Adding redirects for helm client

This will enable helm to be used in a manner like:
helm install https://monocular.example.com/charts/foo/bar

Monocular will redirect to the URL with the tarball for the chart
or the provenance file if the call to monocular ends in .prov

Signed-off-by: Matt Farina <matt@mattfarina.com>

Author: mattfarina

chart/monocular/templates/ui-vhost.yaml

@@ -13,6 +13,10 @@ data:
       server {{ template "fullname" . }}-prerender;
     }
 
+    upstream chartsvc {
+      server {{ template "fullname" . }}-chartsvc:{{ .Values.chartsvc.service.port }};
+    }
+
     server {
       listen {{ .Values.ui.service.internalPort }};
 
@@ -21,33 +25,46 @@ data:
       gzip_static  on;
 
       location / {
-        try_files $uri @prerender;
+        try_files $uri @findredirect;
       }
 
-      location @prerender {
-        set $prerender 0;
+      location @findredirect {
+        set $findredirect 0;
+
+        # Intercept some errors, like redirects, and follow them.
+        proxy_intercept_errors on;
 
+        # Look for the Helm user agent. If a Helm client wants the URL we redirect
+        # to the file being requested.
+        if ($http_user_agent ~* "helm") {
+          set $findredirect 2;
+        }
+
+        # Detect bots that want HTML. We send this to a prerender service
         if ($http_user_agent ~* "baiduspider|twitterbot|facebookexternalhit|rogerbot|linkedinbot|embedly|quora link preview|showyoubot|outbrain|pinterest|slackbot|vkShare|W3C_Validator") {
-          set $prerender 1;
+          set $findredirect 1;
         }
 
         if ($args ~ "_escaped_fragment_") {
-          set $prerender 1;
+          set $findredirect 1;
         }
 
         if ($http_user_agent ~ "Prerender") {
-          set $prerender 0;
+          set $findredirect 0;
         }
 
         if ($uri ~* "\.(js|css|xml|less|png|jpg|jpeg|gif|pdf|doc|txt|ico|rss|zip|mp3|rar|exe|wmv|doc|avi|ppt|mpg|mpeg|tif|wav|mov|psd|ai|xls|mp4|m4a|swf|dat|dmg|iso|flv|m4v|torrent|ttf|woff|svg|eot)") {
-          set $prerender 0;
+          set $findredirect 0;
         }
 
-        if ($prerender = 1) {
+        if ($findredirect = 2) {
+          proxy_pass http://chartsvc/v1/redirect$request_uri;
+        }
+        if ($findredirect = 1) {
           rewrite .* /https://$host$request_uri? break;
           proxy_pass http://target_service;
         }
-        if ($prerender = 0) {
+        if ($findredirect = 0) {
           rewrite .* /index.html break;
         }
       }

cmd/chartsvc/handler.go

@@ -21,6 +21,7 @@ import (
 	"math"
 	"net/http"
 	"strconv"
+	"strings"
 
 	"github.com/globalsign/mgo/bson"
 	"github.com/gorilla/mux"
@@ -444,3 +445,75 @@ func newChartVersionListResponse(c *models.Chart) apiListResponse {
 
 	return cvl
 }
+
+func handleRedirect(w http.ResponseWriter, req *http.Request) {
+
+	// The URL can be in one of two forms:
+	// - /v1/redirect/charts/stable/aerospike
+	// - /v1/redirect/charts/stable/aerospike/v1.2.3
+	// And either of these can optionally have a trailing /
+
+	// Make sure the path is valid
+	ct := strings.TrimPrefix(req.URL.Path, "/v1/redirect/charts/")
+
+	// check if URL for provenance
+	prov := strings.HasSuffix(ct, ".prov")
+	ct = strings.TrimSuffix(ct, ".prov")
+
+	ct = strings.TrimSuffix(ct, "/") // Removing the optional / on the end
+	p := strings.Split(ct, "/")
+
+	// Not enough parts passed in to the path
+	if len(p) < 2 || len(p) > 3 {
+		response.NewErrorResponse(http.StatusNotFound, "could not find chart").Write(w)
+		return
+	}
+
+	// Decide if latest or a version
+	var version string
+	if len(p) == 3 {
+		version = p[2]
+	}
+
+	// Look it up. This will be different if there is a version or we are getting
+	// the latest
+	db, closer := dbSession.DB()
+	defer closer()
+	var chart models.Chart
+	chartID := fmt.Sprintf("%s/%s", p[0], p[1])
+
+	if version == "" {
+		if err := db.C(chartCollection).FindId(chartID).One(&chart); err != nil {
+			log.WithError(err).Errorf("could not find chart with id %s", chartID)
+			response.NewErrorResponse(http.StatusNotFound, "could not find chart").Write(w)
+			return
+		}
+	} else {
+		if err := db.C(chartCollection).Find(bson.M{
+			"_id":           chartID,
+			"chartversions": bson.M{"$elemMatch": bson.M{"version": version}},
+		}).Select(bson.M{
+			"name": 1, "repo": 1, "description": 1, "home": 1, "keywords": 1, "maintainers": 1, "sources": 1,
+			"chartversions.$": 1,
+		}).One(&chart); err != nil {
+			log.WithError(err).Errorf("could not find chart with id %s", chartID)
+			response.NewErrorResponse(http.StatusNotFound, "could not find chart version").Write(w)
+			return
+		}
+	}
+
+	// Respond with proper redirect for tarball and prov
+	if len(chart.ChartVersions) > 0 {
+		cv := chart.ChartVersions[0]
+		if len(cv.URLs) > 0 {
+			if prov {
+				http.Redirect(w, req, cv.URLs[0]+".prov", http.StatusTemporaryRedirect)
+			} else {
+				http.Redirect(w, req, cv.URLs[0], http.StatusTemporaryRedirect)
+			}
+			return
+		}
+	}
+
+	response.NewErrorResponse(http.StatusNotFound, "could not find chart version").Write(w)
+}

cmd/chartsvc/handler_test.go

@@ -842,3 +842,89 @@ func Test_findLatestChart(t *testing.T) {
 		assert.Equal(t, len(data), 2, "it should return both charts")
 	})
 }
+
+func Test_handleRedirect(t *testing.T) {
+	tests := []struct {
+		name     string
+		err      error
+		chart    models.Chart
+		wantCode int
+		location string
+	}{
+		{
+			"chart does not exist",
+			errors.New("return an error when checking if chart exists"),
+			models.Chart{ID: "my-repo/my-chart"},
+			http.StatusNotFound,
+			"",
+		},
+		{
+			"chart exists",
+			nil,
+			models.Chart{ID: "my-repo/my-chart", ChartVersions: []models.ChartVersion{{Version: "0.1.0", URLs: []string{"https://example.com/my-chart-0.1.0.tgz"}}, {Version: "0.0.1", URLs: []string{"https://example.com/my-chart-0.0.1.tgz"}}}},
+			http.StatusTemporaryRedirect,
+			"https://example.com/my-chart-0.1.0.tgz",
+		},
+		{
+			"chart exists with trailing /",
+			nil,
+			models.Chart{ID: "my-repo/my-chart/", ChartVersions: []models.ChartVersion{{Version: "0.1.0", URLs: []string{"https://example.com/my-chart-0.1.0.tgz"}}, {Version: "0.0.1", URLs: []string{"https://example.com/my-chart-0.0.1.tgz"}}}},
+			http.StatusTemporaryRedirect,
+			"https://example.com/my-chart-0.1.0.tgz",
+		},
+		{
+			"chart with version",
+			nil,
+			models.Chart{ID: "my-repo/my-chart/0.1.0", ChartVersions: []models.ChartVersion{{Version: "0.1.0", URLs: []string{"https://example.com/my-chart-0.1.0.tgz"}}}},
+			http.StatusTemporaryRedirect,
+			"https://example.com/my-chart-0.1.0.tgz",
+		},
+		{
+			"chart with version with trailing /",
+			nil,
+			models.Chart{ID: "my-repo/my-chart/0.1.0/", ChartVersions: []models.ChartVersion{{Version: "0.1.0", URLs: []string{"https://example.com/my-chart-0.1.0.tgz"}}}},
+			http.StatusTemporaryRedirect,
+			"https://example.com/my-chart-0.1.0.tgz",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var m mock.Mock
+			dbSession = mockstore.NewMockSession(&m)
+
+			if tt.err != nil {
+				m.On("One", mock.Anything).Return(tt.err)
+			} else {
+				m.On("One", &models.Chart{}).Return(nil).Run(func(args mock.Arguments) {
+					*args.Get(0).(*models.Chart) = tt.chart
+				})
+			}
+
+			w := httptest.NewRecorder()
+			req := httptest.NewRequest("GET", "/v1/redirect/charts/"+tt.chart.ID, nil)
+
+			handleRedirect(w, req)
+
+			m.AssertExpectations(t)
+			assert.Equal(t, tt.wantCode, w.Code)
+			if tt.wantCode == http.StatusTemporaryRedirect {
+				resp := w.Result()
+				assert.Equal(t, tt.location, resp.Header.Get("Location"), "response header location should be chart url")
+			}
+
+			// Check for provenance file
+			w = httptest.NewRecorder()
+			req = httptest.NewRequest("GET", "/v1/redirect/charts/"+tt.chart.ID+".prov", nil)
+
+			handleRedirect(w, req)
+
+			m.AssertExpectations(t)
+			assert.Equal(t, tt.wantCode, w.Code)
+			if tt.wantCode == http.StatusTemporaryRedirect {
+				resp := w.Result()
+				assert.Equal(t, tt.location+".prov", resp.Header.Get("Location"), "response header location should be chart provenance url")
+			}
+		})
+	}
+}

cmd/chartsvc/main.go

@@ -60,6 +60,11 @@ func setupRoutes() http.Handler {
 	apiv1.Methods("GET").Path("/assets/{repo}/{chartName}/versions/{version}/README.md").Handler(WithParams(getChartVersionReadme))
 	apiv1.Methods("GET").Path("/assets/{repo}/{chartName}/versions/{version}/values.yaml").Handler(WithParams(getChartVersionValues))
 
+	// Handle redirects to the root chart. That way you can
+	// `helm install monocular.example.com/charts/foo/bar` and have monocular
+	// redirect to the right place.
+	apiv1.Methods("GET").PathPrefix("/redirect").HandlerFunc(handleRedirect)
+
 	n := negroni.Classic()
 	n.UseHandler(r)
 	return n