RDS

One might be tempted to think that getting the statuses of RDS instances would be just as easy as with EC2. Let's see if that is the case.

The describeDBInstances endpoint

This endpoint is equivalent in purpose to the analogous EC2 endpoint we just looked at. Its input, however, is slightly different: it accepts a single instance ID as input and, as of the time of this writing, doesn't support filters.

This means that if our stack has multiple RDS instances—say, in a primary/replica setup—we need to make multiple API calls to gather information about each one of them. Not a big deal, of course, but a limitation to be aware of.

Once given a specific database instance ID, this service responds with the following code:

{"DBInstances"
   [{"DBInstanceIdentifier" "RDS123", "DBInstanceStatus" "available"}]}

The fact that a single instance comes inside a vector hints at the fact that filtering will be supported in the future. It just hasn't happened yet.