fix: add ACME schedule environment variable for Azure Function deployment

README.md

@@ -80,6 +80,7 @@ All configuration is via environment variables. CLI flags override env vars when
 | `ACME_DNS_PROPAGATION_WAIT` | `60` | Maximum seconds to wait for DNS TXT record propagation |
 | `ACME_DNS_CHALLENGE_TTL` | `60` | TTL (seconds) for DNS-01 challenge TXT records |
 | `ACME_LOG_LEVEL` | `info` | Log level: `debug`, `info`, `warn`, `error` |
+| `ACME_SCHEDULE` | `0 0 2 * * *` | Azure Function timer schedule (cron expression, 6-field format). Only used when deployed as an Azure Function. |
 
 ### Azure Authentication
 
@@ -95,15 +96,136 @@ For sovereign clouds (Azure Government, Azure China), set `AZURE_AUTHORITY_HOST`
 
 ## Azure Function
 
-The package includes an Azure Functions v4 timer trigger that runs the provisioner daily at 02:00 UTC. To deploy, point the function app at this package's entry point and configure the environment variables above as application settings.
+The package includes an Azure Functions v4 timer trigger that runs the provisioner daily at 02:00 UTC.
 
 The function app requires a Managed Identity with the following RBAC assignments:
 
 | Scope | Role |
 |---|---|
-| Key Vault | Key Vault Certificates Officer |
-| Key Vault | Key Vault Secrets Officer |
-| DNS Zone(s) | DNS Zone Contributor |
+| Key Vault instance | Key Vault Certificates Officer |
+| Key Vault instance | Key Vault Secrets Officer |
+| Each DNS zone | DNS Zone Contributor |
+
+> **Note:** The only DNS changes made are temporary `_acme-challenge.<domain>` TXT records created during the DNS-01 challenge and deleted immediately after validation. No A, CNAME, or other records are modified. If you require tighter permissions than `DNS Zone Contributor`, create a custom role limited to `Microsoft.Network/dnszones/TXT/write` and `Microsoft.Network/dnszones/TXT/delete`.
+
+### Deploying with Azure Functions Core Tools
+
+**Prerequisites:** [Azure CLI](https://learn.microsoft.com/en-us/cli/azure/install-azure-cli), [Azure Functions Core Tools v4](https://learn.microsoft.com/en-us/azure/azure-functions/functions-run-local#install-the-azure-functions-core-tools), Node.js 24.
+
+**1. Log in to Azure**
+
+```sh
+az login
+```
+
+**2. Create a resource group and storage account** (skip if they already exist)
+
+```sh
+az group create --name <resource-group> --location <location>
+
+az storage account create \
+  --name <storage-account-name> \
+  --resource-group <resource-group> \
+  --location <location> \
+  --sku Standard_LRS
+```
+
+**3. Create the Function App**
+
+```sh
+az functionapp create \
+  --name <function-app-name> \
+  --resource-group <resource-group> \
+  --storage-account <storage-account-name> \
+  --consumption-plan-location <location> \
+  --runtime node \
+  --runtime-version 24 \
+  --functions-version 4
+```
+
+**4. Assign a system-assigned Managed Identity**
+
+```sh
+az functionapp identity assign \
+  --name <function-app-name> \
+  --resource-group <resource-group>
+```
+
+Note the `principalId` from the output — you will need it in the next step.
+
+**5. Grant RBAC roles to the Managed Identity**
+
+```sh
+# Key Vault Certificates Officer
+az role assignment create \
+  --assignee <principalId> \
+  --role "Key Vault Certificates Officer" \
+  --scope /subscriptions/<subscription-id>/resourceGroups/<kv-resource-group>/providers/Microsoft.KeyVault/vaults/<keyvault-name>
+
+# Key Vault Secrets Officer
+az role assignment create \
+  --assignee <principalId> \
+  --role "Key Vault Secrets Officer" \
+  --scope /subscriptions/<subscription-id>/resourceGroups/<kv-resource-group>/providers/Microsoft.KeyVault/vaults/<keyvault-name>
+
+# Option A — per zone (minimum permission, repeat for each managed DNS zone)
+az role assignment create \
+  --assignee <principalId> \
+  --role "DNS Zone Contributor" \
+  --scope /subscriptions/<subscription-id>/resourceGroups/<dns-resource-group>/providers/Microsoft.Network/dnszones/<zone-name>
+
+# Option B — per resource group (convenient when all DNS zones are in one group)
+az role assignment create \
+  --assignee <principalId> \
+  --role "DNS Zone Contributor" \
+  --scope /subscriptions/<subscription-id>/resourceGroups/<dns-resource-group>
+```
+
+**6. Configure application settings**
+
+```sh
+az functionapp config appsettings set \
+  --name <function-app-name> \
+  --resource-group <resource-group> \
+  --settings \
+    "ACME_KEYVAULT_URL=https://<keyvault-name>.vault.azure.net" \
+    "ACME_SUBSCRIPTION_ID=<subscription-id>" \
+    "ACME_RESOURCE_GROUPS=<dns-resource-group>" \
+    "ACME_CONTACT_EMAIL=<email>"
+```
+
+**7. Build and deploy**
+
+```sh
+npm run build
+func azure functionapp publish <function-app-name>
+```
+
+### Local testing
+
+Create a `local.settings.json` file at the project root (it is gitignored):
+
+```json
+{
+  "IsEncrypted": false,
+  "Values": {
+    "AzureWebJobsStorage": "UseDevelopmentStorage=true",
+    "FUNCTIONS_WORKER_RUNTIME": "node",
+    "ACME_KEYVAULT_URL": "https://<keyvault-name>.vault.azure.net",
+    "ACME_SUBSCRIPTION_ID": "<subscription-id>",
+    "ACME_RESOURCE_GROUPS": "<dns-resource-group>",
+    "ACME_CONTACT_EMAIL": "<email>",
+    "ACME_SCHEDULE": "0 0 2 * * *"
+  }
+}
+```
+
+Then run:
+
+```sh
+npm run build
+func start
+```
 
 ## Docker