fabric-auth

name

fabric-auth

description

Use when authenticating to Microsoft Fabric APIs — getting 401 Unauthorized errors, choosing token audience/scope for Fabric REST, Power BI REST, OneLake, Warehouse/SQL, KQL, XMLA, or Azure ARM, or running `az login` / `az account get-access-token` / `az rest` for Fabric. Covers the full token-audience table, the OneLake-only `storage.azure.com/.default` requirement, `az login` flow variants (--allow-no-subscriptions, --use-device-code, SPN cert, managed identity), `az rest --resource` requirement (Fabric URL is not a built-in Azure endpoint), JWT decoding for 401 debugging, and why using the wrong audience is the #1 cause of 401s.

Fabric authentication & token audiences

All Fabric operations require Microsoft Entra ID OAuth 2.0 bearer tokens. Using the wrong audience is the #1 cause of 401 errors.

Access Target	Token Audience / Scope
Fabric REST API	https://api.fabric.microsoft.com/.default
Power BI REST API (refresh, data sources, permissions, DAX)	https://analysis.windows.net/powerbi/api/.default
OneLake (DFS/Blob)	https://storage.azure.com/.default
Warehouse / SQL Endpoint / SQL Database (TDS)	https://database.windows.net/.default
KQL / Kusto	https://kusto.kusto.windows.net/.default
XMLA Endpoint	https://analysis.windows.net/powerbi/api/.default
Azure Resource Management	https://management.azure.com/.default

az login
az account get-access-token --resource https://api.fabric.microsoft.com    # Fabric REST
az account get-access-token --resource https://database.windows.net        # SQL / TDS
az account get-access-token --resource https://analysis.windows.net/powerbi/api  # Power BI

Critical: OneLake ONLY accepts https://storage.azure.com/.default — using https://datalake.azure.net/ will fail.

az login flow variants

az login --allow-no-subscriptions --tenant <tid>     # Fabric tenant with no Azure subscription
az login --use-device-code --tenant <tid>            # headless / SSH / no-browser
az login --service-principal -u <appId> -p <secret> --tenant <tid>           # CI/CD with SPN secret
az login --service-principal -u <appId> --certificate /path/cert.pem --tenant <tid>   # SPN cert (preferred — no secret to rotate)
az login --identity                                  # system-assigned managed identity
az login --identity --username <clientId>            # user-assigned managed identity

Without --allow-no-subscriptions, Fabric-only tenants (no Azure subscription attached) get a confusing "No subscriptions found" error before any Fabric call runs.

az rest --resource requirement

api.fabric.microsoft.com is not a built-in Azure cloud endpoint, so az rest cannot derive the audience from the URL. Always pass --resource:

az rest --method get \
  --resource "https://api.fabric.microsoft.com" \
  --url "https://api.fabric.microsoft.com/v1/workspaces"

Without --resource, you get "Can't derive appropriate Azure AD resource from --url" — the single most common az rest Fabric error.

Decoding a token to debug 401s

When you get an unexpected 401, decode the JWT to see what audience the token actually has:

TOKEN=$(az account get-access-token --resource https://api.fabric.microsoft.com --query accessToken -o tsv)
echo "$TOKEN" | cut -d'.' -f2 | base64 -d 2>/dev/null | jq .

Compare the aud claim against the table above. Other useful claims: exp (Unix expiry), oid (principal object ID), tid (tenant ID).

TDS connection essentials (Warehouse / SQL Database)

When connecting via sqlcmd, ODBC drivers, or any TDS client:

Parameter	Value
Port	1433 (TCP, must be open outbound)
Initial Catalog / Database	Item display name (NOT the FQDN)
Authentication	Microsoft Entra ID only — SQL auth is not supported
Encryption	Encrypt=Yes required
Token audience	https://database.windows.net/.default
MARS	Not supported — remove MultipleActiveResultSets from connection strings (or set to false)

Gotcha: Login failed... database not found usually means the connection string passed the FQDN as Initial Catalog instead of the workspace item display name. Allow *.datawarehouse.fabric.microsoft.com and *-pbidedicated.windows.net through any outbound firewall.

Reference

• Microsoft Learn: Authenticate to Azure using Azure CLI
• Microsoft Learn: MSAL overview
• Microsoft Learn: Microsoft Entra authentication for Fabric SQL
• Comprehensive MS Learn link bundle (concept / Fabric REST auth / Azure CLI / OAuth flows / MSAL by language / SPN & managed identity / scopes & claims / Fabric-specific): references/REFERENCE.md