Support GitHub Apps Installation authentication (#69)

* Initial commit of github apps poc

* Demo of GitHub Apps auth working in go-sdk

* Remove unnecessary auth configuration functions

* Docs comments cleanup

* Differentiate App and token auth examples

* Switch to using fork of ghinstallation

* Bump to latest ghinstallation fork version

* Allow authorizing with clientID

* Refactor naming to default to clientID for App auth

* Bump kfcampbell/ghinstallation version

* Rename WithAuthorizationToken to WithTokenAuthentication

* Add README note about different types of App auth

* Simplify token initialization client

* Another ghinstallation version bump

* Use env vars for App auth example

* Test coverage for Apps auth

* Update pkg/client.go

Co-authored-by: Nick Floyd <139819+nickfloyd@users.noreply.github.com>

* Fix build error from code suggestion

---------

Co-authored-by: Nick Floyd <139819+nickfloyd@users.noreply.github.com>

README.md

@@ -4,15 +4,48 @@ An "alpha" version of a generated Go SDK from [GitHub's OpenAPI spec](https://gi
 
 ## How do I use it?
 
-See example client instantiations and requests in [example_test.go](pkg/example_test.go).
+See example client instantiations and requests in [example_test.go](pkg/example_test.go) or in the [cmd/ directory](cmd/).
 
 ⚠️ **Note**: This SDK is not yet stable. Breaking changes may occur at any time.
 
 ### Authentication
 
-Currently, this SDK supports both [Personal Access Tokens (classic)](https://docs.github.com/en/authentication/keeping-your-account-and-data-secure/managing-your-personal-access-tokens#personal-access-tokens-classic) and [fine-grained Personal Access Tokens](https://docs.github.com/en/authentication/keeping-your-account-and-data-secure/managing-your-personal-access-tokens#fine-grained-personal-access-tokens).
+This SDK supports [Personal Access Tokens (classic)](https://docs.github.com/en/authentication/keeping-your-account-and-data-secure/managing-your-personal-access-tokens#personal-access-tokens-classic), [fine-grained Personal Access Tokens](https://docs.github.com/en/authentication/keeping-your-account-and-data-secure/managing-your-personal-access-tokens#fine-grained-personal-access-tokens), and [GitHub Apps](https://docs.github.com/en/apps/creating-github-apps/authenticating-with-a-github-app/about-authentication-with-a-github-app) authentication.
 
-Future work is planned for the SDK to support [GitHub Apps](https://docs.github.com/en/apps/overview) authentication as well.
+In order to use either type of Personal Access token, you can use the `WithTokenAuthentication("YOUR_TOKEN_HERE")` functional option when constructing a client, like so:
+
+```go
+client, err := pkg.NewApiClient(
+	pkg.WithTokenAuthentication(os.Getenv("GITHUB_TOKEN")),
+)
+if err != nil {
+	log.Fatalf("error creating client: %v", err)
+}
+```
+
+In order to authenticate as a GitHub App, you can use the `WithGitHubAppAuthentication` functional option:
+
+```go
+client, err := pkg.NewApiClient(
+	pkg.WithGitHubAppAuthentication("/path/to/your/pem/file.pem", "your-client-ID", yourInstallationIDInt),
+)
+if err != nil {
+	log.Fatalf("error creating client: %v", err)
+}
+```
+
+To see more detailed examples, view [the cmd/ directory in this repo](cmd/).
+
+⚠️ **Note**: There are [three types](https://docs.github.com/en/apps/creating-github-apps/authenticating-with-a-github-app/about-authentication-with-a-github-app) of GitHub App authentication:
+1. [As the App itself (meta endpoints)](https://docs.github.com/en/rest/apps/apps?apiVersion=2022-11-28)
+1. [As an App installation](https://docs.github.com/en/rest/authentication/endpoints-available-for-github-app-installation-access-tokens?apiVersion=2022-11-28)
+1. On behalf of a user
+
+Authenticating on behalf of a user is not supported in an SDK, as it requires a UI authentication flow with redirects. This SDK supports authenticating as the App itself and as an App installation.
+
+Note that the SDK **does not yet** support authenticating as the App itself and as an App installation using the same client transparently to the user. Authenticating as the App itself requires [creating a JSON Web Token (JWT)](https://docs.github.com/en/apps/creating-github-apps/authenticating-with-a-github-app/generating-a-json-web-token-jwt-for-a-github-app) and using that as token authentication. For helpers to create and sign a JWT in Go, you may use the [golang-jwt/jwt](https://github.com/golang-jwt/jwt) library.
+
+Authenticating as an App installation can be done using the `WithGitHubAppAuthentication` functional option. Future work is planned to make the App meta endpoints vs. App installation endpoints auth schemes transparent to the user and only require one client setup.
 
 ## Why a generated SDK?
 

cmd/app-example/main.go

@@ -0,0 +1,49 @@
+package main
+
+import (
+	"context"
+	"log"
+	"os"
+	"strconv"
+	"time"
+
+	abs "github.com/microsoft/kiota-abstractions-go"
+	"github.com/octokit/go-sdk/pkg"
+	"github.com/octokit/go-sdk/pkg/github/installation"
+)
+
+func main() {
+	installationID, err := strconv.ParseInt(os.Getenv("INSTALLATION_ID"), 10, 64)
+	if err != nil {
+		log.Fatalf("error parsing installation ID from string to int64: %v", err)
+	}
+
+	client, err := pkg.NewApiClient(
+		pkg.WithUserAgent("my-user-agent"),
+		pkg.WithRequestTimeout(5*time.Second),
+		pkg.WithBaseUrl("https://api.github.com"),
+		pkg.WithGitHubAppAuthentication(os.Getenv("PATH_TO_PEM_FILE"), os.Getenv("CLIENT_ID"), installationID),
+	)
+
+	// equally valid:
+	//client, err := pkg.NewApiClient()
+	if err != nil {
+		log.Fatalf("error creating client: %v", err)
+	}
+
+	queryParams := &installation.RepositoriesRequestBuilderGetQueryParameters{}
+	requestConfig := &abs.RequestConfiguration[installation.RepositoriesRequestBuilderGetQueryParameters]{
+		QueryParameters: queryParams,
+	}
+	repos, err := client.Installation().Repositories().Get(context.Background(), requestConfig)
+	if err != nil {
+		log.Fatalf("error getting repositories: %v", err)
+	}
+
+	if len(repos.GetRepositories()) > 0 {
+		log.Printf("Repositories:\n")
+		for _, repo := range repos.GetRepositories() {
+			log.Printf("%v\n", *repo.GetFullName())
+		}
+	}
+}

cmd/example/main.go → cmd/token-example/main.go

@@ -16,7 +16,7 @@ func main() {
 		pkg.WithUserAgent("my-user-agent"),
 		pkg.WithRequestTimeout(5*time.Second),
 		pkg.WithBaseUrl("https://api.github.com"),
-		pkg.WithAuthorizationToken(os.Getenv("GITHUB_TOKEN")),
+		pkg.WithTokenAuthentication(os.Getenv("GITHUB_TOKEN")),
 	)
 
 	// equally valid:
@@ -31,8 +31,7 @@ func main() {
 	}
 	zen, err := client.Zen().Get(context.Background(), requestConfig)
 	if err != nil {
-		fmt.Printf("error getting Zen: %v\n", err)
-		return
+		log.Fatalf("error getting repositories: %v", err)
 	}
-	fmt.Printf("%v\n", *zen)
+	fmt.Printf("GitHub Zen principle: %v\n", *zen)
 }

go.mod

@@ -3,19 +3,22 @@ module github.com/octokit/go-sdk
 go 1.21.5
 
 require (
+	github.com/kfcampbell/ghinstallation v0.0.6
 	github.com/microsoft/kiota-abstractions-go v1.6.0
 	github.com/microsoft/kiota-http-go v1.4.1
 	github.com/microsoft/kiota-serialization-form-go v1.0.0
 	github.com/microsoft/kiota-serialization-json-go v1.0.7
 	github.com/microsoft/kiota-serialization-multipart-go v1.0.0
 	github.com/microsoft/kiota-serialization-text-go v1.0.0
+	golang.org/x/sync v0.7.0
 )
 
 require (
 	github.com/cjlapao/common-go v0.0.39 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/go-logr/logr v1.4.1 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
+	github.com/golang-jwt/jwt/v5 v5.2.1 // indirect
 	github.com/google/uuid v1.6.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/std-uritemplate/std-uritemplate/go v0.0.55 // indirect

go.sum

@@ -7,10 +7,14 @@ github.com/go-logr/logr v1.4.1 h1:pKouT5E8xu9zeFC39JXRDukb6JFQPXM5p5I91188VAQ=
 github.com/go-logr/logr v1.4.1/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
 github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
 github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
+github.com/golang-jwt/jwt/v5 v5.2.1 h1:OuVbFODueb089Lh128TAcimifWaLhJwVflnrgM17wHk=
+github.com/golang-jwt/jwt/v5 v5.2.1/go.mod h1:pqrtFR0X4osieyHYxtmOUWsAWrfe1Q5UVIyoH402zdk=
 github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/kfcampbell/ghinstallation v0.0.6 h1:L4QkjRqNosJ6Kyetymq7FswY1wUxMQO+fyYXJAWl0WY=
+github.com/kfcampbell/ghinstallation v0.0.6/go.mod h1:UXWfCKaLwF+AiyCo8gxE5oA0VMQsAmCdRXgTyyRdUnA=
 github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
@@ -39,6 +43,8 @@ go.opentelemetry.io/otel/metric v1.24.0 h1:6EhoGWWK28x1fbpA4tYTOWBkPefTDQnb8WSGX
 go.opentelemetry.io/otel/metric v1.24.0/go.mod h1:VYhLe1rFfxuTXLgj4CBiyz+9WYBA8pNGJgDcSFRKBco=
 go.opentelemetry.io/otel/trace v1.24.0 h1:CsKnnL4dUAr/0llH9FKuc698G04IrpWV0MQA/Y1YELI=
 go.opentelemetry.io/otel/trace v1.24.0/go.mod h1:HPc3Xr/cOApsBI154IU0OI0HJexz+aw5uPdbs3UCjNU=
+golang.org/x/sync v0.7.0 h1:YsImfSBoP9QPYL0xyKJPq0gcaJdG3rInoqxTWbfQu9M=
+golang.org/x/sync v0.7.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=

pkg/authentication/request.go

@@ -12,9 +12,9 @@ type Request struct {
 	*abs.RequestInformation
 }
 
-// WithAuthorization sets the Authorization header to the given token,
+// WithTokenAuthentication sets the Authorization header to the given token,
 // prepended by the AuthType
-func (r *Request) WithAuthorization(token string) {
+func (r *Request) WithTokenAuthentication(token string) {
 	if r.Headers.ContainsKey(headers.AuthorizationKey) {
 		r.Headers.Remove(headers.AuthorizationKey)
 	}

pkg/authentication/token_provider.go

@@ -6,16 +6,22 @@ import (
 	abs "github.com/microsoft/kiota-abstractions-go"
 )
 
+// TokenProvider may use a token to authenticate each request. It also can be
+// used to configure UserAgent strings, API Versions, and other request configuration.
+// Note that GitHub App authentication is set at the client transport level. See the
+// docs for pkg.NewApiClient for more.
 type TokenProvider struct {
 	options []TokenProviderOption
 }
 
+// TokenProviderOption provides a functional option
+// for configuring a TokenProvider.
 type TokenProviderOption func(*TokenProvider, *Request)
 
-// WithAuthorizationToken sets the AuthorizationToken for each request to the given token.
-func WithAuthorizationToken(token string) TokenProviderOption {
+// WithTokenAuthentication sets the AuthorizationToken for each request to the given token.
+func WithTokenAuthentication(token string) TokenProviderOption {
 	return func(t *TokenProvider, r *Request) {
-		r.WithAuthorization(token)
+		r.WithTokenAuthentication(token)
 	}
 }
 
@@ -55,7 +61,6 @@ func NewTokenProvider(options ...TokenProviderOption) *TokenProvider {
 	provider := &TokenProvider{
 		options: options,
 	}
-
 	return provider
 }
 
@@ -80,6 +85,5 @@ func (t *TokenProvider) AuthenticateRequest(context context.Context, request *ab
 	for _, option := range t.options {
 		option(t, reqWrapper)
 	}
-
 	return nil
 }

pkg/authentication/token_provider_test.go

@@ -18,7 +18,7 @@ import (
 
 func TestTokenIsSetInAuthenticatedRequest(t *testing.T) {
 	token := "help i'm trapped in a Go binary"
-	provider := authentication.NewTokenProvider(authentication.WithAuthorizationToken(token))
+	provider := authentication.NewTokenProvider(authentication.WithTokenAuthentication(token))
 
 	reqInfo := abstractions.NewRequestInformation()
 	addtlContext := make(map[string]interface{})
@@ -41,7 +41,7 @@ func TestTokenIsSetInAuthenticatedRequest(t *testing.T) {
 // TODO(kfcampbell): this code could be refactored to use table-based tests
 func TestDefaultRequestOptions(t *testing.T) {
 	token := "this is not the token you're looking for"
-	provider := authentication.NewTokenProvider(authentication.WithAuthorizationToken(token))
+	provider := authentication.NewTokenProvider(authentication.WithTokenAuthentication(token))
 	reqInfo := abstractions.NewRequestInformation()
 	addtlContext := make(map[string]interface{})
 
@@ -74,7 +74,7 @@ func TestOverwritingDefaultRequestOptions(t *testing.T) {
 	apiVersion := "i'm totally a real API version"
 	userAgent := "i'm totally a real user agent"
 	provider := authentication.NewTokenProvider(
-		authentication.WithAuthorizationToken(token),
+		authentication.WithTokenAuthentication(token),
 		authentication.WithAPIVersion(apiVersion),
 		authentication.WithUserAgent(userAgent))
 
@@ -125,7 +125,7 @@ func TestAnonymousAuthIsAllowed(t *testing.T) {
 func TestTokenSetInRequestIsNotOverwritten(t *testing.T) {
 	providerToken := "dit dit dit / dat dat dat / dit dit dit"
 	provider := authentication.NewTokenProvider(
-		authentication.WithAuthorizationToken(providerToken),
+		authentication.WithTokenAuthentication(providerToken),
 	)
 
 	requestToken := "dit dit dit dit / dit / dit dat dit dit / dit dat dat dit"
@@ -156,7 +156,7 @@ func TestHappyPathIntegration(t *testing.T) {
 	}
 
 	provider := authentication.NewTokenProvider(
-		authentication.WithAuthorizationToken(token),
+		authentication.WithTokenAuthentication(token),
 	)
 
 	adapter, err := http.NewNetHttpRequestAdapter(provider)
@@ -170,17 +170,15 @@ func TestHappyPathIntegration(t *testing.T) {
 
 	// Create a new instance of abstractions.RequestConfiguration
 	requestConfig := &abstractions.RequestConfiguration[user.EmailsRequestBuilderGetQueryParameters]{
-	Headers: headers,
+		Headers: headers,
 	}
 
-
-
 	userEmails, err := client.User().Emails().Get(context.Background(), requestConfig)
 	if err != nil {
-	log.Fatalf("%v\n", err)
+		log.Fatalf("%v\n", err)
 	}
 
 	for _, v := range userEmails {
-	fmt.Printf("%v\n", *v.GetEmail())
+		fmt.Printf("%v\n", *v.GetEmail())
 	}
 }