mirror of
https://github.com/caddyserver/caddy.git
synced 2025-10-31 02:27:19 -04:00
120 lines
3.3 KiB
Go
120 lines
3.3 KiB
Go
package tracing
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import (
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"fmt"
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"net/http"
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"go.uber.org/zap"
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"github.com/caddyserver/caddy/v2"
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"github.com/caddyserver/caddy/v2/caddyconfig/caddyfile"
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"github.com/caddyserver/caddy/v2/caddyconfig/httpcaddyfile"
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"github.com/caddyserver/caddy/v2/modules/caddyhttp"
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)
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func init() {
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caddy.RegisterModule(Tracing{})
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httpcaddyfile.RegisterHandlerDirective("tracing", parseCaddyfile)
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}
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// Tracing implements an HTTP handler that adds support for distributed tracing,
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// using OpenTelemetry. This module is responsible for the injection and
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// propagation of the trace context. Configure this module via environment
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// variables (see https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/sdk-environment-variables.md).
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// Some values can be overwritten in the configuration file.
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type Tracing struct {
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// SpanName is a span name. It should follow the naming guidelines here:
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// https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/api.md#span
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SpanName string `json:"span"`
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// otel implements opentelemetry related logic.
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otel openTelemetryWrapper
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logger *zap.Logger
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}
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// CaddyModule returns the Caddy module information.
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func (Tracing) CaddyModule() caddy.ModuleInfo {
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return caddy.ModuleInfo{
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ID: "http.handlers.tracing",
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New: func() caddy.Module { return new(Tracing) },
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}
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}
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// Provision implements caddy.Provisioner.
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func (ot *Tracing) Provision(ctx caddy.Context) error {
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ot.logger = ctx.Logger()
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var err error
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ot.otel, err = newOpenTelemetryWrapper(ctx, ot.SpanName)
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return err
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}
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// Cleanup implements caddy.CleanerUpper and closes any idle connections. It
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// calls Shutdown method for a trace provider https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/sdk.md#shutdown.
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func (ot *Tracing) Cleanup() error {
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if err := ot.otel.cleanup(ot.logger); err != nil {
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return fmt.Errorf("tracerProvider shutdown: %w", err)
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}
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return nil
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}
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// ServeHTTP implements caddyhttp.MiddlewareHandler.
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func (ot *Tracing) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyhttp.Handler) error {
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return ot.otel.ServeHTTP(w, r, next)
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}
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// UnmarshalCaddyfile sets up the module from Caddyfile tokens. Syntax:
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//
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// tracing {
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// [span <span_name>]
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// }
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func (ot *Tracing) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
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setParameter := func(d *caddyfile.Dispenser, val *string) error {
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if d.NextArg() {
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*val = d.Val()
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} else {
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return d.ArgErr()
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}
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if d.NextArg() {
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return d.ArgErr()
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}
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return nil
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}
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// paramsMap is a mapping between "string" parameter from the Caddyfile and its destination within the module
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paramsMap := map[string]*string{
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"span": &ot.SpanName,
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}
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d.Next() // consume directive name
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if d.NextArg() {
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return d.ArgErr()
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}
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for d.NextBlock(0) {
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if dst, ok := paramsMap[d.Val()]; ok {
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if err := setParameter(d, dst); err != nil {
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return err
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}
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} else {
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return d.ArgErr()
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}
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}
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return nil
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}
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func parseCaddyfile(h httpcaddyfile.Helper) (caddyhttp.MiddlewareHandler, error) {
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var m Tracing
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err := m.UnmarshalCaddyfile(h.Dispenser)
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return &m, err
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}
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// Interface guards
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var (
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_ caddy.Provisioner = (*Tracing)(nil)
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_ caddyhttp.MiddlewareHandler = (*Tracing)(nil)
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_ caddyfile.Unmarshaler = (*Tracing)(nil)
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)
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