Support bearerauthtoken header customization (open-telemetry#38793)

#### Description

Adding a feature - Allow the header name to be customized in the
bearerauthtoken extension

#### Testing

Added tests and ran all tests for the extension.

#### Documentation

Updated readme for the extension

Author: nahguam

.chloggen/bearerauth-header.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: bearertokenauthextension
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Allow the header name to be customized in the bearerauthtoken extension
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [38793]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user]

extension/bearertokenauthextension/README.md

@@ -21,6 +21,8 @@ The authenticator type has to be set to `bearertokenauth`.
 
 ## Configuration
 
+- `header`: Specifies the auth header name. Defaults to "Authorization". Optional.
+
 - `scheme`: Specifies the auth scheme name. Defaults to "Bearer". Optional.
 
 - `token`: Static authorization token that needs to be sent on every gRPC client call as metadata.

extension/bearertokenauthextension/bearertokenauth.go

@@ -6,7 +6,6 @@ package bearertokenauthextension // import "github.com/open-telemetry/openteleme
 import (
 	"context"
 	"crypto/subtle"
-	"errors"
 	"fmt"
 	"net/http"
 	"os"
@@ -30,7 +29,7 @@ type PerRPCAuth struct {
 
 // GetRequestMetadata returns the request metadata to be used with the RPC.
 func (c *PerRPCAuth) GetRequestMetadata(context.Context, ...string) (map[string]string, error) {
-	return map[string]string{"authorization": c.auth.authorizationValue()}, nil
+	return map[string]string{strings.ToLower(c.auth.header): c.auth.authorizationValue()}, nil
 }
 
 // RequireTransportSecurity always returns true for this implementation. Passing bearer tokens in plain-text connections is a bad idea.
@@ -47,6 +46,7 @@ var (
 
 // BearerTokenAuth is an implementation of extensionauth interfaces. It embeds a static authorization "bearer" token in every rpc call.
 type BearerTokenAuth struct {
+	header                    string
 	scheme                    string
 	authorizationValuesAtomic atomic.Value
 
@@ -61,6 +61,7 @@ func newBearerTokenAuth(cfg *Config, logger *zap.Logger) *BearerTokenAuth {
 		logger.Warn("a filename is specified. Configured token(s) is ignored!")
 	}
 	a := &BearerTokenAuth{
+		header:   cfg.Header,
 		scheme:   cfg.Scheme,
 		filename: cfg.Filename,
 		logger:   logger,
@@ -211,19 +212,20 @@ func (b *BearerTokenAuth) PerRPCCredentials() (credentials.PerRPCCredentials, er
 // RoundTripper is not implemented by BearerTokenAuth
 func (b *BearerTokenAuth) RoundTripper(base http.RoundTripper) (http.RoundTripper, error) {
 	return &BearerAuthRoundTripper{
+		header:        b.header,
 		baseTransport: base,
 		auth:          b,
 	}, nil
 }
 
 // Authenticate checks whether the given context contains valid auth data. Validates tokens from clients trying to access the service (incoming requests)
 func (b *BearerTokenAuth) Authenticate(ctx context.Context, headers map[string][]string) (context.Context, error) {
-	auth, ok := headers["authorization"]
+	auth, ok := headers[strings.ToLower(b.header)]
 	if !ok {
-		auth, ok = headers["Authorization"]
+		auth, ok = headers[b.header]
 	}
 	if !ok || len(auth) == 0 {
-		return ctx, errors.New("missing or empty authorization header")
+		return ctx, fmt.Errorf("missing or empty authorization header: %s", b.header)
 	}
 	token := auth[0] // Extract token from authorization header
 	expectedTokens := b.authorizationValues()
@@ -237,6 +239,7 @@ func (b *BearerTokenAuth) Authenticate(ctx context.Context, headers map[string][
 
 // BearerAuthRoundTripper intercepts and adds Bearer token Authorization headers to each http request.
 type BearerAuthRoundTripper struct {
+	header        string
 	baseTransport http.RoundTripper
 	auth          *BearerTokenAuth
 }
@@ -247,6 +250,6 @@ func (interceptor *BearerAuthRoundTripper) RoundTrip(req *http.Request) (*http.R
 	if req2.Header == nil {
 		req2.Header = make(http.Header)
 	}
-	req2.Header.Set("Authorization", interceptor.auth.authorizationValue())
+	req2.Header.Set(interceptor.header, interceptor.auth.authorizationValue())
 	return interceptor.baseTransport.RoundTrip(req2)
 }

extension/bearertokenauthextension/bearertokenauth_test.go

@@ -9,6 +9,7 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
+	"strings"
 	"testing"
 	"time"
 
@@ -384,3 +385,65 @@ func TestBearerTokenMultipleTokensInFile(t *testing.T) {
 
 	assert.NoError(t, bauth.Shutdown(context.Background()))
 }
+
+func TestCustomHeaderRoundTrip(t *testing.T) {
+	cfg := createDefaultConfig().(*Config)
+	cfg.Header = "X-Custom-Authorization"
+	cfg.Scheme = ""
+	cfg.BearerToken = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9..."
+
+	bauth := newBearerTokenAuth(cfg, nil)
+	assert.NotNil(t, bauth)
+
+	base := &mockRoundTripper{}
+	c, err := bauth.RoundTripper(base)
+	assert.NoError(t, err)
+	assert.NotNil(t, c)
+
+	request := &http.Request{Method: http.MethodGet}
+	resp, err := c.RoundTrip(request)
+	assert.NoError(t, err)
+	authHeaderValue := resp.Header.Get(cfg.Header)
+	assert.Equal(t, authHeaderValue, string(cfg.BearerToken))
+}
+
+func TestCustomHeaderGetRequestMetadata(t *testing.T) {
+	cfg := createDefaultConfig().(*Config)
+	cfg.Header = "X-Custom-Authorization"
+	cfg.Scheme = ""
+	cfg.BearerToken = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9..."
+
+	bauth := newBearerTokenAuth(cfg, nil)
+	assert.NotNil(t, bauth)
+
+	assert.NoError(t, bauth.Start(context.Background(), componenttest.NewNopHost()))
+	credential, err := bauth.PerRPCCredentials()
+
+	assert.NoError(t, err)
+	assert.NotNil(t, credential)
+
+	md, err := credential.GetRequestMetadata(context.Background())
+	expectedMd := map[string]string{
+		strings.ToLower(cfg.Header): string(cfg.BearerToken),
+	}
+	assert.Equal(t, expectedMd, md)
+	assert.NoError(t, err)
+}
+
+func TestCustomHeaderAuthenticate(t *testing.T) {
+	cfg := createDefaultConfig().(*Config)
+	cfg.Header = "X-Custom-Authorization"
+	cfg.Scheme = ""
+	cfg.BearerToken = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9..."
+
+	bauth := newBearerTokenAuth(cfg, nil)
+	assert.NotNil(t, bauth)
+
+	ctx := context.Background()
+	assert.NoError(t, bauth.Start(ctx, componenttest.NewNopHost()))
+
+	_, err := bauth.Authenticate(ctx, map[string][]string{cfg.Header: {string(cfg.BearerToken)}})
+	assert.NoError(t, err)
+
+	assert.NoError(t, bauth.Shutdown(context.Background()))
+}

extension/bearertokenauthextension/config.go

@@ -12,6 +12,9 @@ import (
 
 // Config specifies how the Per-RPC bearer token based authentication data should be obtained.
 type Config struct {
+	// Header specifies the auth-header for the token. Defaults to "Authorization"
+	Header string `mapstructure:"header,omitempty"`
+
 	// Scheme specifies the auth-scheme for the token. Defaults to "Bearer"
 	Scheme string `mapstructure:"scheme,omitempty"`
 

extension/bearertokenauthextension/config_test.go

@@ -32,34 +32,39 @@ func TestLoadConfig(t *testing.T) {
 		{
 			id: component.NewIDWithName(metadata.Type, "sometoken"),
 			expected: &Config{
+				Header:      defaultHeader,
 				Scheme:      defaultScheme,
 				BearerToken: "sometoken",
 			},
 		},
 		{
 			id: component.NewIDWithName(metadata.Type, "withscheme"),
 			expected: &Config{
+				Header:      defaultHeader,
 				Scheme:      "MyScheme",
 				BearerToken: "my-token",
 			},
 		},
 		{
 			id: component.NewIDWithName(metadata.Type, "multipletokens"),
 			expected: &Config{
+				Header: defaultHeader,
 				Scheme: "Bearer",
 				Tokens: []configopaque.String{"token1", "thistokenalsoworks"},
 			},
 		},
 		{
 			id: component.NewIDWithName(metadata.Type, "withfilename"),
 			expected: &Config{
+				Header:   defaultHeader,
 				Scheme:   "Bearer",
 				Filename: "file-containing.token",
 			},
 		},
 		{
 			id: component.NewIDWithName(metadata.Type, "both"),
 			expected: &Config{
+				Header:      defaultHeader,
 				Scheme:      "Bearer",
 				BearerToken: "ignoredtoken",
 				Filename:    "file-containing.token",
@@ -68,6 +73,7 @@ func TestLoadConfig(t *testing.T) {
 		{
 			id: component.NewIDWithName(metadata.Type, "tokensandtoken"),
 			expected: &Config{
+				Header:      defaultHeader,
 				Scheme:      "Bearer",
 				BearerToken: "sometoken",
 				Tokens:      []configopaque.String{"token1", "thistokenalsoworks"},
@@ -77,12 +83,22 @@ func TestLoadConfig(t *testing.T) {
 		{
 			id: component.NewIDWithName(metadata.Type, "withtokensandfilename"),
 			expected: &Config{
+				Header:   defaultHeader,
 				Scheme:   "Bearer",
 				Tokens:   []configopaque.String{"ignoredtoken1", "ignoredtoken2"},
 				Filename: "file-containing.token",
 			},
 		},
+		{
+			id: component.NewIDWithName(metadata.Type, "withheader"),
+			expected: &Config{
+				Header:      "X-Custom-Authorization",
+				Scheme:      "",
+				BearerToken: "my-token",
+			},
+		},
 	}
+
 	for _, tt := range tests {
 		t.Run(tt.id.String(), func(t *testing.T) {
 			cm, err := confmaptest.LoadConf(filepath.Join("testdata", "config.yaml"))

extension/bearertokenauthextension/factory.go

@@ -13,6 +13,7 @@ import (
 )
 
 const (
+	defaultHeader = "Authorization"
 	defaultScheme = "Bearer"
 )
 
@@ -28,6 +29,7 @@ func NewFactory() extension.Factory {
 
 func createDefaultConfig() component.Config {
 	return &Config{
+		Header: defaultHeader,
 		Scheme: defaultScheme,
 	}
 }

extension/bearertokenauthextension/factory_test.go

@@ -15,7 +15,7 @@ import (
 
 func TestFactory_CreateDefaultConfig(t *testing.T) {
 	cfg := createDefaultConfig()
-	assert.Equal(t, &Config{Scheme: defaultScheme}, cfg)
+	assert.Equal(t, &Config{Header: defaultHeader, Scheme: defaultScheme}, cfg)
 	assert.NoError(t, componenttest.CheckConfigStruct(cfg))
 }
 

extension/bearertokenauthextension/testdata/config.yaml

@@ -28,3 +28,7 @@ bearertokenauth/tokensandtoken:
     - "token1"
     - "thistokenalsoworks"
   token: "my-token"
+bearertokenauth/withheader:
+  header: "X-Custom-Authorization"
+  scheme: ""
+  token: "my-token"