feat: TF_CLI_ARGS_* Handling

[milldr]

what

• Added logic and warning messages when the user specifies any TF_CLI_* environment variable, since this may conflict with Atmos behavior.
• Added to 2 places: terraform shell and to any terraform command, since these are handled separately
• Append any TF_CLI env vars to the determined TF_CLI env var for terraform shell

why

• When executing Terraform Shell, we should append generate var file to the (if) specified env var rather than overwriting it
• When executing Terraform, var files are already appended (merged). We should add a warning nonetheless

references

• DEV-2793

atmos terraform shell

atmos terraform plan

Summary by CodeRabbit

Summary by CodeRabbit

• New Features

  • Enhanced logging to alert users about potential conflicts with Terraform environment variables.
  • Improved handling of -var-file arguments to respect existing configurations.
  • Introduced a new function for merging environment variables, ensuring Atmos-specific variables take precedence.

• Bug Fixes

  • Enhanced management of Terraform command-line arguments to prevent unintentional overwriting of variable files.

[coderabbitai]

📝 Walkthrough

Walkthrough

The pull request modifies the handling of Terraform command-line arguments and environment variables within the Atmos shell utility functions. It introduces a structured approach to manage -var-file arguments and implements a warning system for existing environment variables. The changes ensure that existing configurations are respected, preventing unintentional overwrites and enhancing logging for potential conflicts with Terraform-related environment variables.

Changes

File	Change Summary
internal/exec/shell_utils.go	Updated execTerraformShellCommand to improve handling of -var-file arguments for Terraform commands. Added mergeEnvVars function.
internal/exec/terraform.go	Introduced logging for environment variables starting with TF_ to warn users about potential conflicts.

Assessment against linked issues

Objective	Addressed	Explanation
Warn about TF_CLI_ env variable replacement [DEV-2793]	✅
Append to existing environment variables instead of replacing	✅

Possibly related PRs

• add support for disabling custom terraform shell prompt #786: Modifies the execTerraformShellCommand function in the same file, focusing on shell command execution logic.
• increment ATMOS_SHLVL each time atmos terraform shell is called #803: Alters the execTerraformShellCommand function to manage the ATMOS_SHLVL environment variable.
• Export configuration information in shell launched by Atmos #827: Changes to the execTerraformShellCommand function to add environment variables for Terraform operations.
• Add support for atmos terraform providers commands #866: Introduces new commands related to Terraform providers, which may interact with the command execution logic.

Suggested reviewers

• Gowiem
• osterman

---

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📥 Commits

Reviewing files that changed from the base of the PR and between 4587133 and accde7a.

📒 Files selected for processing (1)

• internal/exec/shell_utils.go (3 hunks)

⏰ Context from checks skipped due to timeout of 90000ms (2)

• GitHub Check: Acceptance Tests (windows-latest, windows)
• GitHub Check: Summary

🔇 Additional comments (4)

internal/exec/shell_utils.go (4)

230-234: LGTM! Clean and efficient implementation.

The code efficiently handles Terraform commands that require var-file configuration. The slice-based approach makes it easy to maintain and extend the list of commands.

---

271-272: LGTM! Proper environment variable handling.

The code correctly uses mergeEnvVars to ensure that component environment variables take precedence while preserving system environment variables.

Also applies to: 278-278

---

359-367: Consider handling quoted values in TF_CLI_ARGS_ variables.*

The current implementation assumes space-separated values, but TF_CLI_ARGS_* variables might contain quoted values. Consider adding special handling for quoted arguments.

Run this script to check for potential issues with quoted values:

---

336-382: Consider adding unit tests for environment variable merging.

The mergeEnvVars function handles complex environment variable merging logic, especially for TF_CLI_ARGS_* variables. While the implementation looks solid, it would benefit from comprehensive unit tests to verify the behavior of:

1. System environment variable preservation
2. Atmos-specific variable precedence
3. TF_CLI_ARGS_* variable merging

Would you like me to help generate unit tests for this function?

Here's a script to verify the current test coverage:

✅ Verification successful

Unit tests needed for environment variable merging - No existing tests found 💪

The verification confirms there are no existing tests in the internal/exec package. Given the critical nature of environment variable handling, especially for Terraform CLI arguments, adding comprehensive tests is indeed important for reliability.

• No test file exists at internal/exec/shell_utils_test.go
• No environment-related tests found in the package

I can help create unit tests that cover:

1. System environment preservation
2. Atmos variable precedence
3. TF_CLI_ARGS_* merging logic

🏁 Scripts executed

The following scripts were executed for the analysis:

Script:

#!/bin/bash
# Check if there are any existing tests for mergeEnvVars
rg -l "func.*Test.*mergeEnvVars" 

# Look for any existing environment variable related tests
rg -l "os\.Setenv.*TF_CLI_ARGS" 

Length of output: 68

---

Script:

#!/bin/bash
# Find all test files in the internal/exec directory
fd ".*_test\.go$" internal/exec/

# Look for any test functions that deal with environment variables
rg -l "func.*Test.*Env" internal/exec/

# Look for environment-related test utilities
rg -l "test.*env" -t go internal/exec/

# Check if there's any existing test infrastructure
cat internal/exec/shell_utils_test.go 2>/dev/null || echo "File not found"

Length of output: 224

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[coderabbitai]

Actionable comments posted: 0

🧹 Nitpick comments (1)

internal/exec/terraform.go (1)

262-264: Catching var-file collisions in component environment ensures thorough coverage.
These lines do a great job of warning users when environment-level settings might be overridden.

📜 Review details

Configuration used: .coderabbit.yaml
Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 1aa75c6 and 42c3026.

📒 Files selected for processing (2)

• internal/exec/shell_utils.go (1 hunks)
• internal/exec/terraform.go (1 hunks)

🔇 Additional comments (4)

internal/exec/shell_utils.go (3)

188-190: Neat definition of terraform commands.
This approach centralizes the commands that may require var-file handling, simplifying future maintenance and extension.

---

191-197: Clear warning message for potential collisions.
It is helpful to log a warning whenever these TF_CLI_ARGS variables contain a “-var-file” argument, reducing user confusion.

---

198-200: Appending the var file reference to each command is straightforward.
Ensure users understand that this logic overrides any existing “-var-file” specification at runtime.

internal/exec/terraform.go (1)

248-257: Collisions detection is consistent with shell_utils.
Capturing conflicts across both the shell and terraform commands maintains consistent user visibility.

[osterman]

Here's the misunderstanding.

1. execTerraformShellCommand is only called for atmos terraform shell (in your screenshots you're running other commands)
2. The 5th argument is the var file.
3. When running atmos terraform shell, it will squash the TF_CLI_ARG_* environment variables. Not just when we're passing a -var-file. E.g. Setting TF_CLI_ARG_plan=-non-existant-flag will break Terraform. Atmos warning that the ENV is set, will alert the user during debugging.

Here are the new requirements

1. Anytime we execute terraform we should probably warn emit a warning if any of these variables are set, as it can change the deterministic behavior of atmos
2. Modify execTerraformShellCommand so that it does not squash the values of TF_CLI_ARG_* and instead appends (with a space) to it.

[coderabbitai]

Actionable comments posted: 0

🧹 Nitpick comments (1)

internal/exec/shell_utils.go (1)

356-385: Well-structured environment variable merging function!

The implementation is clean and handles the merging of environment variables effectively. However, consider adding error handling for malformed environment variables.

 func mergeEnvVars(baseEnv, overrideEnv []string) []string {
     envMap := make(map[string]string)
 
     // Parse base environment variables
     for _, env := range baseEnv {
         if parts := strings.SplitN(env, "=", 2); len(parts) == 2 {
             envMap[parts[0]] = parts[1]
+        } else {
+            // Log malformed environment variables
+            u.LogWarning(atmosConfig, fmt.Sprintf("Skipping malformed environment variable: %s", env))
         }
     }

📜 Review details

Configuration used: .coderabbit.yaml
Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between b8c2511 and 4587133.

📒 Files selected for processing (1)

• internal/exec/shell_utils.go (3 hunks)

⏰ Context from checks skipped due to timeout of 90000ms (2)

• GitHub Check: Build (windows-latest, windows)
• GitHub Check: Summary

🔇 Additional comments (3)

internal/exec/shell_utils.go (3)

281-283: Excellent use of environment variable merging!

The approach ensures that component-specific variables take precedence while preserving system environment variables.

---

290-298: Good debugging support!

The debug logging of merged environment variables helps with troubleshooting.

---

230-251: Strong approach to handling TF_CLI_ARGS!

The implementation correctly preserves existing TF_CLI_ARGS values while appending Atmos-specific var-file arguments. The warning message helps users understand potential conflicts.

However, consider adding validation for the existing arguments to prevent invalid combinations:

[github-actions]

These changes were released in v1.139.0.