I'm trying to create a stack with CloudFormation. The stack needs to take some data files from a central S3 bucket and copy them to it's own "local" bucket.
I've written a lambda function to do this, and it works when I run it in the Lambda console with a test event (the test event uses the real central repository and successfully copies the file to a specified repo).
My current CloudFormation script does the following things:
It's at step 4 where it starts to go wrong - the Cloudformation execution seems to freeze here ( CREATE_IN_PROGESS
). Also, when I try to delete the stack, it seems to just get stuck on DELETE_IN_PROGRESS
instead.
Here's how I'm invoking the Lambda function in the CloudFormation script:
"DataSync": {
"Type": "Custom::S3DataSync",
"Properties": {
"ServiceToken": { "Fn::GetAtt" : [ "S3DataSync", "Arn" ] },
"InputFile": "data/provided-as-ip-v6.json",
"OutputFile": "data/data.json"
}
},
"KeySync1": {
"Type": "Custom::S3DataSync",
"Properties": {
"ServiceToken": { "Fn::GetAtt" : [ "S3DataSync", "Arn" ] },
"InputFile": "keys/1/public_key.pem"
}
},
"KeySync2": {
"Type": "Custom::S3DataSync",
"Properties": {
"ServiceToken": { "Fn::GetAtt" : [ "S3DataSync", "Arn" ] },
"InputFile": "keys/2/public_key.pem"
}
}
And the Lambda function itself:
exports.handler = function(event, context) {
var buckets = {};
buckets.in = {
"Bucket":"central-data-repository",
"Key":"sandbox" + "/" + event.ResourceProperties.InputFile
};
buckets.out = {
"Bucket":"sandbox-data",
"Key":event.ResourceProperties.OutputFile || event.ResourceProperties.InputFile
};
var AWS = require('aws-sdk');
var S3 = new AWS.S3();
S3.getObject(buckets.in, function(err, data) {
if (err) {
console.log("Couldn't get file " + buckets.in.Key);
context.fail("Error getting file: " + err)
}
else {
buckets.out.Body = data.Body;
S3.putObject(buckets.out, function(err, data) {
if (err) {
console.log("Couln't write to S3 bucket " + buckets.out.Bucket);
context.fail("Error writing file: " + err);
}
else {
console.log("Successfully copied " + buckets.in.Key + " to " + buckets.out.Bucket + " at " + buckets.out.Key);
context.succeed();
}
});
}
});
}
Your Custom Resource function needs to send signals back to CloudFormation to indicate completion, status, and any returned values. You will see CREATE_IN_PROGRESS as the status in CloudFormation until you notify it that your function is complete.
The generic way of signaling CloudFormation is to post a response to a pre-signed S3 URL. But there is a cfn-response module to make this easier in Lambda functions. Interestingly, the two examples provided for Lambda-backed Custom Resources use different methods:
Yup, i did the same thing. We need to upload(PUT request) the status of our request.(Need to send the status as SUCCESS)
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