如何让Cloud Formation创建更改集以更新我的Lambda函数？

Question

I have a Lambda function which I've verified to work correctly. I'm able to update the function by hand on the command line using "update-function-code" but I've been trying to get it working with Code Pipeline and Cloud Formation. Here are the steps I have so far:

1. Source - fetch the code from github. This works correctly.
2. Build - test the code in Solano (3rd party CI). This works too and on the last stage it zips up the repo and uploads it to my S3 bucket.
3. Deploy - This is the "deploy" action category with the action mode "create or replace a change set". This doesn't work if the Lambda function already exists.
4. Beta - Execute the changeset. This works if the change set was generated correctly.

My samTemplate.yml looks like this:

AWSTemplateFormatVersion: '2010-09-09' Transform: AWS::Serverless-2016-10-31 Description: My Lambda function Resources: LambdaFunction: Type: AWS::Serverless::Function Properties: FunctionName: MyLambdaExecute Description: My Lambda function Handler: myhandler.handler Runtime: nodejs6.10 CodeUri: s3://mybucket/mydirectory/mylambdacode.zip AutoPublishAlias: Staging Timeout: 30 DeploymentPreference: Type: AllAtOnce

If the lambda function with the name "MyLambdaExecute" doesn't exist and I push up code to github, it works perfectly. But if I modify some code and push again it runs the first two steps, but then generates an empty change set with the status:

FAILED - No updates are to be performed.

I'm not sure what I have to do to get it to publish a new version. How do I get it to realize it needs to create a new changeset?

Answer 1

I believe you are receiving the "No updates" message because technically nothing is changing in your CloudFormation template. When attempting to build the changeset, the contents of the S3 file are not examined. It just sees that none of the CloudFormation resource properties have changed since the previous deployment.

Instead, you may use a local relative path for the CodeUri, and aws cloudformation package can upload the file to a unique S3 path for you. This ensures that the template changes each time and the new Lambda code is recognized/deployed. For example:

aws cloudformation package --template-file samTemplate.yml --output-template-file sam-output-dev.yml --s3-bucket "$CodePipelineS3Bucket" --s3-prefix "$CloudFormationPackageS3Prefix"

This command can be put into the build step before your create/execute changeset steps.

To see an demonstration of this entire flow in practice, you can look at this repository , although I will warn that it's a bit outdated thanks to the new features released at the end of 2017. (For example, I was publishing Lambda aliases manually via extra steps because it was written pre- AutoPublishAlias .)