adding examples for app auth

README.md

@@ -121,7 +121,10 @@ GitHub Apps authentication can be provided by the [ghinstallation](https://githu
 package.
 
 ```go
-import "github.com/bradleyfalzon/ghinstallation"
+import (
+	"github.com/bradleyfalzon/ghinstallation/v2"
+	"github.com/google/go-github/v41/github"
+)
 
 func main() {
 	// Wrap the shared transport for use with the integration ID 1 authenticating with installation ID 99.
@@ -137,6 +140,9 @@ func main() {
 }
 ```
 
+*Note*: In order to interact with certain APIs, for example writing a file to a repo, one must generate an installation token
+using the installation ID of the GitHub app and authenticate with the OAuth method mentioned above. See the examples.
+
 ### Rate Limiting ###
 
 GitHub imposes a rate limit on all API clients. Unauthenticated clients are

example/newfilewithappauth/main.go

@@ -0,0 +1,95 @@
+// Copyright 2021 The go-github AUTHORS. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// newfilewithappauth demonstrates the functionality of GitHub's app authentication
+// methods by fetching an installation access token and reauthenticating to GitHub
+// with OAuth configurations.
+package main
+
+import (
+	"context"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"time"
+
+	"github.com/bradleyfalzon/ghinstallation/v2"
+	"github.com/google/go-github/v41/github"
+	"golang.org/x/oauth2"
+)
+
+func main() {
+	const gitHost = "https://git.api.com"
+
+	privatePem, err := ioutil.ReadFile("path/to/pem")
+	if err != nil {
+		log.Fatalf("failed to read pem: %v", err)
+	}
+
+	itr, err := ghinstallation.NewAppsTransport(http.DefaultTransport, 10, privatePem)
+	if err != nil {
+		log.Fatalf("faild to create app transport: %v\n", err)
+	}
+	itr.BaseURL = gitHost
+
+	//create git client with app transport
+	client, err := github.NewEnterpriseClient(
+		gitHost,
+		gitHost,
+		&http.Client{
+			Transport: itr,
+			Timeout:   time.Second * 30,
+		})
+	if err != nil {
+		log.Fatalf("faild to create git client for app: %v\n", err)
+	}
+
+	installations, _, err := client.Apps.ListInstallations(context.Background(), &github.ListOptions{})
+	if err != nil {
+		log.Fatalf("failed to list installations: %v\n", err)
+	}
+
+	//capture our installationId for our app
+	//we need this for the access token
+	var installID int64
+	for _, val := range installations {
+		installID = val.GetID()
+	}
+
+	token, _, err := client.Apps.CreateInstallationToken(
+		context.Background(),
+		installID,
+		&github.InstallationTokenOptions{})
+	if err != nil {
+		log.Fatalf("failed to create installation token: %v\n", err)
+	}
+
+	ts := oauth2.StaticTokenSource(
+		&oauth2.Token{AccessToken: token.GetToken()},
+	)
+	oAuthClient := oauth2.NewClient(context.Background(), ts)
+
+	//create new git hub client with accessToken
+	apiClient, err := github.NewEnterpriseClient(gitHost, gitHost, oAuthClient)
+	if err != nil {
+		log.Fatalf("failed to create new git client with token: %v\n", err)
+	}
+
+	_, resp, err := apiClient.Repositories.CreateFile(
+		context.Background(),
+		"repoOwner",
+		"sample-repo",
+		"example/foo.txt",
+		&github.RepositoryContentFileOptions{
+			Content: []byte("foo"),
+			Message: github.String("sample commit"),
+			SHA:     nil,
+		})
+	if err != nil {
+		log.Fatalf("failed to create new file: %v\n", err)
+	}
+
+	log.Printf("file written status code: %v", resp.StatusCode)
+}

go.mod

@@ -1,6 +1,7 @@
 module github.com/google/go-github/v41
 
 require (
+	github.com/bradleyfalzon/ghinstallation/v2 v2.0.3
 	github.com/google/go-cmp v0.5.6
 	github.com/google/go-querystring v1.1.0
 	golang.org/x/crypto v0.0.0-20210817164053-32db794688a5
@@ -9,7 +10,9 @@ require (
 )
 
 require (
+	github.com/golang-jwt/jwt/v4 v4.0.0 // indirect
 	github.com/golang/protobuf v1.3.2 // indirect
+	github.com/google/go-github/v39 v39.0.0 // indirect
 	golang.org/x/net v0.0.0-20210226172049-e18ecbb05110 // indirect
 	golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1 // indirect
 	golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1 // indirect

go.sum

@@ -1,9 +1,15 @@
+github.com/bradleyfalzon/ghinstallation/v2 v2.0.3 h1:ywF/8q+GVpvlsEuvRb1SGSDQDUxntW1d4kFu/9q/YAE=
+github.com/bradleyfalzon/ghinstallation/v2 v2.0.3/go.mod h1:tlgi+JWCXnKFx/Y4WtnDbZEINo31N5bcvnCoqieefmk=
+github.com/golang-jwt/jwt/v4 v4.0.0 h1:RAqyYixv1p7uEnocuy8P1nru5wprCh/MH2BIlW5z5/o=
+github.com/golang-jwt/jwt/v4 v4.0.0/go.mod h1:/xlHOz8bRuivTWchD4jCa+NbatV+wEUSzwAxVc6locg=
 github.com/golang/protobuf v1.3.1/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
 github.com/golang/protobuf v1.3.2 h1:6nsPYzhq5kReh6QImI3k5qWzO4PEbvbIW2cwSfR/6xs=
 github.com/golang/protobuf v1.3.2/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
 github.com/google/go-cmp v0.5.2/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.6 h1:BKbKCqvP6I+rmFHt06ZmyQtvB8xAkWdhFyr0ZUNZcxQ=
 github.com/google/go-cmp v0.5.6/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/google/go-github/v39 v39.0.0 h1:pygGA5ySwxEez1N39GnDauD0PaWWuGgayudyZAc941s=
+github.com/google/go-github/v39 v39.0.0/go.mod h1:C1s8C5aCC9L+JXIYpJM5GYytdX52vC1bLvHEF1IhBrE=
 github.com/google/go-querystring v1.1.0 h1:AnCroh3fv4ZBgVIf1Iwtovgjaw/GiKJo8M8yD/fhyJ8=
 github.com/google/go-querystring v1.1.0/go.mod h1:Kcdr2DB4koayq7X8pmAG4sNG59So17icRSOU623lUBU=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=