[Experiment] provider: support core build tag

[jar-b]

Description

Setting the core tag will limit the services which are registered to the provider. This is an experiment to explore whether it is feasible to publish a scoped down version of the provider without maintaining an entirely separate project. The goal is to reduce binary size and corresponding memory usage in cases where only the most common services are required.

---

When built with the core tag, binary size reduces from 1.2GB to 179MB on an M1 MacBook Pro.

% go build && go build -tags=core -o terraform-provider-aws-core
% ls -lh terraform-provider-aws*
-rwxr-xr-x 1 jaredbaker staff 1.2G Apr 13 13:38 terraform-provider-aws
-rwxr-xr-x 1 jaredbaker staff 179M Apr 13 13:38 terraform-provider-aws-core

Planning a simple configuration with a single IAM policy document data source and IAM role with v6.40.0 and a locally built version of the provider with the core build tag exhibits a maximum resident set size savings in line with the reduction in binary size.

% /usr/bin/time -l terraform plan
<snip>

Note: You didn't use the -out option to save this plan, so Terraform can't guarantee to take exactly these actions if you run "terraform apply" now.
        9.91 real         4.12 user         0.54 sys
           555745280  maximum resident set size
<snip>

% /usr/bin/time -l make plan
TF_CLI_CONFIG_FILE=dev.tfrc terraform plan
<snip>

Note: You didn't use the -out option to save this plan, so Terraform can't guarantee to take exactly these actions if you run "terraform apply" now.
        0.84 real         0.53 user         0.11 sys
            73203712  maximum resident set size
<snip>

Maximum resident set size is reported in bytes on MacOS.

Version	Max Resident Size
v6.40.0	555745280 (555MB)
core tag build	73203712 (73MB)

Future Considerations

This branch in solely intended as an experiment. Acceptance testing is non-functional with the build tag enabled, and there is no precedent (to my knowledge) for releasing multiple providers from a single repository as would be necessary to distribute the "core" variant.

This branch is merely a proof of concept as we continue to explore how to best balance API coverage with performance of the provider as the surface area of the AWS SDK continues to grow.

[github-actions]

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