Remove Content-Type auto-detection

Co-authored-by: mpl <mathieu.lonjaret@gmail.com>

pkg/config/dynamic/middlewares.go

@@ -35,6 +35,22 @@ type Middleware struct {
 	Compress          *Compress          `json:"compress,omitempty" toml:"compress,omitempty" yaml:"compress,omitempty" label:"allowEmpty"`
 	PassTLSClientCert *PassTLSClientCert `json:"passTLSClientCert,omitempty" toml:"passTLSClientCert,omitempty" yaml:"passTLSClientCert,omitempty"`
 	Retry             *Retry             `json:"retry,omitempty" toml:"retry,omitempty" yaml:"retry,omitempty"`
+	ContentType       *ContentType       `json:"contentType,omitempty" toml:"contentType,omitempty" yaml:"contentType,omitempty"`
+}
+
+// +k8s:deepcopy-gen=true
+
+// ContentType middleware - or rather its unique `autoDetect` option -
+// specifies whether to let the `Content-Type` header,
+// if it has not been set by the backend,
+// be automatically set to a value derived from the contents of the response.
+// As a proxy, the default behavior should be to leave the header alone,
+// regardless of what the backend did with it.
+// However, the historic default was to always auto-detect and set the header if it was nil,
+// and it is going to be kept that way in order to support users currently relying on it.
+// This middleware exists to enable the correct behavior until at least the default one can be changed in a future version.
+type ContentType struct {
+	AutoDetect bool `json:"autoDetect,omitempty" toml:"autoDetect,omitempty" yaml:"autoDetect,omitempty"`
 }
 
 // +k8s:deepcopy-gen=true

pkg/config/dynamic/zz_generated.deepcopy.go

@@ -252,6 +252,22 @@ func (in Configurations) DeepCopy() Configurations {
 	return *out
 }
 
+// DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
+func (in *ContentType) DeepCopyInto(out *ContentType) {
+	*out = *in
+	return
+}
+
+// DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new ContentType.
+func (in *ContentType) DeepCopy() *ContentType {
+	if in == nil {
+		return nil
+	}
+	out := new(ContentType)
+	in.DeepCopyInto(out)
+	return out
+}
+
 // DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
 func (in *Cookie) DeepCopyInto(out *Cookie) {
 	*out = *in
@@ -679,6 +695,11 @@ func (in *Middleware) DeepCopyInto(out *Middleware) {
 		*out = new(Retry)
 		**out = **in
 	}
+	if in.ContentType != nil {
+		in, out := &in.ContentType, &out.ContentType
+		*out = new(ContentType)
+		**out = **in
+	}
 	return
 }
 

pkg/provider/consulcatalog/consul_catalog.go

@@ -54,7 +54,7 @@ type Provider struct {
 type EndpointConfig struct {
 	Address          string                  `description:"The address of the Consul server" json:"address,omitempty" toml:"address,omitempty" yaml:"address,omitempty" export:"true"`
 	Scheme           string                  `description:"The URI scheme for the Consul server" json:"scheme,omitempty" toml:"scheme,omitempty" yaml:"scheme,omitempty" export:"true"`
-	DataCenter       string                  `description:"Data center to use. If not provided, the default agent data center is used" json:"data center,omitempty" toml:"data center,omitempty" yaml:"datacenter,omitempty" export:"true"`
+	DataCenter       string                  `description:"Data center to use. If not provided, the default agent data center is used" json:"datacenter,omitempty" toml:"datacenter,omitempty" yaml:"datacenter,omitempty" export:"true"`
 	Token            string                  `description:"Token is used to provide a per-request ACL token which overrides the agent's default token" json:"token,omitempty" toml:"token,omitempty" yaml:"token,omitempty" export:"true"`
 	TLS              *types.ClientTLS        `description:"Enable TLS support." json:"tls,omitempty" toml:"tls,omitempty" yaml:"tls,omitempty" export:"true"`
 	HTTPAuth         *EndpointHTTPAuthConfig `description:"Auth info to use for http access" json:"httpAuth,omitempty" toml:"httpAuth,omitempty" yaml:"httpAuth,omitempty" export:"true"`

pkg/provider/kubernetes/crd/traefik/v1alpha1/middleware.go

@@ -41,6 +41,7 @@ type MiddlewareSpec struct {
 	Compress          *dynamic.Compress          `json:"compress,omitempty"`
 	PassTLSClientCert *dynamic.PassTLSClientCert `json:"passTLSClientCert,omitempty"`
 	Retry             *dynamic.Retry             `json:"retry,omitempty"`
+	ContentType       *dynamic.ContentType       `json:"contentType,omitempty"`
 }
 
 // +k8s:deepcopy-gen=true

pkg/provider/kubernetes/crd/traefik/v1alpha1/zz_generated.deepcopy.go

@@ -606,6 +606,11 @@ func (in *MiddlewareSpec) DeepCopyInto(out *MiddlewareSpec) {
 		*out = new(dynamic.Retry)
 		**out = **in
 	}
+	if in.ContentType != nil {
+		in, out := &in.ContentType, &out.ContentType
+		*out = new(dynamic.ContentType)
+		**out = **in
+	}
 	return
 }
 

pkg/server/middleware/middlewares.go

@@ -172,6 +172,21 @@ func (b *Builder) buildConstructor(ctx context.Context, middlewareName string) (
 		}
 	}
 
+	// ContentType
+	if config.ContentType != nil {
+		if middleware != nil {
+			return nil, badConf
+		}
+		middleware = func(next http.Handler) (http.Handler, error) {
+			return http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
+				if !config.ContentType.AutoDetect {
+					rw.Header()["Content-Type"] = nil
+				}
+				next.ServeHTTP(rw, req)
+			}), nil
+		}
+	}
+
 	// CustomErrors
 	if config.Errors != nil {
 		if middleware != nil {

pkg/server/server_entrypoint_tcp.go

@@ -467,6 +467,7 @@ func createHTTPServer(ctx context.Context, ln net.Listener, configuration *stati
 		configuration.ForwardedHeaders.Insecure,
 		configuration.ForwardedHeaders.TrustedIPs,
 		httpSwitcher)
+
 	if err != nil {
 		return nil, err
 	}