
+	u.mu.RLock()
+	defer u.mu.RUnlock()
+	if cleanedPath == "/-/cable" {
+		return &u.geoProxyCableRoute
+	}
+
+	return &u.geoProxyRoute
+}
+
+func (u *upstream) setGeoProxyRoutes(geoProxyURL *url.URL) {
+	u.mu.Lock()
+	defer u.mu.Unlock()
+	if u.geoProxyBackend == nil || u.geoProxyBackend.String() != geoProxyURL.String() {
+		log.WithFields(log.Fields{"geoProxyURL": geoProxyURL}).Debug("Geo Proxy: Update GeoProxyRoute")
+		u.geoProxyBackend = geoProxyURL
+		geoProxyRoundTripper := roundtripper.NewBackendRoundTripper(u.geoProxyBackend, "", u.ProxyHeadersTimeout, u.DevelopmentMode)
+		geoProxyUpstream := proxypkg.NewProxy(u.geoProxyBackend, u.Version, geoProxyRoundTripper)
+		u.geoProxyCableRoute = u.wsRoute(`^/-/cable\z`, geoProxyUpstream)
+		u.geoProxyRoute = u.route("", "", geoProxyUpstream)
+	}
+}

workhorse/internal/upstream/upstream_test.go

 package upstream
 
 import (
+	"fmt"
 	"io"
 	"io/ioutil"
 	"net/http"
@@ -11,8 +12,21 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"gitlab.com/gitlab-org/gitlab/workhorse/internal/config"
+	"gitlab.com/gitlab-org/gitlab/workhorse/internal/helper"
+	"gitlab.com/gitlab-org/gitlab/workhorse/internal/testhelper"
 )
 
+const (
+	geoProxyEndpoint = "/api/v4/geo/proxy"
+	testDocumentRoot = "testdata/public"
+)
+
+type testCase struct {
+	desc             string
+	path             string
+	expectedResponse string
+}
+
 func TestRouting(t *testing.T) {
 	handle := func(u *upstream, regex string) routeEntry {
 		handler := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
@@ -34,15 +48,10 @@ func TestRouting(t *testing.T) {
 			handle(u, main),
 		}
 	})
-
 	ts := httptest.NewServer(u)
 	defer ts.Close()
 
-	testCases := []struct {
-		desc  string
-		path  string
-		route string
-	}{
+	testCases := []testCase{
 		{"main route works", "/", main},
 		{"foobar route works", "/foobar", foobar},
 		{"quxbaz route works", "/quxbaz", quxbaz},
@@ -51,9 +60,109 @@ func TestRouting(t *testing.T) {
 		{"double escaped path traversal does not match any route", "/foobar%252f%252e%252e%252fquxbaz", main},
 	}
 
+	runTestCases(t, ts, testCases)
+}
+
+// This test can be removed when the environment variable `GEO_SECONDARY_PROXY` is removed
+func TestGeoProxyFeatureDisabledOnGeoSecondarySite(t *testing.T) {
+	// We could just not set up the primary, but then we'd have to assert
+	// that the internal API call isn't made. This is easier.
+	remoteServer, rsDeferredClose := startRemoteServer("Geo primary")
+	defer rsDeferredClose()
+
+	geoProxyEndpointResponseBody := fmt.Sprintf(`{"geo_proxy_url":"%v"}`, remoteServer.URL)
+	railsServer, deferredClose := startRailsServer("Local Rails server", geoProxyEndpointResponseBody)
+	defer deferredClose()
+
+	ws, wsDeferredClose := startWorkhorseServer(railsServer.URL, false)
+	defer wsDeferredClose()
+
+	testCases := []testCase{
+		{"jobs request is served locally", "/api/v4/jobs/request", "Local Rails server received request to path /api/v4/jobs/request"},
+		{"health check is served locally", "/-/health", "Local Rails server received request to path /-/health"},
+		{"unknown route is served locally", "/anything", "Local Rails server received request to path /anything"},
+	}
+
+	runTestCases(t, ws, testCases)
+}
+
+func TestGeoProxyFeatureEnabledOnGeoSecondarySite(t *testing.T) {
+	remoteServer, rsDeferredClose := startRemoteServer("Geo primary")
+	defer rsDeferredClose()
+
+	geoProxyEndpointResponseBody := fmt.Sprintf(`{"geo_proxy_url":"%v"}`, remoteServer.URL)
+	railsServer, deferredClose := startRailsServer("Local Rails server", geoProxyEndpointResponseBody)
+	defer deferredClose()
+
+	ws, wsDeferredClose := startWorkhorseServer(railsServer.URL, true)
+	defer wsDeferredClose()
+
+	testCases := []testCase{
+		{"jobs request is forwarded", "/api/v4/jobs/request", "Geo primary received request to path /api/v4/jobs/request"},
+		{"health check is served locally", "/-/health", "Local Rails server received request to path /-/health"},
+		{"unknown route is forwarded", "/anything", "Geo primary received request to path /anything"},
+	}
+
+	runTestCases(t, ws, testCases)
+}
+
+// This test can be removed when the environment variable `GEO_SECONDARY_PROXY` is removed
+func TestGeoProxyFeatureDisabledOnNonGeoSecondarySite(t *testing.T) {
+	geoProxyEndpointResponseBody := "{}"
+	railsServer, deferredClose := startRailsServer("Local Rails server", geoProxyEndpointResponseBody)
+	defer deferredClose()
+
+	ws, wsDeferredClose := startWorkhorseServer(railsServer.URL, false)
+	defer wsDeferredClose()
+
+	testCases := []testCase{
+		{"jobs request is served locally", "/api/v4/jobs/request", "Local Rails server received request to path /api/v4/jobs/request"},
+		{"health check is served locally", "/-/health", "Local Rails server received request to path /-/health"},
+		{"unknown route is served locally", "/anything", "Local Rails server received request to path /anything"},
+	}
+
+	runTestCases(t, ws, testCases)
+}
+
+func TestGeoProxyFeatureEnabledOnNonGeoSecondarySite(t *testing.T) {
+	geoProxyEndpointResponseBody := "{}"
+	railsServer, deferredClose := startRailsServer("Local Rails server", geoProxyEndpointResponseBody)
+	defer deferredClose()
+
+	ws, wsDeferredClose := startWorkhorseServer(railsServer.URL, true)
+	defer wsDeferredClose()
+
+	testCases := []testCase{
+		{"jobs request is served locally", "/api/v4/jobs/request", "Local Rails server received request to path /api/v4/jobs/request"},
+		{"health check is served locally", "/-/health", "Local Rails server received request to path /-/health"},
+		{"unknown route is served locally", "/anything", "Local Rails server received request to path /anything"},
+	}
+
+	runTestCases(t, ws, testCases)
+}
+
+func TestGeoProxyWithAPIError(t *testing.T) {
+	geoProxyEndpointResponseBody := "Invalid response"
+	railsServer, deferredClose := startRailsServer("Local Rails server", geoProxyEndpointResponseBody)
+	defer deferredClose()
+
+	ws, wsDeferredClose := startWorkhorseServer(railsServer.URL, true)
+	defer wsDeferredClose()
+
+	testCases := []testCase{
+		{"jobs request is served locally", "/api/v4/jobs/request", "Local Rails server received request to path /api/v4/jobs/request"},
+		{"health check is served locally", "/-/health", "Local Rails server received request to path /-/health"},
+		{"unknown route is served locally", "/anything", "Local Rails server received request to path /anything"},
+	}
+
+	runTestCases(t, ws, testCases)
+}
+
+func runTestCases(t *testing.T, ws *httptest.Server, testCases []testCase) {
+	t.Helper()
 	for _, tc := range testCases {
 		t.Run(tc.desc, func(t *testing.T) {
-			resp, err := http.Get(ts.URL + tc.path)
+			resp, err := http.Get(ws.URL + tc.path)
 			require.NoError(t, err)
 			defer resp.Body.Close()
 
@@ -61,7 +170,61 @@ func TestRouting(t *testing.T) {
 			require.NoError(t, err)
 
 			require.Equal(t, 200, resp.StatusCode, "response code")
-			require.Equal(t, tc.route, string(body))
+			require.Equal(t, tc.expectedResponse, string(body))
 		})
 	}
 }
+
+func newUpstreamConfig(authBackend string) *config.Config {
+	return &config.Config{
+		Version:            "123",
+		DocumentRoot:       testDocumentRoot,
+		Backend:            helper.URLMustParse(authBackend),
+		ImageResizerConfig: config.DefaultImageResizerConfig,
+	}
+}
+
+func startRemoteServer(serverName string) (*httptest.Server, func()) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		body := serverName + " received request to path " + r.URL.Path
+
+		w.WriteHeader(200)
+		fmt.Fprint(w, body)
+	}))
+
+	return ts, ts.Close
+}
+
+func startRailsServer(railsServerName string, geoProxyEndpointResponseBody string) (*httptest.Server, func()) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		var body string
+
+		if r.URL.Path == geoProxyEndpoint {
+			w.Header().Set("Content-Type", "application/vnd.gitlab-workhorse+json")
+			body = geoProxyEndpointResponseBody
+		} else {
+			body = railsServerName + " received request to path " + r.URL.Path
+		}
+
+		w.WriteHeader(200)
+		fmt.Fprint(w, body)
+	}))
+
+	return ts, ts.Close
+}
+
+func startWorkhorseServer(railsServerURL string, enableGeoProxyFeature bool) (*httptest.Server, func()) {
+	myConfigureRoutes := func(u *upstream) {
+		// Enable environment variable "feature flag"
+		u.enableGeoProxyFeature = enableGeoProxyFeature
+
+		// call original
+		configureRoutes(u)
+	}
+	cfg := newUpstreamConfig(railsServerURL)
+	upstreamHandler := newUpstream(*cfg, logrus.StandardLogger(), myConfigureRoutes)
+	ws := httptest.NewServer(upstreamHandler)
+	testhelper.ConfigureSecret()
+
+	return ws, ws.Close
+}