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shadow.go
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shadow.go
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// SPDX-License-Identifier: Apache-2.0
package proxy
import (
"context"
"github.com/luraproject/lura/v2/config"
)
const (
shadowKey = "shadow"
)
type shadowFactory struct {
f Factory
}
// New check the Backends for an ExtraConfig with the "shadow" param to true
// implements the Factory interface
func (s shadowFactory) New(cfg *config.EndpointConfig) (p Proxy, err error) {
if len(cfg.Backend) == 0 {
err = ErrNoBackends
return
}
shadow := []*config.Backend{}
regular := []*config.Backend{}
for _, b := range cfg.Backend {
if isShadowBackend(b) {
shadow = append(shadow, b)
continue
}
regular = append(regular, b)
}
cfg.Backend = regular
p, err = s.f.New(cfg)
if len(shadow) > 0 {
cfg.Backend = shadow
pShadow, _ := s.f.New(cfg)
p = ShadowMiddleware(p, pShadow)
}
return
}
// NewShadowFactory creates a new shadowFactory using the provided Factory
func NewShadowFactory(f Factory) Factory {
return shadowFactory{f}
}
// ShadowMiddleware is a Middleware that creates a shadowProxy
func ShadowMiddleware(next ...Proxy) Proxy {
switch len(next) {
case 0:
panic(ErrNotEnoughProxies)
case 1:
return next[0]
case 2:
return NewShadowProxy(next[0], next[1])
default:
panic(ErrTooManyProxies)
}
}
// NewShadowProxy returns a Proxy that sends requests to p1 and p2 but ignores
// the response of p2
func NewShadowProxy(p1, p2 Proxy) Proxy {
return func(ctx context.Context, request *Request) (*Response, error) {
go p2(newcontextWrapper(ctx), CloneRequest(request))
return p1(ctx, request)
}
}
func isShadowBackend(c *config.Backend) bool {
if v, ok := c.ExtraConfig[Namespace]; ok {
if e, ok := v.(map[string]interface{}); ok {
if v, ok := e[shadowKey]; ok {
c, ok := v.(bool)
return ok && c
}
}
}
return false
}
type contextWrapper struct {
context.Context
data context.Context
}
func (c contextWrapper) Value(key interface{}) interface{} {
return c.data.Value(key)
}
func newcontextWrapper(data context.Context) contextWrapper {
return contextWrapper{
Context: context.Background(),
data: data,
}
}