Function buildDockerCommandWithExpandableVars

pkg/workflow/shell.go:141–188

that allows ${VAR_NAME} variables to be expanded at runtime.

(cmd string)

// that allows ${VAR_NAME} variables to be expanded at runtime.
func buildDockerCommandWithExpandableVars(cmd string) string {
	shellLog.Printf("Building docker command with expandable vars (length: %d)", len(cmd))
	// Find all ${VAR_NAME} patterns that need expansion outside of single quotes.
	// We want: 'docker run ... -v '"${GITHUB_WORKSPACE}"':'"${GITHUB_WORKSPACE}"':rw ...'
	// This closes the single quote, adds the variable in double quotes, then reopens single quote.

	// Collect all unique variable references
	expandableVars := findExpandableVars(cmd)

	if len(expandableVars) == 0 {
		shellLog.Print("No expandable variables found, using normal escaping")
		return shellEscapeArg(cmd)
	}

	shellLog.Printf("Docker command built with expandable variables: %v", expandableVars)

	// Process the command: wrap in single quotes, break out for each variable
	var result strings.Builder
	result.WriteString("'")
	remaining := cmd
	for len(remaining) > 0 {
		// Find the next variable reference
		nextIdx := -1
		nextVar := ""
		for _, v := range expandableVars {
			idx := strings.Index(remaining, v)
			if idx >= 0 && (nextIdx < 0 || idx < nextIdx) {
				nextIdx = idx
				nextVar = v
			}
		}
		if nextIdx < 0 {
			// No more variables, write the rest
			escapedPart := strings.ReplaceAll(remaining, "'", "'\\''")
			result.WriteString(escapedPart)
			break
		}
		// Write text before the variable
		before := remaining[:nextIdx]
		escapedBefore := strings.ReplaceAll(before, "'", "'\\''")
		result.WriteString(escapedBefore)
		// Break out of single quotes, add variable in double quotes, reopen single quotes
		result.WriteString("'\"" + nextVar + "\"'")
		remaining = remaining[nextIdx+len(nextVar):]
	}
	result.WriteString("'")
	return result.String()
}

// findExpandableVars returns all unique ${VAR_NAME} patterns in the string.
// It intentionally skips ${{ }} GitHub Actions expressions: those are evaluated