Amazon web services – How to use the –query and –filters with aws rds describe-db-instances to retrieve the OptionGroupName value of an RDS

The Output of describe-db-instances looks something like:

{
    "DBInstances": [
        {
            "PubliclyAccessible": true, 
            "MasterUsername": "bos", 
            "OptionGroupMemberships": [
                {
                    "Status": "in-sync", 
                    "OptionGroupName": "default:postgres-9-6"
                }
            ], 
            ...

The OptionGroupMemberships element is a list, so it might contain multiple values. If you are only seeking the value of the first item in the list, you would use:

--query 'DBInstances[*].OptionGroupMemberships[0].OptionGroupName'

You can combine it with other elements like this:

--query 'DBInstances[*].[MasterUsername,OptionGroupMemberships[0].OptionGroupName]'

You can also append --output text to obtain the value without JSON formatting.

If I ever need to experiment with the --query values, I go to JMESPath Tutorial — JMESPath and paste my JSON into the examples. I can then interactively attempt to write the correct query (which is how I derived the above answers).