Files
ctrld/cmd/cli/prometheus.go
Cuong Manh Le 4792183c0d Add comprehensive documentation to CLI components and core functionality
This commit extends the documentation effort by adding detailed explanatory
comments to key CLI components and core functionality throughout the cmd/
directory. The changes focus on explaining WHY certain logic is needed,
not just WHAT the code does, improving code maintainability and helping
developers understand complex business decisions.

Key improvements:
- Main entry points: Document CLI initialization, logging setup, and cache
  configuration with reasoning for design decisions
- DNS proxy core: Explain DNS proxy constants, data structures, and core
  processing pipeline for handling DNS queries
- Service management: Document service command structure, configuration
  patterns, and platform-specific service handling
- Logging infrastructure: Explain log buffer management, level encoders,
  and log formatting decisions for different use cases
- Metrics and monitoring: Document Prometheus metrics structure, HTTP
  endpoints, and conditional metric collection for performance
- Network handling: Explain Linux-specific network interface filtering,
  virtual interface detection, and DNS configuration management
- Hostname validation: Document RFC1123 compliance and DNS naming
  standards for system compatibility
- Mobile integration: Explain HTTP retry logic, fallback mechanisms, and
  mobile platform integration patterns
- Connection management: Document connection wrapper design to prevent
  log pollution during process lifecycle

Technical details:
- Added explanatory comments to 11 additional files in cmd/cli/
- Maintained consistent documentation style and format
- Preserved all existing functionality while improving code clarity
- Enhanced understanding of complex business logic and platform-specific
  behavior

These comments help future developers understand the reasoning behind
complex decisions, making the codebase more maintainable and reducing
the risk of incorrect modifications during maintenance.
2025-10-09 17:49:21 +07:00

67 lines
2.6 KiB
Go

package cli
import "github.com/prometheus/client_golang/prometheus"
// Prometheus metrics label constants for consistent labeling across all metrics
// These ensure standardized metric labeling for monitoring and alerting
const (
metricsLabelListener = "listener"
metricsLabelClientSourceIP = "client_source_ip"
metricsLabelClientMac = "client_mac"
metricsLabelClientHostname = "client_hostname"
metricsLabelUpstream = "upstream"
metricsLabelRRType = "rr_type"
metricsLabelRCode = "rcode"
)
// statsVersion represent ctrld version.
// This metric provides version information for monitoring and debugging
var statsVersion = prometheus.NewCounterVec(prometheus.CounterOpts{
Name: "ctrld_build_info",
Help: "Version of ctrld process.",
}, []string{"gitref", "goversion", "version"})
// statsTimeStart represents start time of ctrld service.
// This metric tracks service uptime and helps with monitoring service restarts
var statsTimeStart = prometheus.NewGauge(prometheus.GaugeOpts{
Name: "ctrld_time_seconds",
Help: "Start time of the ctrld process since unix epoch in seconds.",
})
// statsQueriesCountLabels defines the labels for query count metrics
// These labels provide detailed breakdown of DNS query statistics
var statsQueriesCountLabels = []string{
metricsLabelListener,
metricsLabelClientSourceIP,
metricsLabelClientMac,
metricsLabelClientHostname,
metricsLabelUpstream,
metricsLabelRRType,
metricsLabelRCode,
}
// statsQueriesCount counts total number of queries.
// This provides comprehensive DNS query statistics for monitoring and alerting
var statsQueriesCount = prometheus.NewCounterVec(prometheus.CounterOpts{
Name: "ctrld_queries_count",
Help: "Total number of queries.",
}, statsQueriesCountLabels)
// statsClientQueriesCount counts total number of queries of a client.
//
// The labels "client_source_ip", "client_mac", "client_hostname" are unbounded,
// thus this stat is highly inefficient if there are many devices.
// This metric should be used carefully in high-client environments
var statsClientQueriesCount = prometheus.NewCounterVec(prometheus.CounterOpts{
Name: "ctrld_client_queries_count",
Help: "Total number queries of a client.",
}, []string{metricsLabelClientSourceIP, metricsLabelClientMac, metricsLabelClientHostname})
// WithLabelValuesInc increases prometheus counter by 1 if query stats is enabled.
// This provides conditional metric collection to avoid performance impact when metrics are disabled
func (p *prog) WithLabelValuesInc(c *prometheus.CounterVec, lvs ...string) {
if p.metricsQueryStats.Load() {
c.WithLabelValues(lvs...).Inc()
}
}