logging: Add support for additional logger filters other than hostname (#6082)

Co-authored-by: Francis Lavoie <lavofr@gmail.com>

caddyconfig/httpcaddyfile/builtins.go

@@ -51,6 +51,7 @@ func init() {
 	RegisterDirective("log", parseLog)
 	RegisterHandlerDirective("skip_log", parseLogSkip)
 	RegisterHandlerDirective("log_skip", parseLogSkip)
+	RegisterHandlerDirective("log_name", parseLogName)
 }
 
 // parseBind parses the bind directive. Syntax:
@@ -914,7 +915,7 @@ func parseLogHelper(h Helper, globalLogNames map[string]struct{}) ([]ConfigValue
 	// this is useful for setting up loggers per subdomain in a site block
 	// with a wildcard domain
 	customHostnames := []string{}
-
+	noHostname := false
 	for h.NextBlock(0) {
 		switch h.Val() {
 		case "hostnames":
@@ -1000,6 +1001,12 @@ func parseLogHelper(h Helper, globalLogNames map[string]struct{}) ([]ConfigValue
 				cl.Exclude = append(cl.Exclude, h.Val())
 			}
 
+		case "no_hostname":
+			if h.NextArg() {
+				return nil, h.ArgErr()
+			}
+			noHostname = true
+
 		default:
 			return nil, h.Errf("unrecognized subdirective: %s", h.Val())
 		}
@@ -1007,7 +1014,7 @@ func parseLogHelper(h Helper, globalLogNames map[string]struct{}) ([]ConfigValue
 
 	var val namedCustomLog
 	val.hostnames = customHostnames
-
+	val.noHostname = noHostname
 	isEmptyConfig := reflect.DeepEqual(cl, new(caddy.CustomLog))
 
 	// Skip handling of empty logging configs
@@ -1058,3 +1065,13 @@ func parseLogSkip(h Helper) (caddyhttp.MiddlewareHandler, error) {
 	}
 	return caddyhttp.VarsMiddleware{"log_skip": true}, nil
 }
+
+// parseLogName parses the log_name directive. Syntax:
+//
+//	log_name <names...>
+func parseLogName(h Helper) (caddyhttp.MiddlewareHandler, error) {
+	h.Next() // consume directive name
+	return caddyhttp.VarsMiddleware{
+		caddyhttp.AccessLoggerNameVarKey: h.RemainingArgs(),
+	}, nil
+}

caddyconfig/httpcaddyfile/directives.go

@@ -53,6 +53,7 @@ var defaultDirectiveOrder = []string{
 	"log_append",
 	"skip_log", // TODO: deprecated, renamed to log_skip
 	"log_skip",
+	"log_name",
 
 	"header",
 	"copy_response_headers", // only in reverse_proxy's handle_response

caddyconfig/httpcaddyfile/httptype.go

@@ -797,6 +797,15 @@ func (st *ServerType) serversFromPairings(
 			sblockLogHosts := sblock.hostsFromKeys(true)
 			for _, cval := range sblock.pile["custom_log"] {
 				ncl := cval.Value.(namedCustomLog)
+
+				// if `no_hostname` is set, then this logger will not
+				// be associated with any of the site block's hostnames,
+				// and only be usable via the `log_name` directive
+				// or the `access_logger_names` variable
+				if ncl.noHostname {
+					continue
+				}
+
 				if sblock.hasHostCatchAllKey() && len(ncl.hostnames) == 0 {
 					// all requests for hosts not able to be listed should use
 					// this log because it's a catch-all-hosts server block
@@ -1598,9 +1607,10 @@ func (c counter) nextGroup() string {
 }
 
 type namedCustomLog struct {
-	name      string
-	hostnames []string
-	log       *caddy.CustomLog
+	name       string
+	hostnames  []string
+	log        *caddy.CustomLog
+	noHostname bool
 }
 
 // sbAddrAssociation is a mapping from a list of

caddytest/integration/caddyfile_adapt/log_filter_with_header.txt

@@ -0,0 +1,151 @@
+localhost {
+	log {
+		output file ./caddy.access.log
+	}
+	log health_check_log {
+		output file ./caddy.access.health.log
+		no_hostname
+	}
+	log general_log {
+		output file ./caddy.access.general.log
+		no_hostname
+	}
+	@healthCheck `header_regexp('User-Agent', '^some-regexp$') || path('/healthz*')`
+	handle @healthCheck {
+		log_name health_check_log general_log
+		respond "Healthy"
+	}
+
+	handle {
+		respond "Hello World"
+	}
+}
+----------
+{
+	"logging": {
+		"logs": {
+			"default": {
+				"exclude": [
+					"http.log.access.general_log",
+					"http.log.access.health_check_log",
+					"http.log.access.log0"
+				]
+			},
+			"general_log": {
+				"writer": {
+					"filename": "./caddy.access.general.log",
+					"output": "file"
+				},
+				"include": [
+					"http.log.access.general_log"
+				]
+			},
+			"health_check_log": {
+				"writer": {
+					"filename": "./caddy.access.health.log",
+					"output": "file"
+				},
+				"include": [
+					"http.log.access.health_check_log"
+				]
+			},
+			"log0": {
+				"writer": {
+					"filename": "./caddy.access.log",
+					"output": "file"
+				},
+				"include": [
+					"http.log.access.log0"
+				]
+			}
+		}
+	},
+	"apps": {
+		"http": {
+			"servers": {
+				"srv0": {
+					"listen": [
+						":443"
+					],
+					"routes": [
+						{
+							"match": [
+								{
+									"host": [
+										"localhost"
+									]
+								}
+							],
+							"handle": [
+								{
+									"handler": "subroute",
+									"routes": [
+										{
+											"group": "group2",
+											"handle": [
+												{
+													"handler": "subroute",
+													"routes": [
+														{
+															"handle": [
+																{
+																	"access_logger_names": [
+																		"health_check_log",
+																		"general_log"
+																	],
+																	"handler": "vars"
+																},
+																{
+																	"body": "Healthy",
+																	"handler": "static_response"
+																}
+															]
+														}
+													]
+												}
+											],
+											"match": [
+												{
+													"expression": {
+														"expr": "header_regexp('User-Agent', '^some-regexp$') || path('/healthz*')",
+														"name": "healthCheck"
+													}
+												}
+											]
+										},
+										{
+											"group": "group2",
+											"handle": [
+												{
+													"handler": "subroute",
+													"routes": [
+														{
+															"handle": [
+																{
+																	"body": "Hello World",
+																	"handler": "static_response"
+																}
+															]
+														}
+													]
+												}
+											]
+										}
+									]
+								}
+							],
+							"terminal": true
+						}
+					],
+					"logs": {
+						"logger_names": {
+							"localhost": [
+								"log0"
+							]
+						}
+					}
+				}
+			}
+		}
+	}
+}

modules/caddyhttp/logging.go

@@ -69,15 +69,35 @@ type ServerLogConfig struct {
 
 // wrapLogger wraps logger in one or more logger named
 // according to user preferences for the given host.
-func (slc ServerLogConfig) wrapLogger(logger *zap.Logger, host string) []*zap.Logger {
-	// logger config should always be only
-	// the hostname, without the port
-	hostWithoutPort, _, err := net.SplitHostPort(host)
-	if err != nil {
-		hostWithoutPort = host
+func (slc ServerLogConfig) wrapLogger(logger *zap.Logger, req *http.Request) []*zap.Logger {
+	// using the `log_name` directive or the `access_logger_names` variable,
+	// the logger names can be overridden for the current request
+	if names := GetVar(req.Context(), AccessLoggerNameVarKey); names != nil {
+		if namesSlice, ok := names.([]any); ok {
+			loggers := make([]*zap.Logger, 0, len(namesSlice))
+			for _, loggerName := range namesSlice {
+				// no name, use the default logger
+				if loggerName == "" {
+					loggers = append(loggers, logger)
+					continue
+				}
+				// make a logger with the given name
+				loggers = append(loggers, logger.Named(loggerName.(string)))
+			}
+			return loggers
+		}
 	}
 
-	hosts := slc.getLoggerHosts(hostWithoutPort)
+	// get the hostname from the request, with the port number stripped
+	host, _, err := net.SplitHostPort(req.Host)
+	if err != nil {
+		host = req.Host
+	}
+
+	// get the logger names for this host from the config
+	hosts := slc.getLoggerHosts(host)
+
+	// make a list of named loggers, or the default logger
 	loggers := make([]*zap.Logger, 0, len(hosts))
 	for _, loggerName := range hosts {
 		// no name, use the default logger
@@ -85,6 +105,7 @@ func (slc ServerLogConfig) wrapLogger(logger *zap.Logger, host string) []*zap.Lo
 			loggers = append(loggers, logger)
 			continue
 		}
+		// make a logger with the given name
 		loggers = append(loggers, logger.Named(loggerName))
 	}
 	return loggers
@@ -211,4 +232,7 @@ const (
 
 	// For adding additional fields to the access logs
 	ExtraLogFieldsCtxKey caddy.CtxKey = "extra_log_fields"
+
+	// Variable name used to indicate the logger to be used
+	AccessLoggerNameVarKey string = "access_logger_names"
 )

modules/caddyhttp/server.go

@@ -369,7 +369,7 @@ func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	errLog = errLog.With(zap.Duration("duration", duration))
 	errLoggers := []*zap.Logger{errLog}
 	if s.Logs != nil {
-		errLoggers = s.Logs.wrapLogger(errLog, r.Host)
+		errLoggers = s.Logs.wrapLogger(errLog, r)
 	}
 
 	// get the values that will be used to log the error
@@ -778,7 +778,7 @@ func (s *Server) logRequest(
 
 	loggers := []*zap.Logger{accLog}
 	if s.Logs != nil {
-		loggers = s.Logs.wrapLogger(accLog, r.Host)
+		loggers = s.Logs.wrapLogger(accLog, r)
 	}
 
 	// wrapping may return multiple loggers, so we log to all of them
@@ -835,7 +835,6 @@ func PrepareRequest(r *http.Request, repl *caddy.Replacer, w http.ResponseWriter
 	ctx = context.WithValue(ctx, OriginalRequestCtxKey, originalRequest(r, &url2))
 
 	ctx = context.WithValue(ctx, ExtraLogFieldsCtxKey, new(ExtraLogFields))
-
 	r = r.WithContext(ctx)
 
 	// once the pointer to the request won't change