Support multiple repositories via sub-addresses, fixes #2

Author: abhidg

README.md

@@ -1,8 +1,15 @@
 # ticket-dispatcher
 
 ticket-dispatcher posts comments on GitHub issues via email sent to a specific
-domain such as `NNN@issues.example.com` which will post to a GitHub repository
-for issue NNN.
+domain such as `NNN@issues.example.com` which will post to an issue in the
+GitHub repository `org/foo` defined via the `GITHUB_PROJECT` environment
+variable.
+
+Emails sent to
+[sub-addresses](https://en.wikipedia.org/wiki/Email_address#Sub-addressing)
+such as `NNN+other-project@issues.example.com` where `other-project` is the
+sub-address or tag, are forwarded to org/other-project, with the organisation
+name `org` determined from `GITHUB_PROJECT`.
 
 ## Development
 
@@ -17,6 +24,12 @@ go build
 go test
 ```
 
+## Infrastructure
+
+ticket-dispatcher is currently deployed on AWS infrastructure and makes use of
+AWS Lambda for the ticket-dispatcher function, AWS SES for email receiving and
+AWS S3 for email storage.
+
 ## Deployment
 
 ### Generate a GitHub PAT
@@ -128,4 +141,4 @@ Once deployed, the ticket-dispatcher lambda function can be updated by calling
 ./scripts/update-lambda.sh
 ```
 
-**Logs**: Cloudwatch logs can be found at `/aws/lambda/ticket-dispatcher`
+**Logs**: Cloudwatch logs can be found at `/aws/lambda/ticket-dispatcher`

extract_metadata.go

@@ -6,8 +6,9 @@ import (
 	"unicode"
 )
 
-// extractIssueNumber scans To and Cc headers and returns the first numeric local-part found.
-func extractIssueNumber(toHeader, ccHeader string) string {
+// extractIssueNumber scans To and Cc headers and returns the first numeric local-part found,
+// along with an optional repo suffix extracted from a + tag (e.g. 123+myrepo@domain → "123", "myrepo").
+func extractIssueNumber(toHeader, ccHeader string) (issueNumber, repoSuffix string) {
 	// Combine headers; ParseAddressList handles comma-separated lists
 	headers := []string{toHeader, ccHeader}
 
@@ -24,8 +25,9 @@ func extractIssueNumber(toHeader, ccHeader string) string {
 			for _, p := range parts {
 				if strings.Contains(p, "@") {
 					stringParts := strings.SplitN(p, "@", 2)
-					if isDigits(stringParts[0]) && stringParts[1] == ticketDomain {
-						return stringParts[0]
+					num, repo := splitLocalPart(stringParts[0])
+					if isDigits(num) && stringParts[1] == ticketDomain {
+						return num, repo
 					}
 				}
 			}
@@ -42,12 +44,22 @@ func extractIssueNumber(toHeader, ccHeader string) string {
 			}
 			local := parts[0]
 			domain := parts[1]
-			if isDigits(local) && domain == ticketDomain {
-				return local
+			num, repo := splitLocalPart(local)
+			if isDigits(num) && domain == ticketDomain {
+				return num, repo
 			}
 		}
 	}
-	return ""
+	return "", ""
+}
+
+// splitLocalPart splits an email local part on the first '+'.
+// "123+myrepo" → ("123", "myrepo"); "123" → ("123", "").
+func splitLocalPart(local string) (num, repo string) {
+	if i := strings.IndexByte(local, '+'); i >= 0 {
+		return local[:i], local[i+1:]
+	}
+	return local, ""
 }
 
 // extractSenderDomain parses the From header and returns the domain (lowercased) or empty string.

extract_metadata_test.go

@@ -11,22 +11,40 @@ func setupTests(t *testing.T) {
 func TestExtractIssueNumber(t *testing.T) {
 	setupTests(t)
 	tests := []struct {
-		to   string
-		want string
-	}{{
-		to:   "John Doe <johndoe@example.com>",
-		want: "",
-	},
-		{to: "John Doe <johndoe@example.com>, 123@issues.example.com",
-			want: "123",
+		to         string
+		wantIssue  string
+		wantRepo   string
+	}{
+		{
+			to:        "John Doe <johndoe@example.com>",
+			wantIssue: "",
+			wantRepo:  "",
+		},
+		{
+			to:        "John Doe <johndoe@example.com>, 123@issues.example.com",
+			wantIssue: "123",
+			wantRepo:  "",
+		},
+		{
+			to:        "123+myrepo@issues.example.com",
+			wantIssue: "123",
+			wantRepo:  "myrepo",
+		},
+		{
+			to:        "John Doe <johndoe@example.com>, 456+other-repo@issues.example.com",
+			wantIssue: "456",
+			wantRepo:  "other-repo",
 		},
 	}
 
 	for _, tc := range tests {
 		t.Run(tc.to, func(t *testing.T) {
-			got := extractIssueNumber(tc.to, "")
-			if got != tc.want {
-				t.Errorf("extractIssueNumber mismatch:\n--- got ---\n%q\n--- want ---\n%q\n", got, tc.want)
+			gotIssue, gotRepo := extractIssueNumber(tc.to, "")
+			if gotIssue != tc.wantIssue {
+				t.Errorf("extractIssueNumber issue mismatch:\n--- got ---\n%q\n--- want ---\n%q\n", gotIssue, tc.wantIssue)
+			}
+			if gotRepo != tc.wantRepo {
+				t.Errorf("extractIssueNumber repo mismatch:\n--- got ---\n%q\n--- want ---\n%q\n", gotRepo, tc.wantRepo)
 			}
 		})
 	}

issue_comments.go

@@ -16,8 +16,8 @@ type ghComment struct {
 	Body string `json:"body"`
 }
 
-func postIssueComment(issueNumber, msgId, comment string) error {
-	exists, err := commentWithMessageIDExists(issueNumber, msgId)
+func postIssueComment(project, issueNumber, msgId, comment string) error {
+	exists, err := commentWithMessageIDExists(project, issueNumber, msgId)
 	// only suppress posting if we get confirmation that Message-ID was found
 	// better to post twice than silently fail
 	if exists {
@@ -33,7 +33,7 @@ func postIssueComment(issueNumber, msgId, comment string) error {
 
 	url := fmt.Sprintf(
 		"https://api.github.com/repos/%s/issues/%s/comments",
-		githubProject, issueNumber,
+		project, issueNumber,
 	)
 	payload := map[string]string{
 		"body": fmt.Sprintf("Message-ID: %s\n", msgId) + comment,
@@ -72,7 +72,7 @@ func postIssueComment(issueNumber, msgId, comment string) error {
 
 // commentWithMessageIDExists checks whether an issue already has a comment
 // whose first line contains the given Message-ID (exact match or contains).
-func commentWithMessageIDExists(issueNumber, messageID string) (bool, error) {
+func commentWithMessageIDExists(project, issueNumber, messageID string) (bool, error) {
 	token := os.Getenv("GITHUB_TOKEN")
 
 	if token == "" {
@@ -86,7 +86,7 @@ func commentWithMessageIDExists(issueNumber, messageID string) (bool, error) {
 	for {
 		url := fmt.Sprintf(
 			"https://api.github.com/repos/%s/issues/%s/comments?per_page=100&page=%d",
-			githubProject, issueNumber, page,
+			project, issueNumber, page,
 		)
 
 		req, err := http.NewRequest(http.MethodGet, url, nil)

main.go

@@ -82,7 +82,7 @@ func handler(ctx context.Context, s3Event events.S3Event) error {
 		subject := msg.Header.Get("Subject")
 		auth := msg.Header.Get("Authentication-Results")
 
-		issue := extractIssueNumber(toHeader, ccHeader)
+		issue, repoSuffix := extractIssueNumber(toHeader, ccHeader)
 		senderDomain := extractSenderDomain(fromHeader)
 
 		if !strings.Contains(auth, "spf=pass") && !strings.Contains(auth, "dkim=pass") {
@@ -94,13 +94,21 @@ func handler(ctx context.Context, s3Event events.S3Event) error {
 		if issue == "" {
 			log.Fatalf("no issue number found in To: or Cc:")
 		}
-		log.Printf("%s | From: %s; To: %s; Subject: %s\n", msgId, fromHeader, toHeader, subject)
+		effectiveProject := githubProject
+		if repoSuffix != "" && githubProject != "" {
+			org := githubProject
+			if i := strings.IndexByte(githubProject, '/'); i >= 0 {
+				org = githubProject[:i]
+			}
+			effectiveProject = org + "/" + repoSuffix
+		}
+		log.Printf("%s | From: %s; To: %s; Subject: %s; Project: %s\n", msgId, fromHeader, toHeader, subject, effectiveProject)
 		body, err := extractBodyAsMarkdown(msg)
 		if err != nil {
 			log.Fatalf("error in extracting message body")
 		} else {
 			header := fmt.Sprintf("From: %s\n\n", fromHeader)
-			err := postIssueComment(issue, msgId, header+hideQuotedPart(body, removeQuotes))
+			err := postIssueComment(effectiveProject, issue, msgId, header+hideQuotedPart(body, removeQuotes))
 			if err != nil {
 				log.Printf("postIssueComment err=%v", err)
 			}