feat: Support GCP destination auth

REFERENCE.md

@@ -976,7 +976,21 @@ hookdeck connection create \
   --destination-url "https://api.example.com/stripe"
 ```
 
-**4. Destination with Bearer Token**
+**4. Destination with Hookdeck Signature (Default)**
+```bash
+# Hookdeck automatically signs outgoing webhooks - no configuration needed
+hookdeck connection create \
+  --source-name "stripe-webhooks" \
+  --source-type STRIPE \
+  --source-webhook-secret "whsec_stripe_secret" \
+  --destination-name "api-with-verification" \
+  --destination-type HTTP \
+  --destination-url "https://api.example.com/webhook" \
+  --destination-auth-method hookdeck
+```
+*Note: Hookdeck Signature authentication is the default. Hookdeck automatically signs all outgoing webhooks with a signature that can be verified using Hookdeck's verification libraries. No webhook secret needs to be configured.*
+
+**5. Destination with Bearer Token**
 ```bash
 hookdeck connection create \
   --source-name "github-webhooks" \
@@ -985,9 +999,11 @@ hookdeck connection create \
   --destination-name "ci-system" \
   --destination-type HTTP \
   --destination-url "https://ci.example.com/webhook" \
+  --destination-auth-method bearer \
   --destination-bearer-token "bearer_token_xyz"
+```
 
-**5. Source with Custom Response and Allowed HTTP Methods**
+**6. Source with Custom Response and Allowed HTTP Methods**
 ```bash
 hookdeck connection create \
   --source-name "api-webhooks" \
@@ -1002,7 +1018,7 @@ hookdeck connection create \
 
 #### Rule Configuration Examples
 
-**6. Retry Rules**
+**7. Retry Rules**
 ```bash
 hookdeck connection create \
   --source-name "payment-webhooks" \
@@ -1015,7 +1031,7 @@ hookdeck connection create \
   --rule-retry-interval 60000
 ```
 
-**7. Filter Rules**
+**8. Filter Rules**
 ```bash
 hookdeck connection create \
   --source-name "events" \
@@ -1026,7 +1042,7 @@ hookdeck connection create \
   --rule-filter-body '{"event_type":"payment.succeeded"}'
 ```
 
-**8. All Rule Types Combined**
+**9. All Rule Types Combined**
 ```bash
 hookdeck connection create \
   --source-name "shopify-webhooks" \
@@ -1042,7 +1058,7 @@ hookdeck connection create \
   --rule-delay 5000
 ```
 
-**9. Rate Limiting**
+**10. Rate Limiting**
 ```bash
 hookdeck connection create \
   --source-name "high-volume-source" \
@@ -1054,6 +1070,19 @@ hookdeck connection create \
   --destination-rate-limit-period minute
 ```
 
+**11. GCP Service Account Authentication**
+```bash
+hookdeck connection create \
+  --source-name "webhooks" \
+  --source-type HTTP \
+  --destination-name "gcp-cloud-function" \
+  --destination-type HTTP \
+  --destination-url "https://us-central1-project-id.cloudfunctions.net/function" \
+  --destination-auth-method gcp \
+  --destination-gcp-service-account-key '{"type":"service_account","project_id":"project-id","private_key_id":"key-id","private_key":"-----BEGIN PRIVATE KEY-----\n...\n-----END PRIVATE KEY-----\n","client_email":"service-account@project-id.iam.gserviceaccount.com"}' \
+  --destination-gcp-scope "https://www.googleapis.com/auth/cloud-platform"
+```
+
 #### Available Flags
 
 **Connection Configuration:**
@@ -1084,7 +1113,7 @@ hookdeck connection create \
 - `--destination-cli-path <path>` - CLI path (default: `/`)
 - `--destination-path-forwarding-disabled <true|false>` - Disable path forwarding for HTTP destinations (default: false)
 - `--destination-http-method <method>` - HTTP method for HTTP destinations: `GET`, `POST`, `PUT`, `PATCH`, `DELETE`
-- `--destination-auth-method <method>` - Authentication method: `hookdeck`, `bearer`, `basic`, `api_key`, `custom_signature`, `oauth2_client_credentials`, `oauth2_authorization_code`, `aws`
+- `--destination-auth-method <method>` - Authentication method: `hookdeck`, `bearer`, `basic`, `api_key`, `custom_signature`, `oauth2_client_credentials`, `oauth2_authorization_code`, `aws`, `gcp`
 - `--destination-rate-limit <number>` - Rate limit (requests per period)
 - `--destination-rate-limit-period <period>` - Period: `second`, `minute`, `hour`, `day`, `month`, `year`
 
@@ -1136,6 +1165,11 @@ hookdeck connection create \
 - `--destination-aws-region <region>` - AWS region
 - `--destination-aws-service <service>` - AWS service name
 
+*GCP Service Account:*
+- `--destination-auth-method gcp`
+- `--destination-gcp-service-account-key <json>` - GCP service account key JSON
+- `--destination-gcp-scope <scope>` - GCP scope (optional)
+
 **Rules - Retry:**
 - `--rule-retry-strategy <strategy>` - Strategy: `linear`, `exponential`
 - `--rule-retry-count <number>` - Number of retry attempts (1-20)

pkg/cmd/connection_auth_test.go

@@ -295,6 +295,55 @@ func TestBuildAuthConfig(t *testing.T) {
 			wantErr:     true,
 			errContains: "--destination-aws-region is required",
 		},
+		{
+			name: "gcp service account auth - valid",
+			setup: func(cc *connectionCreateCmd) {
+				cc.DestinationAuthMethod = "gcp"
+				cc.DestinationGCPServiceAccountKey = `{"type":"service_account","project_id":"test"}`
+				cc.DestinationGCPScope = "https://www.googleapis.com/auth/cloud-platform"
+			},
+			wantType: "GCP_SERVICE_ACCOUNT",
+			wantErr:  false,
+			validate: func(t *testing.T, config map[string]interface{}) {
+				if config["type"] != "GCP_SERVICE_ACCOUNT" {
+					t.Errorf("expected type GCP_SERVICE_ACCOUNT, got %v", config["type"])
+				}
+				if config["service_account_key"] == "" {
+					t.Error("expected service_account_key to be set")
+				}
+				if config["scope"] != "https://www.googleapis.com/auth/cloud-platform" {
+					t.Errorf("expected scope, got %v", config["scope"])
+				}
+			},
+		},
+		{
+			name: "gcp service account auth - valid without scope",
+			setup: func(cc *connectionCreateCmd) {
+				cc.DestinationAuthMethod = "gcp"
+				cc.DestinationGCPServiceAccountKey = `{"type":"service_account","project_id":"test"}`
+			},
+			wantType: "GCP_SERVICE_ACCOUNT",
+			wantErr:  false,
+			validate: func(t *testing.T, config map[string]interface{}) {
+				if config["type"] != "GCP_SERVICE_ACCOUNT" {
+					t.Errorf("expected type GCP_SERVICE_ACCOUNT, got %v", config["type"])
+				}
+				if config["service_account_key"] == "" {
+					t.Error("expected service_account_key to be set")
+				}
+				if _, hasScope := config["scope"]; hasScope {
+					t.Error("expected scope to not be set when not provided")
+				}
+			},
+		},
+		{
+			name: "gcp service account auth - missing key",
+			setup: func(cc *connectionCreateCmd) {
+				cc.DestinationAuthMethod = "gcp"
+			},
+			wantErr:     true,
+			errContains: "--destination-gcp-service-account-key is required",
+		},
 		{
 			name: "unsupported auth method",
 			setup: func(cc *connectionCreateCmd) {

pkg/cmd/connection_create.go

@@ -84,6 +84,10 @@ type connectionCreateCmd struct {
 	DestinationAWSRegion          string
 	DestinationAWSService         string
 
+	// GCP Service Account flags
+	DestinationGCPServiceAccountKey string
+	DestinationGCPScope             string
+
 	// Destination rate limiting flags
 	DestinationRateLimit       int
 	DestinationRateLimitPeriod string
@@ -207,7 +211,7 @@ func newConnectionCreateCmd() *connectionCreateCmd {
 	cc.cmd.Flags().StringVar(&cc.destinationHTTPMethod, "destination-http-method", "", "HTTP method for HTTP destinations (GET, POST, PUT, PATCH, DELETE)")
 
 	// Destination authentication flags
-	cc.cmd.Flags().StringVar(&cc.DestinationAuthMethod, "destination-auth-method", "", "Authentication method for HTTP destinations (hookdeck, bearer, basic, api_key, custom_signature, oauth2_client_credentials, oauth2_authorization_code, aws)")
+	cc.cmd.Flags().StringVar(&cc.DestinationAuthMethod, "destination-auth-method", "", "Authentication method for HTTP destinations (hookdeck, bearer, basic, api_key, custom_signature, oauth2_client_credentials, oauth2_authorization_code, aws, gcp)")
 
 	// Bearer Token
 	cc.cmd.Flags().StringVar(&cc.DestinationBearerToken, "destination-bearer-token", "", "Bearer token for destination authentication")
@@ -241,6 +245,10 @@ func newConnectionCreateCmd() *connectionCreateCmd {
 	cc.cmd.Flags().StringVar(&cc.DestinationAWSRegion, "destination-aws-region", "", "AWS region")
 	cc.cmd.Flags().StringVar(&cc.DestinationAWSService, "destination-aws-service", "", "AWS service name")
 
+	// GCP Service Account
+	cc.cmd.Flags().StringVar(&cc.DestinationGCPServiceAccountKey, "destination-gcp-service-account-key", "", "GCP service account key JSON for destination authentication")
+	cc.cmd.Flags().StringVar(&cc.DestinationGCPScope, "destination-gcp-scope", "", "GCP scope for service account authentication")
+
 	// Destination rate limiting flags
 	cc.cmd.Flags().IntVar(&cc.DestinationRateLimit, "destination-rate-limit", 0, "Rate limit for destination (requests per period)")
 	cc.cmd.Flags().StringVar(&cc.DestinationRateLimitPeriod, "destination-rate-limit-period", "", "Rate limit period (second, minute, hour, concurrent)")
@@ -790,8 +798,20 @@ func (cc *connectionCreateCmd) buildAuthConfig() (map[string]interface{}, error)
 		authConfig["region"] = cc.DestinationAWSRegion
 		authConfig["service"] = cc.DestinationAWSService
 
+	case "gcp":
+		// GCP_SERVICE_ACCOUNT
+		if cc.DestinationGCPServiceAccountKey == "" {
+			return nil, fmt.Errorf("--destination-gcp-service-account-key is required for gcp auth method")
+		}
+		authConfig["type"] = "GCP_SERVICE_ACCOUNT"
+		authConfig["service_account_key"] = cc.DestinationGCPServiceAccountKey
+
+		if cc.DestinationGCPScope != "" {
+			authConfig["scope"] = cc.DestinationGCPScope
+		}
+
 	default:
-		return nil, fmt.Errorf("unsupported destination authentication method: %s (supported: hookdeck, bearer, basic, api_key, custom_signature, oauth2_client_credentials, oauth2_authorization_code, aws)", cc.DestinationAuthMethod)
+		return nil, fmt.Errorf("unsupported destination authentication method: %s (supported: hookdeck, bearer, basic, api_key, custom_signature, oauth2_client_credentials, oauth2_authorization_code, aws, gcp)", cc.DestinationAuthMethod)
 	}
 
 	return authConfig, nil

pkg/cmd/connection_upsert.go

@@ -116,7 +116,7 @@ func newConnectionUpsertCmd() *connectionUpsertCmd {
 	cu.cmd.Flags().StringVar(&cu.destinationHTTPMethod, "destination-http-method", "", "HTTP method for HTTP destinations (GET, POST, PUT, PATCH, DELETE)")
 
 	// Destination authentication flags
-	cu.cmd.Flags().StringVar(&cu.DestinationAuthMethod, "destination-auth-method", "", "Authentication method for HTTP destinations (hookdeck, bearer, basic, api_key, custom_signature, oauth2_client_credentials, oauth2_authorization_code, aws)")
+	cu.cmd.Flags().StringVar(&cu.DestinationAuthMethod, "destination-auth-method", "", "Authentication method for HTTP destinations (hookdeck, bearer, basic, api_key, custom_signature, oauth2_client_credentials, oauth2_authorization_code, aws, gcp)")
 
 	// Bearer Token
 	cu.cmd.Flags().StringVar(&cu.DestinationBearerToken, "destination-bearer-token", "", "Bearer token for destination authentication")
@@ -150,6 +150,10 @@ func newConnectionUpsertCmd() *connectionUpsertCmd {
 	cu.cmd.Flags().StringVar(&cu.DestinationAWSRegion, "destination-aws-region", "", "AWS region")
 	cu.cmd.Flags().StringVar(&cu.DestinationAWSService, "destination-aws-service", "", "AWS service name")
 
+	// GCP Service Account
+	cu.cmd.Flags().StringVar(&cu.DestinationGCPServiceAccountKey, "destination-gcp-service-account-key", "", "GCP service account key JSON for destination authentication")
+	cu.cmd.Flags().StringVar(&cu.DestinationGCPScope, "destination-gcp-scope", "", "GCP scope for service account authentication")
+
 	// Destination rate limiting flags
 	cu.cmd.Flags().IntVar(&cu.DestinationRateLimit, "destination-rate-limit", 0, "Rate limit for destination (requests per period)")
 	cu.cmd.Flags().StringVar(&cu.DestinationRateLimitPeriod, "destination-rate-limit-period", "", "Rate limit period (second, minute, hour, concurrent)")

test/acceptance/connection_oauth_aws_test.go

@@ -184,4 +184,62 @@ func TestConnectionOAuth2AWSAuthentication(t *testing.T) {
 
 		t.Logf("Successfully tested HTTP destination with AWS Signature: %s", connID)
 	})
+
+	t.Run("HTTP_Destination_GCP_ServiceAccount", func(t *testing.T) {
+		if testing.Short() {
+			t.Skip("Skipping acceptance test in short mode")
+		}
+
+		cli := NewCLIRunner(t)
+		timestamp := generateTimestamp()
+
+		connName := "test-gcp-sa-conn-" + timestamp
+		sourceName := "test-gcp-sa-source-" + timestamp
+		destName := "test-gcp-sa-dest-" + timestamp
+		destURL := "https://api.hookdeck.com/dev/null"
+
+		// Create connection with HTTP destination (GCP Service Account)
+		// Using a minimal but valid JSON structure for service account key
+		serviceAccountKey := `{"type":"service_account","project_id":"test-project","private_key_id":"test-key-id","private_key":"-----BEGIN PRIVATE KEY-----\nMIIEvQIBADANBgkqhkiG9w0BAQEFAASCBKcwggSjAgEAAoIBAQC\n-----END PRIVATE KEY-----\n","client_email":"test@test-project.iam.gserviceaccount.com","client_id":"123456789","auth_uri":"https://accounts.google.com/o/oauth2/auth","token_uri":"https://oauth2.googleapis.com/token"}`
+
+		stdout, stderr, err := cli.Run("connection", "create",
+			"--name", connName,
+			"--source-type", "WEBHOOK",
+			"--source-name", sourceName,
+			"--destination-type", "HTTP",
+			"--destination-name", destName,
+			"--destination-url", destURL,
+			"--destination-auth-method", "gcp",
+			"--destination-gcp-service-account-key", serviceAccountKey,
+			"--destination-gcp-scope", "https://www.googleapis.com/auth/cloud-platform",
+			"--output", "json")
+		require.NoError(t, err, "Failed to create connection: stderr=%s", stderr)
+
+		var createResp map[string]interface{}
+		err = json.Unmarshal([]byte(stdout), &createResp)
+		require.NoError(t, err, "Failed to parse creation response: %s", stdout)
+
+		connID, ok := createResp["id"].(string)
+		require.True(t, ok && connID != "", "Expected connection ID in creation response")
+
+		// Verify destination auth configuration
+		dest, ok := createResp["destination"].(map[string]interface{})
+		require.True(t, ok, "Expected destination object in creation response")
+
+		destConfig, ok := dest["config"].(map[string]interface{})
+		require.True(t, ok, "Expected destination config object")
+
+		if authMethod, ok := destConfig["auth_method"].(map[string]interface{}); ok {
+			assert.Equal(t, "GCP_SERVICE_ACCOUNT", authMethod["type"], "Auth type should be GCP_SERVICE_ACCOUNT")
+			assert.Equal(t, "https://www.googleapis.com/auth/cloud-platform", authMethod["scope"], "GCP scope should match")
+			// Service account key should not be returned for security reasons
+		}
+
+		// Cleanup
+		t.Cleanup(func() {
+			deleteConnection(t, cli, connID)
+		})
+
+		t.Logf("Successfully tested HTTP destination with GCP Service Account: %s", connID)
+	})
 }

test/acceptance/connection_test.go

@@ -1323,7 +1323,7 @@ func TestConnectionWithDeduplicateRule(t *testing.T) {
 		"--destination-name", destName,
 		"--destination-type", "CLI",
 		"--destination-cli-path", "/webhooks",
-		"--rule-deduplicate-window", "86400",
+		"--rule-deduplicate-window", "60000",
 		"--rule-deduplicate-include-fields", "body.id,body.timestamp",
 	)
 	require.NoError(t, err, "Should create connection with deduplicate rule")
@@ -1344,7 +1344,7 @@ func TestConnectionWithDeduplicateRule(t *testing.T) {
 
 	rule := getConn.Rules[0]
 	assert.Equal(t, "deduplicate", rule["type"], "Rule type should be deduplicate")
-	assert.Equal(t, float64(86400), rule["window"], "Deduplicate window should be 86400 milliseconds")
+	assert.Equal(t, float64(60000), rule["window"], "Deduplicate window should be 60000 milliseconds (60 seconds)")
 
 	// Verify include_fields is correctly set and matches our input
 	if includeFields, ok := rule["include_fields"].([]interface{}); ok {