feat: Workload identity federation support for Fabric using STS

[rrajagopalan-equinix]

This pull request introduces support for Workload Identity Federation (WIF) using Equinix STS, along with updates to documentation, provider configuration, and acceptance testing. The changes enable authentication via OIDC tokens, enhance the Equinix Terraform provider, and improve testing capabilities.

Workload Identity Federation (WIF) Support:

• docs/guides/sts_wif_setup.md: Added a comprehensive guide for setting up Workload Identity Federation using Equinix STS, including steps for obtaining authentication tokens, establishing trust with an identity provider, and authorizing workloads.
• docs/index.md: Updated documentation to include details about using Workload Identity Tokens for authentication with Equinix Fabric, including alpha feature limitations and configuration examples. [1] [2] [3]
• examples/example_4.tf: Added an example Terraform configuration demonstrating the use of Workload Identity Federation with sts_auth_scope and sts_source_token.

Provider Enhancements:

• equinix/provider.go: Added new provider arguments (sts_auth_scope, sts_endpoint, sts_source_token) for configuring STS authentication. Updated the configureProvider function to support STS-based authentication. [1] [2]
• internal/config/config.go: Introduced STS-related environment variables and default values. Enhanced the Config struct and authentication logic to support STS tokens. Refactored client creation methods for improved modularity. [1] [2] [3] [4] [5] [6] [7] [8]

Acceptance Testing Improvements:

• internal/acceptance/acceptance.go: Updated acceptance testing utilities to include checks for STS authentication credentials. Enhanced pre-check methods to validate STS setup alongside existing authentication mechanisms. [1] [2] [3] [4]

Dependency Updates:

• go.mod: Upgraded github.com/equinix/equinix-sdk-go to version v0.54.0 to support new STS features. Removed unused dependencies.

Documentation Improvements:

• internal/provider/provider.go: Added package-level documentation for the Terraform provider implementation.

[codecov]

Codecov Report

❌ Patch coverage is 43.58974% with 132 lines in your changes missing coverage. Please review.
✅ Project coverage is 59.14%. Comparing base (dfd8929) to head (b32d706).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/sts/context_aware_token_source.go	0.00%	58 Missing ⚠️
internal/sts/context_aware_transport.go	0.00%	32 Missing ⚠️
internal/config/config.go	54.76%	15 Missing and 4 partials ⚠️
internal/sts/config.go	0.00%	13 Missing ⚠️
internal/acceptance/acceptance.go	0.00%	10 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #908       +/-   ##
===========================================
+ Coverage   29.30%   59.14%   +29.83%     
===========================================
  Files         242      245        +3     
  Lines       28101    28297      +196     
===========================================
+ Hits         8236    16737     +8501     
+ Misses      19715    10698     -9017     
- Partials      150      862      +712     

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[ctreatma]

Looks good to me! Acceptance test workflow results demonstrate that the introduction of token exchange support has not impacted existing usage of the provider. I appreciate the introduction of multiple acceptance test jobs to exercise different provider configurations! Long-term, we should enact/adopt that pattern more broadly across the provider.

[github-actions]

This PR is included in version 4.7.0 🎉