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Azure Subscriptions Setup

How to prepare Azure so the infra/azure Terraform can create and name subscriptions. You do this once. After it's done, subscriptions are managed by editing subscriptions.auto.tfvars and running make azure-plan / make azure-apply (or the CI workflow).

What you're creating​

  1. An app registration + service principal — the non-human identity Terraform authenticates as.
  2. Federated credentials (OIDC) on it — so GitHub Actions can authenticate without a stored secret.
  3. A billing-scope role assignment — the permission that actually lets it create subscriptions.
sp-opennav-tf-subscriptions

Rationale (CAF convention): sp- = service principal, opennav = org, tf = managed by Terraform, subscriptions = its job (Microsoft calls this pattern subscription vending). Use the same string for the app registration display name and the SP.

Prerequisites​

  • An EA, MCA, or MPA billing account. Pay-As-You-Go cannot create subscriptions via API/Terraform — verify with az billing account list -o table (see Azure Subscriptions Setup billing scope).
  • Your own account must be Owner / Global Admin (to create the app registration) and have rights on the billing scope (to delegate subscription-creation to the SP).
  • Azure CLI + Terraform installed. Get both via the installer's opt-in infra flag: 
    INSTALL_INFRA_TOOLS=1 ./install.sh        # Linux/macOS
    $env:INSTALL_INFRA_TOOLS = "1"; .\install.ps1   # Windows
    It prefers the OS package manager (apt/dnf/brew/winget/choco) and falls back to a rootless install into .venv when sudo isn't available. Then az login.

Shortcut: run the bootstrap script​

Steps 1–2 (and printing every value you need) are automated. After az login:

./infra/azure/setup-azure.sh              # creates the SP + OIDC creds, prints values
./infra/azure/setup-azure.sh --set-github # also sets the GitHub repo Variables

It prints ARM_CLIENT_ID, ARM_TENANT_ID, ARM_SUBSCRIPTION_ID ready to paste into .env — the only value you must still look up yourself is the billing scope (Step 3). The manual steps below explain what it does.

Step 1 — Create the app registration + service principal​

# Create the app registration and capture its appId (client id)
APP_ID=$(az ad app create \
  --display-name "sp-opennav-tf-subscriptions" \
  --query appId -o tsv)

# Create the service principal for that app
az ad sp create --id "$APP_ID"

# Note these for later — they are NOT secrets:
echo "ARM_CLIENT_ID    = $APP_ID"
echo "ARM_TENANT_ID    = $(az account show --query tenantId -o tsv)"

We deliberately do not create a client secret here — CI uses OIDC (Step 2), and local runs can use your own az login (Step 4).

Step 2 — Add federated credentials (OIDC) for GitHub Actions​

This lets the CI workflow exchange a short-lived GitHub token for an Azure token — no secret is stored anywhere.

# Trust pushes to main
az ad app federated-credential create --id "$APP_ID" --parameters '{
  "name": "github-main",
  "issuer": "https://token.actions.githubusercontent.com",
  "subject": "repo:getcommunityone/open-navigator:ref:refs/heads/main",
  "audiences": ["api://AzureADTokenExchange"]
}'

# Trust pull requests (so PR plans authenticate too)
az ad app federated-credential create --id "$APP_ID" --parameters '{
  "name": "github-pr",
  "issuer": "https://token.actions.githubusercontent.com",
  "subject": "repo:getcommunityone/open-navigator:pull_request",
  "audiences": ["api://AzureADTokenExchange"]
}'

These subjects match the triggers in .github/workflows/azure-subscriptions.yml (push to main and pull_request).

Step 3 — Grant the SP rights on the billing scope (the key step)​

Subscription creation is a billing permission, not normal subscription RBAC — az role assignment does not do this. The exact role/path depends on your agreement:

MCA (Microsoft Customer Agreement)​

Assign the Azure subscription creator role on the invoice section:

  • Portal: Cost Management + Billing → Billing scopes → your account → Billing profiles → Invoice sections → pick the section → Access control (IAM) → Add → role Azure subscription creator → select sp-opennav-tf-subscriptions.
  • The invoice section's resource ID is your TF_VAR_billing_scope_id.

EA (Enterprise Agreement)​

Add the SP as owner of the enrollment account (a.k.a. SubscriptionCreator):

  • Portal: Cost Management + Billing → Billing scopes → enrollment account → assign the SP, or via the EA portal (ea.azure.com) → Enrollment account → Add the service principal.
  • Scope shape: /providers/Microsoft.Billing/billingAccounts/<enrollmentNumber>/enrollmentAccounts/<id>.

MPA (Partner)​

Assign on the customer scope: /providers/Microsoft.Billing/billingAccounts/<ba>/customers/<id>.

See Azure Subscriptions Setup billing scope for the az billing … commands that print each scope's full resource ID — that string is what goes in TF_VAR_billing_scope_id.

Step 4 — (Optional) Management Group placement​

If any subscription in subscriptions.auto.tfvars sets management_group_id, also grant the SP Management Group Contributor on that MG (this one is normal RBAC):

az role assignment create \
  --assignee "$APP_ID" \
  --role "Management Group Contributor" \
  --scope "/providers/Microsoft.Management/managementGroups/<mg-id>"

Step 5 — Wire the values in​

CI (GitHub Actions)​

gh variable set AZURE_CLIENT_ID        --body "$APP_ID"
gh variable set AZURE_TENANT_ID        --body "$(az account show --query tenantId -o tsv)"
gh variable set AZURE_SUBSCRIPTION_ID  --body "<any-existing-sub-id-to-auth-against>"
gh secret   set AZURE_BILLING_SCOPE_ID --body "<scope-id-from-step-3>"

Local (infra/azure/.env, gitignored)​

Two options:

  • Simplest — use your own az login. The azurerm provider falls back to Azure CLI auth, so locally you only need the billing scope: 
    export TF_VAR_billing_scope_id="<scope-id-from-step-3>"
    (Your user account must itself have the Step 3 permission for this to work.)
  • Use the SP via OIDC/secret as documented in .env.example if you want local runs to use the same identity as CI.

Verify​

cd infra/azure
set -a && source .env && set +a
make azure-plan        # from repo root, or: terraform plan

A clean plan listing the opennav-* subscriptions means everything is wired. Then make azure-apply (or merge the PR — CI applies on main).

Reference​

  • Azure Naming Conventions — the CAF naming/tagging standard for resources created inside these subscriptions.
  • Module + naming convention: infra/azure/README.md
  • CI workflow: .github/workflows/azure-subscriptions.yml
  • Microsoft docs: Programmatically create Azure subscriptions and Workload identity federation.