Time-based retention policies for immutable blob container

Navigate to the desired container.
Select the More button on the right, then select Access policy.
In the Immutable blob storage section, select Add policy.
In the Policy type field, select Time-based retention, and specify the retention period in days.
To create a policy with container scope, do not check the box for Enable version-level immutability.
If desired, select Allow additional protected appends to enable writes to append blobs that are protected by an immutability policy.
After you’ve configured the immutability policy, you will see that it is scoped to the container:

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