What is the difference between PackageType: Image and build --use-container in a SAM App?

Question

PackageType: image seems to require a Dockerfile (looking at the hello-world example) along with ImageUri and Metadata And it also doesn't want me to use Runtime, Handler, Layers (not even using layers)

whereas build --use-container does not seem to need anything. Does it figure it all out from the Runtime: nodejs14.x-v1

In the documentation I don't see anything

When I google there are tons of docs and resources but none related

I would really like to know because I'm at building a pipeline stage now. I got it to work great with a single stage and would now like to use the multi-stage multi-account and from what I read, it is recommended to use Images.

I noticed that the current pipeline does have --use-container , but my PackageType is zip , and at some point when I built it (using sam pipeline --bootstrap ) it asked me if any of my functions use images. I would like for my multi stage/account one to answer Y

It may not be related, but that is also how I plan on using environment variables for each account, since the databases used to fetch data are different. So I think I'll have to go and add --container-env-var-file in the gitlab-ci.yml script, or maybe in the samconfig.toml [dev.build.parameters] and under [prod.build.parameters] for its env-prod.json` file

Answer 1

SAM application package types can be either Zip or Images (container images). The details of their differences are described in their docs here: https://docs.aws.amazon.com/lambda/latest/dg/gettingstarted-package.html

I came across that page when I was reading the AWS docs for auto-creating a new SAM app here: https://docs.aws.amazon.com/toolkit-for-vscode/latest/userguide/serverless-apps.html#serverless-apps-create

(when you need to: "Choose the runtime for your AWS SAM application")