Expose TokenSource through ClientCreators

This installation token retrievable from TokenSource can be used to clone repositories.

example/issue_comment.go

@@ -58,7 +58,7 @@ func (h *PRCommentHandler) Handle(ctx context.Context, eventType, deliveryID str
 		return nil
 	}
 
-	client, err := h.NewInstallationClient(installationID)
+	client, _, err := h.NewInstallationClient(installationID)
 	if err != nil {
 		return err
 	}

githubapp/caching_client_creator.go

@@ -27,6 +27,16 @@ const (
 	DefaultCachingClientCapacity = 64
 )
 
+type clientTokenSource struct {
+	client      *github.Client
+	tokenSource TokenSource
+}
+
+type clientV4TokenSource struct {
+	client      *githubv4.Client
+	tokenSource TokenSource
+}
+
 // NewDefaultCachingClientCreator returns a ClientCreator using values from the
 // configuration or other defaults.
 func NewDefaultCachingClientCreator(c Config, opts ...ClientOption) (ClientCreator, error) {
@@ -70,42 +80,42 @@ func (c *cachingClientCreator) NewAppV4Client() (*githubv4.Client, error) {
 	return c.delegate.NewAppV4Client()
 }
 
-func (c *cachingClientCreator) NewInstallationClient(installationID int64) (*github.Client, error) {
+func (c *cachingClientCreator) NewInstallationClient(installationID int64) (*github.Client, TokenSource, error) {
 	// if client is in cache, return it
 	key := c.toCacheKey("v3", installationID)
 	val, ok := c.cachedClients.Get(key)
 	if ok {
-		if client, ok := val.(*github.Client); ok {
-			return client, nil
+		if cts, ok := val.(clientTokenSource); ok {
+			return cts.client, cts.tokenSource, nil
 		}
 	}
 
 	// otherwise, create and return
-	client, err := c.delegate.NewInstallationClient(installationID)
+	client, ts, err := c.delegate.NewInstallationClient(installationID)
 	if err != nil {
-		return nil, err
+		return nil, nil, err
 	}
-	c.cachedClients.Add(key, client)
-	return client, nil
+	c.cachedClients.Add(key, clientTokenSource{client, ts})
+	return client, ts, nil
 }
 
-func (c *cachingClientCreator) NewInstallationV4Client(installationID int64) (*githubv4.Client, error) {
+func (c *cachingClientCreator) NewInstallationV4Client(installationID int64) (*githubv4.Client, TokenSource, error) {
 	// if client is in cache, return it
 	key := c.toCacheKey("v4", installationID)
 	val, ok := c.cachedClients.Get(key)
 	if ok {
-		if client, ok := val.(*githubv4.Client); ok {
-			return client, nil
+		if cts, ok := val.(clientV4TokenSource); ok {
+			return cts.client, cts.tokenSource, nil
 		}
 	}
 
 	// otherwise, create and return
-	client, err := c.delegate.NewInstallationV4Client(installationID)
+	client, ts, err := c.delegate.NewInstallationV4Client(installationID)
 	if err != nil {
-		return nil, err
+		return nil, nil, err
 	}
-	c.cachedClients.Add(key, client)
-	return client, nil
+	c.cachedClients.Add(key, clientV4TokenSource{client, ts})
+	return client, ts, nil
 }
 
 func (c *cachingClientCreator) NewTokenClient(token string) (*github.Client, error) {

githubapp/client_creator.go

@@ -75,10 +75,10 @@ type ClientCreator interface {
 	//  * the installation ID is the ID that is shown in the URL of https://{githubURL}/settings/installations/{#}
 	//      (navigate to the "installations" page without the # and go to the app's page to see the number)
 	//  * the key bytes must be a PEM-encoded PKCS1 or PKCS8 private key for the application
-	NewInstallationClient(installationID int64) (*github.Client, error)
+	NewInstallationClient(installationID int64) (*github.Client, TokenSource, error)
 
 	// NewInstallationV4Client returns an installation-authenticated v4 API client, similar to NewInstallationClient.
-	NewInstallationV4Client(installationID int64) (*githubv4.Client, error)
+	NewInstallationV4Client(installationID int64) (*githubv4.Client, TokenSource, error)
 
 	// NewTokenClient returns a *github.Client that uses the passed in OAuth token for authentication.
 	NewTokenClient(token string) (*github.Client, error)
@@ -209,9 +209,9 @@ func (c *clientCreator) NewAppV4Client() (*githubv4.Client, error) {
 	return client, nil
 }
 
-func (c *clientCreator) NewInstallationClient(installationID int64) (*github.Client, error) {
+func (c *clientCreator) NewInstallationClient(installationID int64) (*github.Client, TokenSource, error) {
 	base := c.newHTTPClient()
-	installation, transportError := newInstallation(c.integrationID, installationID, c.privKeyBytes, c.v3BaseURL)
+	installation, ghTransport, transportError := newInstallation(c.integrationID, installationID, c.privKeyBytes, c.v3BaseURL)
 
 	middleware := []ClientMiddleware{installation}
 	if c.cacheFunc != nil {
@@ -220,30 +220,34 @@ func (c *clientCreator) NewInstallationClient(installationID int64) (*github.Cli
 
 	client, err := c.newClient(base, middleware, fmt.Sprintf("installation: %d", installationID), installationID)
 	if err != nil {
-		return nil, err
+		return nil, nil, err
 	}
 	if *transportError != nil {
-		return nil, *transportError
+		return nil, nil, *transportError
 	}
-	return client, nil
+	return client, *ghTransport, nil
 }
 
-func (c *clientCreator) NewInstallationV4Client(installationID int64) (*githubv4.Client, error) {
+func (c *clientCreator) NewInstallationV4Client(installationID int64) (*githubv4.Client, TokenSource, error) {
 	base := c.newHTTPClient()
-	installation, transportError := newInstallation(c.integrationID, installationID, c.privKeyBytes, c.v3BaseURL)
+	installation, ghTransport, transportError := newInstallation(c.integrationID, installationID, c.privKeyBytes, c.v3BaseURL)
 
 	// The v4 API primarily uses POST requests (except for introspection queries)
 	// which we cannot cache, so don't construct the middleware
 	middleware := []ClientMiddleware{installation}
 
 	client, err := c.newV4Client(base, middleware, fmt.Sprintf("installation: %d", installationID))
 	if err != nil {
-		return nil, err
+		return nil, nil, err
 	}
 	if *transportError != nil {
-		return nil, *transportError
+		return nil, nil, *transportError
 	}
-	return client, nil
+	return client, *ghTransport, nil
+}
+
+type TokenSource interface {
+	Token(ctx context.Context) (string, error)
 }
 
 func (c *clientCreator) NewTokenClient(token string) (*github.Client, error) {
@@ -334,19 +338,22 @@ func newAppInstallation(integrationID int64, privKeyBytes []byte, v3BaseURL stri
 	return installation, &transportError
 }
 
-func newInstallation(integrationID, installationID int64, privKeyBytes []byte, v3BaseURL string) (ClientMiddleware, *error) {
+func newInstallation(integrationID, installationID int64, privKeyBytes []byte, v3BaseURL string) (ClientMiddleware, **ghinstallation.Transport, *error) {
 	var transportError error
+	var itr *ghinstallation.Transport
 	installation := func(next http.RoundTripper) http.RoundTripper {
-		itr, err := ghinstallation.New(next, integrationID, installationID, privKeyBytes)
+		var err error
+		itr, err = ghinstallation.New(next, integrationID, installationID, privKeyBytes)
 		if err != nil {
 			transportError = err
+
 			return next
 		}
 		// leaving the v3 URL since this is used to refresh the token, not make queries
 		itr.BaseURL = strings.TrimSuffix(v3BaseURL, "/")
 		return itr
 	}
-	return installation, &transportError
+	return installation, &itr, &transportError
 }
 
 func cache(cacheFunc func() httpcache.Cache) ClientMiddleware {