Add Custom header parsing to Docker Provider

docs/configuration/backends/docker.md

@@ -169,6 +169,8 @@ Labels can be used on containers to override default behaviour.
 | `traefik.frontend.entryPoints=http,https`                 | Assign this frontend to entry points `http` and `https`. Overrides `defaultEntryPoints`                                                                                                                                                                                                                                                                                                                                         |
 | `traefik.frontend.auth.basic=EXPR`                        | Sets basic authentication for that frontend in CSV format: `User:Hash,User:Hash`                                                                                                                                                                                                                                                                                                                                                |
 | `traefik.frontend.whitelistSourceRange:RANGE`             | List of IP-Ranges which are allowed to access. An unset or empty list allows all Source-IPs to access. If one of the Net-Specifications are invalid, the whole list is invalid and allows all Source-IPs to access.                                                                                                                                                                                                             |
+| `traefik.frontend.headers.customrequestheaders=EXPR `             | Provides the container with custom request headers that will be appended to each request forwarded to the container. Format:  `HEADER:value,HEADER2:value2`                                                                                                                                                                                                            |
+| `traefik.frontend.headers.customresponseheaders=EXPR`             | Appends the headers to each response returned by the container, before forwarding the response to the client. Format:  `HEADER:value,HEADER2:value2`                                                                                                                                                                                                            |
 | `traefik.docker.network`                                  | Set the docker network to use for connections to this container. If a container is linked to several networks, be sure to set the proper network name (you can check with `docker inspect <container_id>`) otherwise it will randomly pick one (depending on how docker is returning them). For instance when deploying docker `stack` from compose files, the compose defined networks will be prefixed with the `stack` name. |
 
 ### On Service

provider/docker/docker.go

@@ -291,6 +291,10 @@ func (p *Provider) loadDockerConfig(containersInspected []dockerData) *types.Con
 		"getServicePriority":          p.getServicePriority,
 		"getServiceBackend":           p.getServiceBackend,
 		"getWhitelistSourceRange":     p.getWhitelistSourceRange,
+		"getRequestHeaders":           p.getRequestHeaders,
+		"getResponseHeaders":          p.getResponseHeaders,
+		"hasRequestHeaders":           p.hasRequestHeaders,
+		"hasResponseHeaders":          p.hasResponseHeaders,
 	}
 	// filter containers
 	filteredContainers := fun.Filter(func(container dockerData) bool {
@@ -726,6 +730,41 @@ func (p *Provider) getBasicAuth(container dockerData) []string {
 	return []string{}
 }
 
+func (p *Provider) hasRequestHeaders(container dockerData) bool {
+	label, err := getLabel(container, types.LabelFrontendRequestHeader)
+	return err == nil && len(label) > 0
+}
+
+func (p *Provider) hasResponseHeaders(container dockerData) bool {
+	label, err := getLabel(container, types.LabelFrontendResponseHeader)
+	return err == nil && len(label) > 0
+}
+
+func (p *Provider) getRequestHeaders(container dockerData) map[string]string {
+	return parseCustomHeaders(container, types.LabelFrontendRequestHeader)
+}
+
+func (p *Provider) getResponseHeaders(container dockerData) map[string]string {
+	return parseCustomHeaders(container, types.LabelFrontendResponseHeader)
+}
+
+func parseCustomHeaders(container dockerData, containerType string) map[string]string {
+	customHeaders := make(map[string]string)
+	if label, err := getLabel(container, containerType); err == nil {
+		for _, headers := range strings.Split(label, ",") {
+			pair := strings.Split(headers, ":")
+			if len(pair) != 2 {
+				log.Warnf("Could not load header %v, skipping...", pair)
+			} else {
+				customHeaders[pair[0]] = pair[1]
+			}
+		}
+	}
+	if len(customHeaders) == 0 {
+		log.Errorf("Could not load any custom headers")
+	}
+	return customHeaders
+}
 func isContainerEnabled(container dockerData, exposedByDefault bool) bool {
 	return exposedByDefault && container.Labels[types.LabelEnable] != "false" || container.Labels[types.LabelEnable] == "true"
 }

templates/docker.tmpl

@@ -78,6 +78,18 @@
   basicAuth = [{{range getBasicAuth $container}}
     "{{.}}",
   {{end}}]
+  {{if hasRequestHeaders $container}}
+    [frontends."frontend-{{$frontend}}".headers.customrequestheaders]
+    {{range $k, $v := getRequestHeaders $container}}
+    {{$k}} = "{{$v}}"
+    {{end}}
+  {{end}}
+  {{if hasResponseHeaders $container}}
+    [frontends."frontend-{{$frontend}}".headers.customresponseheaders]
+    {{range $k, $v := getResponseHeaders $container}}
+    {{$k}} = "{{$v}}"
+    {{end}}
+  {{end}}
     [frontends."frontend-{{$frontend}}".routes."route-frontend-{{$frontend}}"]
     rule = "{{getFrontendRule $container}}"
   {{end}}

types/common_label.go

@@ -14,6 +14,8 @@ const (
 	LabelWeight                                  = LabelPrefix + "weight"
 	LabelFrontendAuthBasic                       = LabelPrefix + "frontend.auth.basic"
 	LabelFrontendEntryPoints                     = LabelPrefix + "frontend.entryPoints"
+	LabelFrontendRequestHeader                   = LabelPrefix + "frontend.headers.customrequestheaders"
+	LabelFrontendResponseHeader                  = LabelPrefix + "frontend.headers.customresoponseheaders"
 	LabelFrontendPassHostHeader                  = LabelPrefix + "frontend.passHostHeader"
 	LabelFrontendPriority                        = LabelPrefix + "frontend.priority"
 	LabelFrontendRule                            = LabelPrefix + "frontend.rule"