Service Map

The service map is a blueprint that Pedestal uses to create all the necessary parts to begin processing requests: a service function, server function, chain provider, router, routes, and default set of interceptors.

Server vs. Service

A server is just the part of the overall system that listens for requests and sends responses; it’s the part most closely tied to your underlying servlet container (Jetty, Tomcat, and so forth). The service runs the show: it’s the server plus everything else: chain provider, the interceptors (including those responsible for routing), and so forth.

An application creates the service map and passes it to create-server. The result is a server map that is ready to be started.

Keep in mind, however, that this is strictly a convenience function that assembles the parts for you. There are use cases where you would not call create-server, but instead assemble a service function, chain provider, and so forth, directly.

Pedestal may add other keys to this map for its own use. Other applications should treat any such keys and their values as implementation details and their behaviour will remain unspecified.

In the details below, ::http is an alias to :io.pedestal.http.

Key Always present? Type Description

Key	Always present?	Type	Description
::http/allowed-origins	N	Function, map, or sequence of strings	Determines which origins are allowed for the `cors/allow-origin` interceptor. See "CORS" below.
::http/chain-provider	N	Function	Only assigned when replacing the Servlet Interceptor. Receives the service map, returns an updated with whatever additional pieces the server function expects. (See ::http/type, below.)
::http/container-options	N	Map	Map of options to pass to the container. Each container, such as Jetty 9, defines it own container-specific options.
::http/enable-csrf	N	Map	A settings map to pass to the `csrf/anti-forgery` interceptor. See CSRF below.
::http/enable-session	N	Map	A settings map to pass to the `ring-middlewares/session` interceptor. Settings are session-store specific. If non-`nil`, this interceptor is added. Default is `nil`.
::http/file-path	N	String	File path used as root by the `ring-middlewares/file` interceptor. If non-`nil`, this interceptor is added. Default is `nil`.
::http/host	N	String	Hostname, e.g., "localhost". Passed to the container. Defaults to `localhost` ^[1].
::http/interceptors	N	Vector	Vector of items that satisfy `http/default-interceptors`.
::http/join?	N	Boolean	If `false`, do not block the thread that starts the web server. Passed to the container.
::http/method-param-name	N	Keyword	Query string parameter used to set the current HTTP verb. Default is :_method.
::http/mime-types	N	Map of String → String	Mime-types map used by the `ring-middlewares/content-type` interceptor. Default is `{}`.
::http/not-found-interceptor	N	Interceptor	Interceptor to use when returning a 404 Not Found response. Default is the `http/not-found` interceptor.
::http/port	N	Integer	Port for the running server. If `nil`, Pedestal defaults to port 80 and HTTP.
::http/resource-path	N	string	File path used as root by the `ring-middlewares/resource` interceptor. If non-`nil`, the interceptor is added. Default is `nil`.
::http/router	N	Keyword or route constructor	The router implementation to use. Can be :linear-search, :map-tree :prefix-tree, or a custom `router/Router` constructor function. Defaults to :map-tree, which falls back to :prefix-tree.
::http/routes	Y	Function, `ExpandableRoutes`, or sequence of maps	Something that satisfies the `route/expand-routes` as the full route map contains some redundancies to make processing easier which `expand-routes` adds automatically.
::http/secure-headers	N	map of keyword → string	A settings map for various secure headers. See "Secure Headers" below
::http/service-fn	N	function	A function which can be used as an implementation of the `javax.servlet.Servlet.service` method. The function is defined by `http/create-server`.
::http/servlet	N	`javax.servlet.Servlet`	Present if the servlet is running.
::http/start-fn	N	function	Zero-arity function that starts the server.
::http/stop-fn	N	function	Zero-arity function that stops the server.
::http/type	Y	Keyword or Function	Container for service or server function. As a keyword, names the container - currently, only :jetty is supported out of the box. As a function, acts as the server function.

::http/allowed-origins

Function, map, or sequence of strings

Determines which origins are allowed for the cors/allow-origin interceptor. See "CORS" below.

::http/chain-provider

Function

Only assigned when replacing the Servlet Interceptor. Receives the service map, returns an updated with whatever additional pieces the server function expects. (See ::http/type, below.)

::http/container-options

Map

Map of options to pass to the container. Each container, such as Jetty 9, defines it own container-specific options.

::http/enable-csrf

Map

A settings map to pass to the csrf/anti-forgery interceptor. See CSRF below.

::http/enable-session

Map

A settings map to pass to the ring-middlewares/session interceptor. Settings are session-store specific. If non-nil, this interceptor is added. Default is nil.

::http/file-path

String

File path used as root by the ring-middlewares/file interceptor. If non-nil, this interceptor is added. Default is nil.

::http/host

String

Hostname, e.g., "localhost". Passed to the container. Defaults to localhost ^[1].

::http/interceptors

Vector

Vector of items that satisfy http/default-interceptors.

::http/join?

Boolean

If false, do not block the thread that starts the web server. Passed to the container.

::http/method-param-name

Keyword

Query string parameter used to set the current HTTP verb. Default is :_method.

::http/mime-types

Map of String → String

Mime-types map used by the ring-middlewares/content-type interceptor. Default is {}.

::http/not-found-interceptor

Interceptor

Interceptor to use when returning a 404 Not Found response. Default is the http/not-found interceptor.

::http/port

Integer

Port for the running server. If nil, Pedestal defaults to port 80 and HTTP.

::http/resource-path

string

File path used as root by the ring-middlewares/resource interceptor. If non-nil, the interceptor is added. Default is nil.

::http/router

Keyword or route constructor

The router implementation to use. Can be :linear-search, :map-tree :prefix-tree, or a custom router/Router constructor function. Defaults to :map-tree, which falls back to :prefix-tree.

::http/routes

Function, ExpandableRoutes, or sequence of maps

Something that satisfies the route/expand-routes as the full route map contains some redundancies to make processing easier which expand-routes adds automatically.

::http/secure-headers

map of keyword → string

A settings map for various secure headers. See "Secure Headers" below

::http/service-fn

function

A function which can be used as an implementation of the javax.servlet.Servlet.service method. The function is defined by http/create-server.

::http/servlet

javax.servlet.Servlet

Present if the servlet is running.

::http/start-fn

function

Zero-arity function that starts the server.

::http/stop-fn

function

Zero-arity function that stops the server.

::http/type

Keyword or Function

Container for service or server function. As a keyword, names the container - currently, only :jetty is supported out of the box. As a function, acts as the server function.

Cross-Origin Resource Sharing (CORS)

If the ::http/allowed-origins key is non-nil, the allow-origin interceptor is added. The default is nil.

The allowed values are:

a function of one argument that returns a truthy value when an origin is allowed;
a map containing the following keys and values :allowed-origins sequence of strings or a function, :creds boolean indicating whether the client is allowed to send credentials, :max-age a long indicating the number of seconds a client should cache the response, and :methods, indicating the accepted HTTP methods, defaulting to "GET, POST, PUT, DELETE, HEAD, PATCH, OPTIONS";
a sequence of strings matching the the scheme, host and port (scheme://host:port) of allowed origins.

Cross-Site Request Forgery (CSRF)

When a value for ::http/enable-csrf is present, the anti-forgery interceptor is added to the queue. This implies that support for HTTP sessions are enabled (Pedestal will add the necessary interceptor automatically).

The value must be a map with the following keys:

Key Value type Description

Key	Value type	Description
:read-token	Function	This function takes a request and returns an anti-forgery token or `nil` if the token does not exist.
:cookie-token	any	truthy value for CSRF double-submit cookies
:error-response	Function	This function takes the response body and returns a 403 Not Authorized response
:error-handler	Function	This function takes the context and returns the appropriate response.

:read-token

Function

This function takes a request and returns an anti-forgery token or nil if the token does not exist.

:cookie-token

any

truthy value for CSRF double-submit cookies

:error-response

Function

This function takes the response body and returns a 403 Not Authorized response

:error-handler

Function

This function takes the context and returns the appropriate response.

Only one of :error-response or :error-handler may be specified.

Secure Headers

When the ::http/secure-headers value is present and non-nil, the secure-headers/secure-headers interceptor is added.

If the key is simply not present in the service map, then a set of default secure headers will be provided:

Key	HTTP Header	Content
:hsts-settings	Strict-Transport-Security	"max-age=31536000; includeSubdomains"
:frame-options-settings	X-Frame-Options	"DENY"
:content-type-settings	X-Content-Type-Options	"nosniff"
:xss-protection-settings	X-XSS-Protection	"1; mode=block"
:download-options-settings	X-Download-Options	"noopen"
:cross-domain-policies-settings	X-Permitted-Cross-Domain-Policies	"none"
:content-security-policy-settings	Content-Security-Policy	"object-src 'none'; script-src 'unsafe-inline' 'unsafe-eval' 'strict-dynamic' https: http:;"

Key

HTTP Header

Content

:hsts-settings

Strict-Transport-Security

"max-age=31536000; includeSubdomains"

:frame-options-settings

X-Frame-Options

"DENY"

:content-type-settings

X-Content-Type-Options

"nosniff"

:xss-protection-settings

X-XSS-Protection

"1; mode=block"

:download-options-settings

X-Download-Options

"noopen"

:cross-domain-policies-settings

X-Permitted-Cross-Domain-Policies

"none"

:content-security-policy-settings

Content-Security-Policy

"object-src 'none'; script-src 'unsafe-inline' 'unsafe-eval' 'strict-dynamic' https: http:;"

If the value for ::http/secure-headers is present, it may contain keys and string values for the security headers. Any other keys will be ignored.

1. localhost is a safe default and works with local testing, as your test code will be on the same host as the server. However, only connections originating on the local host will be accepted. For production deployments, however, you will usually set this to be 0.0.0.0, which accepts connections from anywhere. This is especially true when running Pedestal inside a Docker container, as all connections (even those from the host, or from another container on the same host) will be network, not localhost, connections.