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Resource Types

On Windmill, credentials and configuration are stored in resources and passed as parameters to main.

Use the RT namespace for resource types:

export async function main(stripe: RT.Stripe) {
  // stripe contains API key and config from the resource
}

Only use resource types if you need them to satisfy the instructions. Always use the RT namespace.

Before using a resource type, check the rt.d.ts file in the project root to see all available resource types and their fields. This file is generated by wmill resource-type generate-namespace.

Imports

No imports allowed. Use the globally available fetch function:

export async function main(url: string) {
  const response = await fetch(url);
  return await response.json();
}

Windmill Client

The windmill client is not available in native TypeScript mode. Use fetch to call APIs directly.

Preprocessor Scripts

For preprocessor scripts, the function should be named preprocessor and receives an event parameter:

type Event = {
  kind:
    | "webhook"
    | "http"
    | "websocket"
    | "kafka"
    | "email"
    | "nats"
    | "postgres"
    | "sqs"
    | "mqtt"
    | "gcp";
  body: any;
  headers: Record<string, string>;
  query: Record<string, string>;
};

export async function preprocessor(event: Event) {
  return {
    param1: event.body.field1,
    param2: event.query.id,
  };
}

S3 Object Operations

Windmill provides built-in support for S3-compatible storage operations.

S3Object Type

The S3Object type represents a file in S3 storage:

type S3Object = {
  s3: string; // Path within the bucket
};

TypeScript Operations

import * as wmill from "windmill-client";

// Load file content from S3
const content: Uint8Array = await wmill.loadS3File(s3object);

// Load file as stream
const blob: Blob = await wmill.loadS3FileStream(s3object);

// Write file to S3
const result: S3Object = await wmill.writeS3File(
  s3object, // Target path (or undefined to auto-generate)
  fileContent, // string or Blob
  s3ResourcePath // Optional: specific S3 resource to use
);

TypeScript SDK (windmill-client)

Import: import * as wmill from 'windmill-client'

workerHasInternalServer(): boolean

/**

• Initialize the Windmill client with authentication token and base URL
• @param token - Authentication token (defaults to WM_TOKEN env variable)
• @param baseUrl - API base URL (defaults to BASE_INTERNAL_URL or BASE_URL env variable) */ setClient(token?: string, baseUrl?: string): void

/**

• Create a client configuration from env variables
• @returns client configuration */ getWorkspace(): string

/**

• Get a resource value by path
• @param path path of the resource, default to internal state path
• @param undefinedIfEmpty if the resource does not exist, return undefined instead of throwing an error
• @returns resource value */ async getResource(path?: string, undefinedIfEmpty?: boolean): Promise<any>

/**

• Get the true root job id
• @param jobId job id to get the root job id from (default to current job)
• @returns root job id */ async getRootJobId(jobId?: string): Promise<string>

/**

• @deprecated Use runScriptByPath or runScriptByHash instead */ async runScript(path: string | null = null, hash_: string | null = null, args: Record<string, any> | null = null, verbose: boolean = false): Promise<any>

/**

• Run a script synchronously by its path and wait for the result
• @param path - Script path in Windmill
• @param args - Arguments to pass to the script
• @param verbose - Enable verbose logging
• @returns Script execution result */ async runScriptByPath(path: string, args: Record<string, any> | null = null, verbose: boolean = false): Promise<any>

/**

• Run a script synchronously by its hash and wait for the result
• @param hash_ - Script hash in Windmill
• @param args - Arguments to pass to the script
• @param verbose - Enable verbose logging
• @returns Script execution result */ async runScriptByHash(hash_: string, args: Record<string, any> | null = null, verbose: boolean = false): Promise<any>

/**

• Append a text to the result stream
• @param text text to append to the result stream */ appendToResultStream(text: string): void

/**

• Stream to the result stream
• @param stream stream to stream to the result stream */ async streamResult(stream: AsyncIterable<string>): Promise<void>

/**

• Run a flow synchronously by its path and wait for the result
• @param path - Flow path in Windmill
• @param args - Arguments to pass to the flow
• @param verbose - Enable verbose logging
• @returns Flow execution result */ async runFlow(path: string | null = null, args: Record<string, any> | null = null, verbose: boolean = false): Promise<any>

/**

• Wait for a job to complete and return its result
• @param jobId - ID of the job to wait for
• @param verbose - Enable verbose logging
• @returns Job result when completed */ async waitJob(jobId: string, verbose: boolean = false): Promise<any>

/**

• Get the result of a completed job
• @param jobId - ID of the completed job
• @returns Job result */ async getResult(jobId: string): Promise<any>

/**

• Get the result of a job if completed, or its current status
• @param jobId - ID of the job
• @returns Object with started, completed, success, and result properties */ async getResultMaybe(jobId: string): Promise<any>

/**

• @deprecated Use runScriptByPathAsync or runScriptByHashAsync instead */ async runScriptAsync(path: string | null, hash_: string | null, args: Record<string, any> | null, scheduledInSeconds: number | null = null): Promise<string>

/**

• Run a script asynchronously by its path
• @param path - Script path in Windmill
• @param args - Arguments to pass to the script
• @param scheduledInSeconds - Schedule execution for a future time (in seconds)
• @returns Job ID of the created job */ async runScriptByPathAsync(path: string, args: Record<string, any> | null = null, scheduledInSeconds: number | null = null): Promise<string>

/**

• Run a script asynchronously by its hash
• @param hash_ - Script hash in Windmill
• @param args - Arguments to pass to the script
• @param scheduledInSeconds - Schedule execution for a future time (in seconds)
• @returns Job ID of the created job */ async runScriptByHashAsync(hash_: string, args: Record<string, any> | null = null, scheduledInSeconds: number | null = null): Promise<string>

/**

• Run a flow asynchronously by its path
• @param path - Flow path in Windmill
• @param args - Arguments to pass to the flow
• @param scheduledInSeconds - Schedule execution for a future time (in seconds)
• @param doNotTrackInParent - If false, tracks state in parent job (only use when fully awaiting the job)
• @returns Job ID of the created job */ async runFlowAsync(path: string | null, args: Record<string, any> | null, scheduledInSeconds: number | null = null, // can only be set to false if this the job will be fully await and not concurrent with any other job // as otherwise the child flow and its own child will store their state in the parent job which will // lead to incorrectness and failures doNotTrackInParent: boolean = true): Promise<string>

/**

• Resolve a resource value in case the default value was picked because the input payload was undefined
• @param obj resource value or path of the resource under the format $res:path
• @returns resource value */ async resolveDefaultResource(obj: any): Promise<any>

/**

• Get the state file path from environment variables
• @returns State path string */ getStatePath(): string

/**

• Set a resource value by path
• @param path path of the resource to set, default to state path
• @param value new value of the resource to set
• @param initializeToTypeIfNotExist if the resource does not exist, initialize it with this type */ async setResource(value: any, path?: string, initializeToTypeIfNotExist?: string): Promise<void>

/**

• Set the state
• @param state state to set
• @deprecated use setState instead */ async setInternalState(state: any): Promise<void>

/**

• Set the state
• @param state state to set
• @param path Optional state resource path override. Defaults to getStatePath(). */ async setState(state: any, path?: string): Promise<void>

/**

• Set the progress
• Progress cannot go back and limited to 0% to 99% range
• @param percent Progress to set in %
• @param jobId? Job to set progress for */ async setProgress(percent: number, jobId?: any): Promise<void>

/**

• Get the progress
• @param jobId? Job to get progress from
• @returns Optional clamped between 0 and 100 progress value */ async getProgress(jobId?: any): Promise<number | null>

/**

• Set a flow user state
• @param key key of the state
• @param value value of the state */ async setFlowUserState(key: string, value: any, errorIfNotPossible?: boolean): Promise<void>

/**

• Get a flow user state
• @param path path of the variable */ async getFlowUserState(key: string, errorIfNotPossible?: boolean): Promise<any>

/**

• Get the internal state
• @deprecated use getState instead */ async getInternalState(): Promise<any>

/**

• Get the state shared across executions
• @param path Optional state resource path override. Defaults to getStatePath(). */ async getState(path?: string): Promise<any>

/**

• Get a variable by path
• @param path path of the variable
• @returns variable value */ async getVariable(path: string): Promise<string>

/**

• Set a variable by path, create if not exist
• @param path path of the variable
• @param value value of the variable
• @param isSecretIfNotExist if the variable does not exist, create it as secret or not (default: false)
• @param descriptionIfNotExist if the variable does not exist, create it with this description (default: "") */ async setVariable(path: string, value: string, isSecretIfNotExist?: boolean, descriptionIfNotExist?: string): Promise<void>

/**

• Build a PostgreSQL connection URL from a database resource
• @param path - Path to the database resource
• @returns PostgreSQL connection URL string */ async databaseUrlFromResource(path: string): Promise<string>

async polarsConnectionSettings(s3_resource_path: string | undefined): Promise<any>

async duckdbConnectionSettings(s3_resource_path: string | undefined): Promise<any>

/**

• Get S3 client settings from a resource or workspace default
• @param s3_resource_path - Path to S3 resource (uses workspace default if undefined)
• @returns S3 client configuration settings */ async denoS3LightClientSettings(s3_resource_path: string | undefined): Promise<DenoS3LightClientSettings>

/**

• Load the content of a file stored in S3. If the s3ResourcePath is undefined, it will default to the workspace S3 resource.
• let fileContent = await wmill.loadS3FileContent(inputFile)
• // if the file is a raw text file, it can be decoded and printed directly:
• const text = new TextDecoder().decode(fileContentStream)
• console.log(text);

*/ async loadS3File(s3object: S3Object, s3ResourcePath: string | undefined = undefined): Promise<Uint8Array | undefined>

/**

• Load the content of a file stored in S3 as a stream. If the s3ResourcePath is undefined, it will default to the workspace S3 resource.
• let fileContentBlob = await wmill.loadS3FileStream(inputFile)
• // if the content is plain text, the blob can be read directly:
• console.log(await fileContentBlob.text());

*/ async loadS3FileStream(s3object: S3Object, s3ResourcePath: string | undefined = undefined): Promise<Blob | undefined>

/**

• Persist a file to the S3 bucket. If the s3ResourcePath is undefined, it will default to the workspace S3 resource.
• const s3object = await writeS3File(s3Object, "Hello Windmill!")
• const fileContentAsUtf8Str = (await s3object.toArray()).toString('utf-8')
• console.log(fileContentAsUtf8Str)

*/ async writeS3File(s3object: S3Object | undefined, fileContent: string | Blob, s3ResourcePath: string | undefined = undefined, contentType: string | undefined = undefined, contentDisposition: string | undefined = undefined): Promise<S3Object>

/**

• Sign S3 objects to be used by anonymous users in public apps
• @param s3objects s3 objects to sign
• @returns signed s3 objects */ async signS3Objects(s3objects: S3Object[]): Promise<S3Object[]>

/**

• Sign S3 object to be used by anonymous users in public apps
• @param s3object s3 object to sign
• @returns signed s3 object */ async signS3Object(s3object: S3Object): Promise<S3Object>

/**

• Generate a presigned public URL for an array of S3 objects.
• If an S3 object is not signed yet, it will be signed first.
• @param s3Objects s3 objects to sign
• @returns list of signed public URLs */ async getPresignedS3PublicUrls(s3Objects: S3Object[], { baseUrl }: { baseUrl?: string } = {}): Promise<string[]>

/**

• Generate a presigned public URL for an S3 object. If the S3 object is not signed yet, it will be signed first.
• @param s3Object s3 object to sign
• @returns signed public URL */ async getPresignedS3PublicUrl(s3Objects: S3Object, { baseUrl }: { baseUrl?: string } = {}): Promise<string>

/**

• Get URLs needed for resuming a flow after this step
• @param approver approver name
• @param flowLevel if true, generate resume URLs for the parent flow instead of the specific step.

•              This allows pre-approvals that can be consumed by any later suspend step in the same flow.
  

• @returns approval page UI URL, resume and cancel API URLs for resuming the flow */ async getResumeUrls(approver?: string, flowLevel?: boolean): Promise<{ approvalPage: string; resume: string; cancel: string; }>

/**

• @deprecated use getResumeUrls instead */ getResumeEndpoints(approver?: string): Promise<{ approvalPage: string; resume: string; cancel: string; }>

/**

• Get an OIDC jwt token for auth to external services (e.g: Vault, AWS) (ee only)
• @param audience audience of the token
• @param expiresIn Optional number of seconds until the token expires
• @returns jwt token */ async getIdToken(audience: string, expiresIn?: number): Promise<string>

/**

• Convert a base64-encoded string to Uint8Array
• @param data - Base64-encoded string
• @returns Decoded Uint8Array */ base64ToUint8Array(data: string): Uint8Array

/**

• Convert a Uint8Array to base64-encoded string
• @param arrayBuffer - Uint8Array to encode
• @returns Base64-encoded string */ uint8ArrayToBase64(arrayBuffer: Uint8Array): string

/**

• Get email from workspace username
• This method is particularly useful for apps that require the email address of the viewer.
• Indeed, in the viewer context, WM_USERNAME is set to the username of the viewer but WM_EMAIL is set to the email of the creator of the app.
• @param username
• @returns email address */ async usernameToEmail(username: string): Promise<string>

/**

• Sends an interactive approval request via Slack, allowing optional customization of the message, approver, and form fields.
• [Enterprise Edition Only] To include form fields in the Slack approval request, go to Advanced -> Suspend -> Form
• and define a form. Learn more at Windmill Documentation.
• @param {Object} options - The configuration options for the Slack approval request.
• @param {string} options.slackResourcePath - The path to the Slack resource in Windmill.
• @param {string} options.channelId - The Slack channel ID where the approval request will be sent.
• @param {string} [options.message] - Optional custom message to include in the Slack approval request.
• @param {string} [options.approver] - Optional user ID or name of the approver for the request.
• @param {DefaultArgs} [options.defaultArgsJson] - Optional object defining or overriding the default arguments to a form field.
• @param {Enums} [options.dynamicEnumsJson] - Optional object overriding the enum default values of an enum form field.
• @param {string} [options.resumeButtonText] - Optional text for the resume button.
• @param {string} [options.cancelButtonText] - Optional text for the cancel button.
• @returns {Promise<void>} Resolves when the Slack approval request is successfully sent.
• @throws {Error} If the function is not called within a flow or flow preview.
• @throws {Error} If the JobService.getSlackApprovalPayload call fails.
• Usage Example:
• await requestInteractiveSlackApproval({
• slackResourcePath: "/u/alex/my_slack_resource",
• channelId: "admins-slack-channel",
• message: "Please approve this request",
• approver: "approver123",
• defaultArgsJson: { key1: "value1", key2: 42 },
• dynamicEnumsJson: { foo: ["choice1", "choice2"], bar: ["optionA", "optionB"] },
• resumeButtonText: "Resume",
• cancelButtonText: "Cancel",
• });
• Note: This function requires execution within a Windmill flow or flow preview. */ async requestInteractiveSlackApproval({ slackResourcePath, channelId, message, approver, defaultArgsJson, dynamicEnumsJson, resumeButtonText, cancelButtonText, }: SlackApprovalOptions): Promise<void>

/**

• Sends an interactive approval request via Teams, allowing optional customization of the message, approver, and form fields.
• [Enterprise Edition Only] To include form fields in the Teams approval request, go to Advanced -> Suspend -> Form
• and define a form. Learn more at Windmill Documentation.
• @param {Object} options - The configuration options for the Teams approval request.
• @param {string} options.teamName - The Teams team name where the approval request will be sent.
• @param {string} options.channelName - The Teams channel name where the approval request will be sent.
• @param {string} [options.message] - Optional custom message to include in the Teams approval request.
• @param {string} [options.approver] - Optional user ID or name of the approver for the request.
• @param {DefaultArgs} [options.defaultArgsJson] - Optional object defining or overriding the default arguments to a form field.
• @param {Enums} [options.dynamicEnumsJson] - Optional object overriding the enum default values of an enum form field.
• @returns {Promise<void>} Resolves when the Teams approval request is successfully sent.
• @throws {Error} If the function is not called within a flow or flow preview.
• @throws {Error} If the JobService.getTeamsApprovalPayload call fails.
• Usage Example:
• await requestInteractiveTeamsApproval({
• teamName: "admins-teams",
• channelName: "admins-teams-channel",
• message: "Please approve this request",
• approver: "approver123",
• defaultArgsJson: { key1: "value1", key2: 42 },
• dynamicEnumsJson: { foo: ["choice1", "choice2"], bar: ["optionA", "optionB"] },
• });
• Note: This function requires execution within a Windmill flow or flow preview. */ async requestInteractiveTeamsApproval({ teamName, channelName, message, approver, defaultArgsJson, dynamicEnumsJson, }: TeamsApprovalOptions): Promise<void>

/**

• Parse an S3 object from URI string or record format
• @param s3Object - S3 object as URI string (s3://storage/key) or record
• @returns S3 object record with storage and s3 key */ parseS3Object(s3Object: S3Object): S3ObjectRecord

setWorkflowCtx(ctx: WorkflowCtx | null): void

async sleep(seconds: number): Promise<void>

async step<T>(name: string, fn: () => T | Promise<T>): Promise<T>

/**

• Create a task that dispatches to a separate Windmill script.
• @example
• const extract = taskScript("f/data/extract");
• // inside workflow: await extract({ url: "https://..." }) */ taskScript(path: string, options?: TaskOptions): (...args: any[]) => PromiseLike<any>

/**

• Create a task that dispatches to a separate Windmill flow.
• @example
• const pipeline = taskFlow("f/etl/pipeline");
• // inside workflow: await pipeline({ input: data }) */ taskFlow(path: string, options?: TaskOptions): (...args: any[]) => PromiseLike<any>

/**

• Mark an async function as a workflow-as-code entry point.
• The function must be deterministic: given the same inputs it must call
• tasks in the same order on every replay. Branching on task results is fine
• (results are replayed from checkpoint), but branching on external state
• (current time, random values, external API calls) must use step() to
• checkpoint the value so replays see the same result. */ workflow<T>(fn: (...args: any[]) => Promise<T>): void

/**

• Suspend the workflow and wait for an external approval.
• Use getResumeUrls() (wrapped in step()) to obtain resume/cancel/approvalPage
• URLs before calling this function.
• @example
• const urls = await step("urls", () => getResumeUrls());
• await step("notify", () => sendEmail(urls.approvalPage));
• const { value, approver } = await waitForApproval({ timeout: 3600 }); */ waitForApproval(options?: { timeout?: number; form?: object; selfApproval?: boolean; }): PromiseLike<{ value: any; approver: string; approved: boolean }>

/**

• Process items in parallel with optional concurrency control.
• Each item is processed by calling fn(item), which should be a task().
• Items are dispatched in batches of concurrency (default: all at once).
• @example
• const process = task(async (item: string) => { ... });
• const results = await parallel(items, process, { concurrency: 5 }); */ async parallel<T, R>(items: T[], fn: (item: T) => PromiseLike<R> | R, options?: { concurrency?: number },): Promise<R[]>

/**

• Commit Kafka offsets for a trigger with auto_commit disabled.
• @param triggerPath - Path to the Kafka trigger (from event.wm_trigger.trigger_path)
• @param topic - Kafka topic name (from event.topic)
• @param partition - Partition number (from event.partition)
• @param offset - Message offset to commit (from event.offset) */ async commitKafkaOffsets(triggerPath: string, topic: string, partition: number, offset: number,): Promise<void>

/**

• Create a SQL template function for PostgreSQL/datatable queries
• @param name - Database/datatable name (default: "main")
• @returns SQL template function for building parameterized queries
• @example
• let sql = wmill.datatable()
• let name = 'Robin'
• let age = 21
• await sql`
• SELECT * FROM friends

• WHERE name = ${name} AND age = ${age}::int
  

• `.fetch() */ datatable(name: string = "main"): DatatableSqlTemplateFunction

/**

• Create a SQL template function for DuckDB/ducklake queries
• @param name - DuckDB database name (default: "main")
• @returns SQL template function for building parameterized queries
• @example
• let sql = wmill.ducklake()
• let name = 'Robin'
• let age = 21
• await sql`
• SELECT * FROM friends

• WHERE name = ${name} AND age = ${age}
  

• `.fetch() */ ducklake(name: string = "main"): SqlTemplateFunction