No matter how you like to participate in developer communities, Pulumi wants to meet you there. If you want to meet other Pulumi users to share use-cases and best practices, contribute code or documentation, see us at an event, or just tell a story about something cool you did with Pulumi, you are part of our community.

Pulumi Community

What's the best way to do the following cloudformation replacement:
`!Sub "arn:aws:ssm:${AWS::Region}:${AWS::AccountId}:parameter${SsmParameterPrefix}*"`
where ${AWS::*} are standard cloudformation values replaced at runtime by the current region/account id and ${SsmParameterPrefix} is a passed in value as a parameter.

One solution:

```type AwsData = {
    region: string,
    accountId: string,
}
type FnSubCallback = (data: AwsData) =&gt; string
function fnSub(fn: FnSubCallback, provider?: aws.Provider) {
    const
        opts = {provider: provider},
        callerId = aws.getCallerIdentity(opts),
        region = aws.getRegion({}, opts)

    return pulumi
        .all([callerId, region])
        .apply(
            ([callerId, region]) =&gt; {
                const data: AwsData = {
                    region: region.name,
                    accountId: callerId.accountId,
                }
                return fn(data)
            }
        )
}```
Used like:

```const myarn = fnSub(AWS =&gt; `arn:aws:ssm:${AWS.region}:${AWS.accountId}:parameter${SsmParameterPrefix}*````


aws.getRegion/getCallerIdentity seem to need providers using keys

This fixes the above: `AWS_SDK_LOAD_CONFIG=true pulumi up`