Copies an rds parameter group with support for cross-region copying. Quick bashed out script because AWS cli doesn't support.

cp-parameter-group.py

"""
 Copies a parameter group in RDS, particularly useful for doing cross-region copies (which AWS documents,
 but doesn't actually support at the time of this writing.

 Usage:  python cp-parameter-group.py us-west-1:lookerdb-56 us-west-2:lookerdb-56
"""

import boto3
import sys


def chunks(sequence, chunk_size):
    """
     Yields the sequence as a sequence of sequences size chunk_size (or fewer,
     in the case of the last chunk). Guarantees delivery of everything (as
     opposed to strategies that leave elements off of the end when
     len(sequence) % chunk_size != 0
    """
    start = 0
    while start < len(sequence):
        end = start + chunk_size
        yield sequence[start : start + chunk_size]
        start = end


# region:parameter_name
source_region, source_name = sys.argv[1].split(":")
source_client = boto3.client("rds", region_name=source_region)
source_summary = source_client.describe_db_parameter_groups(
    DBParameterGroupName=source_name
)
source_family = source_summary["DBParameterGroups"][0]["DBParameterGroupFamily"]
source_description = source_summary["DBParameterGroups"][0]["Description"]
source_parameters = source_client.describe_db_parameters(
    DBParameterGroupName=source_name
)["Parameters"]
source_parameters = [
    p for p in source_parameters if p["IsModifiable"] and "ParameterValue" in p
]

target_region, target_name = sys.argv[2].split(":")
target_client = boto3.client("rds", region_name=target_region)
groups_in_target_region = set(
    [
        g["DBParameterGroupName"]
        for g in target_client.describe_db_parameter_groups()["DBParameterGroups"]
    ]
)
if target_name in groups_in_target_region:
    raise ValueError(
        "This group (%s) already exists in region %s" % (target_name, target_region)
    )

print "Created %s in %s" % (target_name, target_region)
target_client.create_db_parameter_group(
    DBParameterGroupName=target_name,
    DBParameterGroupFamily=source_family,
    Description=source_description,
)

# AWS limits parameter modifications to 20 at a time
for parameters in chunks(source_parameters, 20):
    target_client.modify_db_parameter_group(
        DBParameterGroupName=target_name, Parameters=parameters
    )
    for parameter in parameters:
        print "%s = %s" % (parameter["ParameterName"], parameter["ParameterValue"])

print "Complete."

Please be careful: describe_db_parameters returns paginated results and this ignores next pages, so you'll miss parameters at an ordinal position >100. Have an updated version (for python3) at https://github.com/pchatzou/copy-aws-rds-parameter-group.