log

README

log

log enables request logging. The request log is also known in some vernacular as an access log.

Syntax

log

• With no arguments, a query log entry is written to query.log in the common log format for all requests (base name = .).

log file

• file is the log file to create (or append to). The base path is assumed to be . .

log name file [format]

• name is the base name to match in order to be logged
• file is the log file to create (or append to)
• format is the log format to use (default is Common Log Format)

Log File

The log file can be any filename. It could also be stdout or stderr to write the log to the console, or syslog to write to the system log (except on Windows). If the log file does not exist beforehand, CoreDNS will create it before appending to it.

Log Format

You can specify a custom log format with any placeholder values. Log supports both request and response placeholders.

The following place holders are supported:

• {type}: qtype of the request.
• {name}: qname of the request.
• {class}: qclass of the request.
• {proto}: protocol used (tcp or udp).
• {when}: time of the query.
• {remote}: client's IP address.
• {port}: client's port.
• {rcode}: response RCODE.
• {size}: response size.
• {duration}: response duration.
• {>bufsize}: the EDNS0 buffer size advertized by the client.
• {>do}: is the EDNS0 DO (DNSSEC OK) bit set.
• {>id}: query ID
• {>opcode}: query OPCODE

Examples

Log all requests to a file:

log /var/log/query.log

Custom log format:

log . ../query.log "{proto} Request: {name} {type} {>id}"

Documentation

Overview

Package log implements basic but useful request (access) logging middleware.

Index

• Constants
• type Logger
  • func (l Logger) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error)
• type Rule

Constants

const (
	// DefaultLogFilename is the default log filename.
	DefaultLogFilename = "query.log"
	// CommonLogFormat is the common log format.
	CommonLogFormat = `{remote} ` + CommonLogEmptyValue + ` [{when}] "{type} {class} {name} {proto} {>do} {>bufsize}" {rcode} {size} {duration}`
	// CommonLogEmptyValue is the common empty log value.
	CommonLogEmptyValue = "-"
	// CombinedLogFormat is the combined log format.
	CombinedLogFormat = CommonLogFormat + ` "{>opcode}"`
	// DefaultLogFormat is the default log format.
	DefaultLogFormat = CommonLogFormat
)

Types

type Logger

type Logger struct {
	Next      middleware.Handler
	Rules     []Rule
	ErrorFunc func(dns.ResponseWriter, *dns.Msg, int) // failover error handler
}

Logger is a basic request logging middleware.

func (Logger) ServeDNS

func (l Logger) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error)

ServeDNS implements the middleware.Handler interface.

type Rule

type Rule struct {
	NameScope  string
	OutputFile string
	Format     string
	Log        *log.Logger
}

Rule configures the logging middleware.