I'm trying to migrate data from a csv file into an existing AWS DynamoDB table, as part of an AWS Amplify web app.
I followed this CloudFormation tutorial, using the below template.
I was only able to create a new DynamoDB table, but not use an existing table and add data to it.
QUESTION: Is there a way to modify the template so that I can provide an existing table name at the "Specify stack details" step in the wizard, under "DynamoDBTableName", so that the csv data will be added to the table? If not, is there an alternative process?
{
"AWSTemplateFormatVersion": "2010-09-09",
"Metadata": {
},
"Parameters" : {
"BucketName": {
"Description": "Name of the S3 bucket you will deploy the CSV file to",
"Type": "String",
"ConstraintDescription": "must be a valid bucket name."
},
"FileName": {
"Description": "Name of the S3 file (including suffix)",
"Type": "String",
"ConstraintDescription": "Valid S3 file name."
},
"DynamoDBTableName": {
"Description": "Name of the dynamoDB table you will use",
"Type": "String",
"ConstraintDescription": "must be a valid dynamoDB name."
}
},
"Resources": {
"DynamoDBTable":{
"Type": "AWS::DynamoDB::Table",
"Properties":{
"TableName": {"Ref" : "DynamoDBTableName"},
"BillingMode": "PAY_PER_REQUEST",
"AttributeDefinitions":[
{
"AttributeName": "id",
"AttributeType": "S"
}
],
"KeySchema":[
{
"AttributeName": "id",
"KeyType": "HASH"
}
],
"Tags":[
{
"Key": "Name",
"Value": {"Ref" : "DynamoDBTableName"}
}
]
}
},
"LambdaRole" : {
"Type" : "AWS::IAM::Role",
"Properties" : {
"AssumeRolePolicyDocument": {
"Version" : "2012-10-17",
"Statement" : [
{
"Effect" : "Allow",
"Principal" : {
"Service" : ["lambda.amazonaws.com","s3.amazonaws.com"]
},
"Action" : [
"sts:AssumeRole"
]
}
]
},
"Path" : "/",
"ManagedPolicyArns":["arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole","arn:aws:iam::aws:policy/AWSLambdaInvocation-DynamoDB","arn:aws:iam::aws:policy/AmazonS3ReadOnlyAccess"],
"Policies": [{
"PolicyName": "policyname",
"PolicyDocument": {
"Version": "2012-10-17",
"Statement": [{
"Effect": "Allow",
"Resource": "*",
"Action": [
"dynamodb:PutItem",
"dynamodb:BatchWriteItem"
]
}]
}
}]
}
},
"CsvToDDBLambdaFunction": {
"Type": "AWS::Lambda::Function",
"Properties": {
"Handler": "index.lambda_handler",
"Role": {
"Fn::GetAtt": [
"LambdaRole",
"Arn"
]
},
"Code": {
"ZipFile": {
"Fn::Join": [
"\n",
[
"import json",
"import boto3",
"import os",
"import csv",
"import codecs",
"import sys",
"",
"s3 = boto3.resource('s3')",
"dynamodb = boto3.resource('dynamodb')",
"",
"bucket = os.environ['bucket']",
"key = os.environ['key']",
"tableName = os.environ['table']",
"",
"def lambda_handler(event, context):",
"",
"",
" #get() does not store in memory",
" try:",
" obj = s3.Object(bucket, key).get()['Body']",
" except:",
" print(\"S3 Object could not be opened. Check environment variable. \")",
" try:",
" table = dynamodb.Table(tableName)",
" except:",
" print(\"Error loading DynamoDB table. Check if table was created correctly and environment variable.\")",
"",
" batch_size = 100",
" batch = []",
"",
" #DictReader is a generator; not stored in memory",
" for row in csv.DictReader(codecs.getreader('utf-8-sig')(obj)):",
" if len(batch) >= batch_size:",
" write_to_dynamo(batch)",
" batch.clear()",
"",
" batch.append(row)",
"",
" if batch:",
" write_to_dynamo(batch)",
"",
" return {",
" 'statusCode': 200,",
" 'body': json.dumps('Uploaded to DynamoDB Table')",
" }",
"",
"",
"def write_to_dynamo(rows):",
" try:",
" table = dynamodb.Table(tableName)",
" except:",
" print(\"Error loading DynamoDB table. Check if table was created correctly and environment variable.\")",
"",
" try:",
" with table.batch_writer() as batch:",
" for i in range(len(rows)):",
" batch.put_item(",
" Item=rows[i]",
" )",
" except:",
" print(\"Error executing batch_writer\")"
]
]
}
},
"Runtime": "python3.7",
"Timeout": 900,
"MemorySize": 3008,
"Environment" : {
"Variables" : {"bucket" : { "Ref" : "BucketName" }, "key" : { "Ref" : "FileName" },"table" : { "Ref" : "DynamoDBTableName" }}
}
}
},
"S3Bucket": {
"DependsOn" : ["CsvToDDBLambdaFunction","BucketPermission"],
"Type": "AWS::S3::Bucket",
"Properties": {
"BucketName": {"Ref" : "BucketName"},
"AccessControl": "BucketOwnerFullControl",
"NotificationConfiguration":{
"LambdaConfigurations":[
{
"Event":"s3:ObjectCreated:*",
"Function":{
"Fn::GetAtt": [
"CsvToDDBLambdaFunction",
"Arn"
]
}
}
]
}
}
},
"BucketPermission":{
"Type": "AWS::Lambda::Permission",
"Properties":{
"Action": "lambda:InvokeFunction",
"FunctionName":{"Ref" : "CsvToDDBLambdaFunction"},
"Principal": "s3.amazonaws.com",
"SourceAccount": {"Ref":"AWS::AccountId"}
}
}
},
"Outputs" : {
}
}
Another answer
Dennis' answer is one solution, but you can also comment out the "DynamoDBTable" part within the "Resources" of the JSON file.
