[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, 87 insertions, 0 deletions

diff --git a/vendor/go.opentelemetry.io/contrib/exporters/autoexport/noop.go b/vendor/go.opentelemetry.io/contrib/exporters/autoexport/noop.go
new file mode 100644
index 000000000..2a8b173b2
--- /dev/null
+++ b/vendor/go.opentelemetry.io/contrib/exporters/autoexport/noop.go
@@ -0,0 +1,87 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package autoexport // import "go.opentelemetry.io/contrib/exporters/autoexport"
+
+import (
+	"context"
+
+	"go.opentelemetry.io/otel/sdk/log"
+	"go.opentelemetry.io/otel/sdk/metric"
+	"go.opentelemetry.io/otel/sdk/metric/metricdata"
+	"go.opentelemetry.io/otel/sdk/trace"
+)
+
+// noopSpanExporter is an implementation of trace.SpanExporter that performs no operations.
+type noopSpanExporter struct{}
+
+var _ trace.SpanExporter = noopSpanExporter{}
+
+// ExportSpans is part of trace.SpanExporter interface.
+func (e noopSpanExporter) ExportSpans(ctx context.Context, spans []trace.ReadOnlySpan) error {
+	return nil
+}
+
+// Shutdown is part of trace.SpanExporter interface.
+func (e noopSpanExporter) Shutdown(ctx context.Context) error {
+	return nil
+}
+
+// IsNoneSpanExporter returns true for the exporter returned by [NewSpanExporter]
+// when OTEL_TRACES_EXPORTER environment variable is set to "none".
+func IsNoneSpanExporter(e trace.SpanExporter) bool {
+	_, ok := e.(noopSpanExporter)
+	return ok
+}
+
+type noopMetricReader struct {
+	*metric.ManualReader
+}
+
+func newNoopMetricReader() noopMetricReader {
+	return noopMetricReader{metric.NewManualReader()}
+}
+
+// IsNoneMetricReader returns true for the exporter returned by [NewMetricReader]
+// when OTEL_METRICS_EXPORTER environment variable is set to "none".
+func IsNoneMetricReader(e metric.Reader) bool {
+	_, ok := e.(noopMetricReader)
+	return ok
+}
+
+type noopMetricProducer struct{}
+
+func (e noopMetricProducer) Produce(ctx context.Context) ([]metricdata.ScopeMetrics, error) {
+	return nil, nil
+}
+
+func newNoopMetricProducer() noopMetricProducer {
+	return noopMetricProducer{}
+}
+
+// noopLogExporter is an implementation of log.SpanExporter that performs no operations.
+type noopLogExporter struct{}
+
+var _ log.Exporter = noopLogExporter{}
+
+// ExportSpans is part of log.Exporter interface.
+func (e noopLogExporter) Export(ctx context.Context, records []log.Record) error {
+	return nil
+}
+
+// Shutdown is part of log.Exporter interface.
+func (e noopLogExporter) Shutdown(ctx context.Context) error {
+	return nil
+}
+
+// ForceFlush is part of log.Exporter interface.
+func (e noopLogExporter) ForceFlush(ctx context.Context) error {
+	return nil
+}
+
+// IsNoneLogExporter returns true for the exporter returned by [NewLogExporter]
+// when OTEL_LOGSS_EXPORTER environment variable is set to "none".
+func IsNoneLogExporter(e log.Exporter) bool {
+	_, ok := e.(noopLogExporter)
+	return ok
+}