Merge pull request #1153 from weaveworks/docs-add-nov29

Adds a starter docs page on Azure

docs/use_tf_controller/with-azure.md

@@ -0,0 +1,61 @@
+## Use TF-Controller with Azure
+
+This content was [provided](https://github.com/weaveworks/tf-controller/issues/561) by users [@mingmingshiliyu](https://github.com/mingmingshiliyu) and [@maciekdude](https://github.com/maciekdude).
+
+Use the OIDC flag and explicitly point to the token. Due to a bug in AzureRM 3.44.x, use version 3.47.x or later.
+
+Set env variables on the runner pod:
+
+```
+        - name: ARM_USE_OIDC
+          value: "true"
+        - name: ARM_OIDC_TOKEN_FILE_PATH
+          value: "/var/run/secrets/azure/tokens/azure-identity-token"
+```
+
+Example yaml:
+
+```yaml
+apiVersion: infra.contrib.fluxcd.io/v1alpha1
+kind: Terraform
+metadata:
+  name: terraformhello
+  namespace: default
+spec:
+  tfstate:
+    forceUnlock: auto
+  backendConfig:
+    customConfiguration: |
+      backend "azurerm" {
+        resource_group_name  = "l"
+        storage_account_name = ""
+        container_name       = "tfstate"
+        key                  = "helloworld.tfstate"
+        use_oidc             = true
+      }
+  interval: 1m
+  serviceAccountName: service_account_registered_in_aad
+  approvePlan: auto
+  destroy: true
+  path: ./tests/fixture
+  sourceRef:
+    kind: GitRepository
+    name: terraformhello
+    namespace: flux-system
+  runnerPodTemplate:
+    spec:
+      image: azure_cli_runner.xxx
+      env:
+        - name: ARM_USE_OIDC
+          value: "true"
+        - name: ARM_SUBSCRIPTION_ID
+          value: ""
+        - name: ARM_TENANT_ID
+          value: ""
+        - name: ARM_CLIENT_ID
+          value: ""
+        - name: ARM_OIDC_TOKEN_FILE_PATH
+          value: "/var/run/secrets/azure/tokens/azure-identity-token"
+```
+
+Import existing resources to a tfstate file stored on a storage account.