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package middleware
import (
"context"
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"errors"
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"fmt"
"net/http"
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"strings"
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"github.com/containous/alice"
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"github.com/containous/traefik/pkg/config/runtime"
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"github.com/containous/traefik/pkg/middlewares/addprefix"
"github.com/containous/traefik/pkg/middlewares/auth"
"github.com/containous/traefik/pkg/middlewares/buffering"
"github.com/containous/traefik/pkg/middlewares/chain"
"github.com/containous/traefik/pkg/middlewares/circuitbreaker"
"github.com/containous/traefik/pkg/middlewares/compress"
"github.com/containous/traefik/pkg/middlewares/customerrors"
"github.com/containous/traefik/pkg/middlewares/headers"
"github.com/containous/traefik/pkg/middlewares/ipwhitelist"
"github.com/containous/traefik/pkg/middlewares/maxconnection"
"github.com/containous/traefik/pkg/middlewares/passtlsclientcert"
"github.com/containous/traefik/pkg/middlewares/ratelimiter"
"github.com/containous/traefik/pkg/middlewares/redirect"
"github.com/containous/traefik/pkg/middlewares/replacepath"
"github.com/containous/traefik/pkg/middlewares/replacepathregex"
"github.com/containous/traefik/pkg/middlewares/retry"
"github.com/containous/traefik/pkg/middlewares/stripprefix"
"github.com/containous/traefik/pkg/middlewares/stripprefixregex"
"github.com/containous/traefik/pkg/middlewares/tracing"
"github.com/containous/traefik/pkg/server/internal"
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)
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type middlewareStackType int
const (
middlewareStackKey middlewareStackType = iota
)
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// Builder the middleware builder
type Builder struct {
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configs map [ string ] * runtime . MiddlewareInfo
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serviceBuilder serviceBuilder
}
type serviceBuilder interface {
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BuildHTTP ( ctx context . Context , serviceName string , responseModifier func ( * http . Response ) error ) ( http . Handler , error )
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}
// NewBuilder creates a new Builder
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func NewBuilder ( configs map [ string ] * runtime . MiddlewareInfo , serviceBuilder serviceBuilder ) * Builder {
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return & Builder { configs : configs , serviceBuilder : serviceBuilder }
}
// BuildChain creates a middleware chain
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func ( b * Builder ) BuildChain ( ctx context . Context , middlewares [ ] string ) * alice . Chain {
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chain := alice . New ( )
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for _ , name := range middlewares {
middlewareName := internal . GetQualifiedName ( ctx , name )
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chain = chain . Append ( func ( next http . Handler ) ( http . Handler , error ) {
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constructorContext := internal . AddProviderInContext ( ctx , middlewareName )
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if midInf , ok := b . configs [ middlewareName ] ; ! ok || midInf . Middleware == nil {
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return nil , fmt . Errorf ( "middleware %q does not exist" , middlewareName )
}
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var err error
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if constructorContext , err = checkRecursion ( constructorContext , middlewareName ) ; err != nil {
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b . configs [ middlewareName ] . AddError ( err )
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return nil , err
}
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constructor , err := b . buildConstructor ( constructorContext , middlewareName )
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if err != nil {
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b . configs [ middlewareName ] . AddError ( err )
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return nil , err
}
handler , err := constructor ( next )
if err != nil {
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b . configs [ middlewareName ] . AddError ( err )
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return nil , err
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}
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return handler , nil
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} )
}
return & chain
}
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func checkRecursion ( ctx context . Context , middlewareName string ) ( context . Context , error ) {
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currentStack , ok := ctx . Value ( middlewareStackKey ) . ( [ ] string )
if ! ok {
currentStack = [ ] string { }
}
if inSlice ( middlewareName , currentStack ) {
return ctx , fmt . Errorf ( "could not instantiate middleware %s: recursion detected in %s" , middlewareName , strings . Join ( append ( currentStack , middlewareName ) , "->" ) )
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}
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return context . WithValue ( ctx , middlewareStackKey , append ( currentStack , middlewareName ) ) , nil
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}
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// it is the responsibility of the caller to make sure that b.configs[middlewareName].Middleware exists
func ( b * Builder ) buildConstructor ( ctx context . Context , middlewareName string ) ( alice . Constructor , error ) {
config := b . configs [ middlewareName ]
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var middleware alice . Constructor
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badConf := errors . New ( "cannot create middleware: multi-types middleware not supported, consider declaring two different pieces of middleware instead" )
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// AddPrefix
if config . AddPrefix != nil {
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middleware = func ( next http . Handler ) ( http . Handler , error ) {
return addprefix . New ( ctx , next , * config . AddPrefix , middlewareName )
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}
}
// BasicAuth
if config . BasicAuth != nil {
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if middleware != nil {
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return nil , badConf
}
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middleware = func ( next http . Handler ) ( http . Handler , error ) {
return auth . NewBasic ( ctx , next , * config . BasicAuth , middlewareName )
}
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}
// Buffering
if config . Buffering != nil && config . MaxConn . Amount != 0 {
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if middleware != nil {
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return nil , badConf
}
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middleware = func ( next http . Handler ) ( http . Handler , error ) {
return buffering . New ( ctx , next , * config . Buffering , middlewareName )
}
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}
// Chain
if config . Chain != nil {
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if middleware != nil {
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return nil , badConf
}
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middleware = func ( next http . Handler ) ( http . Handler , error ) {
return chain . New ( ctx , next , * config . Chain , b , middlewareName )
}
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}
// CircuitBreaker
if config . CircuitBreaker != nil {
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if middleware != nil {
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return nil , badConf
}
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middleware = func ( next http . Handler ) ( http . Handler , error ) {
return circuitbreaker . New ( ctx , next , * config . CircuitBreaker , middlewareName )
}
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}
// Compress
if config . Compress != nil {
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if middleware != nil {
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return nil , badConf
}
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middleware = func ( next http . Handler ) ( http . Handler , error ) {
return compress . New ( ctx , next , middlewareName )
}
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}
// CustomErrors
if config . Errors != nil {
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if middleware != nil {
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return nil , badConf
}
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middleware = func ( next http . Handler ) ( http . Handler , error ) {
return customerrors . New ( ctx , next , * config . Errors , b . serviceBuilder , middlewareName )
}
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}
// DigestAuth
if config . DigestAuth != nil {
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if middleware != nil {
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return nil , badConf
}
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middleware = func ( next http . Handler ) ( http . Handler , error ) {
return auth . NewDigest ( ctx , next , * config . DigestAuth , middlewareName )
}
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}
// ForwardAuth
if config . ForwardAuth != nil {
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if middleware != nil {
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return nil , badConf
}
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middleware = func ( next http . Handler ) ( http . Handler , error ) {
return auth . NewForward ( ctx , next , * config . ForwardAuth , middlewareName )
}
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}
// Headers
if config . Headers != nil {
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if middleware != nil {
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return nil , badConf
}
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middleware = func ( next http . Handler ) ( http . Handler , error ) {
return headers . New ( ctx , next , * config . Headers , middlewareName )
}
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}
// IPWhiteList
if config . IPWhiteList != nil {
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if middleware != nil {
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return nil , badConf
}
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middleware = func ( next http . Handler ) ( http . Handler , error ) {
return ipwhitelist . New ( ctx , next , * config . IPWhiteList , middlewareName )
}
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}
// MaxConn
if config . MaxConn != nil && config . MaxConn . Amount != 0 {
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if middleware != nil {
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return nil , badConf
}
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middleware = func ( next http . Handler ) ( http . Handler , error ) {
return maxconnection . New ( ctx , next , * config . MaxConn , middlewareName )
}
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}
// PassTLSClientCert
if config . PassTLSClientCert != nil {
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if middleware != nil {
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return nil , badConf
}
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middleware = func ( next http . Handler ) ( http . Handler , error ) {
return passtlsclientcert . New ( ctx , next , * config . PassTLSClientCert , middlewareName )
}
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}
// RateLimit
if config . RateLimit != nil {
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if middleware != nil {
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return nil , badConf
}
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middleware = func ( next http . Handler ) ( http . Handler , error ) {
return ratelimiter . New ( ctx , next , * config . RateLimit , middlewareName )
}
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}
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// RedirectRegex
if config . RedirectRegex != nil {
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if middleware != nil {
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return nil , badConf
}
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middleware = func ( next http . Handler ) ( http . Handler , error ) {
return redirect . NewRedirectRegex ( ctx , next , * config . RedirectRegex , middlewareName )
}
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}
// RedirectScheme
if config . RedirectScheme != nil {
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if middleware != nil {
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return nil , badConf
}
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middleware = func ( next http . Handler ) ( http . Handler , error ) {
return redirect . NewRedirectScheme ( ctx , next , * config . RedirectScheme , middlewareName )
}
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}
// ReplacePath
if config . ReplacePath != nil {
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if middleware != nil {
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return nil , badConf
}
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middleware = func ( next http . Handler ) ( http . Handler , error ) {
return replacepath . New ( ctx , next , * config . ReplacePath , middlewareName )
}
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}
// ReplacePathRegex
if config . ReplacePathRegex != nil {
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if middleware != nil {
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return nil , badConf
}
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middleware = func ( next http . Handler ) ( http . Handler , error ) {
return replacepathregex . New ( ctx , next , * config . ReplacePathRegex , middlewareName )
}
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}
// Retry
if config . Retry != nil {
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if middleware != nil {
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return nil , badConf
}
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middleware = func ( next http . Handler ) ( http . Handler , error ) {
// FIXME missing metrics / accessLog
return retry . New ( ctx , next , * config . Retry , retry . Listeners { } , middlewareName )
}
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}
// StripPrefix
if config . StripPrefix != nil {
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if middleware != nil {
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return nil , badConf
}
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middleware = func ( next http . Handler ) ( http . Handler , error ) {
return stripprefix . New ( ctx , next , * config . StripPrefix , middlewareName )
}
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}
// StripPrefixRegex
if config . StripPrefixRegex != nil {
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if middleware != nil {
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return nil , badConf
}
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middleware = func ( next http . Handler ) ( http . Handler , error ) {
return stripprefixregex . New ( ctx , next , * config . StripPrefixRegex , middlewareName )
}
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}
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if middleware == nil {
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return nil , errors . New ( "middleware does not exist" )
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}
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return tracing . Wrap ( ctx , middleware ) , nil
}
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func inSlice ( element string , stack [ ] string ) bool {
for _ , value := range stack {
if value == element {
return true
}
}
return false
}