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proxy.go
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proxy.go
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package restapi
import (
"fmt"
"net/url"
"strings"
"sync"
"github.com/labstack/echo/v4"
"github.com/labstack/echo/v4/middleware"
)
type DynamicProxy struct {
group *echo.Group
balancer *balancer
}
type balancer struct {
mutex sync.RWMutex
prefix string
targets map[string]*middleware.ProxyTarget
}
func (b *balancer) AddTarget(target *middleware.ProxyTarget) bool {
b.mutex.Lock()
defer b.mutex.Unlock()
b.targets[target.Name] = target
return false
}
func (b *balancer) RemoveTarget(prefix string) bool {
b.mutex.Lock()
defer b.mutex.Unlock()
delete(b.targets, prefix)
return true
}
func (b *balancer) Next(c echo.Context) *middleware.ProxyTarget {
b.mutex.RLock()
defer b.mutex.RUnlock()
uri := b.uriFromRequest(c)
name := strings.TrimPrefix(uri, "/")
for k, v := range b.targets {
if strings.HasPrefix(name, k) {
return v
}
}
return nil
}
func (b *balancer) uriFromRequest(c echo.Context) string {
req := c.Request()
rawURI := req.RequestURI
if rawURI != "" && rawURI[0] != '/' {
prefix := ""
if req.URL.Scheme != "" {
prefix = req.URL.Scheme + "://"
}
if req.URL.Host != "" {
prefix += req.URL.Host // host or host:port
}
if prefix != "" {
rawURI = strings.TrimPrefix(rawURI, prefix)
}
}
rawURI = strings.TrimPrefix(rawURI, b.prefix)
return rawURI
}
func (b *balancer) skipper(c echo.Context) bool {
return b.Next(c) == nil
}
func (b *balancer) AddTargetHostAndPort(prefix string, host string, port uint32) error {
apiURL, err := url.Parse(fmt.Sprintf("http://%s:%d", host, port))
if err != nil {
return err
}
b.AddTarget(&middleware.ProxyTarget{
Name: prefix,
URL: apiURL,
})
return nil
}
func NewDynamicProxy(e *echo.Echo, prefix string) *DynamicProxy {
balancer := &balancer{
prefix: prefix,
targets: map[string]*middleware.ProxyTarget{},
}
proxy := &DynamicProxy{
group: e.Group(prefix),
balancer: balancer,
}
return proxy
}
func (p *DynamicProxy) middleware(prefix string) echo.MiddlewareFunc {
config := middleware.DefaultProxyConfig
config.Skipper = p.balancer.skipper
config.Balancer = p.balancer
config.Rewrite = map[string]string{
fmt.Sprintf("^%s/%s/*", p.balancer.prefix, prefix): "/$1",
}
return middleware.ProxyWithConfig(config)
}
func (p *DynamicProxy) AddGroup(prefix string) *echo.Group {
return p.group.Group("/" + prefix)
}
func (p *DynamicProxy) AddReverseProxy(prefix string, host string, port uint32) error {
if err := p.balancer.AddTargetHostAndPort(prefix, host, port); err != nil {
return err
}
p.AddGroup(prefix).Use(p.middleware(prefix))
return nil
}
func (p *DynamicProxy) RemoveReverseProxy(prefix string) {
p.balancer.RemoveTarget(prefix)
}