feat: Add support for separate deployments of infra and code

[anoshi]

Description

Ignores changes to the source code hash of the lambda function code to maintain an idempotent terraform build in cases where the application code (lambda package) deployment is managed by an external pipeline / party.

Because the content of lifecycle ignore_changes lists cannot be dynamically generated, this update simply sets the aws_lambda_function's optional argument source_code_hash to null if the new variable ignore_source_code_hash is set to true.

Motivation and Context

Allow terraform to manage infrastructure components and application developers to manage the application code

Breaking Changes

none

How Has This Been Tested?

• I have tested this against multiple concurrent calls to the module with and without the ignore_source_code_hash variable specified / set to true

[asiegman]

This change would be useful for us as well.

[vhsantos]

We have tested it and its works us expected.

[antonbabenko]

You can deploy any package using local_existing_package argument and then update
it and run terraform apply again to redeploy it.

See this:

terraform-aws-lambda/examples/complete/main.tf

Lines 276 to 277 in afbf7bd

	create_package = false
	local_existing_package = "${path.module}/../fixtures/python3.8-zip/existing_package.zip"

There is no need for extra work unless I am missing something important.

[anoshi]

G'day Anton, love your work. You've contributed a massive amount to Terraform and its uptake. Thank you!

The purpose of this update is for Terraform not to manage the deployed code but only the lambda resource and associated attributes, triggers, etc. This update allows another group (e.g. pure developers) to publish the lambda code package on their own schedule and via a separate pipeline i.e. not through terraform apply, and for Terraform not to track the state of the deployed code package.

I don't believe the module currently supports this type of infrastructure vs code behaviour?

[antonbabenko]

@anoshi 👍 Thanks for the explanation - I now understand the use case! :)

Let me finish this PR a bit and extend it to work with Lambda Layers also.

[antonbabenko]

Thanks for the PR!

v2.10.0 has been just released.

[github-actions]

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