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Manage secrets for Azure Functions on Azure Container Apps

When you run Azure Functions on Azure Container Apps, you work with two categories of secrets:

Category Description Consumed by
App-level secrets Configuration values your function code reads at runtime, such as database connection strings, API keys, and trigger/binding credentials. Your code and the Functions runtime bindings.
Functions access keys Authentication tokens (access keys) that secure HTTP-triggered function endpoints, including master, host, function, and system keys. External callers of your HTTP functions (services, webhooks, developers).

These two categories differ in direction:

App-level secrets Functions access keys
Direction Outbound - your function authenticates to other services Inbound - callers authenticate to your function
Who holds the secret Your function app The caller (webhook provider, service, developer)
What it protects What your function connects to Who can invoke your HTTP endpoint
Validated by The target service The Functions runtime

App-level secrets

App-level secrets are the credentials your function code and bindings need to connect to external services. You can store them in two ways:

Option Best for Rotation Audit Guide
Container Apps secrets Dev/test, simple single-app workloads Manual Activity logs only Store app-level secrets
Key Vault references Production, multi-app, compliance Automatic (versionless URI) Full Key Vault diagnostics Store app-level secrets

Tip

Start with Container Apps secrets for simplicity. Move to Key Vault references when you need centralized management, automatic rotation, or compliance-grade auditing.

Functions access keys

Access keys provide lightweight shared-secret authentication for HTTP endpoints. Use access keys when callers can't present Microsoft Entra ID tokens, such as third-party webhooks, service-to-service calls, or during development.

Set the AzureWebJobsSecretStorageType environment variable to choose a storage backend:

Backend Setting value Best for Guide
Container Apps secret store containerapps Most workloads - no external dependencies (Recommended) Configure host keys
Azure Key Vault keyvault Centralized governance, compliance auditing Configure host keys
Azure Blob Storage blob Legacy apps or existing AzureWebJobsStorage dependency Configure host keys
Local file system files Not recommended on Container Apps - see warning N/A

Keep these backend considerations in mind:

  • The runtime doesn't automatically select Container Apps secret storage. If you don't set AzureWebJobsSecretStorageType or set it to an unrecognized value, the Functions host uses Blob Storage when AzureWebJobsStorage is available.
  • Keep AzureWebJobsStorage configured for storage health checks and storage-dependent features.
  • Don't set AzureWebJobsSecretStorageType to files. The Container Apps file system is ephemeral, so keys stored with this backend are lost when the app scales to zero, restarts, or deploys a new revision.

Next steps

Choose the guide that matches the type of secret you need to manage:

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