Kubernetes Namespace-Based Azure Identity Segregation

Question

Pulumi · Accepted Answer

To create a Kubernetes namespace-based Azure identity segregation, you will need to perform the following steps:

1. **Create Namespaces**: Namespaces in Kubernetes are a way to divide cluster resources between multiple users. They provide a scope for names, and you can assign resources and permissions separately for each namespace.

2. **Create Azure Identity**: An Azure Identity represents an Azure Active Directory (AAD) identity within Kubernetes and is used by pods to access Azure resources. You will need to create an Azure identity that your applications can use to authenticate with Azure services.

3. **Create Azure Identity Binding**: Once the Azure Identity is created, you'll need to create an AzureIdentityBinding to bind the Azure Identity to a specific namespace. This binding tells the cluster which Azure Identity to use when a pod in the namespace requires access to Azure resources.

4. **Apply Role-Based Access Control (RBAC)**: In each namespace, you will use Kubernetes Role and RoleBinding to grant permissions to the Azure Identity to perform specific actions within the namespace. This is a crucial step in enforcing segregation and ensuring secure access management.

5. **Associate Applications to Namespace**: Finally, you deploy your applications to their respective namespaces. Each application uses the Azure Identity assigned to that namespace for anything that requires interaction with Azure resources.

Now, let me provide you with Pulumi code in Python that demonstrates how you can create this segregated environment on a Kubernetes cluster. This assumes you have the `pulumi`, `pulumi_kubernetes` and `pulumi_azure_native` SDKs installed and configured.

```python
import pulumi
import pulumi_kubernetes as k8s
import pulumi_azure_native as azure_native

# Create a new Kubernetes namespace for each segregated identity
namespace_a = k8s.core.v1.Namespace("namespace-a",
    metadata=k8s.meta.v1.ObjectMetaArgs(name="namespace-a"))

namespace_b = k8s.core.v1.Namespace("namespace-b",
    metadata=k8s.meta.v1.ObjectMetaArgs(name="namespace-b"))

# Create an Azure AD identity for each namespace
identity_a = azure_native.authorization.UserAssignedIdentity("identity-a",
    location="East US",
    resource_group_name="my-resource-group")

identity_b = azure_native.authorization.UserAssignedIdentity("identity-b",
    location="East US",
    resource_group_name="my-resource-group")

# Bind the identity to the namespace using AzureIdentity and AzureIdentityBinding
# For this, you will normally use `aadpodidentity.k8s.io/v1.AzureIdentity` and
# `aadpodidentity.k8s.io/v1.AzureIdentityBinding`, which are CustomResourceDefinitions (CRDs)
# that must be installed in your cluster separately via the Azure AD Pod Identity add-on.

# Let's assume those CRDs are installed and you have their Pulumi classes available
# Here is hypothetical code that would represent these bindings:

# azure_identity_a = k8s.apiextensions.CustomResource("azure-identity-a",
#     api_version="aadpodidentity.k8s.io/v1",
#     kind="AzureIdentity",
#     metadata=k8s.meta.v1.ObjectMetaArgs(
#         name="azure-identity-a",
#         namespace=namespace_a.metadata.name),
#     spec={
#         "type": 0,
#         "resourceID": identity_a.id,
#         "clientID": identity_a.client_id
#     })

# azure_identity_binding_a = k8s.apiextensions.CustomResource("azure-identity-binding-a",
#     api_version="aadpodidentity.k8s.io/v1",
#     kind="AzureIdentityBinding",
#     metadata=k8s.meta.v1.ObjectMetaArgs(
#         name="azure-identity-binding-a",
#         namespace=namespace_a.metadata.name),
#     spec={
#         "azureIdentity": azure_identity_a.metadata.name,
#         "selector": "selector-a"
#     })

# Do the same for the second namespace and identity

# Role-based access control (RBAC) to grant the identities necessary roles within their namespace
role_a = k8s.rbac.v1.Role("role-a",
    metadata=k8s.meta.v1.ObjectMetaArgs(
        namespace=namespace_a.metadata.name),
    rules=[k8s.rbac.v1.PolicyRuleArgs(
        api_groups=[""],
        resources=["pods", "secrets"],
        verbs=["get", "list", "watch", "create", "update", "patch", "delete"]
    )])

role_binding_a = k8s.rbac.v1.RoleBinding("role-binding-a",
    metadata=k8s.meta.v1.ObjectMetaArgs(
        namespace=namespace_a.metadata.name),
    subjects=[k8s.rbac.v1.SubjectArgs(
        kind="User",
        name="system:serviceaccount:namespace-a:default",
        api_group="rbac.authorization.k8s.io"
    )],
    role_ref=k8s.rbac.v1.RoleRefArgs(
        kind="Role",
        name=role_a.metadata.name,
        api_group="rbac.authorization.k8s.io"
    ))

# Do the same for the second namespace and identity

# Export the names of the namespaces
pulumi.export("namespace_a", namespace_a.metadata.name)
pulumi.export("namespace_b", namespace_b.metadata.name)

# Export the IDs of the Azure identities
pulumi.export("identity_a_id", identity_a.id)
pulumi.export("identity_b_id", identity_b.id)
```

Here we define two Kubernetes namespaces (`namespace-a` and `namespace-b`), two Azure identities (`identity-a` and `identity-b`), bindings for each identity to its respective namespace, and role bindings to set the permissions for each identity within its namespace.

Keep in mind that you would need to have the appropriate Pulumi classes for `AzureIdentity` and `AzureIdentityBinding` which are not standard Kubernetes resources but are provided by an Azure add-on called Azure AD Pod Identity, and thus you need to install this add-on and configure it in your Pulumi scripts separately.

In the actual environment, after defining these resources, you would deploy your applications to the namespaces and configure them to use the appropriate Azure identity. This setup enables applications in different namespaces to use different Azure identities, allowing for secure segregation of duties and resources.