[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, 93 insertions, 0 deletions

diff --git a/vendor/go.opentelemetry.io/contrib/exporters/autoexport/logs.go b/vendor/go.opentelemetry.io/contrib/exporters/autoexport/logs.go
new file mode 100644
index 000000000..dd12d0332
--- /dev/null
+++ b/vendor/go.opentelemetry.io/contrib/exporters/autoexport/logs.go
@@ -0,0 +1,93 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package autoexport // import "go.opentelemetry.io/contrib/exporters/autoexport"
+
+import (
+	"context"
+	"os"
+
+	"go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploggrpc"
+	"go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploghttp"
+	"go.opentelemetry.io/otel/exporters/stdout/stdoutlog"
+	"go.opentelemetry.io/otel/sdk/log"
+)
+
+const otelExporterOTLPLogsProtoEnvKey = "OTEL_EXPORTER_OTLP_LOGS_PROTOCOL"
+
+// LogOption applies an autoexport configuration option.
+type LogOption = option[log.Exporter]
+
+var logsSignal = newSignal[log.Exporter]("OTEL_LOGS_EXPORTER")
+
+// WithFallbackLogExporter sets the fallback exporter to use when no exporter
+// is configured through the OTEL_LOGS_EXPORTER environment variable.
+func WithFallbackLogExporter(logExporterFactory func(ctx context.Context) (log.Exporter, error)) LogOption {
+	return withFallbackFactory[log.Exporter](logExporterFactory)
+}
+
+// NewLogExporter returns a configured [go.opentelemetry.io/otel/sdk/log.Exporter]
+// defined using the environment variables described below.
+//
+// OTEL_LOGS_EXPORTER defines the logs exporter; supported values:
+//   - "none" - "no operation" exporter
+//   - "otlp" (default) - OTLP exporter; see [go.opentelemetry.io/otel/exporters/otlp/otlplog]
+//   - "console" - Standard output exporter; see [go.opentelemetry.io/otel/exporters/stdout/stdoutlog]
+//
+// OTEL_EXPORTER_OTLP_PROTOCOL defines OTLP exporter's transport protocol;
+// supported values:
+//   - "http/protobuf" (default) -  protobuf-encoded data over HTTP connection;
+//     see: [go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploghttp]
+//   - "grpc" - gRPC with protobuf-encoded data over HTTP/2 connection;
+//     see: [go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploggrpc]
+//
+// OTEL_EXPORTER_OTLP_LOGS_PROTOCOL defines OTLP exporter's transport protocol for the logs signal;
+// supported values are the same as OTEL_EXPORTER_OTLP_PROTOCOL.
+//
+// An error is returned if an environment value is set to an unhandled value.
+//
+// Use [RegisterLogExporter] to handle more values of OTEL_LOGS_EXPORTER.
+//
+// Use [WithFallbackLogExporter] option to change the returned exporter
+// when OTEL_LOGS_EXPORTER is unset or empty.
+//
+// Use [IsNoneLogExporter] to check if the returned exporter is a "no operation" exporter.
+func NewLogExporter(ctx context.Context, opts ...LogOption) (log.Exporter, error) {
+	return logsSignal.create(ctx, opts...)
+}
+
+// RegisterLogExporter sets the log.Exporter factory to be used when the
+// OTEL_LOGS_EXPORTER environment variable contains the exporter name.
+// This will panic if name has already been registered.
+func RegisterLogExporter(name string, factory func(context.Context) (log.Exporter, error)) {
+	must(logsSignal.registry.store(name, factory))
+}
+
+func init() {
+	RegisterLogExporter("otlp", func(ctx context.Context) (log.Exporter, error) {
+		proto := os.Getenv(otelExporterOTLPLogsProtoEnvKey)
+		if proto == "" {
+			proto = os.Getenv(otelExporterOTLPProtoEnvKey)
+		}
+
+		// Fallback to default, http/protobuf.
+		if proto == "" {
+			proto = "http/protobuf"
+		}
+
+		switch proto {
+		case "grpc":
+			return otlploggrpc.New(ctx)
+		case "http/protobuf":
+			return otlploghttp.New(ctx)
+		default:
+			return nil, errInvalidOTLPProtocol
+		}
+	})
+	RegisterLogExporter("console", func(ctx context.Context) (log.Exporter, error) {
+		return stdoutlog.New()
+	})
+	RegisterLogExporter("none", func(ctx context.Context) (log.Exporter, error) {
+		return noopLogExporter{}, nil
+	})
+}