[feature] Make log format configurable (#2130)

* [feature] Don't emit timestamp in log lines

When running gotosocial with a service manager like systemd, or a
container runtime, the associated log driver usually emits timestamps
itself. In those cases, having the extra timestamp from our own log
lines ends up being a bit noisy and when centrally ingesting logs is
duplicate information.

This introduces a configuration flag that allows disabling emitting the
timestamp. It's only wired up for "daemonised" processes, meaning server
and testrig.

* [chore] Add docs for log-timestamp

* [feature] Simplify timestamp handling

Co-Authored-By: kim <89579420+NyaaaWhatsUpDoc@users.noreply.github.com>

* [chore] Less escaped double-quotes

* [chore] Fix help string

---------

Co-authored-by: kim <89579420+NyaaaWhatsUpDoc@users.noreply.github.com>

12 files changed, 128 insertions, 47 deletions

diff --git a/cmd/gotosocial/common.go b/cmd/gotosocial/common.go
index b797e6590..baf8a15b5 100644
--- a/cmd/gotosocial/common.go
+++ b/cmd/gotosocial/common.go
@@ -63,6 +63,7 @@ func preRun(a preRunArgs) error {
 // The idea here is to take a GTSAction and run it with the given
 // context, after initializing any last-minute things like loggers etc.
 func run(ctx context.Context, action action.GTSAction) error {
+	log.SetTimeFormat(config.GetLogTimestampFormat())
 	// Set the global log level from configuration
 	if err := log.ParseLevel(config.GetLogLevel()); err != nil {
 		return fmt.Errorf("error parsing log level: %w", err)
diff --git a/docs/configuration/general.md b/docs/configuration/general.md
index 285852afe..8ae2ec4f7 100644
--- a/docs/configuration/general.md
+++ b/docs/configuration/general.md
@@ -28,6 +28,17 @@ log-db-queries: false
 # Default: true
 log-client-ip: true
 
+# String. Format to use for the timestamp in log lines.
+# If set to the empty string, the timestamp will be
+# ommitted from the logs entirely.
+#
+# The format must be compatible with Go's time.Layout, as
+# documented on https://pkg.go.dev/time#pkg-constants.
+#
+# Examples: [true, false]
+# Default: "02/01/2006 15:04:05.000"
+log-timestamp-format: "02/01/2006 15:04:05.000"
+
 # String. Application name to use internally.
 # Examples: ["My Application","gotosocial"]
 # Default: "gotosocial"
diff --git a/example/config.yaml b/example/config.yaml
index d3a6102bd..bc8e3d7c1 100644
--- a/example/config.yaml
+++ b/example/config.yaml
@@ -35,6 +35,17 @@ log-db-queries: false
 # Default: true
 log-client-ip: true
 
+# String. Format to use for the timestamp in log lines.
+# If set to the empty string, the timestamp will be
+# ommitted from the logs entirely.
+#
+# The format must be compatible with Go's time.Layout, as
+# documented on https://pkg.go.dev/time#pkg-constants.
+#
+# Examples: [true, false]
+# Default: "02/01/2006 15:04:05.000"
+log-timestamp-format: "02/01/2006 15:04:05.000"
+
 # String. Application name to use internally.
 # Examples: ["My Application","gotosocial"]
 # Default: "gotosocial"
diff --git a/internal/config/config.go b/internal/config/config.go
index f1a5bf6e5..86f6b00dd 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -44,19 +44,20 @@ func fieldtag(field, tag string) string {
 // will need to regenerate the global Getter/Setter helpers by running:
 // `go run ./internal/config/gen/ -out ./internal/config/helpers.gen.go`
 type Configuration struct {
-	LogLevel        string   `name:"log-level" usage:"Log level to run at: [trace, debug, info, warn, fatal]"`
-	LogDbQueries    bool     `name:"log-db-queries" usage:"Log database queries verbosely when log-level is trace or debug"`
-	LogClientIP     bool     `name:"log-client-ip" usage:"Include the client IP in logs"`
-	ApplicationName string   `name:"application-name" usage:"Name of the application, used in various places internally"`
-	LandingPageUser string   `name:"landing-page-user" usage:"the user that should be shown on the instance's landing page"`
-	ConfigPath      string   `name:"config-path" usage:"Path to a file containing gotosocial configuration. Values set in this file will be overwritten by values set as env vars or arguments"`
-	Host            string   `name:"host" usage:"Hostname to use for the server (eg., example.org, gotosocial.whatever.com). DO NOT change this on a server that's already run!"`
-	AccountDomain   string   `name:"account-domain" usage:"Domain to use in account names (eg., example.org, whatever.com). If not set, will default to the setting for host. DO NOT change this on a server that's already run!"`
-	Protocol        string   `name:"protocol" usage:"Protocol to use for the REST api of the server (only use http if you are debugging or behind a reverse proxy!)"`
-	BindAddress     string   `name:"bind-address" usage:"Bind address to use for the GoToSocial server (eg., 0.0.0.0, 172.138.0.9, [::], localhost). For ipv6, enclose the address in square brackets, eg [2001:db8::fed1]. Default binds to all interfaces."`
-	Port            int      `name:"port" usage:"Port to use for GoToSocial. Change this to 443 if you're running the binary directly on the host machine."`
-	TrustedProxies  []string `name:"trusted-proxies" usage:"Proxies to trust when parsing x-forwarded headers into real IPs."`
-	SoftwareVersion string   `name:"software-version" usage:""`
+	LogLevel           string   `name:"log-level" usage:"Log level to run at: [trace, debug, info, warn, fatal]"`
+	LogTimestampFormat string   `name:"log-timestamp-format" usage:"Format to use for the log timestamp, as supported by Go's time.Layout"`
+	LogDbQueries       bool     `name:"log-db-queries" usage:"Log database queries verbosely when log-level is trace or debug"`
+	LogClientIP        bool     `name:"log-client-ip" usage:"Include the client IP in logs"`
+	ApplicationName    string   `name:"application-name" usage:"Name of the application, used in various places internally"`
+	LandingPageUser    string   `name:"landing-page-user" usage:"the user that should be shown on the instance's landing page"`
+	ConfigPath         string   `name:"config-path" usage:"Path to a file containing gotosocial configuration. Values set in this file will be overwritten by values set as env vars or arguments"`
+	Host               string   `name:"host" usage:"Hostname to use for the server (eg., example.org, gotosocial.whatever.com). DO NOT change this on a server that's already run!"`
+	AccountDomain      string   `name:"account-domain" usage:"Domain to use in account names (eg., example.org, whatever.com). If not set, will default to the setting for host. DO NOT change this on a server that's already run!"`
+	Protocol           string   `name:"protocol" usage:"Protocol to use for the REST api of the server (only use http if you are debugging or behind a reverse proxy!)"`
+	BindAddress        string   `name:"bind-address" usage:"Bind address to use for the GoToSocial server (eg., 0.0.0.0, 172.138.0.9, [::], localhost). For ipv6, enclose the address in square brackets, eg [2001:db8::fed1]. Default binds to all interfaces."`
+	Port               int      `name:"port" usage:"Port to use for GoToSocial. Change this to 443 if you're running the binary directly on the host machine."`
+	TrustedProxies     []string `name:"trusted-proxies" usage:"Proxies to trust when parsing x-forwarded headers into real IPs."`
+	SoftwareVersion    string   `name:"software-version" usage:""`
 
 	DbType                   string        `name:"db-type" usage:"Database type: eg., postgres"`
 	DbAddress                string        `name:"db-address" usage:"Database ipv4 address, hostname, or filename"`
diff --git a/internal/config/defaults.go b/internal/config/defaults.go
index 61a037157..3703d8372 100644
--- a/internal/config/defaults.go
+++ b/internal/config/defaults.go
@@ -27,17 +27,18 @@ import (
 // Defaults contains a populated Configuration with reasonable defaults. Note that
 // if you use this, you will still need to set Host, and, if desired, ConfigPath.
 var Defaults = Configuration{
-	LogLevel:        "info",
-	LogDbQueries:    false,
-	ApplicationName: "gotosocial",
-	LandingPageUser: "",
-	ConfigPath:      "",
-	Host:            "",
-	AccountDomain:   "",
-	Protocol:        "https",
-	BindAddress:     "0.0.0.0",
-	Port:            8080,
-	TrustedProxies:  []string{"127.0.0.1/32", "::1"}, // localhost
+	LogLevel:           "info",
+	LogTimestampFormat: "02/01/2006 15:04:05.000",
+	LogDbQueries:       false,
+	ApplicationName:    "gotosocial",
+	LandingPageUser:    "",
+	ConfigPath:         "",
+	Host:               "",
+	AccountDomain:      "",
+	Protocol:           "https",
+	BindAddress:        "0.0.0.0",
+	Port:               8080,
+	TrustedProxies:     []string{"127.0.0.1/32", "::1"}, // localhost
 
 	DbType:                   "postgres",
 	DbAddress:                "",
diff --git a/internal/config/flags.go b/internal/config/flags.go
index 386e47293..927f4ddfb 100644
--- a/internal/config/flags.go
+++ b/internal/config/flags.go
@@ -38,6 +38,7 @@ func (s *ConfigState) AddGlobalFlags(cmd *cobra.Command) {
 		cmd.PersistentFlags().String(AccountDomainFlag(), cfg.AccountDomain, fieldtag("AccountDomain", "usage"))
 		cmd.PersistentFlags().String(ProtocolFlag(), cfg.Protocol, fieldtag("Protocol", "usage"))
 		cmd.PersistentFlags().String(LogLevelFlag(), cfg.LogLevel, fieldtag("LogLevel", "usage"))
+		cmd.PersistentFlags().String(LogTimestampFormatFlag(), cfg.LogTimestampFormat, fieldtag("LogTimestampFormat", "usage"))
 		cmd.PersistentFlags().Bool(LogDbQueriesFlag(), cfg.LogDbQueries, fieldtag("LogDbQueries", "usage"))
 		cmd.PersistentFlags().String(ConfigPathFlag(), cfg.ConfigPath, fieldtag("ConfigPath", "usage"))
 
diff --git a/internal/config/helpers.gen.go b/internal/config/helpers.gen.go
index aed111129..ab7d38a8a 100644
--- a/internal/config/helpers.gen.go
+++ b/internal/config/helpers.gen.go
@@ -49,6 +49,31 @@ func GetLogLevel() string { return global.GetLogLevel() }
 // SetLogLevel safely sets the value for global configuration 'LogLevel' field
 func SetLogLevel(v string) { global.SetLogLevel(v) }
 
+// GetLogTimestampFormat safely fetches the Configuration value for state's 'LogTimestampFormat' field
+func (st *ConfigState) GetLogTimestampFormat() (v string) {
+	st.mutex.RLock()
+	v = st.config.LogTimestampFormat
+	st.mutex.RUnlock()
+	return
+}
+
+// SetLogTimestampFormat safely sets the Configuration value for state's 'LogTimestampFormat' field
+func (st *ConfigState) SetLogTimestampFormat(v string) {
+	st.mutex.Lock()
+	defer st.mutex.Unlock()
+	st.config.LogTimestampFormat = v
+	st.reloadToViper()
+}
+
+// LogTimestampFormatFlag returns the flag name for the 'LogTimestampFormat' field
+func LogTimestampFormatFlag() string { return "log-timestamp-format" }
+
+// GetLogTimestampFormat safely fetches the value for global configuration 'LogTimestampFormat' field
+func GetLogTimestampFormat() string { return global.GetLogTimestampFormat() }
+
+// SetLogTimestampFormat safely sets the value for global configuration 'LogTimestampFormat' field
+func SetLogTimestampFormat(v string) { global.SetLogTimestampFormat(v) }
+
 // GetLogDbQueries safely fetches the Configuration value for state's 'LogDbQueries' field
 func (st *ConfigState) GetLogDbQueries() (v bool) {
 	st.mutex.RLock()
diff --git a/internal/log/log.go b/internal/log/log.go
index ae8607fc3..15c917757 100644
--- a/internal/log/log.go
+++ b/internal/log/log.go
@@ -23,7 +23,6 @@ import (
 	"log/syslog"
 	"os"
 	"strings"
-	"sync/atomic"
 	"syscall"
 	"time"
 
@@ -33,7 +32,7 @@ import (
 
 var (
 	// loglvl is the currently set logging level.
-	loglvl atomic.Uint32
+	loglvl level.LEVEL
 
 	// lvlstrs is the lookup table of log levels to strings.
 	lvlstrs = level.Default()
@@ -41,8 +40,9 @@ var (
 	// syslog output, only set if enabled.
 	sysout *syslog.Writer
 
-	// timefmt is the logging time format used.
-	timefmt = "02/01/2006 15:04:05.000"
+	// timefmt is the logging time format used, which includes
+	// the full field and required quoting
+	timefmt = `timestamp="02/01/2006 15:04:05.000" `
 
 	// ctxhooks allows modifying log content based on context.
 	ctxhooks []func(context.Context, []kv.Field) []kv.Field
@@ -55,12 +55,26 @@ func Hook(hook func(ctx context.Context, kvs []kv.Field) []kv.Field) {
 
 // Level returns the currently set log level.
 func Level() level.LEVEL {
-	return level.LEVEL(loglvl.Load())
+	return loglvl
 }
 
 // SetLevel sets the max logging level.
 func SetLevel(lvl level.LEVEL) {
-	loglvl.Store(uint32(lvl))
+	loglvl = lvl
+}
+
+// TimeFormat returns the currently-set timestamp format.
+func TimeFormat() string {
+	return timefmt
+}
+
+// SetTimeFormat sets the timestamp format to the given string.
+func SetTimeFormat(format string) {
+	if format == "" {
+		timefmt = format
+		return
+	}
+	timefmt = `timestamp="` + format + `" `
 }
 
 // New starts a new log entry.
@@ -164,10 +178,8 @@ func printf(depth int, fields []kv.Field, s string, a ...interface{}) {
 	// Acquire buffer
 	buf := getBuf()
 
-	// Append formatted timestamp
-	buf.B = append(buf.B, `timestamp="`...)
+	// Append formatted timestamp according to `timefmt`
 	buf.B = time.Now().AppendFormat(buf.B, timefmt)
-	buf.B = append(buf.B, `" `...)
 
 	// Append formatted caller func
 	buf.B = append(buf.B, `func=`...)
@@ -217,10 +229,8 @@ func logf(ctx context.Context, depth int, lvl level.LEVEL, fields []kv.Field, s
 	// Acquire buffer
 	buf := getBuf()
 
-	// Append formatted timestamp
-	buf.B = append(buf.B, `timestamp="`...)
+	// Append formatted timestamp according to `timefmt`
 	buf.B = time.Now().AppendFormat(buf.B, timefmt)
-	buf.B = append(buf.B, `" `...)
 
 	// Append formatted caller func
 	buf.B = append(buf.B, `func=`...)
diff --git a/internal/log/syslog_test.go b/internal/log/syslog_test.go
index e7e82ec58..7432e61b3 100644
--- a/internal/log/syslog_test.go
+++ b/internal/log/syslog_test.go
@@ -71,6 +71,22 @@ func (suite *SyslogTestSuite) TestSyslog() {
 	suite.Regexp(regexp.MustCompile(`timestamp=.* func=.* level=INFO msg="this is a test of the emergency broadcast system!"`), entry["content"])
 }
 
+func (suite *SyslogTestSuite) TestSyslogDisableTimestamp() {
+	// Get the current format.
+	timefmt := log.TimeFormat()
+
+	// Set an empty timestamp.
+	log.SetTimeFormat("")
+
+	// Set old timestamp on return.
+	defer log.SetTimeFormat(timefmt)
+
+	log.Info(nil, "this is a test of the emergency broadcast system!")
+
+	entry := <-suite.syslogChannel
+	suite.Regexp(regexp.MustCompile(`func=.* level=INFO msg="this is a test of the emergency broadcast system!"`), entry["content"])
+}
+
 func (suite *SyslogTestSuite) TestSyslogLongMessage() {
 	log.Warn(nil, longMessage)
 
diff --git a/test/envparsing.sh b/test/envparsing.sh
index 0cad04416..2ab17dbfb 100755
--- a/test/envparsing.sh
+++ b/test/envparsing.sh
@@ -86,6 +86,7 @@ EXPECT=$(cat << "EOF"
     "log-client-ip": false,
     "log-db-queries": true,
     "log-level": "info",
+    "log-timestamp-format": "banana",
     "media-description-max-chars": 5000,
     "media-description-min-chars": 69,
     "media-emoji-local-max-size": 420,
@@ -155,6 +156,7 @@ EOF
 # Set all the environment variables to 
 # ensure that these are parsed without panic
 OUTPUT=$(GTS_LOG_LEVEL='info' \
+GTS_LOG_TIMESTAMP_FORMAT="banana" \
 GTS_LOG_DB_QUERIES=true \
 GTS_LOG_CLIENT_IP=false \
 GTS_APPLICATION_NAME=gts \
diff --git a/testrig/config.go b/testrig/config.go
index c5cbb2c80..a85a88477 100644
--- a/testrig/config.go
+++ b/testrig/config.go
@@ -33,17 +33,18 @@ func InitTestConfig() {
 }
 
 var testDefaults = config.Configuration{
-	LogLevel:        "info",
-	LogDbQueries:    true,
-	ApplicationName: "gotosocial",
-	LandingPageUser: "",
-	ConfigPath:      "",
-	Host:            "localhost:8080",
-	AccountDomain:   "localhost:8080",
-	Protocol:        "http",
-	BindAddress:     "127.0.0.1",
-	Port:            8080,
-	TrustedProxies:  []string{"127.0.0.1/32", "::1"},
+	LogLevel:           "info",
+	LogTimestampFormat: "02/01/2006 15:04:05.000",
+	LogDbQueries:       true,
+	ApplicationName:    "gotosocial",
+	LandingPageUser:    "",
+	ConfigPath:         "",
+	Host:               "localhost:8080",
+	AccountDomain:      "localhost:8080",
+	Protocol:           "http",
+	BindAddress:        "127.0.0.1",
+	Port:               8080,
+	TrustedProxies:     []string{"127.0.0.1/32", "::1"},
 
 	DbType:                   "sqlite",
 	DbAddress:                ":memory:",
diff --git a/testrig/log.go b/testrig/log.go
index 2761eb3f8..439ed72b0 100644
--- a/testrig/log.go
+++ b/testrig/log.go
@@ -26,6 +26,7 @@ import (
 
 // InitTestLog sets the global logger to trace level for logging
 func InitTestLog() {
+	log.SetTimeFormat(config.GetLogTimestampFormat())
 	// Set the global log level from configuration
 	if err := log.ParseLevel(config.GetLogLevel()); err != nil {
 		log.Panicf(nil, "error parsing log level: %v", err)