go.mod: Tidy

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

.gitignore

@@ -0,0 +1,50 @@
+# IDE
+.idea
+.vscode
+
+# Vendoring
+vendor
+
+# tempfiles
+.DS_Store
+*~
+.cache
+
+temp
+tmp
+
+# binary
+bin/
+release/
+
+# coverage
+coverage.txt
+coverage.html
+
+# testing
+cmd/test
+/plugins/
+testfile
+
+# misc
+
+# debhelpers
+debian/*debhelper*
+
+# logfiles
+debian/*.log
+
+# .substvars
+debian/*.substvars
+
+# .bash-completion
+debian/*.bash-completion
+
+# Install folders and files
+debian/frostfs-cli/
+debian/frostfs-ir/
+debian/files
+debian/frostfs-storage/
+debian/changelog
+man/
+debs/

.gitlint

@@ -0,0 +1,11 @@
+[general]
+fail-without-commits=True
+regex-style-search=True
+contrib=CC1
+
+[title-match-regex]
+regex=^\[\#[0-9Xx]+\]\s
+
+[ignore-by-title]
+regex=^Release(.*)
+ignore=title-match-regex

.golangci.yml

@@ -0,0 +1,66 @@
+# This file contains all available configuration options
+# with their default values.
+
+# options for analysis running
+run:
+  # timeout for analysis, e.g. 30s, 5m, default is 1m
+  timeout: 10m
+
+  # include test files or not, default is true
+  tests: false
+
+# output configuration options
+output:
+  # colored-line-number|line-number|json|tab|checkstyle|code-climate, default is "colored-line-number"
+  format: tab
+
+# all available settings of specific linters
+linters-settings:
+  exhaustive:
+    # indicates that switch statements are to be considered exhaustive if a
+    # 'default' case is present, even if all enum members aren't listed in the
+    # switch
+    default-signifies-exhaustive: true
+  govet:
+    # report about shadowed variables
+    check-shadowing: false
+  staticcheck:
+    checks: ["all", "-SA1019"] # TODO Enable SA1019 after deprecated warning are fixed.
+  funlen:
+    lines: 80 # default 60
+    statements: 60 # default 40
+  gocognit:
+    min-complexity: 40 # default 30
+
+linters:
+  enable:
+    # mandatory linters
+    - govet
+    - revive
+
+    # some default golangci-lint linters
+    - errcheck
+    - gosimple
+    - godot
+    - ineffassign
+    - staticcheck
+    - typecheck
+    - unused
+
+    # extra linters
+    - bidichk
+    - durationcheck
+    - exhaustive
+    - exportloopref
+    - gofmt
+    - goimports
+    - misspell
+    - predeclared
+    - reassign
+    - whitespace
+    - containedctx
+    - funlen
+    - gocognit
+    - contextcheck
+  disable-all: true
+  fast: false

.pre-commit-config.yaml

@@ -0,0 +1,45 @@
+ci:
+  autofix_prs: false
+
+repos:
+  - repo: https://github.com/jorisroovers/gitlint
+    rev:  v0.19.1
+    hooks:
+      - id: gitlint
+        stages: [commit-msg]
+      - id: gitlint-ci
+
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v4.4.0
+    hooks:
+      - id: check-added-large-files
+      - id: check-case-conflict
+      - id: check-executables-have-shebangs
+      - id: check-shebang-scripts-are-executable
+      - id: check-merge-conflict
+      - id: check-json
+      - id: check-xml
+      - id: check-yaml
+      - id: trailing-whitespace
+        args: [--markdown-linebreak-ext=md]
+      - id: end-of-file-fixer
+        exclude: ".key$"
+
+  - repo: https://github.com/shellcheck-py/shellcheck-py
+    rev: v0.9.0.2
+    hooks:
+      - id: shellcheck
+
+  - repo: https://github.com/golangci/golangci-lint
+    rev: v1.51.2
+    hooks:
+      - id: golangci-lint
+
+  - repo: local
+    hooks:
+      - id: go-unit-tests
+        name: go unit tests
+        entry: make test
+        pass_filenames: false
+        types: [go]
+        language: system

LICENSE

@@ -0,0 +1,201 @@
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
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+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
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+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
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+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
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+   you may not use this file except in compliance with the License.
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+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.

README.md

@@ -0,0 +1,119 @@
+# Zap Core for systemd Journal
+Package `zapjournld` provides `zap` Core for systemd Journal. It supports structured logging.
+
+Applications may use zap logger to write logs directly into journald and may relatively freely define additional fields, which will be indexed by journald.
+
+Information about common and custom journald fields is available on https://www.freedesktop.org/software/systemd/man/systemd.journal-fields.html.
+## Example
+```go
+package main
+
+import (
+	"fmt"
+
+	"git.frostfs.info/TrueCloudLab/zapjournald"
+	"go.uber.org/zap"
+
+	"github.com/ssgreg/journald"
+	"go.uber.org/zap/zapcore"
+)
+
+func main() {
+	// StandardLogger
+	standardLogger, _ := NewStandardLogger("info")
+
+	standardLogger.Info("Simple log raw 1")
+}
+
+func NewStandardLogger(lvlStr string) (*zap.Logger, zap.AtomicLevel) {
+	lvl, err := getLogLevel(lvlStr)
+	if err != nil {
+		panic(err)
+	}
+
+	zc := zap.NewProductionConfig()
+	zc.EncoderConfig.EncodeTime = zapcore.ISO8601TimeEncoder
+	zc.Level = zap.NewAtomicLevelAt(lvl)
+
+	// Initialize Zap.
+	encoder := zapcore.NewJSONEncoder(zc.EncoderConfig)
+
+	core := zapjournald.NewCore(zap.NewAtomicLevelAt(lvl), encoder, &journald.Journal{}, zapjournald.SyslogFields)
+	coreWithContext := core.With([]zapcore.Field{
+		zapjournald.SyslogFacility(zapjournald.LogDaemon),
+		zapjournald.SyslogIdentifier(),
+		zapjournald.SyslogPid(),
+	})
+	l := zap.New(coreWithContext, zap.AddStacktrace(zap.NewAtomicLevelAt(zap.FatalLevel)))
+	return l, zc.Level
+}
+
+func getLogLevel(lvlStr string) (zapcore.Level, error) {
+	var lvl zapcore.Level
+	err := lvl.UnmarshalText([]byte(lvlStr))
+	if err != nil {
+		return lvl, fmt.Errorf("incorrect logger level configuration %s (%v), "+
+			"value should be one of %v", lvlStr, err, [...]zapcore.Level{
+			zapcore.DebugLevel,
+			zapcore.InfoLevel,
+			zapcore.WarnLevel,
+			zapcore.ErrorLevel,
+			zapcore.DPanicLevel,
+			zapcore.PanicLevel,
+			zapcore.FatalLevel,
+		})
+	}
+	return lvl, nil
+}
+```
+
+### Results
+
+#### You can read simple view like this:
+```
+sudo journalctl -f
+Apr 07 13:06:34 user ___11go_build_git_frostfs_info_TrueCloudLab_zapjournald_main[330983]: {"level":"info","ts":"2023-04-07T13:06:34.990+0300","msg":"Simple log raw 1","SYSLOG_FACILITY":3,"SYSLOG_IDENTIFIER":"___11go_build_git_frostfs_info_TrueCloudLab_zapjournald_main","SYSLOG_PID":330983}
+```
+#### Or you can find lines by indexed field
+```
+sudo journalctl SYSLOG_PID=76385
+Apr 07 13:06:34 user ___11go_build_git_frostfs_info_TrueCloudLab_zapjournald_main[330983]: {"level":"info","ts":"2023-04-07T13:06:34.990+0300","msg":"Simple log raw 1","SYSLOG_FACILITY":3,"SYSLOG_ID>
+```
+#### Or you can read full-structured view like this:
+```
+sudo journalctl SYSLOG_PID=76385 --output=json-pretty
+{
+        "PRIORITY" : "6",
+        "_SYSTEMD_OWNER_UID" : "1000",
+        "_HOSTNAME" : "user",
+        "__MONOTONIC_TIMESTAMP" : "153798818198",
+        "_SYSTEMD_SLICE" : "user-1000.slice",
+        "_GID" : "1000",
+        "_AUDIT_LOGINUID" : "1000",
+        "_UID" : "1000",
+        "SYSLOG_IDENTIFIER" : "___11go_build_git_frostfs_info_TrueCloudLab_zapjournald_main",
+        "__REALTIME_TIMESTAMP" : "1680861994990646",
+        "_CAP_EFFECTIVE" : "0",
+        "_COMM" : "___11go_build_g",
+        "_AUDIT_SESSION" : "59",
+        "__CURSOR" : "s=9e2d157a286a437ea3405618239c1e07;i=14a96;b=bc1bc632f462476abc9e3e3b0c517f6c;m=23cf1fb996;t=5f8bc2e20bc36;x=9c6c4a86b6da43c",
+        "_SYSTEMD_USER_SLICE" : "app.slice",
+        "_SYSTEMD_CGROUP" : "/user.slice/user-1000.slice/user@1000.service/app.slice/app-gnome-jetbrains\\x2dgoland-203587.scope",
+        "MESSAGE" : "{\"level\":\"info\",\"ts\":\"2023-04-07T13:06:34.990+0300\",\"msg\":\"Simple log raw 1\",\"SYSLOG_FACILITY\":3,\"SYSLOG_IDENTIFIER\":\"___11go_build_git_frostfs_info_TrueCloudLab_zapjournal>
+        "_SOURCE_REALTIME_TIMESTAMP" : "1680861994990539",
+        "_MACHINE_ID" : "82be99c92deb4b36850366d7742de698",
+        "SYSLOG_FACILITY" : "3",
+        "_BOOT_ID" : "bc1bc632f462476abc9e3e3b0c517f6c",
+        "_PID" : "330983",
+        "_SELINUX_CONTEXT" : "unconfined\n",
+        "_SYSTEMD_UNIT" : "user@1000.service",
+        "_TRANSPORT" : "journal",
+        "_SYSTEMD_INVOCATION_ID" : "ed23dc57a96340029ef8bf9956182c20",
+        "_SYSTEMD_USER_UNIT" : "app-gnome-jetbrains\\x2dgoland-203587.scope",
+        "SYSLOG_PID" : "330983"
+}
+```
+
+# License
+
+- [Apache License, Version 2.0](LICENSE)

benchmark_test.go

@@ -0,0 +1,65 @@
+package zapjournald
+
+import (
+	"testing"
+
+	"github.com/ssgreg/journald"
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
+)
+
+type nopSync struct{}
+
+func (nopSync) Write([]byte) (int, error) { return 0, nil }
+func (nopSync) Sync() error               { return nil }
+
+func BenchmarkLogger(b *testing.B) {
+	zc := zap.NewProductionConfig()
+	zc.EncoderConfig.EncodeTime = zapcore.ISO8601TimeEncoder
+	zc.Level = zap.NewAtomicLevelAt(zap.InfoLevel)
+
+	b.Run("standard", func(b *testing.B) {
+		encoder := zapcore.NewJSONEncoder(zc.EncoderConfig)
+		core := zapcore.NewCore(encoder, nopSync{}, zc.Level)
+		coreWithContext := core.With([]zapcore.Field{
+			SyslogFacility(LogDaemon),
+			SyslogIdentifier(),
+			SyslogPid()})
+		l := zap.New(coreWithContext)
+		benchmarkLog(b, l)
+	})
+	b.Run("journald", func(b *testing.B) {
+		encoder := zapcore.NewJSONEncoder(zc.EncoderConfig)
+		core := NewCore(zc.Level, encoder, &journald.Journal{}, SyslogFields)
+		core.j.TestModeEnabled = true // Disable actual writing to the journal.
+
+		coreWithContext := core.With([]zapcore.Field{
+			SyslogFacility(LogDaemon),
+			SyslogIdentifier(),
+			SyslogPid(),
+		})
+		l := zap.New(coreWithContext)
+		benchmarkLog(b, l)
+	})
+}
+
+func benchmarkLog(b *testing.B, l *zap.Logger) {
+	b.Run("no fields", func(b *testing.B) {
+		b.ReportAllocs()
+		for i := 0; i < b.N; i++ {
+			l.Info("Simple log message")
+		}
+	})
+	b.Run("application fields", func(b *testing.B) {
+		b.ReportAllocs()
+		for i := 0; i < b.N; i++ {
+			l.Info("Simple log message", zap.Uint32("count", 123), zap.String("details", "nothing"))
+		}
+	})
+	b.Run("journald fields", func(b *testing.B) {
+		b.ReportAllocs()
+		for i := 0; i < b.N; i++ {
+			l.Info("Simple log message", SyslogIdentifier())
+		}
+	})
+}

encoder.go

@@ -0,0 +1,70 @@
+package zapjournald
+
+import (
+	"bytes"
+	"fmt"
+	"strings"
+
+	"go.uber.org/zap/buffer"
+)
+
+var pool = buffer.NewPool()
+
+func encodeJournaldField(buf *buffer.Buffer, key string, value any) {
+	switch v := value.(type) {
+	case string:
+		writeField(buf, key, v)
+	case []byte:
+		writeFieldBytes(buf, key, v)
+	default:
+		writeField(buf, key, fmt.Sprint(v))
+	}
+}
+
+func writeFieldBytes(buf *buffer.Buffer, name string, value []byte) {
+	buf.Write([]byte(name))
+	if bytes.ContainsRune(value, '\n') {
+		// According to the format, if the value includes a newline
+		// need to write the field name, plus a newline, then the
+		// size (64bit LE), the field data and a final newline.
+
+		buf.Write([]byte{'\n'})
+		appendUint64Binary(buf, uint64(len(value)))
+	} else {
+		buf.Write([]byte{'='})
+	}
+	buf.Write(value)
+	buf.Write([]byte{'\n'})
+}
+
+func writeField(buf *buffer.Buffer, name string, value string) {
+	buf.Write([]byte(name))
+	if strings.ContainsRune(value, '\n') {
+		// According to the format, if the value includes a newline
+		// need to write the field name, plus a newline, then the
+		// size (64bit LE), the field data and a final newline.
+
+		buf.Write([]byte{'\n'})
+		// 1 allocation here.
+		// binary.Write(w, binary.LittleEndian, uint64(len(value)))
+		appendUint64Binary(buf, uint64(len(value)))
+	} else {
+		buf.Write([]byte{'='})
+	}
+	buf.WriteString(value)
+	buf.Write([]byte{'\n'})
+}
+
+func appendUint64Binary(buf *buffer.Buffer, v uint64) {
+	// Copied from https://github.com/golang/go/blob/go1.21.3/src/encoding/binary/binary.go#L119
+	buf.Write([]byte{
+		byte(v),
+		byte(v >> 8),
+		byte(v >> 16),
+		byte(v >> 24),
+		byte(v >> 32),
+		byte(v >> 40),
+		byte(v >> 48),
+		byte(v >> 56),
+	})
+}

go.mod

@@ -1,3 +1,18 @@
 module git.frostfs.info/TrueCloudLab/zapjournald
 
 go 1.19
+
+require (
+	github.com/ssgreg/journald v1.0.0
+	github.com/stretchr/testify v1.8.1
+	go.uber.org/zap v1.27.0
+	golang.org/x/exp v0.0.0-20230321023759-10a507213a29
+)
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	go.uber.org/multierr v1.10.0 // indirect
+	golang.org/x/sys v0.1.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)

go.sum

@@ -0,0 +1,28 @@
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/ssgreg/journald v1.0.0 h1:0YmTDPJXxcWDPba12qNMdO6TxvfkFSYpFIJ31CwmLcU=
+github.com/ssgreg/journald v1.0.0/go.mod h1:RUckwmTM8ghGWPslq2+ZBZzbb9/2KgjzYZ4JEP+oRt0=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
+github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpEOglKo=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
+github.com/stretchr/testify v1.8.1 h1:w7B6lhMri9wdJUVmEZPGGhZzrYTPvgJArz7wNPgYKsk=
+github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
+go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
+go.uber.org/multierr v1.10.0 h1:S0h4aNzvfcFsC3dRF1jLoaov7oRaKqRGC/pUEJ2yvPQ=
+go.uber.org/multierr v1.10.0/go.mod h1:20+QtiLqy0Nd6FdQB9TLXag12DsQkrbs3htMFfDN80Y=
+go.uber.org/zap v1.27.0 h1:aJMhYGrd5QSmlpLMr2MftRKl7t8J8PTZPA732ud/XR8=
+go.uber.org/zap v1.27.0/go.mod h1:GB2qFLM7cTU87MWRP2mPIjqfIDnGu+VIO4V/SdhGo2E=
+golang.org/x/exp v0.0.0-20230321023759-10a507213a29 h1:ooxPy7fPvB4kwsA2h+iBNHkAbp/4JxTSwCmvdjEYmug=
+golang.org/x/exp v0.0.0-20230321023759-10a507213a29/go.mod h1:CxIveKay+FTh1D0yPZemJVgC/95VzuuOLq5Qi4xnoYc=
+golang.org/x/sys v0.1.0 h1:kunALQeHf1/185U1i0GOB/fy1IPRDDpuoOOqRReG57U=
+golang.org/x/sys v0.1.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

partial_encoder.go

@@ -0,0 +1,214 @@
+package zapjournald
+
+import (
+	"time"
+
+	"go.uber.org/zap/buffer"
+	"go.uber.org/zap/zapcore"
+	"golang.org/x/exp/maps"
+)
+
+type partialEncoder struct {
+	wrap   zapcore.Encoder
+	ignore map[string]struct{}
+}
+
+// NewPartialEncoder wraps existing encoder to avoid output of some provided
+// fields. The main use case is to ignore SyslogFields that leak into
+// ConsoleEncoder and provide no additional info for the human.
+func NewPartialEncoder(enc zapcore.Encoder, ignore []string) zapcore.Encoder {
+	m := make(map[string]struct{}, len(ignore))
+	for _, i := range ignore {
+		m[i] = struct{}{}
+	}
+	return partialEncoder{
+		wrap:   enc,
+		ignore: m,
+	}
+}
+
+func (enc partialEncoder) AddArray(key string, marshaler zapcore.ArrayMarshaler) error {
+	if _, ok := enc.ignore[key]; ok {
+		return nil
+	}
+	return enc.wrap.AddArray(key, marshaler)
+}
+
+func (enc partialEncoder) AddObject(key string, marshaler zapcore.ObjectMarshaler) error {
+	if _, ok := enc.ignore[key]; ok {
+		return nil
+	}
+	return enc.wrap.AddObject(key, marshaler)
+}
+
+func (enc partialEncoder) AddBinary(key string, value []byte) {
+	if _, ok := enc.ignore[key]; ok {
+		return
+	}
+	enc.wrap.AddBinary(key, value)
+}
+
+func (enc partialEncoder) AddByteString(key string, value []byte) {
+	if _, ok := enc.ignore[key]; ok {
+		return
+	}
+	enc.wrap.AddByteString(key, value)
+}
+
+func (enc partialEncoder) AddBool(key string, value bool) {
+	if _, ok := enc.ignore[key]; ok {
+		return
+	}
+	enc.wrap.AddBool(key, value)
+}
+
+func (enc partialEncoder) AddComplex128(key string, value complex128) {
+	if _, ok := enc.ignore[key]; ok {
+		return
+	}
+	enc.wrap.AddComplex128(key, value)
+}
+
+func (enc partialEncoder) AddComplex64(key string, value complex64) {
+	if _, ok := enc.ignore[key]; ok {
+		return
+	}
+	enc.wrap.AddComplex64(key, value)
+}
+
+func (enc partialEncoder) AddDuration(key string, value time.Duration) {
+	if _, ok := enc.ignore[key]; ok {
+		return
+	}
+	enc.wrap.AddDuration(key, value)
+}
+
+func (enc partialEncoder) AddFloat64(key string, value float64) {
+	if _, ok := enc.ignore[key]; ok {
+		return
+	}
+	enc.wrap.AddFloat64(key, value)
+}
+
+func (enc partialEncoder) AddFloat32(key string, value float32) {
+	if _, ok := enc.ignore[key]; ok {
+		return
+	}
+	enc.wrap.AddFloat32(key, value)
+}
+
+func (enc partialEncoder) AddInt(key string, value int) {
+	if _, ok := enc.ignore[key]; ok {
+		return
+	}
+	enc.wrap.AddInt(key, value)
+}
+
+func (enc partialEncoder) AddInt64(key string, value int64) {
+	if _, ok := enc.ignore[key]; ok {
+		return
+	}
+	enc.wrap.AddInt64(key, value)
+}
+
+func (enc partialEncoder) AddInt32(key string, value int32) {
+	if _, ok := enc.ignore[key]; ok {
+		return
+	}
+	enc.wrap.AddInt32(key, value)
+}
+
+func (enc partialEncoder) AddInt16(key string, value int16) {
+	if _, ok := enc.ignore[key]; ok {
+		return
+	}
+	enc.wrap.AddInt16(key, value)
+}
+
+func (enc partialEncoder) AddInt8(key string, value int8) {
+	if _, ok := enc.ignore[key]; ok {
+		return
+	}
+	enc.wrap.AddInt8(key, value)
+}
+
+func (enc partialEncoder) AddString(key, value string) {
+	if _, ok := enc.ignore[key]; ok {
+		return
+	}
+	enc.wrap.AddString(key, value)
+}
+
+func (enc partialEncoder) AddTime(key string, value time.Time) {
+	if _, ok := enc.ignore[key]; ok {
+		return
+	}
+	enc.wrap.AddTime(key, value)
+}
+
+func (enc partialEncoder) AddUint(key string, value uint) {
+	if _, ok := enc.ignore[key]; ok {
+		return
+	}
+	enc.wrap.AddUint(key, value)
+}
+
+func (enc partialEncoder) AddUint64(key string, value uint64) {
+	if _, ok := enc.ignore[key]; ok {
+		return
+	}
+	enc.wrap.AddUint64(key, value)
+}
+
+func (enc partialEncoder) AddUint32(key string, value uint32) {
+	if _, ok := enc.ignore[key]; ok {
+		return
+	}
+	enc.wrap.AddUint32(key, value)
+}
+
+func (enc partialEncoder) AddUint16(key string, value uint16) {
+	if _, ok := enc.ignore[key]; ok {
+		return
+	}
+	enc.wrap.AddUint16(key, value)
+}
+
+func (enc partialEncoder) AddUint8(key string, value uint8) {
+	if _, ok := enc.ignore[key]; ok {
+		return
+	}
+	enc.wrap.AddUint8(key, value)
+}
+
+func (enc partialEncoder) AddUintptr(key string, value uintptr) {
+	if _, ok := enc.ignore[key]; ok {
+		return
+	}
+	enc.wrap.AddUintptr(key, value)
+}
+
+func (enc partialEncoder) AddReflected(key string, value interface{}) error {
+	if _, ok := enc.ignore[key]; ok {
+		return nil
+	}
+	return enc.wrap.AddReflected(key, value)
+}
+
+func (enc partialEncoder) OpenNamespace(key string) {
+	if _, ok := enc.ignore[key]; ok {
+		return
+	}
+	enc.wrap.OpenNamespace(key)
+}
+
+func (enc partialEncoder) Clone() zapcore.Encoder {
+	return partialEncoder{
+		wrap:   enc.wrap.Clone(),
+		ignore: maps.Clone(enc.ignore),
+	}
+}
+
+func (enc partialEncoder) EncodeEntry(entry zapcore.Entry, fields []zapcore.Field) (*buffer.Buffer, error) {
+	return enc.wrap.EncodeEntry(entry, fields)
+}

partial_encoder_bench_test.go

@@ -0,0 +1,63 @@
+package zapjournald
+
+import (
+	"testing"
+
+	"github.com/ssgreg/journald"
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
+)
+
+func BenchmarkEncoder(b *testing.B) {
+	zc := zap.NewProductionConfig()
+	zc.EncoderConfig.EncodeTime = zapcore.ISO8601TimeEncoder
+	zc.Level = zap.NewAtomicLevelAt(zap.InfoLevel)
+
+	b.Run("console", func(b *testing.B) {
+		encoder := zapcore.NewConsoleEncoder(zc.EncoderConfig)
+		core := NewCore(zc.Level, encoder, &journald.Journal{}, SyslogFields)
+		core.j.TestModeEnabled = true // Disable actual writing to the journal.
+
+		coreWithContext := core.With([]zapcore.Field{
+			SyslogFacility(LogDaemon),
+			SyslogIdentifier(),
+			SyslogPid(),
+		})
+		l := zap.New(coreWithContext)
+		benchmarkEncoder(b, l)
+	})
+	b.Run("partial", func(b *testing.B) {
+		encoder := NewPartialEncoder(zapcore.NewConsoleEncoder(zc.EncoderConfig), SyslogFields)
+		core := NewCore(zc.Level, encoder, &journald.Journal{}, SyslogFields)
+		core.j.TestModeEnabled = true // Disable actual writing to the journal.
+
+		coreWithContext := core.With([]zapcore.Field{
+			SyslogFacility(LogDaemon),
+			SyslogIdentifier(),
+			SyslogPid(),
+		})
+		l := zap.New(coreWithContext)
+		benchmarkEncoder(b, l)
+	})
+}
+
+func benchmarkEncoder(b *testing.B, l *zap.Logger) {
+	b.Run("no fields", func(b *testing.B) {
+		b.ReportAllocs()
+		for i := 0; i < b.N; i++ {
+			l.Info("Simple log message")
+		}
+	})
+	b.Run("application fields", func(b *testing.B) {
+		b.ReportAllocs()
+		for i := 0; i < b.N; i++ {
+			l.Info("Simple log message", zap.Uint32("count", 123), zap.String("details", "nothing"))
+		}
+	})
+	b.Run("journald fields", func(b *testing.B) {
+		b.ReportAllocs()
+		for i := 0; i < b.N; i++ {
+			l.Info("Simple log message", SyslogIdentifier())
+		}
+	})
+}

syslog.go

@@ -0,0 +1,77 @@
+package zapjournald
+
+import (
+	"os"
+	"path/filepath"
+	"time"
+
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
+)
+
+// Facility defines syslog facility from /usr/include/sys/syslog.h .
+type Facility uint32
+
+// Syslog compatibility fields.
+const (
+	SyslogFacilityField   = "SYSLOG_FACILITY"
+	SyslogIdentifierField = "SYSLOG_IDENTIFIER"
+	SyslogPidField        = "SYSLOG_PID"
+	SyslogTimestampField  = "SYSLOG_TIMESTAMP"
+)
+
+// Facilities before LogFtp are the same on Linux, BSD, and OS X.
+const (
+	LogKern Facility = iota << 3
+	LogUser
+	LogMail
+	LogDaemon
+	LogAuth
+	LogSyslog
+	LogLpr
+	LogNews
+	LogUucp
+	LogCron
+	LogAuthpriv
+	LogFtp
+	_        // unused
+	LogAudit // unused
+	_        // unused
+	_        // unused
+	LogLocal0
+	LogLocal1
+	LogLocal2
+	LogLocal3
+	LogLocal4
+	LogLocal5
+	LogLocal6
+	LogLocal7
+)
+
+// LogFacmask is used to extract facility part of the message.
+const LogFacmask = 0x03f8
+
+// SyslogFields contains slice of fields that are
+// indexed by syslog by default.
+var SyslogFields = []string{
+	SyslogFacilityField,
+	SyslogIdentifierField,
+	SyslogPidField,
+	SyslogTimestampField,
+}
+
+func SyslogFacility(facility Facility) zapcore.Field {
+	return zap.Uint32(SyslogFacilityField, uint32(facility&LogFacmask)>>3)
+}
+
+func SyslogIdentifier() zapcore.Field {
+	return zap.String(SyslogIdentifierField, filepath.Base(os.Args[0]))
+}
+
+func SyslogPid() zapcore.Field {
+	return zap.Int(SyslogPidField, os.Getpid())
+}
+
+func SyslogTimestamp(time time.Time) zapcore.Field {
+	return zap.Time(SyslogTimestampField, time)
+}

zapjournald.go

@@ -0,0 +1,193 @@
+package zapjournald
+
+import (
+	"fmt"
+	"math"
+	"strconv"
+	"time"
+
+	"github.com/ssgreg/journald"
+	"go.uber.org/zap/zapcore"
+	"golang.org/x/exp/maps"
+)
+
+// Core for zapjournald.
+//
+// Implements zapcore.LevelEnabler and zapcore.Core interfaces.
+type Core struct {
+	zapcore.LevelEnabler
+	encoder zapcore.Encoder
+	j       *journald.Journal
+	// field names, which will be stored in journald structure
+	storedFieldNames map[string]struct{}
+	// journald fields, which are always present in current core context
+	contextStructuredFields map[string]interface{}
+}
+
+func NewCore(enab zapcore.LevelEnabler, encoder zapcore.Encoder, journal *journald.Journal, journalFields []string) *Core {
+	journalFieldsMap := make(map[string]struct{})
+	for _, field := range journalFields {
+		journalFieldsMap[field] = struct{}{}
+	}
+	return &Core{
+		LevelEnabler:            enab,
+		encoder:                 encoder,
+		j:                       journal,
+		storedFieldNames:        journalFieldsMap,
+		contextStructuredFields: make(map[string]interface{}),
+	}
+}
+
+// With adds structured context to the Core.
+func (core *Core) With(fields []zapcore.Field) zapcore.Core {
+	clone := core.clone()
+	for _, field := range fields {
+		field.AddTo(clone.encoder)
+		clone.contextStructuredFields[field.Key] = getFieldValue(field)
+	}
+
+	return clone
+}
+
+// Check determines whether the supplied Entry should be logged (using the
+// embedded LevelEnabler and possibly some extra logic). If the entry
+// should be logged, the Core adds itself to the CheckedEntry and returns
+// the result.
+//
+// Callers must use Check before calling Write.
+func (core *Core) Check(entry zapcore.Entry, checked *zapcore.CheckedEntry) *zapcore.CheckedEntry {
+	if core.Enabled(entry.Level) {
+		return checked.AddCore(entry, core)
+	}
+	return checked
+}
+
+// Write serializes the Entry and any Fields supplied at the log site and
+// writes them to their destination.
+//
+// If called, Write should always log the Entry and Fields; it should not
+// replicate the logic of Check.
+func (core *Core) Write(entry zapcore.Entry, fields []zapcore.Field) error {
+	prio, err := zapLevelToJournald(entry.Level)
+	if err != nil {
+		return err
+	}
+
+	b := pool.Get()
+	defer b.Free()
+
+	writeField(b, "PRIORITY", strconv.Itoa(int(prio)))
+
+	if len(core.contextStructuredFields) != 0 {
+		for k, v := range core.contextStructuredFields {
+			encodeJournaldField(b, k, v)
+		}
+		for _, field := range fields {
+			if _, isJournalField := core.storedFieldNames[field.Key]; isJournalField {
+				encodeJournaldField(b, field.Key, getFieldValue(field))
+			}
+		}
+	}
+
+	// Generate the message.
+	buffer, err := core.encoder.EncodeEntry(entry, fields)
+	if err != nil {
+		return fmt.Errorf("failed to encode log entry: %w", err)
+	}
+	defer buffer.Free()
+
+	writeFieldBytes(b, "MESSAGE", buffer.Bytes())
+
+	// Write the message.
+	return core.j.WriteMsg(b.Bytes())
+}
+
+// Sync flushes buffered logs (not used).
+func (core *Core) Sync() error {
+	return nil
+}
+
+// clone returns clone of core.
+func (core *Core) clone() *Core {
+	return &Core{
+		LevelEnabler:            core.LevelEnabler,
+		encoder:                 core.encoder.Clone(),
+		j:                       core.j,
+		storedFieldNames:        maps.Clone(core.storedFieldNames),
+		contextStructuredFields: maps.Clone(core.contextStructuredFields),
+	}
+}
+
+// getFieldValue returns underlying value stored in zapcore.Field.
+func getFieldValue(f zapcore.Field) interface{} {
+	switch f.Type {
+	case zapcore.ArrayMarshalerType,
+		zapcore.ObjectMarshalerType,
+		zapcore.InlineMarshalerType,
+		zapcore.BinaryType,
+		zapcore.ByteStringType,
+		zapcore.Complex128Type,
+		zapcore.Complex64Type,
+		zapcore.TimeFullType,
+		zapcore.ReflectType,
+		zapcore.NamespaceType,
+		zapcore.StringerType,
+		zapcore.ErrorType,
+		zapcore.SkipType:
+		return f.Interface
+	case zapcore.DurationType:
+		return time.Duration(f.Integer).String()
+	case zapcore.Float64Type:
+		// See https://github.com/uber-go/zap/blob/v1.26.0/buffer/buffer.go#L79
+		f := math.Float64frombits(uint64(f.Integer))
+		return strconv.FormatFloat(f, 'f', -1, 64)
+	case zapcore.Float32Type:
+		f := math.Float32frombits(uint32(f.Integer))
+		return strconv.FormatFloat(float64(f), 'f', -1, 32)
+	case zapcore.Int64Type,
+		zapcore.Int32Type,
+		zapcore.Int16Type,
+		zapcore.Int8Type:
+		return strconv.FormatInt(f.Integer, 10)
+	case
+		zapcore.Uint64Type,
+		zapcore.Uint32Type,
+		zapcore.Uint16Type,
+		zapcore.Uint8Type,
+		zapcore.UintptrType:
+		return strconv.FormatUint(uint64(f.Integer), 10)
+	case zapcore.BoolType:
+		return strconv.FormatBool(f.Integer == 1)
+	case zapcore.StringType:
+		return f.String
+	case zapcore.TimeType:
+		if f.Interface != nil {
+			// for example: zap.Time("k", time.Unix(100900, 0).In(time.UTC)) - will produce: "100900000000000 UTC" (result in nanoseconds)
+			return fmt.Sprintf("%d %v", f.Integer, f.Interface)
+		}
+		return strconv.FormatUint(uint64(f.Integer), 10)
+	default:
+		panic(fmt.Sprintf("unknown field type: %v", f))
+	}
+}
+
+func zapLevelToJournald(l zapcore.Level) (journald.Priority, error) {
+	switch l {
+	case zapcore.DebugLevel:
+		return journald.PriorityDebug, nil
+	case zapcore.InfoLevel:
+		return journald.PriorityInfo, nil
+	case zapcore.WarnLevel:
+		return journald.PriorityWarning, nil
+	case zapcore.ErrorLevel:
+		return journald.PriorityErr, nil
+	case zapcore.DPanicLevel:
+		return journald.PriorityCrit, nil
+	case zapcore.PanicLevel:
+		return journald.PriorityCrit, nil
+	case zapcore.FatalLevel:
+		return journald.PriorityCrit, nil
+	default:
+		return 0, fmt.Errorf("unknown log level: %v", l)
+	}
+}

zapjournald_test.go

@@ -0,0 +1,94 @@
+package zapjournald
+
+import (
+	"fmt"
+	"net"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
+)
+
+// TestGetFieldValueWithStringFormatting testing unexported function getFieldValue and verifying that all zap field types have correct return values.
+func TestGetFieldValueWithStringFormatting(t *testing.T) {
+	// Interface types.
+	addr := net.ParseIP("1.2.3.4")
+	name := usernameTestExample("phil")
+	ints := []int{5, 6}
+
+	tests := []struct {
+		name   string
+		field  zap.Field
+		expect interface{}
+	}{
+		{"ObjectMarshaler", zap.Object("k", name), "phil"},
+		{"ArrayMarshaler", zap.Array("k", boolsTestExample([]bool{true})), "[true]"},
+		{"Binary", zap.Binary("k", []byte("ab12")), "ab12"},
+		{"Bool", zap.Bool("k", true), "1"},
+		{"ByteString", zap.ByteString("k", []byte("ab12")), "ab12"},
+		{"Complex128", zap.Complex128("k", 1+2i), "(1+2i)"},
+		{"Complex64", zap.Complex64("k", 1+2i), "(1+2i)"},
+		{"Duration", zap.Duration("k", 1), "1"},
+		{"Float64", zap.Float64("k", 3.14), "4614253070214989087"},
+		{"Float32", zap.Float32("k", 3.14), "1078523331"},
+		{"Int64", zap.Int64("k", 1), "1"},
+		{"Int32", zap.Int32("k", 1), "1"},
+		{"Int16", zap.Int16("k", 1), "1"},
+		{"Int8", zap.Int8("k", 1), "1"},
+		{"String", zap.String("k", "foo"), "foo"},
+		{"Time", zap.Time("k", time.Unix(0, 0).In(time.UTC)), "0 UTC"},
+		{"TimeFull", zap.Time("k", time.Time{}), "0001-01-01 00:00:00 +0000 UTC"},
+		{"Uint", zap.Uint("k", 1), "1"},
+		{"Uint64", zap.Uint64("k", 1), "1"},
+		{"Uint32", zap.Uint32("k", 1), "1"},
+		{"Uint16", zap.Uint16("k", 1), "1"},
+		{"Uint8", zap.Uint8("k", 1), "1"},
+		{"Uintptr", zap.Uintptr("k", 0xa), "10"},
+		{"Namespace", zap.Namespace("k"), "<nil>"},
+		{"Stringer", zap.Stringer("k", addr), "1.2.3.4"},
+		{"Reflect", zap.Reflect("k", ints), "[5 6]"},
+		{"Error", zap.Error(fmt.Errorf("test")), "test"},
+		{"Skip", zap.Skip(), "<nil>"},
+		{"InlineMarshaller", zap.Inline(name), "phil"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			fieldValue := valueToString(getFieldValue(tt.field))
+			if !assert.Equal(t, tt.expect, fieldValue, "Unexpected output  %s.", tt.name) {
+				t.Logf("type expected: %T\nGot: %T", tt.expect, fieldValue)
+			}
+		})
+	}
+}
+
+// usernameTestExample type, which are implements ObjectMarshaller interface.
+type usernameTestExample string
+
+func (n usernameTestExample) MarshalLogObject(enc zapcore.ObjectEncoder) error {
+	enc.AddString("username", string(n))
+	return nil
+}
+
+// boolsTestExample type, which are implements ArrayMarshaller interface.
+type boolsTestExample []bool
+
+func (bs boolsTestExample) MarshalLogArray(arr zapcore.ArrayEncoder) error {
+	for i := range bs {
+		arr.AppendBool(bs[i])
+	}
+	return nil
+}
+
+func valueToString(value interface{}) string {
+	switch rv := value.(type) {
+	case string:
+		return rv
+	case []byte:
+		return string(rv)
+	default:
+		return fmt.Sprint(value)
+	}
+}