[chore] Simplify the OTEL setup (#4110)

# Description

This simplifies our OTEL setup by:

* Getting rid of some deprecated things.
* Using `autoexport` and letting things get configured by the `OTEL_` environment variables.
* Removing all the unnecessary config options.

## Checklist

Please put an x inside each checkbox to indicate that you've read and followed it: `[ ]` -> `[x]`

If this is a documentation change, only the first checkbox must be filled (you can delete the others if you want).

- [x] I/we have read the [GoToSocial contribution guidelines](https://codeberg.org/superseriousbusiness/gotosocial/src/branch/main/CONTRIBUTING.md).
- [x] I/we have discussed the proposed changes already, either in an issue on the repository, or in the Matrix chat.
- [x] I/we have not leveraged AI to create the proposed changes.
- [x] I/we have performed a self-review of added code.
- [x] I/we have written code that is legible and maintainable by others.
- [ ] I/we have commented the added code, particularly in hard-to-understand areas.
- [x] I/we have made any necessary changes to documentation.
- [ ] I/we have added tests that cover new code.
- [x] I/we have run tests and they pass locally with the changes.
- [x] I/we have run `go fmt ./...` and `golangci-lint run`.

Reviewed-on: https://codeberg.org/superseriousbusiness/gotosocial/pulls/4110
Reviewed-by: tobi <kipvandenbos@noreply.codeberg.org>
Co-authored-by: Daenney <daenney@noreply.codeberg.org>
Co-committed-by: Daenney <daenney@noreply.codeberg.org>

1 files changed, 103 insertions, 0 deletions

diff --git a/vendor/go.opentelemetry.io/otel/exporters/stdout/stdouttrace/trace.go b/vendor/go.opentelemetry.io/otel/exporters/stdout/stdouttrace/trace.go
new file mode 100644
index 000000000..bdb915ba8
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/exporters/stdout/stdouttrace/trace.go
@@ -0,0 +1,103 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package stdouttrace // import "go.opentelemetry.io/otel/exporters/stdout/stdouttrace"
+
+import (
+	"context"
+	"encoding/json"
+	"sync"
+	"time"
+
+	"go.opentelemetry.io/otel/sdk/trace"
+	"go.opentelemetry.io/otel/sdk/trace/tracetest"
+)
+
+var zeroTime time.Time
+
+var _ trace.SpanExporter = &Exporter{}
+
+// New creates an Exporter with the passed options.
+func New(options ...Option) (*Exporter, error) {
+	cfg := newConfig(options...)
+
+	enc := json.NewEncoder(cfg.Writer)
+	if cfg.PrettyPrint {
+		enc.SetIndent("", "\t")
+	}
+
+	return &Exporter{
+		encoder:    enc,
+		timestamps: cfg.Timestamps,
+	}, nil
+}
+
+// Exporter is an implementation of trace.SpanSyncer that writes spans to stdout.
+type Exporter struct {
+	encoder    *json.Encoder
+	encoderMu  sync.Mutex
+	timestamps bool
+
+	stoppedMu sync.RWMutex
+	stopped   bool
+}
+
+// ExportSpans writes spans in json format to stdout.
+func (e *Exporter) ExportSpans(ctx context.Context, spans []trace.ReadOnlySpan) error {
+	if err := ctx.Err(); err != nil {
+		return err
+	}
+	e.stoppedMu.RLock()
+	stopped := e.stopped
+	e.stoppedMu.RUnlock()
+	if stopped {
+		return nil
+	}
+
+	if len(spans) == 0 {
+		return nil
+	}
+
+	stubs := tracetest.SpanStubsFromReadOnlySpans(spans)
+
+	e.encoderMu.Lock()
+	defer e.encoderMu.Unlock()
+	for i := range stubs {
+		stub := &stubs[i]
+		// Remove timestamps
+		if !e.timestamps {
+			stub.StartTime = zeroTime
+			stub.EndTime = zeroTime
+			for j := range stub.Events {
+				ev := &stub.Events[j]
+				ev.Time = zeroTime
+			}
+		}
+
+		// Encode span stubs, one by one
+		if err := e.encoder.Encode(stub); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Shutdown is called to stop the exporter, it performs no action.
+func (e *Exporter) Shutdown(ctx context.Context) error {
+	e.stoppedMu.Lock()
+	e.stopped = true
+	e.stoppedMu.Unlock()
+
+	return nil
+}
+
+// MarshalLog is the marshaling function used by the logging system to represent this Exporter.
+func (e *Exporter) MarshalLog() interface{} {
+	return struct {
+		Type           string
+		WithTimestamps bool
+	}{
+		Type:           "stdout",
+		WithTimestamps: e.timestamps,
+	}
+}