Using the snapshot command

What is it?

The snapshot command group can be used to generate a normalized list of resources to file, which can then be used to generate a visual diff for changes. This could be used similarly to Snapshot Testing for HTML, and it can also be helpful to understand how expressions will be evaluated in a complex deployment.

Important: The snapshot command is only available in the standalone Bicep CLI and does not work through Azure CLI (az bicep). This means az bicep snapshot functionality is not available - you must use the standalone bicep executable.

Usage

Overwrite a snapshot

The --mode overwrite flag can be used to generate a file named main.snapshot.json. This file contains a normalized list of resources which contains concrete values where possible, and is agnostic to the module structure, making it resilient to refactoring, and useful to inspect the impact of a refactor.

bicep snapshot main.bicepparam --mode overwrite

You can optionally pass specific values for subscriptionId, resourceGroup, location and tenantId if you want to use these instead of placeholders:

bicep snapshot main.bicepparam --subscription-id 3faf6056-8474-4818-a729-1aff55d6b3fa --resource-group myRg --location westus --mode overwrite

Validate a snapshot

The --mode validate flag generates a visual diff similar to the diff we render for a live what-if, comparing the previous and new snapshot. This gives you the ability to quickly understand the impact of a refactor without making any requests, and without having to account for noise.

bicep snapshot main.bicepparam --mode validate

Example output:

Raising bugs or feature requests

Please raise bug reports or feature requests under Bicep Issues as usual.