Headers

Managing Request/Response headers

Headers

The Headers middleware manages the headers of requests and responses.

A set of forwarded headers are automatically added by default. See the FAQ for more information.

Configuration Examples

Adding Headers to the Request and the Response

The following example adds the X-Script-Name header to the proxied request and the X-Custom-Response-Header header to the response

Docker & Swarm

  1. labels:
  2.   - "traefik.http.middlewares.testHeader.headers.customrequestheaders.X-Script-Name=test"
  3.   - "traefik.http.middlewares.testHeader.headers.customresponseheaders.X-Custom-Response-Header=value"

Kubernetes

  1. apiVersion: traefik.io/v1alpha1
  2. kind: Middleware
  3. metadata:
  4.   name: test-header
  5. spec:
  6.   headers:
  7.     customRequestHeaders:
  8.       X-Script-Name: "test"
  9.     customResponseHeaders:
  10.       X-Custom-Response-Header: "value"

Consul Catalog

  1. - "traefik.http.middlewares.testheader.headers.customrequestheaders.X-Script-Name=test"
  2. - "traefik.http.middlewares.testheader.headers.customresponseheaders.X-Custom-Response-Header=value"

File (YAML)

  1. http:
  2.   middlewares:
  3.     testHeader:
  4.       headers:
  5.         customRequestHeaders:
  6.           X-Script-Name: "test"
  7.         customResponseHeaders:
  8.           X-Custom-Response-Header: "value"

File (TOML)

  1. [http.middlewares]
  2.   [http.middlewares.testHeader.headers]
  3.     [http.middlewares.testHeader.headers.customRequestHeaders]
  4.         X-Script-Name = "test"
  5.     [http.middlewares.testHeader.headers.customResponseHeaders]
  6.         X-Custom-Response-Header = "value"

Adding and Removing Headers

In the following example, requests are proxied with an extra X-Script-Name header while their X-Custom-Request-Header header gets stripped, and responses are stripped of their X-Custom-Response-Header header.

Docker & Swarm

  1. labels:
  2.   - "traefik.http.middlewares.testheader.headers.customrequestheaders.X-Script-Name=test"
  3.   - "traefik.http.middlewares.testheader.headers.customrequestheaders.X-Custom-Request-Header="
  4.   - "traefik.http.middlewares.testheader.headers.customresponseheaders.X-Custom-Response-Header="

Kubernetes

  1. apiVersion: traefik.io/v1alpha1
  2. kind: Middleware
  3. metadata:
  4.   name: test-header
  5. spec:
  6.   headers:
  7.     customRequestHeaders:
  8.       X-Script-Name: "test" # Adds
  9.       X-Custom-Request-Header: "" # Removes
  10.     customResponseHeaders:
  11.       X-Custom-Response-Header: "" # Removes

Consul Catalog

  1. - "traefik.http.middlewares.testheader.headers.customrequestheaders.X-Script-Name=test"
  2. - "traefik.http.middlewares.testheader.headers.customrequestheaders.X-Custom-Request-Header="
  3. - "traefik.http.middlewares.testheader.headers.customresponseheaders.X-Custom-Response-Header="

File (YAML)

  1. http:
  2.   middlewares:
  3.     testHeader:
  4.       headers:
  5.         customRequestHeaders:
  6.           X-Script-Name: "test" # Adds
  7.           X-Custom-Request-Header: "" # Removes
  8.         customResponseHeaders:
  9.           X-Custom-Response-Header: "" # Removes

File (TOML)

  1. [http.middlewares]
  2.   [http.middlewares.testHeader.headers]
  3.     [http.middlewares.testHeader.headers.customRequestHeaders]
  4.         X-Script-Name = "test" # Adds
  5.         X-Custom-Request-Header = "" # Removes
  6.     [http.middlewares.testHeader.headers.customResponseHeaders]
  7.         X-Custom-Response-Header = "" # Removes

Using Security Headers

Security-related headers (HSTS headers, Browser XSS filter, etc) can be managed similarly to custom headers as shown above. This functionality makes it possible to easily use security features by adding headers.

Docker & Swarm

  1. labels:
  2.   - "traefik.http.middlewares.testHeader.headers.framedeny=true"
  3.   - "traefik.http.middlewares.testHeader.headers.browserxssfilter=true"

Kubernetes

  1. apiVersion: traefik.io/v1alpha1
  2. kind: Middleware
  3. metadata:
  4.   name: test-header
  5. spec:
  6.   headers:
  7.     frameDeny: true
  8.     browserXssFilter: true

Consul Catalog

  1. - "traefik.http.middlewares.testheader.headers.framedeny=true"
  2. - "traefik.http.middlewares.testheader.headers.browserxssfilter=true"

File (YAML)

  1. http:
  2.   middlewares:
  3.     testHeader:
  4.       headers:
  5.         frameDeny: true
  6.         browserXssFilter: true

File (TOML)

  1. [http.middlewares]
  2.   [http.middlewares.testHeader.headers]
  3.     frameDeny = true
  4.     browserXssFilter = true

CORS Headers

CORS (Cross-Origin Resource Sharing) headers can be added and configured in a manner similar to the custom headers above. This functionality allows for more advanced security features to quickly be set. If CORS headers are set, then the middleware does not pass preflight requests to any service, instead the response will be generated and sent back to the client directly.
Please note that the example below is by no means authoritative or exhaustive, and should not be used as is for production.

Docker & Swarm

  1. labels:
  2.   - "traefik.http.middlewares.testheader.headers.accesscontrolallowmethods=GET,OPTIONS,PUT"
  3.   - "traefik.http.middlewares.testheader.headers.accesscontrolallowheaders=*"
  4.   - "traefik.http.middlewares.testheader.headers.accesscontrolalloworiginlist=https://foo.bar.org,https://example.org"
  5.   - "traefik.http.middlewares.testheader.headers.accesscontrolmaxage=100"
  6.   - "traefik.http.middlewares.testheader.headers.addvaryheader=true"

Kubernetes

  1. apiVersion: traefik.io/v1alpha1
  2. kind: Middleware
  3. metadata:
  4.   name: test-header
  5. spec:
  6.   headers:
  7.     accessControlAllowMethods:
  8.       - "GET"
  9.       - "OPTIONS"
  10.       - "PUT"
  11.     accessControlAllowHeaders:
  12.       - "*"
  13.     accessControlAllowOriginList:
  14.       - "https://foo.bar.org"
  15.       - "https://example.org"
  16.     accessControlMaxAge: 100
  17.     addVaryHeader: true

Consul Catalog

  1. - "traefik.http.middlewares.testheader.headers.accesscontrolallowmethods=GET,OPTIONS,PUT"
  2. - "traefik.http.middlewares.testheader.headers.accesscontrolallowheaders=*"
  3. - "traefik.http.middlewares.testheader.headers.accesscontrolalloworiginlist=https://foo.bar.org,https://example.org"
  4. - "traefik.http.middlewares.testheader.headers.accesscontrolmaxage=100"
  5. - "traefik.http.middlewares.testheader.headers.addvaryheader=true"

File (YAML)

  1. http:
  2.   middlewares:
  3.     testHeader:
  4.       headers:
  5.         accessControlAllowMethods:
  6.           - GET
  7.           - OPTIONS
  8.           - PUT
  9.         accessControlAllowHeaders: "*"
  10.         accessControlAllowOriginList:
  11.           - https://foo.bar.org
  12.           - https://example.org
  13.         accessControlMaxAge: 100
  14.         addVaryHeader: true

File (TOML)

  1. [http.middlewares]
  2.   [http.middlewares.testHeader.headers]
  3.     accessControlAllowMethods = ["GET", "OPTIONS", "PUT"]
  4.     accessControlAllowHeaders = [ "*" ]
  5.     accessControlAllowOriginList = ["https://foo.bar.org","https://example.org"]
  6.     accessControlMaxAge = 100
  7.     addVaryHeader = true

Configuration Options

General

Warning

Custom headers will overwrite existing headers if they have identical names.

The detailed documentation for security headers can be found in unrolled/secure.

customRequestHeaders

The customRequestHeaders option lists the header names and values to apply to the request.

customResponseHeaders

The customResponseHeaders option lists the header names and values to apply to the response.

accessControlAllowCredentials

The accessControlAllowCredentials indicates whether the request can include user credentials.

accessControlAllowHeaders

The accessControlAllowHeaders indicates which header field names can be used as part of the request.

accessControlAllowMethods

The accessControlAllowMethods indicates which methods can be used during requests.

accessControlAllowOriginList

The accessControlAllowOriginList indicates whether a resource can be shared by returning different values.

A wildcard origin * can also be configured, and matches all requests. If this value is set by a backend service, it will be overwritten by Traefik.

This value can contain a list of allowed origins.

More information including how to use the settings can be found at:

Traefik no longer supports the null value, as it is no longer recommended as a return value.

accessControlAllowOriginListRegex

The accessControlAllowOriginListRegex option is the counterpart of the accessControlAllowOriginList option with regular expressions instead of origin values. It allows all origins that contain any match of a regular expression in the accessControlAllowOriginList.

Tip

Regular expressions and replacements can be tested using online tools such as Go Playground or the Regex101.

When defining a regular expression within YAML, any escaped character needs to be escaped twice: example\.com needs to be written as example\\.com.

accessControlExposeHeaders

The accessControlExposeHeaders indicates which headers are safe to expose to the api of a CORS API specification.

accessControlMaxAge

The accessControlMaxAge indicates how many seconds a preflight request can be cached for.

addVaryHeader

The addVaryHeader is used in conjunction with accessControlAllowOriginList to determine whether the Vary header should be added or modified to demonstrate that server responses can differ based on the value of the origin header.

allowedHosts

The allowedHosts option lists fully qualified domain names that are allowed.

hostsProxyHeaders

The hostsProxyHeaders option is a set of header keys that may hold a proxied hostname value for the request.

sslRedirect

Warning

Deprecated in favor of EntryPoint redirection or the RedirectScheme middleware.

The sslRedirect only allow HTTPS requests when set to true.

sslTemporaryRedirect

Warning

Deprecated in favor of EntryPoint redirection or the RedirectScheme middleware.

Set sslTemporaryRedirect to true to force an SSL redirection using a 302 (instead of a 301).

sslHost

Warning

Deprecated in favor of the RedirectRegex middleware.

The sslHost option is the host name that is used to redirect HTTP requests to HTTPS.

sslProxyHeaders

The sslProxyHeaders option is set of header keys with associated values that would indicate a valid HTTPS request. It can be useful when using other proxies (example: "X-Forwarded-Proto": "https").

sslForceHost

Warning

Deprecated in favor of the RedirectRegex middleware.

Set sslForceHost to true and set sslHost to force requests to use SSLHost regardless of whether they already use SSL.

stsSeconds

The stsSeconds is the max-age of the Strict-Transport-Security header. If set to 0, the header is not set.

stsIncludeSubdomains

If the stsIncludeSubdomains is set to true, the includeSubDomains directive is appended to the Strict-Transport-Security header.

stsPreload

Set stsPreload to true to have the preload flag appended to the Strict-Transport-Security header.

forceSTSHeader

Set forceSTSHeader to true to add the STS header even when the connection is HTTP.

frameDeny

Set frameDeny to true to add the X-Frame-Options header with the value of DENY.

customFrameOptionsValue

The customFrameOptionsValue allows the X-Frame-Options header value to be set with a custom value. This overrides the FrameDeny option.

contentTypeNosniff

Set contentTypeNosniff to true to add the X-Content-Type-Options header with the value nosniff.

browserXssFilter

Set browserXssFilter to true to add the X-XSS-Protection header with the value 1; mode=block.

customBrowserXSSValue

The customBrowserXssValue option allows the X-XSS-Protection header value to be set with a custom value. This overrides the BrowserXssFilter option.

contentSecurityPolicy

The contentSecurityPolicy option allows the Content-Security-Policy header value to be set with a custom value.

contentSecurityPolicyReportOnly

The contentSecurityPolicyReportOnly option allows the Content-Security-Policy-Report-Only header value to be set with a custom value.

publicKey

The publicKey implements HPKP to prevent MITM attacks with forged certificates.

referrerPolicy

The referrerPolicy allows sites to control whether browsers forward the Referer header to other sites.

featurePolicy

Warning

Deprecated in favor of permissionsPolicy

The featurePolicy allows sites to control browser features.

permissionsPolicy

The permissionsPolicy allows sites to control browser features.

isDevelopment

Set isDevelopment to true when developing to mitigate the unwanted effects of the AllowedHosts, SSL, and STS options. Usually testing takes place using HTTP, not HTTPS, and on localhost, not your production domain. If you would like your development environment to mimic production with complete Host blocking, SSL redirects, and STS headers, leave this as false.

Using Traefik OSS in Production?

If you are using Traefik at work, consider adding enterprise-grade API gateway capabilities or commercial support for Traefik OSS.

Adding API Gateway capabilities to Traefik OSS is fast and seamless. There’s no rip and replace and all configurations remain intact. See it in action via this short video.