[Feature] Add to rds_instance_info information regarding current engine version support dates

[nikitahlushak]

Is your feature request related to a problem? Please describe

Before recent updates from AWS, the only place you could get info regarding support dates for specific engine versions were only in AWS Documentation. E.g. link

To solve problem for myself I created a separate exporter that scrapes documentation page and calculates number of days before specific engine version becomes EOL

Describe the solution you'd like

Recently AWS added a separate API to describe engine version info, including support dates:
https://docs.aws.amazon.com/AmazonRDS/latest/APIReference/API_DescribeDBMajorEngineVersions.html
It could become part rds_instance_info metric supplying valuable info about rds instance lifecycle and will allow setting up alarms to schedule engine version upgrade beforehand

Describe alternatives you've considered

For me, if things remains the same, I will continue to scrape this data by myself and use promql joins in Grafana to check eol dates for my databases

Additional context

https://aws.amazon.com/about-aws/whats-new/2025/05/amazon-rds-retrieval-engine-lifecycle-support-dates/

[vmercierfr]

Thanks for sharing your use case.
This is a valuable information as EOL need to be anticipated. Also RDS Extended Support impact costs to operate database.

I would love to help on implementation.

@nikitahlushak Can you describe how are you consuming this information? Do you have dashboard or alerts on this? What could be the perfect fit for you?

(Feel free to share your metrics name)

I guess 2 dedicated metrics will be probably more relevant with Prometheus model, like:

rds_standard_support_engine_remaining_days{aws_account_id="****", aws_region="***",dbidentifier="***"} 60
rds_extended_support_engine_remaining_days{aws_account_id="****", aws_region="***",dbidentifier="***"} 730

So we may add it to dashboard, have specific alerts and users could opt-out if they are not using it.