Allows copying RDS parameter groups between AWS Regions and Accounts. Enables version-controlling values of RDS param groups via JSON files. Makes possible RDS cluster provisioning automation for custom parameter groups.

rds-parameter-group-exporter-importer.ps1

<#
Allows exporting RDS Parameter Group parameters as a file and importing it in another AWS Account or a region.

Inspired by https://gist.github.com/phill-tornroth/f0ef50f9402c7c94cbafd8c94bbec9c9.

PowerShell is a *cross-platform* shell compatible with Linux, MacOS and Windows. 
PowerShell can be installed in seconds: https://learn.microsoft.com/en-us/powershell/scripting/install/installing-powershell 

Usage:
To *export* a cluster parameter group named "custom-aurora-postgresql13-babelfish-compat-1", run:
Get-RdsClusterParamGroupDetails custom-aurora-postgresql13-babelfish-compat-1 | ConvertTo-Json -Depth 3 | Out-File RDS-BBF-params.json
or (the easier way):
Get-RdsClusterParamGroupDetailsJson custom-aurora-postgresql13-babelfish-compat-1 -FilePath RDS-BBF-params.json

To create a parameter group named apg-bbf-params from JSON file:
Import-RdsClusterParamGroupDetails RDS-BBF-params.json -ProfileName default -Region us-west-2 `
    -Name "apg-bbf-params"

Note: ProfileName and Region parameters are optional.
#>

Write-Host "Adding all AWS PowerShell commands. It may take a few seconds.."
Import-Module awspowershell.netcore

function Get-RdsClusterParamGroupDetailsJson {
    param (
        [Parameter(mandatory=$true, HelpMessage='Use Get-RDSDBClusterParameterGroup cmdlet to list all cluster parameter groups')] 
            [string] $Name,
        [Parameter(mandatory=$false)] [string] $Region,
        [Parameter(mandatory=$false)] [string] $ProfileName,
        [Parameter(mandatory=$false)] [string] $FilePath
    )

    $result = Get-RdsClusterParamGroupDetails -Name $Name `
                    -Region $Region `
                    -ProfileName $ProfileName

    if(-not $result) {
        return
    }    

    if(-not $FilePath) { $FilePath = "$Name--param-group-details.json" }

    $result | ConvertTo-Json -Depth 9 | Out-File $FilePath
}

function Get-RdsClusterParamGroupDetails {
    param (
        [Parameter(mandatory=$true, HelpMessage='Use Get-RDSDBClusterParameterGroup cmdlet to list all cluster parameter groups')] [string] $Name,
        [Parameter(mandatory=$false)] [string] $Region,
        [Parameter(mandatory=$false)] [string] $ProfileName
    )

    $prevRegion = Get-DefaultAWSRegion
    try{
        if($Region) { Set-DefaultAWSRegion $Region}
        if($ProfileName -eq "") { $ProfileName = $null }

        $sourceParamGroup = Get-RDSDBClusterParameterGroup $Name `
            -ProfileName $ProfileName

        $parameters = Get-RDSDBClusterParameter $Name `
            -ProfileName $ProfileName `
            | Where { $_.ParameterValue -and $_.IsModifiable  }

        $result = [PSCustomObject]@{
            ParameterGroupName = $sourceParamGroup.DBClusterParameterGroupName
            Description = $sourceParamGroup.Description
            GroupFamily = $sourceParamGroup.DBParameterGroupFamily
            Parameters = $parameters
        }
        return $result
    }
    finally{
        if($prevRegion) { Set-DefaultAWSRegion $prevRegion} else {Clear-DefaultAWSRegion}
    }
}

# Test command for export debugging puposes:
# $exportedData = Get-RdsClusterParamGroupDetails custom-aurora-postgresql13-babelfish-compat-1 | ConvertTo-Json -Depth 3
# $exportedData | Out-File custom-aurora-postgresql13-babelfish-compat-1-rds-param-group-details.json
# Get-RdsClusterParamGroupDetailsJson custom-aurora-postgresql13-babelfish-compat-1 -FilePath RDS-BBF-params.json

function Import-RdsClusterParamGroupDetails {
    param (
        [Parameter(mandatory=$true, ValueFromPipeline = $true, 
            HelpMessage='Use Get-RdsClusterParamGroupDetails cmdlet to export details of the cluster parameter groups')
        ] $ImportedParamGroupDetails,
        [Parameter(mandatory=$false)] [string] $Name,
        [Parameter(mandatory=$false)] [string] $Region,
        [Parameter(mandatory=$false)] [string] $ProfileName
    )

    # Write-Debug "Imported data:\n$ImportedParamGroupDetails"

    # The ImportedParamGroupDetails can either be piped-in, already parsed Json,
    # or a path to th eJSON file.
    if($ImportedParamGroupDetails -is [string]) {

        $ImportedParamGroupDetails = Get-Content $ImportedParamGroupDetails | ConvertFrom-Json -Depth 9
    }

    $prevRegion = Get-DefaultAWSRegion
    try{
        if($Region) { Set-DefaultAWSRegion $Region}

        if(-not $Name) {$Name = $ImportedParamGroupDetails.ParameterGroupName}

        New-RDSDBClusterParameterGroup `
            -DBClusterParameterGroupName $Name `
            -DBParameterGroupFamily $ImportedParamGroupDetails.GroupFamily `
            -Description GroupFamily.Description `
            -ProfileName $ProfileName

        $importedParameters = _FilterOutIdenticalValues $ImportedParamGroupDetails.Parameters $Name  $ProfileName

        $paramCollectionLength = $importedParameters.Count
        Write-Information "Will update $paramCollectionLength parameters"

        for($i=0 ; $i -lt $paramCollectionLength ; $i += 20) {

            $chunkSize = $paramCollectionLength - $i
            if($chunkSize -gt 20) { $chunkSize = 20 }

            # Slice out no more than 20 parameters for the batch update
            $params = $importedParameters[$i..($i+$chunkSize-1)] ?? $importedParameters

            foreach ($param in $params) {
                # ApplyMethod cannot be converted autpmatically
                $param.ApplyMethod = [Amazon.RDS.ApplyMethod]::New($param.ApplyMethod.Value)
            }

            # Update the batch of values
            if($params -and ($params.Count -gt 0)){
                Edit-RDSDBClusterParameterGroup -DBClusterParameterGroupName $Name -ProfileName $ProfileName `
                            -Parameter $params
            }

            ## Debug version - updates parameters one by one instead of in chunks of 20, to see which ones are failing
            # foreach($p in $params) {
            #     try{
            #         Edit-RDSDBClusterParameterGroup -DBClusterParameterGroupName $Name -ProfileName $ProfileName `
            #             -Parameter $p
            #     }
            #     catch {
            #         Write-Host "==> UPDATE ERROR: Failed to modify parameter `"$($p.ParameterName)`" with value `"$($p.ParameterValue)`" due to the `"$($_))`" error, with allowed values of `"$($p.AllowedValues)`"."
            #         # throw
            #     }
            # }
        }
    }
    finally{
        if($prevRegion) { Set-DefaultAWSRegion $prevRegion} else {Clear-DefaultAWSRegion}
    }
}

function _FilterOutIdenticalValues($importedParameters, [string] $Name, [string] $ProfileName) 
{
    $stockParameters = Get-RDSDBClusterParameter $Name `
        -ProfileName $ProfileName `
        | Where-Object { $_.ParameterValue -and $_.IsModifiable  }

    $paramsToSkip = [System.Collections.ArrayList]@();

    foreach($importedParam in $importedParameters) {
        $sameParam = $stockParameters | Where-Object { ($_.ParameterName -eq $importedParam.ParameterName) -and ($_.ParameterValue -eq $importedParam.ParameterValue) } | Select-Object -First 1
        if($sameParam) {
            $paramsToSkip.Add($sameParam.ParameterName) | out-null
        }
    }

    # Remove parameters that should be skipped
    $importedParameters = $importedParameters | Where-Object { -not $paramsToSkip.Contains($_.ParameterName) }

    return $importedParameters
}

#Testing import 
# Get-Content RDS-BBF-params.json `
#     | ConvertFrom-Json -Depth 4 `
#     | Import-RdsClusterParamGroupDetails -ProfileName default -Region us-west-2

#Import-RdsClusterParamGroupDetails RDS-BBF-params.json -ProfileName default -Region us-west-2 `
#    -Name "apg-bbf-params"