Transit gateway route propagation.
This Lambda will Pull propagated routes from TGW and update VPC route table.
Tested on python 3.8 Lambda AWS
#### 1- DONOT USE THIS CODE IF YOU USE PREFIX LISTS ####
#### 2- Make sure your Lambda Role has permissions to describe/create routes in TGW/VPC and able to create/read from S3 bucket.
#### 3- This code will only update VPC that belong to same account as of TGW. No cross account support. But feel free to modify the code as per your req.
#### 4- Populate Variables In below section according to your resource ID's
#### 5- Customer can use it as cloudwatch cronjob or manually run it when they need to synch up TGW and VPC route tables
##########################################VARIABLE SECTION, PLEASE POPULATE AS PER YOUR RESOURCE ID'S################
#Update TGW ID/TGW REGION/BUCKETNAME ( If bucket doesnt exist, code will create one )
tgwid='tgw-0532154ce5738cxxxxx'
tgwregion='eu-xxx-1'
bucketname=tgwid+'route-prop'
# Populate this list with comma separated VPC ID for which you dont want Route propagator to take any action
# A good canidate would be inepection VPC as it has different VPC route table needs
VPCExceptionList=['vpc-1234'] # Dont remove this dummy VPC ID