implement change provider

MODULE.bazel

@@ -38,6 +38,7 @@ use_repo(
     "com_github_uber_go_tally_v4",
     "org_golang_google_grpc",
     "org_golang_google_protobuf",
+    "org_golang_x_oauth2",
     "org_uber_go_fx",
     "org_uber_go_mock",
     "org_uber_go_yarpc",

core/httpclient/BUILD.bazel

@@ -0,0 +1,18 @@
+load("@rules_go//go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "httpclient",
+    srcs = ["transport.go"],
+    importpath = "github.com/uber/submitqueue/core/httpclient",
+    visibility = ["//visibility:public"],
+)
+
+go_test(
+    name = "httpclient_test",
+    srcs = ["transport_test.go"],
+    embed = [":httpclient"],
+    deps = [
+        "@com_github_stretchr_testify//assert",
+        "@com_github_stretchr_testify//require",
+    ],
+)

core/httpclient/transport.go

@@ -0,0 +1,52 @@
+package httpclient
+
+import (
+	"net/http"
+	"net/url"
+	"strings"
+)
+
+// BaseURLTransport is an http.RoundTripper that rewrites every request URL
+// to resolve against a fixed base URL. This allows callers to make requests
+// with relative paths (e.g. "/graphql") and have the transport prepend the
+// configured base URL transparently.
+type BaseURLTransport struct {
+	// BaseURL is the API base URL (e.g. "https://api.github.com").
+	BaseURL *url.URL
+	// Next is the underlying RoundTripper. Defaults to http.DefaultTransport if nil.
+	Next http.RoundTripper
+}
+
+// RoundTrip rewrites req.URL to resolve against BaseURL, then delegates to Next.
+// The base URL path and request path are joined explicitly so that base URLs
+// with a path component (e.g. "https://ghe.example.com/api") are handled
+// correctly regardless of whether the request path starts with "/".
+func (t *BaseURLTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	newReq := req.Clone(req.Context())
+
+	merged := *t.BaseURL
+	merged.Path = strings.TrimRight(t.BaseURL.Path, "/") + "/" + strings.TrimLeft(req.URL.Path, "/")
+	merged.RawQuery = req.URL.RawQuery
+	newReq.URL = &merged
+
+	next := t.Next
+	if next == nil {
+		next = http.DefaultTransport
+	}
+	return next.RoundTrip(newReq)
+}
+
+// NewClient builds an *http.Client with BaseURLTransport configured.
+// Callers are responsible for layering additional transports (e.g. auth) and
+// setting Timeout on the returned client.
+func NewClient(rawBaseURL string) (*http.Client, error) {
+	u, err := url.Parse(rawBaseURL)
+	if err != nil {
+		return nil, err
+	}
+
+	return &http.Client{Transport: &BaseURLTransport{
+		BaseURL: u,
+		Next:    http.DefaultTransport,
+	}}, nil
+}

core/httpclient/transport_test.go

@@ -0,0 +1,88 @@
+package httpclient
+
+import (
+	"net/http"
+	"net/url"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// roundTripFunc is a test helper that implements http.RoundTripper via a function.
+type roundTripFunc func(*http.Request) (*http.Response, error)
+
+func (f roundTripFunc) RoundTrip(req *http.Request) (*http.Response, error) {
+	return f(req)
+}
+
+func TestBaseURLTransport_RewritesURL(t *testing.T) {
+	tests := []struct {
+		name        string
+		baseURL     string
+		requestPath string
+		wantURL     string
+	}{
+		{
+			name:        "relative path resolved against base",
+			baseURL:     "https://api.github.com",
+			requestPath: "/graphql",
+			wantURL:     "https://api.github.com/graphql",
+		},
+		{
+			name:        "enterprise base URL",
+			baseURL:     "https://ghe.example.com/api",
+			requestPath: "/graphql",
+			wantURL:     "https://ghe.example.com/api/graphql",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var capturedURL string
+			transport := &BaseURLTransport{
+				BaseURL: mustParseURL(t, tt.baseURL),
+				Next: roundTripFunc(func(req *http.Request) (*http.Response, error) {
+					capturedURL = req.URL.String()
+					return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}, nil
+				}),
+			}
+
+			req, err := http.NewRequest(http.MethodGet, tt.requestPath, nil)
+			require.NoError(t, err)
+
+			_, err = transport.RoundTrip(req)
+			require.NoError(t, err)
+			assert.Equal(t, tt.wantURL, capturedURL)
+		})
+	}
+}
+
+func TestBaseURLTransport_DoesNotMutateOriginalRequest(t *testing.T) {
+	transport := &BaseURLTransport{
+		BaseURL: mustParseURL(t, "https://api.github.com"),
+		Next: roundTripFunc(func(req *http.Request) (*http.Response, error) {
+			return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}, nil
+		}),
+	}
+
+	req, err := http.NewRequest(http.MethodGet, "/graphql", nil)
+	require.NoError(t, err)
+	originalURL := req.URL.String()
+
+	_, err = transport.RoundTrip(req)
+	require.NoError(t, err)
+	assert.Equal(t, originalURL, req.URL.String())
+}
+
+func TestNewClient_InvalidURL(t *testing.T) {
+	_, err := NewClient("://invalid")
+	require.Error(t, err)
+}
+
+func mustParseURL(t *testing.T, raw string) *url.URL {
+	t.Helper()
+	u, err := url.Parse(raw)
+	require.NoError(t, err)
+	return u
+}

example/server/orchestrator/BUILD.bazel

@@ -12,7 +12,10 @@ go_library(
     visibility = ["//visibility:private"],
     deps = [
         "//core/consumer",
+        "//core/httpclient",
         "//entity",
+        "//extension/changeprovider",
+        "//extension/changeprovider/github",
         "//extension/counter",
         "//extension/counter/mysql",
         "//extension/mergechecker",
@@ -38,6 +41,7 @@ go_library(
         "@com_github_uber_go_tally_v4//:tally",
         "@org_golang_google_grpc//:grpc",
         "@org_golang_google_grpc//reflection",
+        "@org_golang_x_oauth2//:oauth2",
         "@org_uber_go_zap//:zap",
     ],
 )

example/server/orchestrator/main.go

@@ -28,9 +28,14 @@ import (
 	"time"
 
 	_ "github.com/go-sql-driver/mysql"
+	"golang.org/x/oauth2"
+
 	"github.com/uber-go/tally/v4"
 	"github.com/uber/submitqueue/core/consumer"
+	"github.com/uber/submitqueue/core/httpclient"
 	"github.com/uber/submitqueue/entity"
+	"github.com/uber/submitqueue/extension/changeprovider"
+	githubprovider "github.com/uber/submitqueue/extension/changeprovider/github"
 	"github.com/uber/submitqueue/extension/counter"
 	mysqlcounter "github.com/uber/submitqueue/extension/counter/mysql"
 	"github.com/uber/submitqueue/extension/mergechecker"
@@ -190,8 +195,14 @@ func run() error {
 	// Create merge checker
 	mc := newMergeChecker(logger, scope)
 
+	// Create change provider
+	cp, err := newChangeProvider(logger, scope)
+	if err != nil {
+		return fmt.Errorf("failed to create change provider: %w", err)
+	}
+
 	// Register controllers
-	if err := registerControllers(c, logger.Sugar(), scope, registry, mc, cnt, store); err != nil {
+	if err := registerControllers(c, logger.Sugar(), scope, registry, mc, cp, cnt, store); err != nil {
 		return err
 	}
 
@@ -376,7 +387,7 @@ func newTopicRegistry(q extqueue.Queue, subscriberName string) (consumer.TopicRe
 //                                        │        │                        │
 //                                        └────────┴────────────────────────┘
 
-func registerControllers(c consumer.Consumer, logger *zap.SugaredLogger, scope tally.Scope, registry consumer.TopicRegistry, mc mergechecker.MergeChecker, cnt counter.Counter, store storage.Storage) error {
+func registerControllers(c consumer.Consumer, logger *zap.SugaredLogger, scope tally.Scope, registry consumer.TopicRegistry, mc mergechecker.MergeChecker, cp changeprovider.ChangeProvider, cnt counter.Counter, store storage.Storage) error {
 	requestController := start.NewController(
 		logger,
 		scope,
@@ -395,6 +406,7 @@ func registerControllers(c consumer.Consumer, logger *zap.SugaredLogger, scope t
 		store,
 		registry,
 		mc,
+		cp,
 		consumer.TopicKeyValidate,
 		"orchestrator-validate",
 	)
@@ -514,6 +526,26 @@ func registerControllers(c consumer.Consumer, logger *zap.SugaredLogger, scope t
 	return nil
 }
 
+// getEnv returns environment variable value or default if not set.
+func getEnv(key, defaultVal string) string {
+	if val := os.Getenv(key); val != "" {
+		return val
+	}
+	return defaultVal
+}
+
+// parseTimeout parses a duration from environment variable with fallback to default.
+// Returns defaultVal if envVal is empty or cannot be parsed.
+func parseTimeout(envVal string, defaultVal time.Duration) time.Duration {
+	if envVal == "" {
+		return defaultVal
+	}
+	if d, err := time.ParseDuration(envVal); err == nil {
+		return d
+	}
+	return defaultVal
+}
+
 // newMergeChecker creates a MergeChecker for GitHub (github.com).
 // Configured via GITHUB_TOKEN and GITHUB_GRAPHQL_URL environment variables.
 func newMergeChecker(logger *zap.Logger, scope tally.Scope) mergechecker.MergeChecker {
@@ -539,6 +571,28 @@ func newMergeChecker(logger *zap.Logger, scope tally.Scope) mergechecker.MergeCh
 	})
 }
 
+// newChangeProvider creates a ChangeProvider for GitHub (github.com).
+// Configured via GITHUB_BASE_URL, GITHUB_TOKEN, and GITHUB_TIMEOUT environment variables.
+func newChangeProvider(logger *zap.Logger, scope tally.Scope) (changeprovider.ChangeProvider, error) {
+	client, err := httpclient.NewClient(getEnv("GITHUB_BASE_URL", "https://api.github.com"))
+	if err != nil {
+		return nil, fmt.Errorf("failed to build GitHub HTTP client: %w", err)
+	}
+
+	if token := os.Getenv("GITHUB_TOKEN"); token != "" {
+		ts := oauth2.StaticTokenSource(&oauth2.Token{AccessToken: token})
+		client.Transport = &oauth2.Transport{Source: ts, Base: client.Transport}
+	}
+
+	client.Timeout = parseTimeout(os.Getenv("GITHUB_TIMEOUT"), 30*time.Second)
+
+	return githubprovider.NewProvider(githubprovider.Params{
+		HTTPClient:   client,
+		Logger:       logger.Sugar(),
+		MetricsScope: scope.SubScope("changeprovider"),
+	}), nil
+}
+
 // bearerTransport is an http.RoundTripper that adds a Bearer token to requests.
 type bearerTransport struct {
 	token string

extension/changeprovider/change_provider.go

@@ -38,14 +38,13 @@ type ChangedFile struct {
 	LinesAdded int
 	// LinesDeleted is the number of lines deleted in this file.
 	LinesDeleted int
-	// LinesModified is the number of lines modified in this file.
-	LinesModified int
 }
 
 // ChangeInfo contains metadata and file changes for a code change.
 type ChangeInfo struct {
-	// ID is the change identifier (e.g., "PR: uber-code/go-code/1" or "diff: uber-code/go-code/D1").
-	ID string
+	// URI is the full change URI for correlation with the input request
+	// (e.g., "github://uber/repo/98/abc123sha" or "phab://D123/xyz789").
+	URI string
 	// User is the author of the change.
 	User User
 	// ChangedFiles is the list of files modified in this change. Order is unspecified.
@@ -56,6 +55,7 @@ type ChangeInfo struct {
 // Each implementation is configured for a specific provider (GitHub, GitLab, Phabricator).
 type ChangeProvider interface {
 	// Get retrieves change information for the provided Change.
-	// Returns the change info containing metadata and file changes.
-	Get(ctx context.Context, change entity.Change) (ChangeInfo, error)
+	// For a Change with multiple URIs (e.g., stacked PRs), returns one ChangeInfo per URI.
+	// Returns a slice of ChangeInfo, one for each change in the stack.
+	Get(ctx context.Context, change entity.Change) ([]ChangeInfo, error)
 }

extension/changeprovider/github/BUILD.bazel

@@ -0,0 +1,41 @@
+load("@rules_go//go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "github",
+    srcs = [
+        "convert.go",
+        "graphql.go",
+        "provider.go",
+        "validate.go",
+    ],
+    importpath = "github.com/uber/submitqueue/extension/changeprovider/github",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//core/metrics",
+        "//entity",
+        "//entity/github",
+        "//extension/changeprovider",
+        "@com_github_uber_go_tally_v4//:tally",
+        "@org_uber_go_zap//:zap",
+    ],
+)
+
+go_test(
+    name = "github_test",
+    srcs = [
+        "graphql_test.go",
+        "provider_test.go",
+        "validate_test.go",
+    ],
+    embed = [":github"],
+    deps = [
+        "//core/httpclient",
+        "//entity",
+        "//entity/github",
+        "//extension/changeprovider",
+        "@com_github_stretchr_testify//assert",
+        "@com_github_stretchr_testify//require",
+        "@com_github_uber_go_tally_v4//:tally",
+        "@org_uber_go_zap//zaptest",
+    ],
+)

extension/changeprovider/github/convert.go

@@ -0,0 +1,36 @@
+package github
+
+import (
+	entitygithub "github.com/uber/submitqueue/entity/github"
+	"github.com/uber/submitqueue/extension/changeprovider"
+)
+
+// convertToChangeInfo converts GitHub PR data to ChangeInfo.
+func convertToChangeInfo(parsed entitygithub.ChangeID, prData *pullRequestData) changeprovider.ChangeInfo {
+	changedFiles := convertFiles(prData.Files.Nodes)
+
+	return changeprovider.ChangeInfo{
+		URI: parsed.String(),
+		User: changeprovider.User{
+			Name:  prData.Author.Name,
+			Email: prData.Author.Email,
+		},
+		ChangedFiles: changedFiles,
+	}
+}
+
+// convertFiles converts GitHub file nodes to ChangedFile structs.
+func convertFiles(nodes []fileNode) []changeprovider.ChangedFile {
+	changedFiles := make([]changeprovider.ChangedFile, 0, len(nodes))
+
+	for _, file := range nodes {
+		changedFiles = append(changedFiles, changeprovider.ChangedFile{
+			Path:         file.Path,
+			Patch:        file.Patch,
+			LinesAdded:   file.Additions,
+			LinesDeleted: file.Deletions,
+		})
+	}
+
+	return changedFiles
+}