Enable Azure OIDC for Azure DevOps Respository

- Add a new provider field to GitRepository API spec which can be set to azure to enable passwordless authentication to Azure DevOps repositories.

- API docs for new provider field and guidance to setup Azure environment with workload identity.

- Controller changes to set the provider options in git authoptions to fetch credential while cloning the repository.

- Add unit tests for testing provider

Signed-off-by: Dipti Pai <diptipai89@outlook.com>

api/v1/gitrepository_types.go

@@ -27,6 +27,14 @@ import (
 const (
 	// GitRepositoryKind is the string representation of a GitRepository.
 	GitRepositoryKind = "GitRepository"
+
+	// GitProviderGeneric provides support for authentication using
+	// credentials specified in secretRef.
+	GitProviderGeneric string = "generic"
+
+	// GitProviderAzure provides support for authentication to azure
+	// repositories using Managed Identity.
+	GitProviderAzure string = "azure"
 )
 
 const (
@@ -80,6 +88,13 @@ type GitRepositorySpec struct {
 	// +optional
 	SecretRef *meta.LocalObjectReference `json:"secretRef,omitempty"`
 
+	// Provider used for authentication, can be 'azure', 'generic'.
+	// When not specified, defaults to 'generic'.
+	// +kubebuilder:validation:Enum=generic;azure
+	// +kubebuilder:default:=generic
+	// +optional
+	Provider string `json:"provider,omitempty"`
+
 	// Interval at which the GitRepository URL is checked for updates.
 	// This interval is approximate and may be subject to jitter to ensure
 	// efficient use of resources.

config/crd/bases/source.toolkit.fluxcd.io_gitrepositories.yaml

@@ -103,6 +103,15 @@ spec:
                   efficient use of resources.
                 pattern: ^([0-9]+(\.[0-9]+)?(ms|s|m|h))+$
                 type: string
+              provider:
+                default: generic
+                description: |-
+                  Provider used for authentication, can be 'azure', 'generic'.
+                  When not specified, defaults to 'generic'.
+                enum:
+                - generic
+                - azure
+                type: string
               proxySecretRef:
                 description: |-
                   ProxySecretRef specifies the Secret containing the proxy configuration

docs/api/v1/source.md

@@ -383,6 +383,19 @@ and &lsquo;known_hosts&rsquo; fields.</p>
 </tr>
 <tr>
 <td>
+<code>provider</code><br>
+<em>
+string
+</em>
+</td>
+<td>
+<em>(Optional)</em>
+<p>Provider used for authentication, can be &lsquo;azure&rsquo;, &lsquo;generic&rsquo;.
+When not specified, defaults to &lsquo;generic&rsquo;.</p>
+</td>
+</tr>
+<tr>
+<td>
 <code>interval</code><br>
 <em>
 <a href="https://pkg.go.dev/k8s.io/apimachinery/pkg/apis/meta/v1#Duration">
@@ -1710,6 +1723,19 @@ and &lsquo;known_hosts&rsquo; fields.</p>
 </tr>
 <tr>
 <td>
+<code>provider</code><br>
+<em>
+string
+</em>
+</td>
+<td>
+<em>(Optional)</em>
+<p>Provider used for authentication, can be &lsquo;azure&rsquo;, &lsquo;generic&rsquo;.
+When not specified, defaults to &lsquo;generic&rsquo;.</p>
+</td>
+</tr>
+<tr>
+<td>
 <code>interval</code><br>
 <em>
 <a href="https://pkg.go.dev/k8s.io/apimachinery/pkg/apis/meta/v1#Duration">

docs/spec/v1/gitrepositories.md

@@ -212,6 +212,91 @@ For password-protected SSH private keys, the password must be provided
 via an additional `password` field in the secret. Flux CLI also supports
 this via the `--password` flag.
 
+### Provider
+
+`.spec.provider` is an optional field that allows specifying an OIDC provider
+used for authentication purposes.
+
+Supported options are:
+
+- `generic`
+- `azure`
+
+When provider is not specified, it defaults to `generic` indicating that
+mechanisms using `spec.secretRef` are used for authentication. 
+
+#### Azure
+
+The `azure` provider can be used to authenticate to Azure DevOps repositories
+automatically using Workload Identity. 
+
+##### Pre-requisites
+
+- Ensure that your Azure DevOps Organization is
+  [connected](https://learn.microsoft.com/en-us/azure/devops/organizations/accounts/connect-organization-to-azure-ad?view=azure-devops)
+  to Microsoft Entra.
+- Ensure Workload Identity is properly [set up on your
+  cluster](https://learn.microsoft.com/en-us/azure/aks/workload-identity-deploy-cluster#create-an-aks-cluster).
+
+##### Configure Flux controller
+
+- Create a managed identity to access Azure DevOps. Establish a federated
+  identity credential between the managed identity and the source-controller
+  service account. In the default installation, the source-controller service
+  account is located in the `flux-system` namespace with name
+  `source-controller`. Ensure the federated credential uses the correct
+  namespace and name of the source-controller service account. For more details,
+  please refer to this
+  [guide](https://azure.github.io/azure-workload-identity/docs/quick-start.html#6-establish-federated-identity-credential-between-the-identity-and-the-service-account-issuer--subject).
+
+- Add the managed identity to the Azure DevOps organization as a user. Ensure
+  that the managed identity has the necessary permissions to access the Azure
+  DevOps repository as described
+  [here](https://learn.microsoft.com/en-us/azure/devops/integrate/get-started/authentication/service-principal-managed-identity?view=azure-devops#2-add-and-manage-service-principals-in-an-azure-devops-organization).
+
+- Add the following patch to your bootstrap repository in
+  `flux-system/kustomization.yaml` file:
+
+
+```yaml
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+resources:
+  - gotk-components.yaml
+  - gotk-sync.yaml
+patches:
+  - patch: |-
+      apiVersion: v1
+      kind: ServiceAccount
+      metadata:
+        name: source-controller
+        namespace: flux-system
+        annotations:
+          azure.workload.identity/client-id: <AZURE_CLIENT_ID>
+        labels:
+          azure.workload.identity/use: "true"
+  - patch: |-
+      apiVersion: apps/v1
+      kind: Deployment
+      metadata:
+        name: source-controller
+        namespace: flux-system
+        labels:
+          azure.workload.identity/use: "true"
+      spec:
+        template:
+          metadata:
+            labels:
+              azure.workload.identity/use: "true"
+```
+
+**Note:** When azure `provider` is used with `GitRepository`, the `.spec.url`
+must follow this format:
+
+```
+https://dev.azure.com/{your-organization}/{your-project}/_git/{your-repository}
+```
+
 ### Interval
 
 `.spec.interval` is a required field that specifies the interval at which the

go.mod

@@ -24,6 +24,7 @@ require (
 	github.com/fluxcd/cli-utils v0.36.0-flux.9
 	github.com/fluxcd/pkg/apis/event v0.10.0
 	github.com/fluxcd/pkg/apis/meta v1.6.0
+	github.com/fluxcd/pkg/auth v0.0.0-00010101000000-000000000000
 	github.com/fluxcd/pkg/git v0.20.0
 	github.com/fluxcd/pkg/git/gogit v0.20.0
 	github.com/fluxcd/pkg/gittestserver v0.13.0
@@ -406,3 +407,9 @@ require (
 )
 
 retract v0.32.0 // Refers to incorrect ./api version.
+
+replace github.com/fluxcd/pkg/auth => github.com/dipti-pai/pkg/auth v0.0.0-20240910203859-abee735aa028
+
+replace github.com/fluxcd/pkg/git/gogit => github.com/dipti-pai/pkg/git/gogit v0.0.0-20240910203859-abee735aa028
+
+replace github.com/fluxcd/pkg/git => github.com/dipti-pai/pkg/git v0.0.0-20240910203859-abee735aa028

go.sum

@@ -291,6 +291,12 @@ github.com/digitorus/timestamp v0.0.0-20231217203849-220c5c2851b7 h1:lxmTCgmHE1G
 github.com/digitorus/timestamp v0.0.0-20231217203849-220c5c2851b7/go.mod h1:GvWntX9qiTlOud0WkQ6ewFm0LPy5JUR1Xo0Ngbd1w6Y=
 github.com/dimchansky/utfbom v1.1.1 h1:vV6w1AhK4VMnhBno/TPVCoK9U/LP0PkLCS9tbxHdi/U=
 github.com/dimchansky/utfbom v1.1.1/go.mod h1:SxdoEBH5qIqFocHMyGOXVAybYJdr71b1Q/j0mACtrfE=
+github.com/dipti-pai/pkg/auth v0.0.0-20240910203859-abee735aa028 h1:Ohfv7mzT0aecvS4DJqDgBCGiKccsH8YcfOJ1fwdWi5g=
+github.com/dipti-pai/pkg/auth v0.0.0-20240910203859-abee735aa028/go.mod h1:0VS8EHPXNoB9q84OJg+t2LlkdIvWzttUPXhSxMKavGk=
+github.com/dipti-pai/pkg/git v0.0.0-20240910203859-abee735aa028 h1:H9PpGshNFcO5yenhJDJOHXF6x5jgof64YI5l+AYkpEQ=
+github.com/dipti-pai/pkg/git v0.0.0-20240910203859-abee735aa028/go.mod h1:XTZfxHFy96sbGzbhN68u8+L6IKjqAxLax/dCq9gaUk4=
+github.com/dipti-pai/pkg/git/gogit v0.0.0-20240910203859-abee735aa028 h1:Ekj1aPhfud5phbZq9rwZeN43YE/IL1RzFghoRDJKC6I=
+github.com/dipti-pai/pkg/git/gogit v0.0.0-20240910203859-abee735aa028/go.mod h1:pX0wDKVhNINddJ3vtUS6ripizHTqjc+kk93CLO0UDmM=
 github.com/distribution/distribution/v3 v3.0.0-beta.1 h1:X+ELTxPuZ1Xe5MsD3kp2wfGUhc8I+MPfRis8dZ818Ic=
 github.com/distribution/distribution/v3 v3.0.0-beta.1/go.mod h1:O9O8uamhHzWWQVTjuQpyYUVm/ShPHPUDgvQMpHGVBDs=
 github.com/distribution/reference v0.6.0 h1:0IXCQ5g4/QMHHkarYzh5l+u8T3t73zM5QvfrDyIgxBk=
@@ -351,10 +357,6 @@ github.com/fluxcd/pkg/apis/meta v1.6.0 h1:93TcRpiph0OCoQh+cI+PM7E35kBW9dScuas9tW
 github.com/fluxcd/pkg/apis/meta v1.6.0/go.mod h1:ZOeHcvyVdZDC5ZOGV7YuwplIvAx6LvmpeyhfTcNZCnc=
 github.com/fluxcd/pkg/cache v0.0.3 h1:VK5joG/p+amh5Ob+r1OFOx0cCYiswEf8mX1/J1BG7Mw=
 github.com/fluxcd/pkg/cache v0.0.3/go.mod h1:UU6oFhV+mG0A5/RwIlvXhyuKlJwQEkk92jVB3vKMLtk=
-github.com/fluxcd/pkg/git v0.20.0 h1:byUbxLLZ9AyVYmK16mvxY/iA/ZhNwA30GHKPKNh7pik=
-github.com/fluxcd/pkg/git v0.20.0/go.mod h1:YnBOFhX7zzyVjg/u1Et1xBqXs30kb2sWWesIl3/glhw=
-github.com/fluxcd/pkg/git/gogit v0.20.0 h1:ZlWq//I465lv9aEEWaJhjJaTiTtnjcH+Td0fg1rPXWU=
-github.com/fluxcd/pkg/git/gogit v0.20.0/go.mod h1:ZA4WsKr28cj1yuplxOw9vHgCL4OCNJJLib1cJ77Tp9o=
 github.com/fluxcd/pkg/gittestserver v0.13.0 h1:6rvD9Z7+4zBcNT+LK0z4H0z6mDaw1Zd8ZaLh/dw8dzI=
 github.com/fluxcd/pkg/gittestserver v0.13.0/go.mod h1:LDw32Wo9mTmKNmJq4g7LRVBqPXlpMIWFBDOrRRh/+As=
 github.com/fluxcd/pkg/helmtestserver v0.19.0 h1:DbidD46we8iLp/Sxn2TO8twtlP5gxFQaP3XTNJC0bl8=

internal/controller/gitrepository_controller.go

@@ -27,6 +27,7 @@ import (
 	"time"
 
 	securejoin "github.com/cyphar/filepath-securejoin"
+	"github.com/fluxcd/pkg/auth/azure"
 	"github.com/fluxcd/pkg/runtime/logger"
 	"github.com/go-git/go-git/v5/plumbing/transport"
 	corev1 "k8s.io/api/core/v1"
@@ -647,6 +648,19 @@ func (r *GitRepositoryReconciler) getAuthOpts(ctx context.Context, obj *sourcev1
 	if err != nil {
 		return nil, err
 	}
+
+	// Configure provider authentication if specified in spec
+	if obj.Spec.Provider != "" && obj.Spec.Provider != sourcev1.GitProviderGeneric {
+		if obj.Spec.Provider == sourcev1.GitProviderAzure {
+			authOpts.ProviderOpts = &git.ProviderOptions{
+				Name: obj.Spec.Provider,
+				AzureOpts: []azure.OptFunc{
+					azure.WithAzureDevOpsScope(),
+				},
+			}
+		}
+	}
+
 	return authOpts, nil
 }
 

internal/controller/gitrepository_controller_test.go

@@ -683,6 +683,54 @@ func TestGitRepositoryReconciler_reconcileSource_authStrategy(t *testing.T) {
 	}
 }
 
+func TestGitRepositoryReconciler_getAuthOpts_provider(t *testing.T) {
+	tests := []struct {
+		name                 string
+		beforeFunc           func(obj *sourcev1.GitRepository)
+		wantProviderOptsName string
+	}{
+		{
+			name: "azure provider",
+			beforeFunc: func(obj *sourcev1.GitRepository) {
+				obj.Spec.Provider = sourcev1.GitProviderAzure
+			},
+			wantProviderOptsName: sourcev1.GitProviderAzure,
+		},
+		{
+			name: "generic provider",
+			beforeFunc: func(obj *sourcev1.GitRepository) {
+				obj.Spec.Provider = sourcev1.GitProviderGeneric
+			},
+		},
+		{
+			name: "no provider",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			g := NewWithT(t)
+			obj := &sourcev1.GitRepository{}
+			r := &GitRepositoryReconciler{}
+			url, _ := url.Parse("https://dev.azure.com/foo/bar/_git/baz")
+
+			if tt.beforeFunc != nil {
+				tt.beforeFunc(obj)
+			}
+			opts, err := r.getAuthOpts(context.TODO(), obj, *url)
+
+			g.Expect(err).ToNot(HaveOccurred())
+			g.Expect(opts).ToNot(BeNil())
+			if tt.wantProviderOptsName != "" {
+				g.Expect(opts.ProviderOpts).ToNot(BeNil())
+				g.Expect(opts.ProviderOpts.Name).To(Equal(tt.wantProviderOptsName))
+			} else {
+				g.Expect(opts.ProviderOpts).To(BeNil())
+			}
+		})
+	}
+}
+
 func TestGitRepositoryReconciler_reconcileSource_checkoutStrategy(t *testing.T) {
 	g := NewWithT(t)