Go package that provides an implementation of log/slog's Handler interface that ensures a strong correlation between log records and Open-Telemetry spans by...
- Adding span and trace IDs to the log record.
- Adding context baggage members to the log record (can be disabled).
- Adding log record as span event.
- Adding log record attributes to the span event.
- Setting span status based on slog record level (only if >= slog.LevelError).
import (
"context"
"log/slog"
"go.opentelemetry.io/otel/baggage"
"go.opentelemetry.io/otel/trace"
sdktrace "go.opentelemetry.io/otel/sdk/trace"
slogotel "github.com/remychantenay/slog-otel"
)
// 1. Configure slog.
slog.SetDefault(slog.New(slogotel.OtelHandler{
Next: slog.NewJSONHandler(os.Stdout, nil),
}))
// 2. Set up your logger.
logger := slog.Default()
logger = logger.With("component", "server")
// 3. (Optional) Add baggage to your context.
m1, _ := baggage.NewMember("key_1", "value_1")
m2, _ := baggage.NewMember("key_2", "value_2")
bag, _ := baggage.New(m1, m2)
ctx := baggage.ContextWithBaggage(context.Background(), bag)
// 4. Start your span.
ctx, span := tracer.Start(ctx, "operation-name")
defer span.End()
// 5. Log.
logger.InfoContext(ctx, "Hello world!", "locale", "en_US")The following initial log:
{
"time": "2023-09-11T08:28:02.77215605Z",
"level": "INFO",
"component": "server",
"msg": "Hello world!",
"locale": "en_US"
}... will be written as:
{
"time": "2023-09-11T08:28:02.77215605Z",
"level": "INFO",
"component": "server",
"msg": "Hello world!",
"locale": "en_US",
"trace_id": "a9938fd7a6313e0f27f3fc87f574bff6",
"span_id": "ed58f84d8971bf60",
"key_1": "value_1",
"key_2": "value_2"
}and the related span will look like:
{
"Name": "GET /resources",
"SpanContext": {
"TraceID": "a9938fd7a6313e0f27f3fc87f574bff6",
"SpanID": "ed58f84d8971bf60",
...
},
"Parent": {
...
},
"SpanKind": 2,
"StartTime": "2023-09-11T08:28:02.761992425Z",
"EndTime": "2023-09-11T08:28:02.773230425Z",
"Attributes": [{
"Key": "http.method",
"Value": {
"Type": "STRING",
"Value": "GET"
}
},
...
],
"Events": [{
"Name": "log_record",
"Attributes": [{
"Key": "msg",
"Value": {
"Type": "STRING",
"Value": "Hello world!"
}
},
{
"Key": "level",
"Value": {
"Type": "STRING",
"Value": "INFO"
}
},
{
"Key": "time",
"Value": {
"Type": "STRING",
"Value": "2023-09-11T08:28:02.77215605Z"
}
},
{
"Key": "locale",
"Value": {
"Type": "STRING",
"Value": "en_US"
}
},
{
"Key": "component",
"Value": {
"Type": "STRING",
"Value": "server"
}
}
],
}],
...
}Apache License Version 2.0
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