Initial commit
This commit is contained in:
commit
9f280a7883
3 changed files with 316 additions and 0 deletions
85
README.md
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85
README.md
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# Purpose
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`Vlog` extends the structured log JSONHandler with sending logs to a VictoriaLogs instance for central logging.
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Logs are first queued to a buffered channel processed by go-routine loop which transform and send the log to the server.
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In case of network error, queue getting full - anything that doesn't get a HTTP 200 from VictoriaLogs; logs get stored to disk to be processed at intervals.
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Streams are set to separate application runs to instances of it running on different servers.
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# Usage
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```golang
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package main
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import (
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// External
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"git.gibonuddevalla.se/go/vlog"
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// Standard
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"log/slog"
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"os"
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"time"
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)
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func main() {
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opts := slog.HandlerOptions{
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Level: slog.LevelInfo, // Minimum level to display.
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}
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handler := vlog.New(
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os.Stdout,
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opts,
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"/tmp/vlog_spool", // Spool directory when logs can't be sent.
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"https://log.hum.se/", // URL to VictoriaLogs instance.
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"vlog", // Application name.
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"srv01", // System/server that runs the instance.
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"dev", // Instance name.
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)
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log := slog.New(handler)
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for {
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log.Warn("server", "foo", "bar", "baz", 123)
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time.Sleep(time.Second * 1)
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}
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}
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```
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# Logging stream
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The stream is created with:
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1) application name.
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1) system name running the software.
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1) instance name (like dev or prod).
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1) run, which is automated to YYMMDD_HHMMSS when application is started.
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These are prefixed with `log`, see JSON data below.
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# Logging data
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Application log attributes (`foo`, `baz` in the example code) are added to the top level log entry.
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The vlog library adds go build information (git repo and such) and a runtime trace when sending logs with level `warn`, `warn` or `error`.
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The `info` level is excepted to this since it would probably be used the most for regular data that wouldn't lead to any troubleshooting. Making the trace eats a bit of performance.
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```json
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{
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"_time": "2026-02-14T08:43:02.760194943Z",
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"_stream_id": "0000000000000000926515688d74d64c8facef73b36a02b5",
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"_stream": "{log.application=\"vlog\",log.instance=\"dev\",log.run=\"260214_094242\",log.system=\"srv01\"}",
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"_msg": "server",
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"baz": "123",
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"foo": "bar",
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"log.application": "vlog",
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"log.instance": "dev",
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"log.level": "WARN",
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"log.run": "260214_094242",
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"log.system": "srv01",
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"log.build": "{\"GoVersion\":\"go1.25.4\",\"Path\":\"hum\",\"Main\":{\"Path\":\"hum\",\"Version\":\"(devel)\"},\"Deps\":[{\"Path\":\"git.gibonuddevalla.se/go/vlog\",\"Version\":\"(devel)\"}],\"Settings\":[{\"Key\":\"-buildmode\",\"Value\":\"exe\"},{\"Key\":\"-compiler\",\"Value\":\"gc\"},{\"Key\":\"CGO_ENABLED\",\"Value\":\"1\"},{\"Key\":\"CGO_CFLAGS\"},{\"Key\":\"CGO_CPPFLAGS\"},{\"Key\":\"CGO_CXXFLAGS\"},{\"Key\":\"CGO_LDFLAGS\"},{\"Key\":\"GOARCH\",\"Value\":\"amd64\"},{\"Key\":\"GOOS\",\"Value\":\"linux\"},{\"Key\":\"GOAMD64\",\"Value\":\"v1\"}]}",
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"log.trace": "goroutine 1 [running]:\nruntime/debug.Stack()\n\t/usr/local/go/src/runtime/debug/stack.go:26 +0x5e\ngit.gibonuddevalla.se/go/vlog.(*VictoriaHandler).queue(_, {{0xc25c2b45ad4fa77f, 0x4a9205feb, 0x9bf140}, {0x7339a5, 0x6}, 0x4, 0x65125f, {{{0x73345d, 0x3}, ...}, ...}, ...})\n\t/tmp/foo/vlog/lib.go:146 +0x65\ngit.gibonuddevalla.se/go/vlog.VictoriaHandler.Handle({0xc000074080, {0x7335b3, 0x4}, {0x733793, 0x5}, {0x733466, 0x3}, {0x73842d, 0x14}, {0x7aec30, ...}, ...}, ...)\n\t/tmp/foo/vlog/lib.go:75 +0x65\nlog/slog.(*Logger).log(0xc0000f3f30, {0x7aebf8?, 0x9e03c0?}, 0x4, {0x7339a5, 0x6}, {0xc0000f3ef0, 0x4, 0x4})\n\t/usr/local/go/src/log/slog/logger.go:256 +0x208\nlog/slog.(*Logger).Warn(...)\n\t/usr/local/go/src/log/slog/logger.go:219\nmain.main()\n\t/tmp/foo/hum/main.go:31 +0x1a6\n"
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}
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```
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3
go.mod
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3
go.mod
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module git.gibonuddevalla.se/go/vlog
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go 1.25.4
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228
lib.go
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228
lib.go
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package vlog
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import (
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// Standard
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"bytes"
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"context"
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"encoding/json"
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"fmt"
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"io"
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"io/fs"
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"log/slog"
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"net/http"
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"net/url"
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"os"
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"path"
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"path/filepath"
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"runtime/debug"
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"time"
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)
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type VictoriaHandler struct {
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*slog.JSONHandler
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Application string
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System string
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Instance string
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URL string
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handler slog.Handler
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filecounter int
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logdir string
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logQueue chan []byte
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run string
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log *slog.Logger
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httpClient http.Client
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}
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type LogData struct {
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Level string
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Msg string
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Args []any
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}
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func New(w io.Writer, opts slog.HandlerOptions, logdir, url, application, system, instance string) (vl VictoriaHandler) { // {{{
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var err error
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vl.JSONHandler = slog.NewJSONHandler(w, &opts)
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vl.httpClient = http.Client{}
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vl.logQueue = make(chan []byte, 8192)
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vl.logdir = logdir
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vl.handler = slog.NewJSONHandler(w, &opts)
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// logdir is used to spool logfiles in case of
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err = os.MkdirAll(logdir, 0700)
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if err != nil {
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panic(err)
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}
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vl.log = slog.New(slog.NewJSONHandler(w, &opts))
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vl.log.Debug("VICTORIALOG", "tempory_storage", vl.logdir)
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vl.URL = url
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vl.Application = application
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vl.System = system
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vl.Instance = instance
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vl.run = time.Now().Format("060102_150405")
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go vl.queueHandler()
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go vl.diskHandler()
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return
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} // }}}
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// Handle is overridden to enable central logging.
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func (vl VictoriaHandler) Handle(ctx context.Context, record slog.Record) error {// {{{
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vl.queue(record)
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return vl.handler.Handle(ctx, record)
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}// }}}
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func (vl *VictoriaHandler) diskHandler() { // {{{
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for {
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time.Sleep(time.Second * 5)
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err := filepath.WalkDir(vl.logdir, func(fname string, d fs.DirEntry, err error) error {
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if d.IsDir() {
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return nil
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}
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data, err := os.ReadFile(fname)
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if err != nil {
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vl.log.Error("VICTORIALOG", "error", err)
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return nil
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}
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err = vl.send(data)
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if err != nil {
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vl.log.Error("VICTORIALOG", "error", err)
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return nil
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}
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err = os.Remove(fname)
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if err != nil {
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vl.log.Error("VICTORIALOG", "error", err)
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return nil
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}
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return nil
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})
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if err != nil {
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vl.log.Error("VICTORIALOG", "error", err)
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}
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}
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} // }}}
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func (vl *VictoriaHandler) queueHandler() { // {{{
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var err error
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for {
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msg := <-vl.logQueue
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err = vl.send(msg)
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if err != nil {
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vl.logToFile(msg)
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}
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}
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} // }}}
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func (vl *VictoriaHandler) queue(rec slog.Record) { // {{{
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/*
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{
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"_msg": "hello world"
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"_time": "2026-02-12T09:39:45.374813969Z",
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"log": {
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"level": "info",
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"application": "transcode",
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"system": "server01.hum.ding",
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"instance": "production",
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"run": "260212_123000",
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build: "",
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trace: "",
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},
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"<app_attr>": <data>
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}
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*/
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data := make(map[string]any)
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dataLog := make(map[string]string)
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if rec.Level == slog.LevelDebug || rec.Level == slog.LevelWarn || rec.Level == slog.LevelError {
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trace := debug.Stack()
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buildInfo, _ := debug.ReadBuildInfo()
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buildBytes, _ := json.Marshal(buildInfo)
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dataLog["trace"] = string(trace)
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dataLog["build"] = string(buildBytes)
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}
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dataLog["level"] = rec.Level.String()
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dataLog["application"] = vl.Application
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dataLog["system"] = vl.System
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dataLog["instance"] = vl.Instance
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dataLog["run"] = vl.run
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data["_msg"] = rec.Message
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data["_time"] = rec.Time.Format(time.RFC3339Nano)
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data["log"] = dataLog
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rec.Attrs(func(attr slog.Attr) bool {
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data[attr.Key] = attr.Value.Any()
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return true
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})
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// Data is marshalled into its final form to be queued and sent.
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j, _ := json.Marshal(data)
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select {
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case vl.logQueue <- j:
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vl.log.Debug("VICTORIALOG", "op", "sent to channel")
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default:
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vl.logToFile(j)
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vl.log.Debug("VICTORIALOG", "op", "sent to file")
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}
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} // }}}
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func (vl *VictoriaHandler) send(data []byte) (err error) { // {{{
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request := bytes.NewReader(data)
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// URL is composed with path query cleanly built to
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// ensure correct encoding of it.
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var vlogURL *url.URL
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vlogURL, err = url.Parse(vl.URL + "/insert/jsonline")
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if err != nil {
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vl.log.Error("VICTORIALOG", "error", err)
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return
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}
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values := vlogURL.Query()
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values.Add("_time_field", "_time")
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values.Add("_stream_fields", "log.application,log.system,log.instance,log.run")
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vlogURL.RawQuery = values.Encode()
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// Request is sent to server in order to be centrally lagged.
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var req *http.Request
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req, err = http.NewRequest("POST", vlogURL.String(), request)
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if err != nil {
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vl.log.Error("VICTORIALOG", "error", err)
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return
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}
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var resp *http.Response
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resp, err = vl.httpClient.Do(req)
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if err != nil {
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vl.log.Error("VICTORIALOG", "error", err)
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return
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}
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if resp.StatusCode != 200 {
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body, _ := io.ReadAll(resp.Body)
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vl.log.Error("VICTORIALOG", "error", resp.Status, "body", string(body))
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return fmt.Errorf("Unsuccesful status code, %d", resp.StatusCode)
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}
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vl.log.Debug("VICTORIALOG", "op", "sent to server")
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return
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} // }}}
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func (vl *VictoriaHandler) logToFile(data []byte) { // {{{
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vl.filecounter++
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fname := path.Join(vl.logdir, fmt.Sprintf("%010X.log", vl.filecounter))
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err := os.WriteFile(fname, data, 0600)
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if err != nil {
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vl.log.Error("VICTORIALOG", "error", err)
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return
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}
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vl.log.Error("VICTORIALOG", "op", "sent to disk", "fname", fname)
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} // }}}
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Loading…
Add table
Reference in a new issue