feat: add support for separate GitHub app credentials

.github/actions/spelling/expect.txt

@@ -1,6 +1,7 @@
 
 aeece
 Artifactory
+applicationid
 bacd
 CVE
 credref
@@ -11,9 +12,11 @@ fbd
 ffb
 gitlab
 helmvalues
+installationid
 jfrog
 mep
 myregistry
+PRIVATEKEYDATA
 repocreds
 rollbacked
 someimage

docs/basics/update-methods.md

@@ -123,7 +123,9 @@ Example:
 argocd-image-updater.argoproj.io/write-back-method: git:secret:argocd-image-updater/git-creds
 ```
 
-If the repository is accessed using HTTPS, the secret must contain two fields:
+If the repository is accessed using HTTPS, the secret must contain either user credentials or GitHub app credentials.
+
+If the repository is accessed using user credentials, the secret requires two fields
 `username` which holds the Git username, and `password` which holds the user's
 password or a private access token (PAT) with write access to the repository.
 You can generate such a secret using `kubectl`, e.g.:
@@ -134,6 +136,16 @@ kubectl -n argocd-image-updater create secret generic git-creds \
   --from-literal=password=somepassword
 ```
 
+If the repository is accessed using GitHub app credentials, the secret requires three fields `githubAppID` which holds the GitHub Application ID, `githubAppInstallationID` which holds the GitHub Organization Installation ID, and `githubAppPrivateKey` which holds the GitHub Application private key. The GitHub Application must be installed into the target repository with write access.
+You can generate such a secret using `kubectl`, e.g.:
+
+```bash
+kubectl -n argocd-image-updater create secret generic git-creds \
+  --from-literal=githubAppID=applicationid \
+  --from-literal=githubAppInstallationID=installationid \
+  --from-literal=githubAppPrivateKey='-----BEGIN RSA PRIVATE KEY-----PRIVATEKEYDATA-----END RSA PRIVATE KEY-----'
+```
+
 If the repository is accessed using SSH, the secret must contain the field
 `sshPrivateKey`, which holds a SSH private key in OpenSSH-compatible PEM
 format. To create such a secret from an existing private key, you can use

pkg/argocd/gitcreds.go

@@ -3,6 +3,7 @@ package argocd
 import (
 	"context"
 	"fmt"
+	"strconv"
 	"strings"
 
 	"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1"
@@ -66,14 +67,25 @@ func getCredsFromSecret(wbc *WriteBackConfig, credentialsSecret string, kubeClie
 		}
 		return git.NewSSHCreds(string(sshPrivateKey), "", true), nil
 	} else if git.IsHTTPSURL(wbc.GitRepo) {
-		var username, password []byte
-		if username, ok = credentials["username"]; !ok {
-			return nil, fmt.Errorf("invalid secret %s: does not contain field username", credentialsSecret)
+		var username, password, githubAppID, githubAppInstallationID, githubAppPrivateKey []byte
+		if githubAppID, ok = credentials["githubAppID"]; ok {
+			if githubAppInstallationID, ok = credentials["githubAppInstallationID"]; !ok {
+				return nil, fmt.Errorf("invalid secret %s: does not contain field githubAppInstallationID", credentialsSecret)
+			}
+			if githubAppPrivateKey, ok = credentials["githubAppPrivateKey"]; !ok {
+				return nil, fmt.Errorf("invalid secret %s: does not contain field githubAppPrivateKey", credentialsSecret)
+			}
+			// converting byte array to string and ultimately int64 for NewGitHubAppCreds
+			intGithubAppID, _ := strconv.ParseInt(string(githubAppID), 10, 64)
+			intGithubAppInstallationID, _ := strconv.ParseInt(string(githubAppInstallationID), 10, 64)
+			return git.NewGitHubAppCreds(intGithubAppID, intGithubAppInstallationID, string(githubAppPrivateKey), "", "", "", "", true), nil
+		} else if username, ok = credentials["username"]; ok {
+			if password, ok = credentials["password"]; !ok {
+				return nil, fmt.Errorf("invalid secret %s: does not contain field password", credentialsSecret)
+			}
+			return git.NewHTTPSCreds(string(username), string(password), "", "", true, ""), nil
 		}
-		if password, ok = credentials["password"]; !ok {
-			return nil, fmt.Errorf("invalid secret %s: does not contain field password", credentialsSecret)
-		}
-		return git.NewHTTPSCreds(string(username), string(password), "", "", true, ""), nil
+		return nil, fmt.Errorf("invalid repository credentials in secret %s: does not contain githubAppID or username", credentialsSecret)
 	}
 	return nil, fmt.Errorf("unknown repository type")
 }

pkg/argocd/update_test.go

@@ -2055,7 +2055,7 @@ func Test_GetWriteBackConfig(t *testing.T) {
 }
 
 func Test_GetGitCreds(t *testing.T) {
-	t.Run("HTTP creds from a secret", func(t *testing.T) {
+	t.Run("HTTP user creds from a secret", func(t *testing.T) {
 		argoClient := argomock.ArgoCD{}
 		argoClient.On("UpdateSpec", mock.Anything, mock.Anything).Return(nil, nil)
 		secret := fixture.NewSecret("argocd-image-updater", "git-creds", map[string][]byte{
@@ -2090,11 +2090,52 @@ func Test_GetGitCreds(t *testing.T) {
 		creds, err := wbc.GetCreds(&app)
 		require.NoError(t, err)
 		require.NotNil(t, creds)
-		// Must have HTTPS creds
+		// Must have HTTPS user creds
 		_, ok := creds.(git.HTTPSCreds)
 		require.True(t, ok)
 	})
 
+	t.Run("HTTP GitHub App creds from a secret", func(t *testing.T) {
+		argoClient := argomock.ArgoCD{}
+		argoClient.On("UpdateSpec", mock.Anything, mock.Anything).Return(nil, nil)
+		secret := fixture.NewSecret("argocd-image-updater", "git-creds", map[string][]byte{
+			"githubAppID":             []byte("12345678"),
+			"githubAppInstallationID": []byte("87654321"),
+			"githubAppPrivateKey":     []byte("foo"),
+		})
+		kubeClient := kube.KubernetesClient{
+			Clientset: fake.NewFakeClientsetWithResources(secret),
+		}
+		app := v1alpha1.Application{
+			ObjectMeta: v1.ObjectMeta{
+				Name: "testapp",
+				Annotations: map[string]string{
+					"argocd-image-updater.argoproj.io/image-list":        "nginx",
+					"argocd-image-updater.argoproj.io/write-back-method": "git:secret:argocd-image-updater/git-creds",
+					"argocd-image-updater.argoproj.io/git-credentials":   "argocd-image-updater/git-creds",
+				},
+			},
+			Spec: v1alpha1.ApplicationSpec{
+				Source: &v1alpha1.ApplicationSource{
+					RepoURL:        "https://example.com/example",
+					TargetRevision: "main",
+				},
+			},
+			Status: v1alpha1.ApplicationStatus{
+				SourceType: v1alpha1.ApplicationSourceTypeKustomize,
+			},
+		}
+		wbc, err := getWriteBackConfig(&app, &kubeClient, &argoClient)
+		require.NoError(t, err)
+
+		creds, err := wbc.GetCreds(&app)
+		require.NoError(t, err)
+		require.NotNil(t, creds)
+		// Must have HTTPS GitHub App creds
+		_, ok := creds.(git.GitHubAppCreds)
+		require.True(t, ok)
+	})
+
 	t.Run("SSH creds from a secret", func(t *testing.T) {
 		argoClient := argomock.ArgoCD{}
 		argoClient.On("UpdateSpec", mock.Anything, mock.Anything).Return(nil, nil)