[duplicate-code] Duplicate Code Pattern: Verbose Error Logging Blocks

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🔍 Duplicate Code Pattern: Duplicated Error Logging Blocks

Part of duplicate code analysis: #555

Summary

Throughout the codebase, particularly in internal/launcher/launcher.go, there are multiple instances of verbose, multi-line log.Printf("[PREFIX]") blocks for error diagnostics and warnings. These blocks follow the same pattern of prefixing messages with [LAUNCHER], [DIFC], or other tags, resulting in significant code duplication.

Duplication Details

Pattern: Multi-line Prefixed Log Blocks

• Severity: High
• Occurrences: 50+ instances across the codebase
• Primary Location: internal/launcher/launcher.go (30+ instances)
• Secondary Locations: internal/server/unified.go, internal/difc/*.go, internal/cmd/root.go

Code Sample - Launcher Error Diagnostics

Example 1: Server Launch Failure (appears 2x in launcher.go)

// Lines 193-213 and 339-347
log.Printf("[LAUNCHER] ❌ FAILED to launch server '%s'", serverID)
log.Printf("[LAUNCHER] Error: %v", err)
log.Printf("[LAUNCHER] Debug Information:")
log.Printf("[LAUNCHER]   - Command: %s", serverCfg.Command)
log.Printf("[LAUNCHER]   - Args: %v", serverCfg.Args)
log.Printf("[LAUNCHER]   - Env vars: %v", sanitize.TruncateSecretMap(serverCfg.Env))
log.Printf("[LAUNCHER]   - Running in container: %v", l.runningInContainer)
log.Printf("[LAUNCHER]   - Is direct command: %v", isDirectCommand)
log.Printf("[LAUNCHER]   - Startup timeout: %v", l.startupTimeout)

Example 2: Security Warning (appears 2x in launcher.go)

// Lines 132-134 and 284-286
log.Printf("[LAUNCHER] ⚠️  WARNING: Server '%s' uses direct command execution inside a container", serverID)
log.Printf("[LAUNCHER] ⚠️  Security Notice: Command '%s' will execute with the same privileges as the gateway", serverCfg.Command)
log.Printf("[LAUNCHER] ⚠️  Consider using 'container' field instead for better isolation")

Example 3: Startup Commands (appears 2x in launcher.go)

// Lines 139-141 and 291-293
log.Printf("[LAUNCHER] Starting MCP server: %s", serverID)
log.Printf("[LAUNCHER] Command: %s", serverCfg.Command)
log.Printf("[LAUNCHER] Args: %v", sanitize.SanitizeArgs(serverCfg.Args))

Example 4: Timeout Error (appears 2x in launcher.go)

// Lines 228-230 and 366-368
log.Printf("[LAUNCHER] ❌ Server startup timed out after %v", l.startupTimeout)
log.Printf("[LAUNCHER] ⚠️  The server may be hanging or taking too long to initialize")
log.Printf("[LAUNCHER] ⚠️  Consider increasing 'startupTimeout' in gateway config if server needs more time")

Other Affected Areas

DIFC Logging in internal/server/unified.go:

// Multiple instances of DIFC prefix blocks
log.Printf("[DIFC] Agent %s | Secrecy: %v | Integrity: %v", agentID, ...)
log.Printf("[DIFC] Resource: %s | Operation: %s | Secrecy: %v | Integrity: %v", ...)
log.Printf("[DIFC] Access DENIED for agent %s to %s: %s", ...)

Agent Registry in internal/difc/agent.go:

// Multiple instances of DIFC tag logging
log.Printf("[DIFC] Agent %s gained secrecy tag: %s", a.AgentID, tag)
log.Printf("[DIFC] Agent %s gained integrity tag: %s", a.AgentID, tag)
log.Printf("[DIFC] Agent %s accumulated secrecy tags from read: %v", ...)

Impact Analysis

• Maintainability: When log format changes are needed (e.g., JSON logging, structured logging), updates are required in 50+ locations
• Code Bloat: Verbose multi-line blocks make functions significantly longer and harder to read
• Inconsistency Risk: Different developers may format similar log messages differently
• Testing Overhead: Each log block is difficult to mock or test independently
• Performance: Multiple log.Printf calls have overhead compared to single structured log call

Refactoring Recommendations

1. Create Structured Logging Helpers in launcher package

Extract common logging patterns into helper methods:

// internal/launcher/log_helpers.go

// logLaunchStart logs server launch initiation
func (l *Launcher) logLaunchStart(serverID string, cfg *config.ServerConfig, sessionID string) {
    if sessionID != "" {
        log.Printf("[LAUNCHER] Starting MCP server for session: %s (session: %s)", serverID, sessionID)
    } else {
        log.Printf("[LAUNCHER] Starting MCP server: %s", serverID)
    }
    log.Printf("[LAUNCHER] Command: %s", cfg.Command)
    log.Printf("[LAUNCHER] Args: %v", sanitize.SanitizeArgs(cfg.Args))
}

// logLaunchError logs detailed launch failure diagnostics
func (l *Launcher) logLaunchError(serverID, sessionID string, err error, cfg *config.ServerConfig, isDirectCommand bool) {
    log.Printf("[LAUNCHER] ❌ FAILED to launch server '%s'%s", serverID, sessionSuffix(sessionID))
    log.Printf("[LAUNCHER] Error: %v", err)
    log.Printf("[LAUNCHER] Debug Information:")
    log.Printf("[LAUNCHER]   - Command: %s", cfg.Command)
    log.Printf("[LAUNCHER]   - Args: %v", cfg.Args)
    log.Printf("[LAUNCHER]   - Env vars: %v", sanitize.TruncateSecretMap(cfg.Env))
    log.Printf("[LAUNCHER]   - Running in container: %v", l.runningInContainer)
    log.Printf("[LAUNCHER]   - Is direct command: %v", isDirectCommand)
    log.Printf("[LAUNCHER]   - Startup timeout: %v", l.startupTimeout)
    
    l.logPossibleCauses(isDirectCommand, cfg.Command)
}

// logSecurityWarning logs container security warnings
func (l *Launcher) logSecurityWarning(serverID string, command string) {
    log.Printf("[LAUNCHER] ⚠️  WARNING: Server '%s' uses direct command execution inside a container", serverID)
    log.Printf("[LAUNCHER] ⚠️  Security Notice: Command '%s' will execute with the same privileges as the gateway", command)
    log.Printf("[LAUNCHER] ⚠️  Consider using 'container' field instead for better isolation")
}

// logTimeoutError logs startup timeout diagnostics
func (l *Launcher) logTimeoutError() {
    log.Printf("[LAUNCHER] ❌ Server startup timed out after %v", l.startupTimeout)
    log.Printf("[LAUNCHER] ⚠️  The server may be hanging or taking too long to initialize")
    log.Printf("[LAUNCHER] ⚠️  Consider increasing 'startupTimeout' in gateway config if server needs more time")
}

func sessionSuffix(sessionID string) string {
    if sessionID == "" {
        return ""
    }
    return fmt.Sprintf(" for session '%s'", sessionID)
}

Usage:

// Before:
log.Printf("[LAUNCHER] Starting MCP server: %s", serverID)
log.Printf("[LAUNCHER] Command: %s", serverCfg.Command)
log.Printf("[LAUNCHER] Args: %v", sanitize.SanitizeArgs(serverCfg.Args))

// After:
l.logLaunchStart(serverID, serverCfg, "")

Estimated effort: 2-3 hours
Benefits:

• Single source of truth for log message format
• Easier to add structured logging later
• Cleaner, more readable launch functions
• Consistent error diagnostics across all launch paths

2. Consider Structured Logging (Future Enhancement)

Instead of formatted strings, use structured fields:

import "log/slog"

// Example structured logging (future work)
slog.Error("server launch failed",
    "server_id", serverID,
    "command", cfg.Command,
    "error", err,
    "in_container", l.runningInContainer,
    "timeout", l.startupTimeout,
)

Estimated effort: 4-6 hours (major refactor)
Benefits:

• Machine-parseable logs
• Better integration with log aggregation tools
• Easier filtering and searching
• Better performance (single log call)

3. Extract DIFC Logging Helpers

Similar pattern for internal/difc and internal/server/unified.go:

// internal/difc/log_helpers.go

func logAgentState(agentID string, secrecy, integrity []Tag) {
    log.Printf("[DIFC] Agent %s | Secrecy: %v | Integrity: %v", agentID, secrecy, integrity)
}

func logResourceAccess(agentID, resource, operation string, allowed bool, reason string) {
    if allowed {
        log.Printf("[DIFC] Access ALLOWED for agent %s to %s", agentID, resource)
    } else {
        log.Printf("[DIFC] Access DENIED for agent %s to %s: %s", agentID, resource, reason)
    }
}

Estimated effort: 1-2 hours
Benefits:

• Consistent DIFC logging format
• Easier to add audit logging later

Implementation Checklist

• Review logging helper approach with team
• Create internal/launcher/log_helpers.go
• Implement launcher logging helper methods
• Refactor GetOrLaunch to use helpers
• Refactor GetOrLaunchForSession to use helpers
• (Optional) Create DIFC logging helpers
• (Optional) Create unified server logging helpers
• Update unit tests if needed
• Run make agent-finished to verify no regressions
• Document logging helper usage in AGENTS.md

Parent Issue

See parent analysis report: #555
Related to #555

AI generated by Duplicate Code Detector