var Component=(()=>{var p=Object.create;var l=Object.defineProperty;var m=Object.getOwnPropertyDescriptor;var u=Object.getOwnPropertyNames;var N=Object.getPrototypeOf,k=Object.prototype.hasOwnProperty;var g=(a,e)=>()=>(e||a((e={exports:{}}).exports,e),e.exports),f=(a,e)=>{for(var s in e)l(a,s,{get:e[s],enumerable:!0})},i=(a,e,s,t)=>{if(e&&typeof e=="object"||typeof e=="function")for(let c of u(e))!k.call(a,c)&&c!==s&&l(a,c,{get:()=>e[c],enumerable:!(t=m(e,c))||t.enumerable});return a};var w=(a,e,s)=>(s=a!=null?p(N(a)):{},i(e||!a||!a.__esModule?l(s,"default",{value:a,enumerable:!0}):s,a)),y=a=>i(l({},"__esModule",{value:!0}),a);var r=g((T,o)=>{o.exports=_jsx_runtime});var v={};f(v,{default:()=>h,frontmatter:()=>b});var n=w(r()),b={title:"Hooks"};function d(a){let e={a:"a",code:"code",em:"em",h1:"h1",h2:"h2",h3:"h3",h4:"h4",li:"li",p:"p",pre:"pre",span:"span",ul:"ul",...a.components};return(0,n.jsxs)(n.Fragment,{children:[(0,n.jsx)(e.h1,{children:"Customizing the Grafbase Gateway with hooks"}),` `,(0,n.jsxs)(e.p,{children:["You can customize the Grafbase Gateway with dynamically loaded WebAssembly system interface (WASI) components. ",(0,n.jsx)(e.a,{href:"https://component-model.bytecodealliance.org/language-support.html",children:"A selection of languages"})," are available for implementing the guest components. Rust together with the ",(0,n.jsx)(e.a,{href:"https://github.com/bytecodealliance/cargo-component",children:"Cargo component"})," subcommand is the recommended tool set, with it being the most robust and easy to use solution for building WASI components."]}),` `,(0,n.jsx)(e.p,{children:"The WASI preview 2 enables more features for the guest language -- impossible with the previous preview or normal WebAssembly modules -- such as network requests and file system access. Keep in mind not every library supports network access from WASI in the current versions. See the final chapter for information of libraries tested."}),` `,(0,n.jsx)(e.h2,{children:"Gateway configuration"}),` `,(0,n.jsx)(e.p,{children:"You must deploy the Grafbase Gateway together with the WASM file containing the code for the custom hooks. The first Grafbase Gateway version with support for custom hooks is 0.4.0."}),` `,(0,n.jsx)(e.p,{children:"The minimum configuration to enable hooks must define a valid path to the WASM component:"}),` `,(0,n.jsx)(e.pre,{className:"language-toml",children:(0,n.jsxs)(e.code,{className:"language-toml code-highlight",children:[(0,n.jsxs)(e.span,{className:"code-line",children:[(0,n.jsx)(e.span,{className:"token punctuation",children:"["}),(0,n.jsx)(e.span,{className:"token table class-name",children:"hooks"}),(0,n.jsx)(e.span,{className:"token punctuation",children:"]"}),` `]}),(0,n.jsxs)(e.span,{className:"code-line",children:[(0,n.jsx)(e.span,{className:"token key property",children:"location"})," ",(0,n.jsx)(e.span,{className:"token punctuation",children:"="})," ",(0,n.jsx)(e.span,{className:"token string",children:'"path/to/custom.component.wasm"'}),` `]})]})}),` `,(0,n.jsx)(e.p,{children:"When starting the Gateway, it will display a log if the component loaded successfully. By default, the WASM component has no IO access enabled. You can enable access gradually with the following boolean options:"}),` `,(0,n.jsxs)(e.ul,{children:[` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"networking"})," enables network access with TCP and UDP sockets, name resolution and provides WASI HTTP bindings to the guest. Keep in mind the TCP and UDP sockets only work if the guest language provides support to the WASI preview 2 standard."]}),` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"stdout"})," enables the guest to write to the standard output stream."]}),` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"stderr"})," enables the guest to write to the standard error stream."]}),` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"environment_variables"})," copies the all the host environment variables to the guest."]}),` `]}),` `,(0,n.jsx)(e.p,{children:"You can enable guest access to the filesystem by defining one or more pre-opened directories:"}),` `,(0,n.jsx)(e.pre,{className:"language-toml",children:(0,n.jsxs)(e.code,{className:"language-toml code-highlight",children:[(0,n.jsxs)(e.span,{className:"code-line",children:[(0,n.jsx)(e.span,{className:"token punctuation",children:"["}),(0,n.jsx)(e.span,{className:"token punctuation",children:"["}),(0,n.jsx)(e.span,{className:"token table class-name",children:"hooks.preopened_directories"}),(0,n.jsx)(e.span,{className:"token punctuation",children:"]"}),(0,n.jsx)(e.span,{className:"token punctuation",children:"]"}),` `]}),(0,n.jsxs)(e.span,{className:"code-line",children:[(0,n.jsx)(e.span,{className:"token key property",children:"host_path"})," ",(0,n.jsx)(e.span,{className:"token punctuation",children:"="})," ",(0,n.jsx)(e.span,{className:"token string",children:'"/path/in/host/filesystem"'}),` `]}),(0,n.jsxs)(e.span,{className:"code-line",children:[(0,n.jsx)(e.span,{className:"token key property",children:"guest_path"})," ",(0,n.jsx)(e.span,{className:"token punctuation",children:"="})," ",(0,n.jsx)(e.span,{className:"token string",children:'"/path/in/guest/filesystem"'}),` `]}),(0,n.jsxs)(e.span,{className:"code-line",children:[(0,n.jsx)(e.span,{className:"token key property",children:"read_permission"})," ",(0,n.jsx)(e.span,{className:"token punctuation",children:"="})," ",(0,n.jsx)(e.span,{className:"token boolean",children:"true"}),` `]}),(0,n.jsxs)(e.span,{className:"code-line",children:[(0,n.jsx)(e.span,{className:"token key property",children:"write_permission"})," ",(0,n.jsx)(e.span,{className:"token punctuation",children:"="})," ",(0,n.jsx)(e.span,{className:"token boolean",children:"true"}),` `]})]})}),` `,(0,n.jsxs)(e.ul,{children:[` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"host_path"})," should point to an existing directory in the host filesystem. The user executing the Grafbase Gateway binary must have access to the given directory."]}),` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"guest_path"})," sets the path which is visible in the guest. This path is virtual and can be any value. The guest must use this path when accessing the filesystem."]}),` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"read_permission"})," enables reading all files and directories from the given ",(0,n.jsx)(e.code,{children:"host_path"}),"."]}),` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"write_permission"})," enables creating and modifying files and directories in the given ",(0,n.jsx)(e.code,{children:"host_path"}),"."]}),` `]}),` `,(0,n.jsx)(e.h2,{children:"WebAssembly Interface Type"}),` `,(0,n.jsxs)(e.p,{children:["Grafbase ",(0,n.jsx)(e.a,{href:"https://github.com/grafbase/grafbase/blob/main/engine/crates/wasi-component-loader/gateway-hooks.wit",children:"provides a WebAssembly Interface Type (WIT) file"})," which defines all the interfaces for communication between the host and the guest. The file defines all the types available in the guest, together with the hook function interfaces. You can define the hook functions you want to implement in the world section by exporting the corresponding function interfaces."]}),` `,(0,n.jsx)(e.p,{children:"There will be more hooks in the future Gateway versions. If you use hooks in your deployment, it's a good idea to read the changelog and adapt to any changes in the WIT definition and guest implementation."}),` `,(0,n.jsx)(e.h3,{children:"Context resource"}),` `,(0,n.jsx)(e.p,{children:"The context object is a key-value store available in all hooks during the request lifetime. You can store information into the context object in the beginning of the request, and read it in every subsequent hook. The values are strings, and if needing more structured data, consider storing it as JSON string."}),` `,(0,n.jsx)(e.p,{children:"In the gateway request hook, the storage is mutable and provides the following methods:"}),` `,(0,n.jsxs)(e.ul,{children:[` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"get"})," fetches a value from the context with the given name, returning none if the value doesn't exist."]}),` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"set"})," stores a value to the context with the given name."]}),` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"delete"})," deletes a value from the context with the given name, returning it if existing."]}),` `]}),` `,(0,n.jsxs)(e.p,{children:["The hooks after the gateway request gets the shared version of the context, which provides only the ",(0,n.jsx)(e.code,{children:"get"})," method."]}),` `,(0,n.jsx)(e.h3,{children:"Headers resource"}),` `,(0,n.jsx)(e.p,{children:"In the gateway request hook, the request headers are available to read and modify. The interface works similarly to the context methods, but they will return an error if the given header names or values contain characters not allowed in headers."}),` `,(0,n.jsx)(e.p,{children:"The following methods are available:"}),` `,(0,n.jsxs)(e.ul,{children:[` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"get"})," fetches a header value with the given name."]}),` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"set"})," sets a header value with the given name."]}),` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"delete"})," removes a header value with the given name. The method returns the value on successful deletion."]}),` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"entries"})," lists all header key value pairs"]}),` `]}),` `,(0,n.jsx)(e.h3,{children:"Header error"}),` `,(0,n.jsx)(e.p,{children:"You must provide valid strings for header names and values with only ASCII characters. Otherwise the host responds with an error."}),` `,(0,n.jsxs)(e.ul,{children:[` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"invalid-header-name"}),": you provided an invalid header name."]}),` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"invalid-header-value"}),": you provided an invalid header value."]}),` `]}),` `,(0,n.jsx)(e.h3,{children:"Error"}),` `,(0,n.jsx)(e.p,{children:"The hook can return a GraphQL error. Depending on the hook, the engine either stops processing the request or it adds the error to the request errors and continues processing other parts of the request. The error struct has the following fields:"}),` `,(0,n.jsxs)(e.ul,{children:[` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"message"}),": custom string message."]}),` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"extensions"})," is a list of tuples. The first part of the tuple is the name of the extension, and the second part the contents of the extension. The content can be a string, and if needing more structured data the value can be JSON encoded as string. If the value is JSON, the engine returns it in the structured form."]}),` `]}),` `,(0,n.jsxs)(e.p,{children:["If ",(0,n.jsx)(e.code,{children:"code"})," is provided in the ",(0,n.jsx)(e.code,{children:"extensions"}),", it will override the default error code set by the gateway."]}),` `,(0,n.jsx)(e.h3,{children:"Edge definition"}),` `,(0,n.jsx)(e.p,{children:"The engine calls the edge authorization functions with an edge definition, which holds the following data:"}),` `,(0,n.jsxs)(e.ul,{children:[` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"parent-type-name"}),": is the name of the type the edge is part of."]}),` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"field-name"}),": is the name of the field."]}),` `]}),` `,(0,n.jsx)(e.h3,{children:"Node definition"}),` `,(0,n.jsx)(e.p,{children:"The engine calls the node authorization functions with a node definition, which holds the following data:"}),` `,(0,n.jsxs)(e.ul,{children:[` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"type-name"}),": is the name of the node's type."]}),` `]}),` `,(0,n.jsx)(e.h2,{children:"Hooks"}),` `,(0,n.jsx)(e.p,{children:"The following hooks are available in the Grafbase Gateway. The engine will call the hook if exporting it in the world section of the WIT file and the guest implements it."}),` `,(0,n.jsx)(e.h3,{children:"Gateway request"}),` `,(0,n.jsx)(e.p,{children:"Available in Gateway version 0.4.0."}),` `,(0,n.jsxs)(e.p,{children:["The ",(0,n.jsx)(e.code,{children:"gateway-request"})," interface defines a hook function which the engine calls just before authentication in the federated gateway. It gives a mutable access to the context object, and a mutable access to the request headers. By returning an ",(0,n.jsx)(e.code,{children:"Ok"})," the request execution will continue and by returning an error, the engine ends the execution and the given error returned to the client."]}),` `,(0,n.jsx)(e.p,{children:"The hook has the following WIT definition:"}),` `,(0,n.jsx)(e.pre,{children:(0,n.jsxs)(e.code,{className:"language-wit code-highlight",children:[(0,n.jsx)(e.span,{className:"code-line",children:`interface gateway-request { `}),(0,n.jsx)(e.span,{className:"code-line",children:` use types.{headers, error, context}; `}),(0,n.jsx)(e.span,{className:"code-line",children:` `}),(0,n.jsx)(e.span,{className:"code-line",children:` // The hook is called in the federated gateway just before authentication. It can be used `}),(0,n.jsx)(e.span,{className:"code-line",children:` // to read and modify the request headers. The context object is provided in a mutable form, `}),(0,n.jsx)(e.span,{className:"code-line",children:` // allowing storage for the subsequent hooks to read. `}),(0,n.jsx)(e.span,{className:"code-line",children:` // `}),(0,n.jsx)(e.span,{className:"code-line",children:` // If returning an error from the hook, the request processing is stopped and the given error `}),(0,n.jsx)(e.span,{className:"code-line",children:` // returned to the client. `}),(0,n.jsx)(e.span,{className:"code-line",children:` on-gateway-request: func(context: context, headers: headers) -> result<_, error>; `}),(0,n.jsx)(e.span,{className:"code-line",children:`} `})]})}),` `,(0,n.jsx)(e.h3,{children:"Subgraph request"}),` `,(0,n.jsxs)(e.p,{children:["The ",(0,n.jsx)(e.code,{children:"subgraph-request"})," interface defines a hook function which the engine calls just before sending the HTTP request to the subgraph allowing header modifications. If an error is returned, the subgraph request won't be executed and will be considered as failed with the provided error. The hook has the following WIT definition:"]}),` `,(0,n.jsx)(e.pre,{children:(0,n.jsxs)(e.code,{className:"language-wit code-highlight",children:[(0,n.jsx)(e.span,{className:"code-line",children:`interface subgraph-request { `}),(0,n.jsx)(e.span,{className:"code-line",children:` use types.{shared-context, headers, error}; `}),(0,n.jsx)(e.span,{className:"code-line",children:` `}),(0,n.jsx)(e.span,{className:"code-line",children:` // The hook is called just before sending the HTTP request to the subgraph. `}),(0,n.jsx)(e.span,{className:"code-line",children:` on-subgraph-request: func(context: shared-context, subgraph-name: string, method: string, url: string, headers: headers) -> result<_, error>; `}),(0,n.jsx)(e.span,{className:"code-line",children:`} `})]})}),` `,(0,n.jsx)(e.h3,{children:"Authorization"}),` `,(0,n.jsxs)(e.p,{children:["The ",(0,n.jsx)(e.code,{children:"authorization"})," interface defines hook functions which are called when fetching data for a node or an edge defining an ",(0,n.jsxs)(e.a,{href:"/docs/federation/federation-directives#authorized",children:[(0,n.jsx)(e.code,{children:"@authorized"})," directive"]}),"."]}),` `,(0,n.jsx)(e.p,{children:"The interface must implement the following hooks has the following WIT definition:"}),` `,(0,n.jsx)(e.pre,{children:(0,n.jsxs)(e.code,{className:"language-wit code-highlight",children:[(0,n.jsx)(e.span,{className:"code-line",children:`interface authorization { `}),(0,n.jsx)(e.span,{className:"code-line",children:` use types.{error, shared-context, edge-definition, node-definition}; `}),(0,n.jsx)(e.span,{className:"code-line",children:` `}),(0,n.jsx)(e.span,{className:"code-line",children:` // The hook is called in the request cycle if the schema defines an authorization directive on `}),(0,n.jsx)(e.span,{className:"code-line",children:` // an edge, providing the arguments of the edge selected in the directive, the definition of the esge `}),(0,n.jsx)(e.span,{className:"code-line",children:` // and the metadata of the directive to the hook. `}),(0,n.jsx)(e.span,{className:"code-line",children:` // `}),(0,n.jsx)(e.span,{className:"code-line",children:` // The hook is run before fetching any data. `}),(0,n.jsx)(e.span,{className:"code-line",children:` // `}),(0,n.jsx)(e.span,{className:"code-line",children:` // The result, if an error, will stop the request execution and return an error back to the user. `}),(0,n.jsx)(e.span,{className:"code-line",children:` // Result of the edge will be null for an error response. `}),(0,n.jsx)(e.span,{className:"code-line",children:` authorize-edge-pre-execution: func( `}),(0,n.jsx)(e.span,{className:"code-line",children:` context: shared-context, `}),(0,n.jsx)(e.span,{className:"code-line",children:` definition: edge-definition, `}),(0,n.jsx)(e.span,{className:"code-line",children:` arguments: string, `}),(0,n.jsx)(e.span,{className:"code-line",children:` metadata: string `}),(0,n.jsx)(e.span,{className:"code-line",children:` ) -> result<_, error>; `}),(0,n.jsx)(e.span,{className:"code-line",children:` `}),(0,n.jsx)(e.span,{className:"code-line",children:` // The hook is called in the request cycle if the schema defines an authorization directive to `}),(0,n.jsx)(e.span,{className:"code-line",children:` // a node, providing the definition of the node and the metadata of the directive to the hook. `}),(0,n.jsx)(e.span,{className:"code-line",children:` // `}),(0,n.jsx)(e.span,{className:"code-line",children:` // The hook is run before fetching any data. `}),(0,n.jsx)(e.span,{className:"code-line",children:` // `}),(0,n.jsx)(e.span,{className:"code-line",children:` // The result, if an error, will stop the request execution and return an error back to the user. `}),(0,n.jsx)(e.span,{className:"code-line",children:` // Result of the edge will be null for an error response. `}),(0,n.jsx)(e.span,{className:"code-line",children:` authorize-node-pre-execution: func( `}),(0,n.jsx)(e.span,{className:"code-line",children:` context: shared-context, `}),(0,n.jsx)(e.span,{className:"code-line",children:` definition: node-definition, `}),(0,n.jsx)(e.span,{className:"code-line",children:` metadata: string `}),(0,n.jsx)(e.span,{className:"code-line",children:` ) -> result<_, error>; `}),(0,n.jsx)(e.span,{className:"code-line",children:` `}),(0,n.jsx)(e.span,{className:"code-line",children:" // Called when `@authorized` is used on a field with `fields` argument:\n"}),(0,n.jsx)(e.span,{className:"code-line",children:` // `}),(0,n.jsx)(e.span,{className:"code-line",children:` // type User { `}),(0,n.jsx)(e.span,{className:"code-line",children:` // id: ID! `}),(0,n.jsx)(e.span,{className:"code-line",children:` // address: Address @authorized(fields: "id") `}),(0,n.jsx)(e.span,{className:"code-line",children:` // } `}),(0,n.jsx)(e.span,{className:"code-line",children:` // `}),(0,n.jsx)(e.span,{className:"code-line",children:` // The engine calls the hook after the subgraph response has arrived with the list of parent fields for `}),(0,n.jsx)(e.span,{className:"code-line",children:` // every node containing the address field. `}),(0,n.jsx)(e.span,{className:"code-line",children:` authorize-parent-edge-post-execution: func( `}),(0,n.jsx)(e.span,{className:"code-line",children:` context: shared-context, `}),(0,n.jsx)(e.span,{className:"code-line",children:` definition: edge-definition, `}),(0,n.jsx)(e.span,{className:"code-line",children:` parents: list, `}),(0,n.jsx)(e.span,{className:"code-line",children:` metadata: string `}),(0,n.jsx)(e.span,{className:"code-line",children:` ) -> list>; `}),(0,n.jsx)(e.span,{className:"code-line",children:` `}),(0,n.jsx)(e.span,{className:"code-line",children:" // Called when `@authorized` is used on a field with `node` argument:\n"}),(0,n.jsx)(e.span,{className:"code-line",children:` // `}),(0,n.jsx)(e.span,{className:"code-line",children:` // type User { `}),(0,n.jsx)(e.span,{className:"code-line",children:` // id: ID! `}),(0,n.jsx)(e.span,{className:"code-line",children:` // } `}),(0,n.jsx)(e.span,{className:"code-line",children:` // `}),(0,n.jsx)(e.span,{className:"code-line",children:` // type Query { `}),(0,n.jsx)(e.span,{className:"code-line",children:` // users: [User]! @authorized(node: "id") `}),(0,n.jsx)(e.span,{className:"code-line",children:` // } `}),(0,n.jsx)(e.span,{className:"code-line",children:` // `}),(0,n.jsx)(e.span,{className:"code-line",children:` // The engine calls the hook after the subgraph response has arrived with the list of nodes (User here) for the `}),(0,n.jsx)(e.span,{className:"code-line",children:` // field. `}),(0,n.jsx)(e.span,{className:"code-line",children:` authorize-edge-node-post-execution: func( `}),(0,n.jsx)(e.span,{className:"code-line",children:` context: shared-context, `}),(0,n.jsx)(e.span,{className:"code-line",children:` definition: edge-definition, `}),(0,n.jsx)(e.span,{className:"code-line",children:` nodes: list, `}),(0,n.jsx)(e.span,{className:"code-line",children:` metadata: string `}),(0,n.jsx)(e.span,{className:"code-line",children:` ) -> list>; `}),(0,n.jsx)(e.span,{className:"code-line",children:`} `})]})}),` `,(0,n.jsxs)(e.h4,{children:["The ",(0,n.jsx)(e.code,{children:"authorize-edge-pre-execution"})," hook"]}),` `,(0,n.jsx)(e.p,{children:"Available in Gateway version 0.4.0."}),` `,(0,n.jsxs)(e.p,{children:["Called when ",(0,n.jsx)(e.code,{children:"@authorized"})," is applied on a field with ",(0,n.jsx)(e.code,{children:"arguments"}),":"]}),` `,(0,n.jsx)(e.pre,{className:"language-graphql",children:(0,n.jsxs)(e.code,{className:"language-graphql code-highlight",children:[(0,n.jsxs)(e.span,{className:"code-line",children:[(0,n.jsx)(e.span,{className:"token keyword",children:"type"})," ",(0,n.jsx)(e.span,{className:"token class-name",children:"Query"})," ",(0,n.jsx)(e.span,{className:"token punctuation",children:"{"}),` `]}),(0,n.jsxs)(e.span,{className:"code-line",children:[" ",(0,n.jsx)(e.span,{className:"token attr-name",children:"user"}),(0,n.jsx)(e.span,{className:"token punctuation",children:"("}),(0,n.jsx)(e.span,{className:"token attr-name",children:"id"}),(0,n.jsx)(e.span,{className:"token punctuation",children:":"})," ",(0,n.jsx)(e.span,{className:"token scalar",children:"ID"}),(0,n.jsx)(e.span,{className:"token punctuation",children:")"}),(0,n.jsx)(e.span,{className:"token punctuation",children:":"})," ",(0,n.jsx)(e.span,{className:"token class-name",children:"User"})," ",(0,n.jsx)(e.span,{className:"token directive function",children:"@authorized"}),(0,n.jsx)(e.span,{className:"token punctuation",children:"("}),(0,n.jsx)(e.span,{className:"token attr-name",children:"arguments"}),(0,n.jsx)(e.span,{className:"token punctuation",children:":"})," ",(0,n.jsx)(e.span,{className:"token string",children:'"id"'}),(0,n.jsx)(e.span,{className:"token punctuation",children:")"}),` `]}),(0,n.jsxs)(e.span,{className:"code-line",children:[(0,n.jsx)(e.span,{className:"token punctuation",children:"}"}),` `]})]})}),` `,(0,n.jsxs)(e.p,{children:["The engine calls the hook when a query accesses a field with an ",(0,n.jsx)(e.code,{children:"@authorize"})," directive on the ",(0,n.jsx)(e.a,{href:"/docs/federation/federation-directives#edge-level-pre-request-hook",children:"edge level"})," before executing the query."]}),` `,(0,n.jsx)(e.p,{children:"Engine calls the hook before executing the query with the following:"}),` `,(0,n.jsxs)(e.ul,{children:[` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"context"})," is the request context object, which can be populated in the ",(0,n.jsx)(e.code,{children:"on-gateway-request"})," hook."]}),` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"definition"})," defines the edge with its parent type name and the name of the field."]}),` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"arguments"})," is JSON data in string form, with data taken from the query arguments."]}),` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"metadata"})," is static JSON data in string form taken from the directive's metadata argument."]}),` `]}),` `,(0,n.jsx)(e.p,{children:"Result of the hook can be one of the following:"}),` `,(0,n.jsxs)(e.ul,{children:[` `,(0,n.jsx)(e.li,{children:"An empty response allows the request to fetch the data."}),` `,(0,n.jsxs)(e.li,{children:["An ",(0,n.jsx)(e.code,{children:"error"})," which stops the execution of the request and returns an error back to the user. The requested data will be ",(0,n.jsx)(e.code,{children:"null"}),"."]}),` `]}),` `,(0,n.jsxs)(e.p,{children:["If the queried edge is returning an optional value, this value will be set ",(0,n.jsx)(e.code,{children:"null"})," and an error added to the response errors. If the edge is returning a required value, the ",(0,n.jsx)(e.code,{children:"null"})," gets propagated up to the first nullable edge."]}),` `,(0,n.jsxs)(e.h4,{children:["The ",(0,n.jsx)(e.code,{children:"authorize-parent-edge-post-execution"})," hook"]}),` `,(0,n.jsx)(e.p,{children:"Available in Gateway version 0.7.0."}),` `,(0,n.jsxs)(e.p,{children:["Called when ",(0,n.jsx)(e.code,{children:"@authorized"})," is applied on a field with ",(0,n.jsx)(e.code,{children:"fields"}),":"]}),` `,(0,n.jsx)(e.pre,{className:"language-graphql",children:(0,n.jsxs)(e.code,{className:"language-graphql code-highlight",children:[(0,n.jsxs)(e.span,{className:"code-line",children:[(0,n.jsx)(e.span,{className:"token keyword",children:"type"})," ",(0,n.jsx)(e.span,{className:"token class-name",children:"User"})," ",(0,n.jsx)(e.span,{className:"token punctuation",children:"{"}),` `]}),(0,n.jsxs)(e.span,{className:"code-line",children:[" ",(0,n.jsx)(e.span,{className:"token attr-name",children:"id"}),(0,n.jsx)(e.span,{className:"token punctuation",children:":"})," ",(0,n.jsx)(e.span,{className:"token scalar",children:"ID"}),(0,n.jsx)(e.span,{className:"token operator",children:"!"}),` `]}),(0,n.jsxs)(e.span,{className:"code-line",children:[" ",(0,n.jsx)(e.span,{className:"token attr-name",children:"address"}),(0,n.jsx)(e.span,{className:"token punctuation",children:":"})," ",(0,n.jsx)(e.span,{className:"token class-name",children:"Address"})," ",(0,n.jsx)(e.span,{className:"token directive function",children:"@authorized"}),(0,n.jsx)(e.span,{className:"token punctuation",children:"("}),(0,n.jsx)(e.span,{className:"token attr-name",children:"fields"}),(0,n.jsx)(e.span,{className:"token punctuation",children:":"})," ",(0,n.jsx)(e.span,{className:"token string",children:'"id"'}),(0,n.jsx)(e.span,{className:"token punctuation",children:")"}),` `]}),(0,n.jsxs)(e.span,{className:"code-line",children:[(0,n.jsx)(e.span,{className:"token punctuation",children:"}"}),` `]})]})}),` `,(0,n.jsx)(e.p,{children:"The engine will call the hook after the subgraph response has arrived with:"}),` `,(0,n.jsxs)(e.ul,{children:[` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"context"})," is the request context object, which can be populated in the ",(0,n.jsx)(e.code,{children:"on-gateway-request"})," hook."]}),` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"definition"})," defines the edge with its parent type name and the name of the field."]}),` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"parents"})," is a list of parent fields, defined by the ",(0,n.jsx)(e.code,{children:"fields"})," directive argument, serialized in JSON."]}),` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"metadata"})," is static JSON data in string form taken from the directive's metadata argument."]}),` `]}),` `,(0,n.jsx)(e.p,{children:"Result is a list of results for each parent. If empty the field is authorized for this particular parent otherwise it's denied and an error is raised and propagated following GraphQL spec instead."}),` `,(0,n.jsxs)(e.h4,{children:["The ",(0,n.jsx)(e.code,{children:"authorize-edge-node-post-execution"})," hook"]}),` `,(0,n.jsx)(e.p,{children:"Available in Gateway version 0.7.0."}),` `,(0,n.jsxs)(e.p,{children:["Called when ",(0,n.jsx)(e.code,{children:"@authorized"})," is applied on a field with ",(0,n.jsx)(e.code,{children:"node"}),":"]}),` `,(0,n.jsx)(e.pre,{className:"language-graphql",children:(0,n.jsxs)(e.code,{className:"language-graphql code-highlight",children:[(0,n.jsxs)(e.span,{className:"code-line",children:[(0,n.jsx)(e.span,{className:"token keyword",children:"type"})," ",(0,n.jsx)(e.span,{className:"token class-name",children:"User"})," ",(0,n.jsx)(e.span,{className:"token punctuation",children:"{"}),` `]}),(0,n.jsxs)(e.span,{className:"code-line",children:[" ",(0,n.jsx)(e.span,{className:"token attr-name",children:"id"}),(0,n.jsx)(e.span,{className:"token punctuation",children:":"})," ",(0,n.jsx)(e.span,{className:"token scalar",children:"ID"}),(0,n.jsx)(e.span,{className:"token operator",children:"!"}),` `]}),(0,n.jsxs)(e.span,{className:"code-line",children:[(0,n.jsx)(e.span,{className:"token punctuation",children:"}"}),` `]}),(0,n.jsx)(e.span,{className:"code-line",children:` `}),(0,n.jsxs)(e.span,{className:"code-line",children:[(0,n.jsx)(e.span,{className:"token keyword",children:"type"})," ",(0,n.jsx)(e.span,{className:"token class-name",children:"Query"})," ",(0,n.jsx)(e.span,{className:"token punctuation",children:"{"}),` `]}),(0,n.jsxs)(e.span,{className:"code-line",children:[" ",(0,n.jsx)(e.span,{className:"token attr-name",children:"users"}),(0,n.jsx)(e.span,{className:"token punctuation",children:":"})," ",(0,n.jsx)(e.span,{className:"token punctuation",children:"["}),(0,n.jsx)(e.span,{className:"token class-name",children:"User"}),(0,n.jsx)(e.span,{className:"token punctuation",children:"]"}),(0,n.jsx)(e.span,{className:"token operator",children:"!"})," ",(0,n.jsx)(e.span,{className:"token directive function",children:"@authorized"}),(0,n.jsx)(e.span,{className:"token punctuation",children:"("}),(0,n.jsx)(e.span,{className:"token attr-name",children:"node"}),(0,n.jsx)(e.span,{className:"token punctuation",children:":"})," ",(0,n.jsx)(e.span,{className:"token string",children:'"id"'}),(0,n.jsx)(e.span,{className:"token punctuation",children:")"}),` `]}),(0,n.jsxs)(e.span,{className:"code-line",children:[(0,n.jsx)(e.span,{className:"token punctuation",children:"}"}),` `]})]})}),` `,(0,n.jsx)(e.p,{children:"The engine will call the hook after the subgraph response has arrived with:"}),` `,(0,n.jsxs)(e.ul,{children:[` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"context"})," is the request context object, which can be populated in the ",(0,n.jsx)(e.code,{children:"on-gateway-request"})," hook."]}),` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"definition"})," defines the edge with its parent type name and the name of the field."]}),` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"nodes"})," is a list of field output nodes with the selected fields defined by the ",(0,n.jsx)(e.code,{children:"node"})," directive argument, serialized in JSON."]}),` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"metadata"})," is static JSON data in string form taken from the directive's metadata argument."]}),` `]}),` `,(0,n.jsx)(e.p,{children:"Result is a list of results for each node. If empty the node is authorized, otherwise it's denied and an error is raised and propagated following GraphQL spec instead."}),` `,(0,n.jsxs)(e.h4,{children:["The ",(0,n.jsx)(e.code,{children:"authorize-node-pre-execution"})," hook"]}),` `,(0,n.jsx)(e.p,{children:"Available in Gateway version 0.4.0."}),` `,(0,n.jsxs)(e.p,{children:["The engine calls the hook when a query accesses a type with an ",(0,n.jsx)(e.code,{children:"@authorize"})," directive on the ",(0,n.jsx)(e.a,{href:"/docs/federation/federation-directives#node-level-pre-request-hook",children:"node level"})," before executing the query."]}),` `,(0,n.jsx)(e.p,{children:"Engine sends the following data to the hook:"}),` `,(0,n.jsxs)(e.ul,{children:[` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"context"})," is the request context object, which can be populated in the ",(0,n.jsx)(e.code,{children:"on-gateway-request"})," hook."]}),` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"definition"})," defines the node with the name of the type."]}),` `,(0,n.jsxs)(e.li,{children:[(0,n.jsx)(e.code,{children:"metadata"})," is static JSON data in string form taken from the directive's metadata argument."]}),` `]}),` `,(0,n.jsx)(e.p,{children:"Result of the hook can be one of the following:"}),` `,(0,n.jsxs)(e.ul,{children:[` `,(0,n.jsx)(e.li,{children:"An empty response allows the request to fetch the data."}),` `,(0,n.jsxs)(e.li,{children:["An ",(0,n.jsx)(e.code,{children:"error"})," which stops the execution of the request and returns an error back to the user. The requested data will be ",(0,n.jsx)(e.code,{children:"null"}),"."]}),` `]}),` `,(0,n.jsxs)(e.p,{children:["If the hook returns an error, the part of the query which tries to access the given node will return ",(0,n.jsx)(e.code,{children:"null"})," together with the error defined in the hook. If the field is required, the ",(0,n.jsx)(e.code,{children:"null"})," value is propagated up to the first optional field in the query."]}),` `,(0,n.jsx)(e.p,{children:"For the following types:"}),` `,(0,n.jsx)(e.pre,{className:"language-graphql",children:(0,n.jsxs)(e.code,{className:"language-graphql code-highlight",children:[(0,n.jsxs)(e.span,{className:"code-line",children:[(0,n.jsx)(e.span,{className:"token keyword",children:"type"})," ",(0,n.jsx)(e.span,{className:"token class-name",children:"User"})," ",(0,n.jsx)(e.span,{className:"token punctuation",children:"{"}),` `]}),(0,n.jsxs)(e.span,{className:"code-line",children:[" ",(0,n.jsx)(e.span,{className:"token attr-name",children:"address"}),(0,n.jsx)(e.span,{className:"token punctuation",children:":"})," ",(0,n.jsx)(e.span,{className:"token class-name",children:"Address"}),` `]}),(0,n.jsxs)(e.span,{className:"code-line",children:[" ",(0,n.jsx)(e.span,{className:"token attr-name",children:"secret"}),(0,n.jsx)(e.span,{className:"token punctuation",children:":"})," ",(0,n.jsx)(e.span,{className:"token class-name",children:"Secret"}),` `]}),(0,n.jsxs)(e.span,{className:"code-line",children:[(0,n.jsx)(e.span,{className:"token punctuation",children:"}"}),` `]}),(0,n.jsx)(e.span,{className:"code-line",children:` `}),(0,n.jsxs)(e.span,{className:"code-line",children:[(0,n.jsx)(e.span,{className:"token keyword",children:"type"})," ",(0,n.jsx)(e.span,{className:"token class-name",children:"Address"})," ",(0,n.jsx)(e.span,{className:"token punctuation",children:"{"}),` `]}),(0,n.jsxs)(e.span,{className:"code-line",children:[" ",(0,n.jsx)(e.span,{className:"token attr-name",children:"street"}),(0,n.jsx)(e.span,{className:"token punctuation",children:":"})," ",(0,n.jsx)(e.span,{className:"token scalar",children:"String"}),(0,n.jsx)(e.span,{className:"token operator",children:"!"}),` 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You must deploy the file with the gateway binary, and you must configure the gateway binary to look for the file in its configuration."]}),` `,(0,n.jsx)(e.h2,{children:"Triggering HTTP requests from the hooks"}),` `,(0,n.jsxs)(e.p,{children:["So far the support for networking and HTTP from WASI components is work in progress. WASI support in common libraries might not be available. If needing to trigger HTTP requests from the hooks, please consider writing them in Rust and using a crate which works in the WASI context, such as ",(0,n.jsx)(e.a,{href:"https://crates.io/crates/waki",children:"waki"}),"."]}),` `,(0,n.jsxs)(e.p,{children:["WASI support in more popular HTTP libraries such as ",(0,n.jsx)(e.a,{href:"https://crates.io/crates/reqwest",children:"reqwest"})," or Go's ",(0,n.jsx)(e.a,{href:"https://pkg.go.dev/net/http",children:"net/http"})," is still work in progress. 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