[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>

vendor/go.opentelemetry.io/otel/sdk/log/provider.go

@@ -0,0 +1,256 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package log // import "go.opentelemetry.io/otel/sdk/log"
+
+import (
+	"context"
+	"errors"
+	"sync"
+	"sync/atomic"
+
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/internal/global"
+	"go.opentelemetry.io/otel/log"
+	"go.opentelemetry.io/otel/log/embedded"
+	"go.opentelemetry.io/otel/log/noop"
+	"go.opentelemetry.io/otel/sdk/instrumentation"
+	"go.opentelemetry.io/otel/sdk/resource"
+)
+
+const (
+	defaultAttrCntLim    = 128
+	defaultAttrValLenLim = -1
+
+	envarAttrCntLim    = "OTEL_LOGRECORD_ATTRIBUTE_COUNT_LIMIT"
+	envarAttrValLenLim = "OTEL_LOGRECORD_ATTRIBUTE_VALUE_LENGTH_LIMIT"
+)
+
+type providerConfig struct {
+	resource       *resource.Resource
+	processors     []Processor
+	fltrProcessors []FilterProcessor
+	attrCntLim     setting[int]
+	attrValLenLim  setting[int]
+}
+
+func newProviderConfig(opts []LoggerProviderOption) providerConfig {
+	var c providerConfig
+	for _, opt := range opts {
+		c = opt.apply(c)
+	}
+
+	if c.resource == nil {
+		c.resource = resource.Default()
+	}
+
+	c.attrCntLim = c.attrCntLim.Resolve(
+		getenv[int](envarAttrCntLim),
+		fallback[int](defaultAttrCntLim),
+	)
+
+	c.attrValLenLim = c.attrValLenLim.Resolve(
+		getenv[int](envarAttrValLenLim),
+		fallback[int](defaultAttrValLenLim),
+	)
+
+	return c
+}
+
+// LoggerProvider handles the creation and coordination of Loggers. All Loggers
+// created by a LoggerProvider will be associated with the same Resource.
+type LoggerProvider struct {
+	embedded.LoggerProvider
+
+	resource                  *resource.Resource
+	processors                []Processor
+	fltrProcessors            []FilterProcessor
+	attributeCountLimit       int
+	attributeValueLengthLimit int
+
+	loggersMu sync.Mutex
+	loggers   map[instrumentation.Scope]*logger
+
+	stopped atomic.Bool
+
+	noCmp [0]func() //nolint: unused  // This is indeed used.
+}
+
+// Compile-time check LoggerProvider implements log.LoggerProvider.
+var _ log.LoggerProvider = (*LoggerProvider)(nil)
+
+// NewLoggerProvider returns a new and configured LoggerProvider.
+//
+// By default, the returned LoggerProvider is configured with the default
+// Resource and no Processors. Processors cannot be added after a LoggerProvider is
+// created. This means the returned LoggerProvider, one created with no
+// Processors, will perform no operations.
+func NewLoggerProvider(opts ...LoggerProviderOption) *LoggerProvider {
+	cfg := newProviderConfig(opts)
+	return &LoggerProvider{
+		resource:                  cfg.resource,
+		processors:                cfg.processors,
+		fltrProcessors:            cfg.fltrProcessors,
+		attributeCountLimit:       cfg.attrCntLim.Value,
+		attributeValueLengthLimit: cfg.attrValLenLim.Value,
+	}
+}
+
+// Logger returns a new [log.Logger] with the provided name and configuration.
+//
+// If p is shut down, a [noop.Logger] instance is returned.
+//
+// This method can be called concurrently.
+func (p *LoggerProvider) Logger(name string, opts ...log.LoggerOption) log.Logger {
+	if name == "" {
+		global.Warn("Invalid Logger name.", "name", name)
+	}
+
+	if p.stopped.Load() {
+		return noop.NewLoggerProvider().Logger(name, opts...)
+	}
+
+	cfg := log.NewLoggerConfig(opts...)
+	scope := instrumentation.Scope{
+		Name:       name,
+		Version:    cfg.InstrumentationVersion(),
+		SchemaURL:  cfg.SchemaURL(),
+		Attributes: cfg.InstrumentationAttributes(),
+	}
+
+	p.loggersMu.Lock()
+	defer p.loggersMu.Unlock()
+
+	if p.loggers == nil {
+		l := newLogger(p, scope)
+		p.loggers = map[instrumentation.Scope]*logger{scope: l}
+		return l
+	}
+
+	l, ok := p.loggers[scope]
+	if !ok {
+		l = newLogger(p, scope)
+		p.loggers[scope] = l
+	}
+
+	return l
+}
+
+// Shutdown shuts down the provider and all processors.
+//
+// This method can be called concurrently.
+func (p *LoggerProvider) Shutdown(ctx context.Context) error {
+	stopped := p.stopped.Swap(true)
+	if stopped {
+		return nil
+	}
+
+	var err error
+	for _, p := range p.processors {
+		err = errors.Join(err, p.Shutdown(ctx))
+	}
+	return err
+}
+
+// ForceFlush flushes all processors.
+//
+// This method can be called concurrently.
+func (p *LoggerProvider) ForceFlush(ctx context.Context) error {
+	if p.stopped.Load() {
+		return nil
+	}
+
+	var err error
+	for _, p := range p.processors {
+		err = errors.Join(err, p.ForceFlush(ctx))
+	}
+	return err
+}
+
+// LoggerProviderOption applies a configuration option value to a LoggerProvider.
+type LoggerProviderOption interface {
+	apply(providerConfig) providerConfig
+}
+
+type loggerProviderOptionFunc func(providerConfig) providerConfig
+
+func (fn loggerProviderOptionFunc) apply(c providerConfig) providerConfig {
+	return fn(c)
+}
+
+// WithResource associates a Resource with a LoggerProvider. This Resource
+// represents the entity producing telemetry and is associated with all Loggers
+// the LoggerProvider will create.
+//
+// By default, if this Option is not used, the default Resource from the
+// go.opentelemetry.io/otel/sdk/resource package will be used.
+func WithResource(res *resource.Resource) LoggerProviderOption {
+	return loggerProviderOptionFunc(func(cfg providerConfig) providerConfig {
+		var err error
+		cfg.resource, err = resource.Merge(resource.Environment(), res)
+		if err != nil {
+			otel.Handle(err)
+		}
+		return cfg
+	})
+}
+
+// WithProcessor associates Processor with a LoggerProvider.
+//
+// By default, if this option is not used, the LoggerProvider will perform no
+// operations; no data will be exported without a processor.
+//
+// The SDK invokes the processors sequentially in the same order as they were
+// registered.
+//
+// For production, use [NewBatchProcessor] to batch log records before they are exported.
+// For testing and debugging, use [NewSimpleProcessor] to synchronously export log records.
+//
+// See [FilterProcessor] for information about how a Processor can support filtering.
+func WithProcessor(processor Processor) LoggerProviderOption {
+	return loggerProviderOptionFunc(func(cfg providerConfig) providerConfig {
+		cfg.processors = append(cfg.processors, processor)
+		if f, ok := processor.(FilterProcessor); ok {
+			cfg.fltrProcessors = append(cfg.fltrProcessors, f)
+		}
+		return cfg
+	})
+}
+
+// WithAttributeCountLimit sets the maximum allowed log record attribute count.
+// Any attribute added to a log record once this limit is reached will be dropped.
+//
+// Setting this to zero means no attributes will be recorded.
+//
+// Setting this to a negative value means no limit is applied.
+//
+// If the OTEL_LOGRECORD_ATTRIBUTE_COUNT_LIMIT environment variable is set,
+// and this option is not passed, that variable value will be used.
+//
+// By default, if an environment variable is not set, and this option is not
+// passed, 128 will be used.
+func WithAttributeCountLimit(limit int) LoggerProviderOption {
+	return loggerProviderOptionFunc(func(cfg providerConfig) providerConfig {
+		cfg.attrCntLim = newSetting(limit)
+		return cfg
+	})
+}
+
+// AttributeValueLengthLimit sets the maximum allowed attribute value length.
+//
+// This limit only applies to string and string slice attribute values.
+// Any string longer than this value will be truncated to this length.
+//
+// Setting this to a negative value means no limit is applied.
+//
+// If the OTEL_LOGRECORD_ATTRIBUTE_VALUE_LENGTH_LIMIT environment variable is set,
+// and this option is not passed, that variable value will be used.
+//
+// By default, if an environment variable is not set, and this option is not
+// passed, no limit (-1) will be used.
+func WithAttributeValueLengthLimit(limit int) LoggerProviderOption {
+	return loggerProviderOptionFunc(func(cfg providerConfig) providerConfig {
+		cfg.attrValLenLim = newSetting(limit)
+		return cfg
+	})
+}