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Fix getter mode baking env vars into generated code #8

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Merged
karngyan merged 1 commit into from
Feb 8, 2026
Merged

Fix getter mode baking env vars into generated code #8

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20 changes: 11 additions & 9 deletions cfgx.go
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Original file line number Diff line number Diff line change
Expand Up @@ -100,14 +100,22 @@ func GenerateFromFile(opts *GenerateOptions) error {
return fmt.Errorf("failed to read input file %s: %w", opts.InputFile, err)
}

// Parse TOML to apply environment variable overrides if enabled
// Set default mode if not specified
mode := opts.Mode
if mode == "" {
mode = "static"
}
Comment on lines +103 to +107
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Copilot AI Feb 8, 2026

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GenerateFromFile’s behavior (including whether env overrides are applied) depends on the exact opts.Mode string matching "getter". Consider normalizing/validating opts.Mode here (e.g., trim + strings.ToLower and reject unknown values) so typos/casing differences don’t accidentally fall back to static-mode behavior and reintroduce secret-baking during generation.

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// Parse TOML to apply environment variable overrides if enabled.
// In getter mode, env vars are resolved at runtime via os.Getenv() calls
// in the generated code, so applying them at generation time would
// incorrectly bake runtime values (e.g. secrets) into the source as defaults.
var configData map[string]any
if err := toml.Unmarshal(data, &configData); err != nil {
return fmt.Errorf("failed to parse TOML: %w", err)
}

// Apply environment variable overrides
if opts.EnableEnv {
if opts.EnableEnv && mode != "getter" {
if err := envoverride.Apply(configData); err != nil {
return fmt.Errorf("failed to apply environment overrides: %w", err)
}
Expand Down Expand Up @@ -137,12 +145,6 @@ func GenerateFromFile(opts *GenerateOptions) error {
maxFileSize = DefaultMaxFileSize
}

// Set default mode if not specified
mode := opts.Mode
if mode == "" {
mode = "static"
}

// Generate code
generated, err := GenerateWithOptions(data, packageName, opts.EnableEnv, inputDir, maxFileSize, mode)
if err != nil {
Expand Down
47 changes: 47 additions & 0 deletions cfgx_test.go
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Expand Up @@ -72,6 +72,53 @@ max_conns = 10
require.NotContains(t, outputStr, `":8080"`, "original server.addr should have been overridden")
}

func TestGenerateFromFile_GetterModeIgnoresEnvOverrides(t *testing.T) {
tmpDir := t.TempDir()
inputFile := filepath.Join(tmpDir, "config.toml")
outputFile := filepath.Join(tmpDir, "config.go")

tomlData := []byte(`
[server]
addr = ":8080"

[secrets]
api_key = "set-from-env"
`)

err := os.WriteFile(inputFile, tomlData, 0644)
require.NoError(t, err)

// Set env var that would override the TOML value at generation time
os.Setenv("CONFIG_SECRETS_API_KEY", "sk-real-secret-key-12345")
defer os.Unsetenv("CONFIG_SECRETS_API_KEY")
Comment on lines +92 to +93
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Copilot AI Feb 8, 2026

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Use testing.T.Setenv (or capture/restore the prior value) instead of os.Setenv + defer os.Unsetenv. Unsetting can clobber an existing value in the parent environment and makes this test less isolated, especially if tests are run in parallel or the env var is already set on the machine/CI runner.

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opts := &GenerateOptions{
InputFile: inputFile,
OutputFile: outputFile,
PackageName: "config",
EnableEnv: true,
Mode: "getter",
}

err = GenerateFromFile(opts)
require.NoError(t, err, "GenerateFromFile() should not error")

output, err := os.ReadFile(outputFile)
require.NoError(t, err)

outputStr := string(output)

// The generated code should use the TOML default, NOT the env var value
require.Contains(t, outputStr, `"set-from-env"`,
"getter mode should use TOML default, not env var value")
require.NotContains(t, outputStr, "sk-real-secret-key-12345",
"getter mode must not bake env var values into generated code")

// It should still have the os.Getenv call for runtime override
require.Contains(t, outputStr, `os.Getenv("CONFIG_SECRETS_API_KEY")`,
"getter mode should still generate runtime env var lookups")
Comment on lines +103 to +119
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Copilot AI Feb 8, 2026

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This test asserts on generated source text but doesn't verify the generated getter-mode file compiles (unlike the other GenerateFromFile tests below). Adding a quick go build on outputFile would catch missing imports / syntax issues and make the regression test stronger.

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}

func TestGenerateFromFile(t *testing.T) {
// Create a temporary TOML file
tmpDir := t.TempDir()
Expand Down
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