Core Interfaces

This document provides a reference for all core interfaces in CMDR.

Command Interfaces

Command

Read-only view of a managed command¹:

type Command interface {
    GetName() string        // Command name (e.g., "kubectl")
    GetVersion() string     // Version string (e.g., "1.28.0")
    GetActivated() bool     // Whether this version is activated
    GetLocation() string    // File path to the binary
}

CommandQuery

Fluent API for querying commands²:

type CommandQuery interface {
    WithName(name string) CommandQuery
    WithVersion(version string) CommandQuery
    WithActivated(activated bool) CommandQuery
    WithLocation(location string) CommandQuery

    All() ([]Command, error)   // Get all matching commands
    One() (Command, error)     // Get first matching command
    Count() (int, error)       // Count matching commands
}

Usage Example:

query, _ := manager.Query()

// Find activated kubectl
cmd, _ := query.WithName("kubectl").WithActivated(true).One()

// List all versions of node
commands, _ := query.WithName("node").All()

// Count total managed commands
count, _ := query.Count()

CommandManager

Full CRUD operations for commands³:

type CommandManager interface {
    Close() error
    Provider() CommandProvider
    Query() (CommandQuery, error)

    Define(name, version, location string) (Command, error)
    Undefine(name, version string) error
    Activate(name, version string) error
    Deactivate(name string) error
}

Providers:

Provider	Value	Implementation
Database	CommandProviderDatabase	core/manager/database.go
Binary	CommandProviderBinary	core/manager/binary.go
Download	CommandProviderDownload	core/manager/download.go
Doctor	CommandProviderDoctor	core/manager/doctor.go

Initialization Interfaces

Initializer

System initialization tasks⁴:

type Initializer interface {
    Init(isUpgrade bool) error
}

Registered Initializers:

Key	Implementation	Purpose
"binary"	BinaryManager	Create bin/ and shims/ directories
"profile-dir-backup"	FSBackup	Backup profile directory
"profile-dir-export"	EmbedFSExporter	Export embedded profile scripts
"profile-dir-render"	DirRender	Render profile templates
"profile-injector"	ProfileInjector	Inject source line into shell profile
"database"	DatabaseInitializer	Initialize database schema
"command"	CommandInitializer	Register cmdr as managed command

Download Interfaces

Fetcher

File download abstraction⁵:

type Fetcher interface {
    Fetch(source, destination string) error
}

Implementations:

• GoGetterFetcher - Uses HashiCorp go-getter for flexible downloads
• GoFetcher - Specialized for Go module downloads

DownloadStrategy

Strategy for URL transformationand retry logic:

type DownloadStrategy interface {
    Name() string
    Prepare(uri string) (string, error)
    ShouldRetry(err error) bool
    ShouldFallback(err error) bool
    Configure(cfg Configuration) error
    IsEnabled(uri string) bool
    SetEnabled(enabled bool)
}

Implementations:

• DirectStrategy - Direct downloads
• ProxyStrategy - HTTP/SOCKS5 proxy
• RewriteStrategy - URL rewriting
• ChainStrategy - Chain of strategies with retry/fallback

Configuration Interface

Configuration

Type alias for Viper configuration⁶:

type Configuration = *viper.Viper

Common Methods:

// Get values
GetString(key string) string
GetInt(key string) int
GetBool(key string) bool
GetStringSlice(key string) []string

// Set values
Set(key string, value interface{})
SetDefault(key string, value interface{})

// Check existence
IsSet(key string) bool

// Bind flags
BindPFlag(key string, flag *pflag.Flag) error

Database Interface

Database

Abstraction over Storm/BoltDB⁷:

type Database interface {
    Init() error
    Close() error

    Save(data interface{}) error
    Select(matchers ...q.Matcher) Query
    DeleteStruct(data interface{}) error
}

Used By: DatabaseManager for persisting command metadata.

CMDR Searcher Interface

CmdrSearcher

Search for CMDR releases (for self-upgrade)⁸:

type CmdrSearcher interface {
    GetReleaseAsset(ctx context.Context, releaseName, assetName string) (CmdrReleaseAsset, error)
}

type CmdrReleaseAsset struct {
    Name    string  // Release name
    Version string  // Version string
    Asset   string  // Asset name
    Url     string  // Download URL
}

Providers:

Provider	Source
CmdrSearcherProviderApi	GitHub API
CmdrSearcherProviderAtom	GitHub Atom feed

Logger Interface

CMDR uses logur for logging:

type Logger interface {
    Trace(msg string, fields ...map[string]interface{})
    Debug(msg string, fields ...map[string]interface{})
    Info(msg string, fields ...map[string]interface{})
    Warn(msg string, fields ...map[string]interface{})
    Error(msg string, fields ...map[string]interface{})
}

Usage:

logger := core.GetLogger()
logger.Info("command installed", map[string]interface{}{
    "name": "kubectl",
    "version": "1.28.0",
})

Event Bus

Simple publish-subscribe for lifecycle events:

func PublishEvent(event string)
func SubscribeEvent(event string, handler func())

Events:

• EventExit - Application exit

Usage:

// Subscribe
core.SubscribeEvent(core.EventExit, func() {
    // Cleanup
})

// Publish
defer core.PublishEvent(core.EventExit)

---

---

1. Command interface in core/command.go L18-L23 ↩

2. CommandQuery interface in core/command.go L25-L34 ↩

3. CommandManager interface in core/command.go L36-L47 ↩

4. Initializer interface in core/initializer.go L5-L7 ↩

5. Fetcher interface in core/fetcher.go ↩

6. Configuration type in core/config.go L7 ↩

7. Database interface in core/database.go ↩

8. CmdrSearcher interface in core/cmdr.go L18-L20 ↩