I’m trying to use the new DynamoDB BatchResolvers to write to two DynamoDB table in an AppSync resolver (currently using a Lambda function to do this). However, I’m getting the following permission error when looking at the CloudWatch logs:
“User: arn:aws:sts::111111111111:assumed-role/appsync-datasource-ddb-xxxxxx-TABLE-ONE/APPSYNC_ASSUME_ROLE is not authorized to perform: dynamodb:BatchWriteItem on resource: arn:aws:dynamodb:us-east-1:111111111111:table/TABLE-TWO (Service: AmazonDynamoDBv2; Status Code: 400; Error Code: AccessDeniedException;
I’m using TABLE-ONE as my data source in my resolver.
I added the "dynamodb:BatchWriteItem" and "dynamodb:BatchGetItem" to TABLE-ONE’s permission:
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "VisualEditor0",
"Effect": "Allow",
"Action": [
"dynamodb:BatchGetItem",
"dynamodb:BatchWriteItem",
"dynamodb:PutItem",
"dynamodb:DeleteItem",
"dynamodb:GetItem",
"dynamodb:Scan",
"dynamodb:Query",
"dynamodb:UpdateItem"
],
"Resource": [
"arn:aws:dynamodb:us-east-1:111111111111:table/TABLE-ONE",
"arn:aws:dynamodb:us-east-1:111111111111:table/TABLE-ONE/*",
"arn:aws:dynamodb:us-east-1:111111111111:table/TABLE-TWO",
"arn:aws:dynamodb:us-east-1:111111111111:table/TABLE-TWO/*"
]
}
]
}
I have another resolver that uses the BatchGetItem operation and was getting null values in my response - changing the table’s policy access level fixed the null values:
However, checking the box for BatchWriteItem doesn’t seem to solve the issue either adding the permissions to the data source table’s policy.
I also tested my resolver test feature in AppSync, the evaluated request and response are working as intended.
Where else could I set the permissions for a BatchWriteItem operation between two tables? It seems like it's invoking the user's assumed-role instead of the table's role - can I 'force' it to use the table's role?
