[Hubs] Tag rules

📝 Scenario

As a FinOps practitioner, I need to change historical tags in order to fix cost reporting based on tags that were not configured or misconfigured

💎 Solution

Add the ability to define tag rules that adjust historical tags. Some examples of tag rules include:

• Required tags
• Allowed values
• Replace tag keys/values to fix misspellings (based on regex match)
• Back-dated tags to rewrite history
• Do not inherit specific tags to lock tags defined on higher-level scopes

All tag rules would have matching compliance reports and optional alerts. This is not intended to compete with Azure Policy. This is required since we are working in a system outside of Azure and are supporting scopes Azure Policy does not support today.

💬 Feedback

• "Are there any plans to be able to adjust historical tags? My biggest problem is that the tags aren't always right and need to be adjusted historically... Thanks. For my company... this is a deal breaker for us. I now have to export all the data to Power BI and use custom groupings. Tags for cost management purposes are useless because of this. With over 111,000 resources and growing daily I need a better way to allocate costs." (Jun 21, 2023)
• "Changing tags back in time would be nice. I quite often work for costumers where tagging is missing or incorrect, so when you want to compare cost over time you can’t get reliable numbers as it is" (Jun 24, 2023)

🙋‍♀️ Ask for the community

We could use your help:

1. Please vote this issue up (👍) to prioritize it.
2. Leave comments to help us solidify the vision.

The issue names no files, tests, or entry points. Start by clarifying the scope and concrete behavior for historical tag rules, compliance reports, and alerts with the community. Done would require an agreed, implementable specification rather than the current list of examples.