Allow hostname specific dependency mirrors

dependency_cache.go

@@ -69,28 +69,25 @@ type DependencyCache struct {
 	// httpClientTimeouts contains the timeout values used by HTTP client
 	HttpClientTimeouts HttpClientTimeouts
 
-	// Alternative source used for downloading dependencies.
-	DependencyMirror string
+	// Alternative sources used for downloading dependencies.
+	DependencyMirrors map[string]string
 }
 
 // NewDependencyCache creates a new instance setting the default cache path (<BUILDPACK_PATH>/dependencies) and user
 // agent (<BUILDPACK_ID>/<BUILDPACK_VERSION>).
 // Mappings will be read from any libcnb.Binding in the context with type "dependency-mappings".
 //
-// In some air-gapped environments, dependencies might not be download directly but need to be pulled from a local mirror registry.
-// In such cases, an alternative URI can either be provided as environment variable "BP_DEPENDENCY_MIRROR", or by a binding of type "dependency-mirror"
-// where a file named "uri" holds the desired location.
-// The two schemes https:// and file:// are supported in mirror URIs where the expected format is (optional parts in "[]"):
-// <scheme>://[<username>:<password>@]<hostname>[:<port>][/<prefix>]
-// The optional path part of the provided URI is used as a prefix that might be necessary in some setups.
-// This (prefix) path may also include a placeholder of "{originalHost}" at any level (in sub-paths or at top-level) and is replaced with the
-// hostname of the original download URI at build time. A sample mirror URI might look like this: https://local-mirror.example.com/buildpacks-dependencies/{originalHost}
+// In some environments, many dependencies might need to be downloaded from a (local) mirror registry or filesystem.
+// Such alternative locations can be configured using bindings of type "dependency-mirror", avoiding too many "dependency-mapping" bindings.
+// Environment variables named "BP_DEPENDENCY_MIRROR" (default) or "BP_DEPENDENCY_MIRROR_<HOSTNAME>" (hostname-specific mirror)
+// can also be used for the same purpose.
 func NewDependencyCache(context libcnb.BuildContext) (DependencyCache, error) {
 	cache := DependencyCache{
-		CachePath:    filepath.Join(context.Buildpack.Path, "dependencies"),
-		DownloadPath: os.TempDir(),
-		UserAgent:    fmt.Sprintf("%s/%s", context.Buildpack.Info.ID, context.Buildpack.Info.Version),
-		Mappings:     map[string]string{},
+		CachePath:         filepath.Join(context.Buildpack.Path, "dependencies"),
+		DownloadPath:      os.TempDir(),
+		UserAgent:         fmt.Sprintf("%s/%s", context.Buildpack.Info.ID, context.Buildpack.Info.Version),
+		Mappings:          map[string]string{},
+		DependencyMirrors: map[string]string{},
 	}
 	mappings, err := filterBindingsByType(context.Platform.Bindings, "dependency-mapping")
 	if err != nil {
@@ -104,11 +101,11 @@ func NewDependencyCache(context libcnb.BuildContext) (DependencyCache, error) {
 	}
 	cache.HttpClientTimeouts = *clientTimeouts
 
-	dependencyMirror, err := getDependencyMirror(context.Platform.Bindings)
+	dependencyMirrors, err := getDependencyMirrors(context.Platform.Bindings)
 	if err != nil {
-		return DependencyCache{}, err
+		return DependencyCache{}, fmt.Errorf("unable to read dependency mirrors\n%w", err)
 	}
-	cache.DependencyMirror = dependencyMirror
+	cache.DependencyMirrors = dependencyMirrors
 
 	return cache, nil
 }
@@ -153,22 +150,46 @@ func customizeHttpClientTimeouts() (*HttpClientTimeouts, error) {
 	}, nil
 }
 
-// Returns the URI of a dependency mirror (optional).
-// Such mirror location can be defined in a binding of type 'dependency-mirror' with filename 'uri'
-// or using the environment variable 'BP_DEPENDENCY_MIRROR'. The latter takes precedence in case both are found.
-func getDependencyMirror(bindings libcnb.Bindings) (string, error) {
-	dependencyMirror := sherpa.GetEnvWithDefault("BP_DEPENDENCY_MIRROR", "")
-	// If no mirror was found in environment variables, try to find one in bindings.
-	if dependencyMirror == "" {
-		dependencyMirrorBindings, err := filterBindingsByType(bindings, "dependency-mirror")
-		if err == nil {
-			// Use the content of the file named "uri" as the mirror's URI.
-			dependencyMirror = dependencyMirrorBindings["uri"]
-		} else {
-			return "", err
+// Returns a key/value map with the URIs of all dependency mirrors. An empty map is returned if no mirrors are set.
+// Mirror locations can be defined in bindings of type 'dependency-mirror' or using env variables prefixed with 'BP_DEPENDENCY_MIRROR'.
+// Settings provided by env variables override those defined in bindings.
+func getDependencyMirrors(bindings libcnb.Bindings) (map[string]string, error) {
+	dependencyMirrors, err := filterBindingsByType(bindings, "dependency-mirror")
+	if err != nil {
+		return nil, err
+	}
+	dependencyMirrorsFromEnv := getDependencyMirrorsFromEnv()
+	for host, uri := range dependencyMirrorsFromEnv {
+		dependencyMirrors[host] = uri
+	}
+	return dependencyMirrors, nil
+}
+
+// Returns a key/value map of all dependency mirrors set in environment variables.
+func getDependencyMirrorsFromEnv() map[string]string {
+	mirrors := map[string]string{}
+	envs := os.Environ()
+	for _, env := range envs {
+		envPair := strings.SplitN(env, "=", 2)
+		hostnameSuffix, isMirror := strings.CutPrefix(envPair[0], "BP_DEPENDENCY_MIRROR")
+		hostnameEncoded, _ := strings.CutPrefix(hostnameSuffix, "_")
+		if isMirror {
+			mirrors[decodeHostnameEnv(hostnameEncoded)] = envPair[1]
 		}
 	}
-	return dependencyMirror, nil
+	return mirrors
+}
+
+// Takes an encoded hostname (from env key) and returns the decoded version in lower case.
+// Replaces double underscores (__) with one dash (-) and single underscores (_) with one period (.).
+func decodeHostnameEnv(encodedHostname string) string {
+	var decodedHostname string
+	if encodedHostname == "" {
+		decodedHostname = "default"
+	} else {
+		decodedHostname = strings.ReplaceAll(strings.ReplaceAll(encodedHostname, "__", "-"), "_", ".")
+	}
+	return strings.ToLower(decodedHostname)
 }
 
 // Returns a key/value map with all entries for a given binding type.
@@ -181,7 +202,7 @@ func filterBindingsByType(bindings libcnb.Bindings, bindingType string) (map[str
 				if _, ok := filteredBindings[key]; ok {
 					return nil, fmt.Errorf("multiple %s bindings found with duplicate keys %s", binding.Type, key)
 				}
-				filteredBindings[key] = value
+				filteredBindings[strings.ToLower(key)] = value
 			}
 		}
 	}
@@ -225,11 +246,17 @@ func (d *DependencyCache) Artifact(dependency BuildpackDependency, mods ...Reque
 		return nil, fmt.Errorf("unable to parse URI. see DEBUG log level")
 	}
 
-	if isBinding && d.DependencyMirror != "" {
+	mirror := d.DependencyMirrors["default"]
+	mirrorHostSpecific := d.DependencyMirrors[urlP.Hostname()]
+	if mirrorHostSpecific != "" {
+		mirror = mirrorHostSpecific
+	}
+
+	if isBinding && mirror != "" {
 		d.Logger.Bodyf("Both dependency mirror and bindings are present. %s Please remove dependency map bindings if you wish to use the mirror.",
 			color.YellowString("Mirror is being ignored."))
 	} else {
-		d.setDependencyMirror(urlP)
+		d.setDependencyMirror(urlP, mirror)
 	}
 
 	if dependency.SHA256 == "" {
@@ -422,18 +449,18 @@ func (DependencyCache) verify(path string, expected string) error {
 	return nil
 }
 
-func (d DependencyCache) setDependencyMirror(urlD *url.URL) {
-	if d.DependencyMirror != "" {
+func (d DependencyCache) setDependencyMirror(urlD *url.URL, mirror string) {
+	if mirror != "" {
 		d.Logger.Bodyf("%s Download URIs will be overridden.", color.GreenString("Dependency mirror found."))
-		urlOverride, err := url.ParseRequestURI(d.DependencyMirror)
+		urlOverride, err := url.ParseRequestURI(mirror)
 
 		if strings.ToLower(urlOverride.Scheme) == "https" || strings.ToLower(urlOverride.Scheme) == "file" {
 			urlD.Scheme = urlOverride.Scheme
 			urlD.User = urlOverride.User
 			urlD.Path = strings.Replace(urlOverride.Path, "{originalHost}", urlD.Hostname(), 1) + urlD.Path
 			urlD.Host = urlOverride.Host
 		} else {
-			d.Logger.Debugf("Dependency mirror URI is invalid: %s\n%w", d.DependencyMirror, err)
+			d.Logger.Debugf("Dependency mirror URI is invalid: %s\n%w", mirror, err)
 			d.Logger.Bodyf("%s is ignored. Have you used one of the supported schemes https:// or file://?", color.YellowString("Invalid dependency mirror"))
 		}
 	}

dependency_cache_test.go

@@ -154,29 +154,39 @@ func testDependencyCache(t *testing.T, context spec.G, it spec.S) {
 		context("dependency mirror from environment variable", func() {
 			it.Before(func() {
 				t.Setenv("BP_DEPENDENCY_MIRROR", "https://env-var-mirror.acme.com")
+				t.Setenv("BP_DEPENDENCY_MIRROR_EXAMP__LE_COM", "https://examp-le.com")
 			})
 
 			it("uses BP_DEPENDENCY_MIRROR environment variable", func() {
 				dependencyCache, err := libpak.NewDependencyCache(ctx)
 				Expect(err).NotTo(HaveOccurred())
-				Expect(dependencyCache.DependencyMirror).To(Equal("https://env-var-mirror.acme.com"))
+				Expect(dependencyCache.DependencyMirrors["default"]).To(Equal("https://env-var-mirror.acme.com"))
+				Expect(dependencyCache.DependencyMirrors["examp-le.com"]).To(Equal("https://examp-le.com"))
 			})
 		})
 
-		context("dependency mirror from binding", func() {
+		context("dependency mirror from binding and environment variable", func() {
 			it.Before(func() {
+				t.Setenv("BP_DEPENDENCY_MIRROR_EXAMP__LE_COM", "https://examp-le.com")
 				ctx.Platform.Bindings = append(ctx.Platform.Bindings, libcnb.Binding{
 					Type: "dependency-mirror",
 					Secret: map[string]string{
-						"uri": "https://bindings-mirror.acme.com",
+						"default":      "https://bindings-mirror.acme.com",
+						"examp-le.com": "https://invalid.com",
 					},
 				})
 			})
 
 			it("uses dependency-mirror binding", func() {
 				dependencyCache, err := libpak.NewDependencyCache(ctx)
 				Expect(err).NotTo(HaveOccurred())
-				Expect(dependencyCache.DependencyMirror).To(Equal("https://bindings-mirror.acme.com"))
+				Expect(dependencyCache.DependencyMirrors["default"]).To(Equal("https://bindings-mirror.acme.com"))
+			})
+
+			it("environment variable overrides binding", func() {
+				dependencyCache, err := libpak.NewDependencyCache(ctx)
+				Expect(err).NotTo(HaveOccurred())
+				Expect(dependencyCache.DependencyMirrors["examp-le.com"]).To(Equal("https://examp-le.com"))
 			})
 		})
 	})
@@ -332,6 +342,7 @@ func testDependencyCache(t *testing.T, context spec.G, it spec.S) {
 
 			it.Before(func() {
 				mirrorServer = ghttp.NewTLSServer()
+				dependencyCache.DependencyMirrors = map[string]string{}
 			})
 
 			it.After(func() {
@@ -347,7 +358,7 @@ func testDependencyCache(t *testing.T, context spec.G, it spec.S) {
 					ghttp.RespondWith(http.StatusOK, "test-fixture"),
 				))
 
-				dependencyCache.DependencyMirror = url.Scheme + "://" + "username:password@" + url.Host + "/foo/bar"
+				dependencyCache.DependencyMirrors["default"] = url.Scheme + "://" + "username:password@" + url.Host + "/foo/bar"
 				a, err := dependencyCache.Artifact(dependency)
 				Expect(err).NotTo(HaveOccurred())
 
@@ -362,7 +373,22 @@ func testDependencyCache(t *testing.T, context spec.G, it spec.S) {
 					ghttp.RespondWith(http.StatusOK, "test-fixture"),
 				))
 
-				dependencyCache.DependencyMirror = url.Scheme + "://" + url.Host + "/{originalHost}"
+				dependencyCache.DependencyMirrors["default"] = url.Scheme + "://" + url.Host + "/{originalHost}"
+				a, err := dependencyCache.Artifact(dependency)
+				Expect(err).NotTo(HaveOccurred())
+
+				Expect(io.ReadAll(a)).To(Equal([]byte("test-fixture")))
+			})
+
+			it("downloads from https mirror host specific", func() {
+				url, err := url.Parse(mirrorServer.URL())
+				Expect(err).NotTo(HaveOccurred())
+				mirrorServer.AppendHandlers(ghttp.CombineHandlers(
+					ghttp.VerifyRequest(http.MethodGet, "/host-specific/test-path", ""),
+					ghttp.RespondWith(http.StatusOK, "test-fixture"),
+				))
+
+				dependencyCache.DependencyMirrors["127.0.0.1"] = url.Scheme + "://" + url.Host + "/host-specific"
 				a, err := dependencyCache.Artifact(dependency)
 				Expect(err).NotTo(HaveOccurred())
 
@@ -384,6 +410,7 @@ func testDependencyCache(t *testing.T, context spec.G, it spec.S) {
 				Expect(err).NotTo(HaveOccurred())
 				mirrorPathPreservedHost = filepath.Join(mirrorPath, originalUrl.Hostname(), "prefix")
 				Expect(os.MkdirAll(mirrorPathPreservedHost, os.ModePerm)).NotTo(HaveOccurred())
+				dependencyCache.DependencyMirrors = map[string]string{}
 			})
 
 			it.After(func() {
@@ -394,7 +421,7 @@ func testDependencyCache(t *testing.T, context spec.G, it spec.S) {
 				mirrorFile := filepath.Join(mirrorPath, "test-path")
 				Expect(os.WriteFile(mirrorFile, []byte("test-fixture"), 0644)).ToNot(HaveOccurred())
 
-				dependencyCache.DependencyMirror = "file://" + mirrorPath
+				dependencyCache.DependencyMirrors["default"] = "file://" + mirrorPath
 				a, err := dependencyCache.Artifact(dependency)
 				Expect(err).NotTo(HaveOccurred())
 
@@ -405,7 +432,7 @@ func testDependencyCache(t *testing.T, context spec.G, it spec.S) {
 				mirrorFilePreservedHost := filepath.Join(mirrorPathPreservedHost, "test-path")
 				Expect(os.WriteFile(mirrorFilePreservedHost, []byte("test-fixture"), 0644)).ToNot(HaveOccurred())
 
-				dependencyCache.DependencyMirror = "file://" + mirrorPath + "/{originalHost}" + "/prefix"
+				dependencyCache.DependencyMirrors["default"] = "file://" + mirrorPath + "/{originalHost}" + "/prefix"
 				a, err := dependencyCache.Artifact(dependency)
 				Expect(err).NotTo(HaveOccurred())