Azure Developer CLI (azd) Style Guide

Overview

This style guide establishes standards for code, user experience, testing, and documentation across the Azure Developer CLI project. Following these guidelines ensures consistency, maintainability, and a high-quality user experience.

Code Style Guidelines

Go Conventions

Pre-commit Checks

Run these commands from cli/azd/ and ensure all files include the copyright header:

gofmt -s -w .
golangci-lint run ./...
cspell lint "**/*.go" --relative --config ./.vscode/cspell.yaml --no-progress

// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License.

Naming

• Packages: Short, lowercase, single-word (e.g., auth, project).
• Interfaces: Descriptive, typically ending in -er (e.g., Runner).
• Constructors: New prefix, injecting dependencies (e.g., NewProjectService).
• Fields: PascalCase for public, camelCase for private.

Dependency Injection (IoC)

ALWAYS use the IoC container. NEVER use direct instantiation for major components.

// 1. Register with container
ioc.RegisterSingleton(container, func() *MyService {
    return &MyService{
        dependency: ioc.Get[*SomeDependency](container),
    }
})

// 2. Definition & Constructor
type myService struct {
    dependency *SomeDependency
}

func NewMyService(dep *SomeDependency) *myService {
    return &myService{dependency: dep}
}

Error Handling & Context

• Errors: Wrap with fmt.Errorf ("%w") to add actionable context and trace IDs.
• Context: ALWAYS propagate context.Context for cancellation and telemetry.

func (s *Service) Run(ctx context.Context) error {
    if err := s.doWork(ctx); err != nil {
        return fmt.Errorf("failed to provision resources: %w", err)
    }
    return nil
}

User Experience Patterns

Progress Reports

Progress reports provide real-time feedback during multi-step operations. Use progress reports to:

• Show status of long-running commands
• Display individual service provisioning/deployment states
• Help users troubleshoot by showing exactly which step failed

Progress Report States

Items in a progress report list can be in one of five states:

1. Loading: |=== | [Verb] Message goes here

   • Indicates operation in progress
   • Shows loading bar animation

2. Done: (✓) Done: [Verb] Message goes here

   • Green checkmark indicates successful completion
   • Past tense verb

3. Failed: (✗) Failed: [Verb] Message goes here

   • Red X indicates error
   • Include specific error message below

4. Warning: (!) Warning: [Verb] Message goes here

   • Yellow exclamation for non-blocking issues
   • Command continues but user should be aware

5. Skipped: (-) Skipped: [Verb] Message goes here

   • Gray dash indicates intentionally skipped step
   • Different from failed - this is expected behavior

Progress Report Guidelines

• Indentation: Progress items are always indented under the main command
• Hierarchy: Sub-steps appear indented under parent steps
• Verb consistency: Use present progressive for loading, past tense for completed
• Contextual information: Include resource names, identifiers when relevant

Examples

Success scenario:

Provisioning Azure resources (azd provision)
Provisioning Azure resources can take some time.

  (✓) Done: Creating App Service Plan: plan-r2w2adrz3rvwxu
  (✓) Done: Creating Log Analytics workspace: log-r2w2adrz3rvwxu
  (✓) Done: Creating Application Insights: appi-r2w2adrz3rvwxu
  (✓) Done: Creating App Service: app-api-r2w2adrz3rvwxu

Failure scenario:

Provisioning Azure resources (azd provision)

  (✓) Done: Creating App Service Plan: plan-r2w2adrz3rvwxu
  (✓) Done: Creating Log Analytics workspace: log-r2w2adrz3rvwxu
  (✗) Failed: Creating Cosmos DB: cosmos-r2w2adrz3rvwxu
  
  The '{US} West US 2 (westus)' region is currently experiencing high demand
  and cannot fulfill your request. Failed to create Cosmos DB account.

ERROR: Unable to complete provisioning of Azure resources, 'azd up' failed

Skipped scenario:

Note: Steps were skipped because _____ (directory, or specified service name)
If you want to deploy all services, you can run azd deploy --all or
move to root directory.

  (✓) Done: [Verb] Message goes here
  (✓) Done: [Verb] Message goes here
  (-) Skipped: [Verb] Message goes here

Command Output Standards

• Structured output: Support --output json for machine-readable output
• Progress indicators: Use spinners and progress bars for long operations
• Colorization: Use consistent colors (green=success, red=error, yellow=warning)
• URLs: Always include relevant portal/console URLs for created resources

CLI Color Standards

The CLI uses consistent color formatting through helper functions defined in cli/azd/pkg/output/colors.go. Always use these helper functions instead of writing raw ANSI escape codes.

Important: Colors will appear differently depending on which terminal and theme (dark/light) the customer prefers. Always test output in both dark and light terminal themes.

Standard Color Helper Functions

Use these functions for consistent color formatting across the CLI:

Purpose	Function	Usage Example
Hyperlinks	WithLinkFormat(text string)	URLs, portal links
Commands & parameters	WithHighLightFormat(text string)	Command names, parameters, system events
Success	WithSuccessFormat(text string)	Success messages, completed operations
Warning	WithWarningFormat(text string)	Warning messages, non-critical issues
Error	WithErrorFormat(text string)	Error messages, failures
Gray text	WithGrayFormat(text string)	Secondary information, muted text
Hint text	WithHintFormat(text string)	Helpful suggestions, tips
Bold text	WithBold(text string)	Emphasis, headers
Underline	WithUnderline(text string)	Emphasis (use sparingly)

Examples

// Success message
fmt.Println(output.WithSuccessFormat("(✓) Done:") + " Creating resource")

// Warning message
fmt.Println(output.WithWarningFormat("(!) Warning:") + " Configuration may need update")

// Error message
fmt.Println(output.WithErrorFormat("(✗) Failed:") + " Unable to connect")

// Hyperlink
fmt.Printf("View in portal: %s\n", output.WithLinkFormat(url))

// Command highlight
fmt.Printf("Run %s to deploy\n", output.WithHighLightFormat("azd deploy"))

Implementation Guidelines

• Consistency: Always use the helper functions for the same purpose across all commands
• Accessibility: Never rely solely on color to convey information (use icons/symbols too)
• Terminal compatibility: Colors will render differently across terminals - test in multiple environments
• Theme support: Test in both light and dark terminal themes
• Fallback: Ensure output remains readable if colors are disabled

📚 Learn more about ANSI color codes (optional reference)

The CLI uses industry-standard ANSI defined colors to ensure accessibility and compatibility across all terminals. This allows users to customize color palettes through their IDE or terminal preferences.

Color Naming Convention

Each color set has a pair: standard and bright variants:

• ANSI naming: "[color]" (FG 30-37) and "Bright [color]" (FG 90-97)
• PowerShell naming: "Dark [color]" and "[color]"

Note: There is a discrepancy in the naming convention between ANSI Color coding (which uses "Bright [color]" and "[color]") and PowerShell (which uses "[color]" and "Dark [color]"). Developers working with ANSI Color definitions should use the darker version of the two.

ANSI Color Code Reference

Standard 3/4-bit Colors (Theme-adaptive - Recommended):

FG	BG	Name	Foreground Code	Background Code	Standard RGB
30	40	Black	\033[30m	\033[40m	0, 0, 0
31	41	Red	\033[31m	\033[41m	170, 0, 0
32	42	Green	\033[32m	\033[42m	0, 170, 0
33	43	Yellow	\033[33m	\033[43m	170, 85, 0
34	44	Blue	\033[34m	\033[44m	0, 0, 170
35	45	Magenta	\033[35m	\033[45m	170, 0, 170
36	46	Cyan	\033[36m	\033[46m	0, 170, 170
37	47	White	\033[37m	\033[47m	170, 170, 170
90	100	Bright Black (Gray)	\033[90m	\033[100m	85, 85, 85
91	101	Bright Red	\033[91m	\033[101m	255, 85, 85
92	102	Bright Green	\033[92m	\033[102m	85, 255, 85
93	103	Bright Yellow	\033[93m	\033[103m	255, 255, 85
94	104	Bright Blue	\033[94m	\033[104m	85, 85, 255
95	105	Bright Magenta	\033[95m	\033[105m	255, 85, 255
96	106	Bright Cyan	\033[96m	\033[106m	85, 255, 255
97	107	Bright White	\033[97m	\033[107m	255, 255, 255

24-bit RGB Colors (Exact colors - Use sparingly):

• Foreground: \033[38;2;R;G;Bm where R, G, B are 0-255
• Background: \033[48;2;R;G;Bm where R, G, B are 0-255
• Example: \033[38;2;255;0;0m for exact red foreground

Note: \033 is the escape character in octal notation (can also be written as \x1b in hex or \e in some languages). Standard RGB values shown are from the VGA specification, but actual rendering varies by terminal and user theme preferences.

Recommendation: Use standard 3/4-bit colors (30-37, 90-97) as they adapt to the user's terminal theme preferences (dark/light mode). Only use 24-bit RGB colors when exact color matching is required. For complete ANSI escape code documentation, see ANSI escape code - Colors.

Testing Standards

Test Structure

Use table-driven tests consistently:

func TestMyFunction(t *testing.T) {
    tests := []struct {
        name     string
        input    string
        expected string
        wantErr  bool
    }{
        {"ValidInput", "test", "result", false},
        {"InvalidInput", "", "", true},
    }

    for _, tt := range tests {
        t.Run(tt.name, func(t *testing.T) {
            result, err := MyFunction(tt.input)
            if tt.wantErr {
                require.Error(t, err)
                return
            }
            require.NoError(t, err)
            require.Equal(t, tt.expected, result)
        })
    }
}

Snapshot Testing

• CLI help output: Test via snapshot files in cli/azd/cmd/testdata/*.snap
• Updating snapshots: Set UPDATE_SNAPSHOTS=true before running go test when output changes
• Review changes: Always review snapshot diffs to ensure they're intentional

Mock Usage

• Use testify/mock framework for mocking dependencies
• Place mocks in cli/azd/test/mocks/ directory
• Mock external dependencies (Azure SDK, file system, HTTP clients)

Architecture Patterns

Action-Based Commands

Commands implement the Action interface rather than traditional Cobra handlers:

type myAction struct {
    dependency *SomeService
}

func newMyAction(dep *SomeService) actions.Action {
    return &myAction{dependency: dep}
}

func (a *myAction) Run(ctx context.Context) (*actions.ActionResult, error) {
    // Implementation
    return &actions.ActionResult{
        Message: &actions.ResultMessage{
            Header: "Success",
        },
    }, nil
}

Middleware Pattern

For cross-cutting concerns, implement middleware:

type MyMiddleware struct {
    options *Options
}

func (m *MyMiddleware) Run(ctx context.Context, next NextFn) (*actions.ActionResult, error) {
    // Pre-processing
    result, err := next(ctx)
    // Post-processing
    return result, err
}

Telemetry Integration

• Add telemetry spans for all major operations
• Use OpenTelemetry conventions
• Include relevant attributes (command, duration, result)
• Respect AZURE_DEV_COLLECT_TELEMETRY=no opt-out

Documentation Standards

Code Comments

• Public APIs: Document all public functions, types, and methods
• Complex logic: Add inline comments explaining non-obvious code
• TODOs: Use // TODO: with context and owner when applicable

Help Text

• Consistency: Match terminology across all commands
• Examples: Include at least one example per command
• Flags: Document all flags with clear descriptions
• See also: Cross-reference related commands

Markdown Documentation

• Use proper formatting with headers, code blocks, and lists
• Include examples with both command and expected output
• Keep language simple and action-oriented
• Link to related documentation when appropriate

Command Design Patterns

See guiding-principles.md for detailed command structure design principles.

Key Principles

• Use verb-first structure (azd add <resource>, not azd <resource> add)
• Build on existing command categories (View, Edit, Run)
• Maintain consistent parameter patterns
• Follow progressive disclosure (simple by default, advanced when needed)

File Organization

Package Structure

cli/azd/
├── cmd/           # Command definitions
├── pkg/           # Core packages
│   ├── auth/      # Authentication
│   ├── project/   # Project management
│   ├── infra/     # Infrastructure providers
│   └── ...
├── internal/      # Internal packages
│   ├── telemetry/ # Telemetry system
│   └── ...
└── test/          # Test utilities and mocks

File Naming

• *_test.go for test files
• mock_*.go for mocks
• Keep related functionality in same package
• Split large files when they exceed ~500 lines

Azure Integration Guidelines

Authentication

• Support multiple auth methods (device code, service principal, managed identity)
• Handle token refresh gracefully
• Provide clear error messages for auth failures

SDK Usage

• Use Azure SDK for Go consistently
• Handle rate limiting and retries
• Log Azure API calls for debugging
• Include correlation IDs in requests

Performance Considerations

• Minimize Azure API calls
• Cache authentication tokens appropriately
• Use parallel operations where safe
• Provide progress feedback for operations >2 seconds

Security Guidelines

• Never log sensitive information (tokens, passwords, keys)
• Respect Azure RBAC and subscription boundaries
• Validate user input before processing
• Use secure defaults for all operations

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For extension development guidelines, see extensions-style-guide.md. For core design principles, see guiding-principles.md.