Open-source developer infrastructure for internal tools (APIs, background jobs, workflows and UIs). Self-hostable alternative to Retool, Pipedream, Superblocks and a simplified Temporal with autogenerated UIs and custom UIs to trigger workflows and scripts as internal apps.

Scripts are turned into sharable UIs automatically, and can be composed together into flows or used into richer apps built with low-code. Supported script languages supported are: Python, TypeScript, Go, Bash, SQL, and GraphQL.

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Windmill - Developer platform for APIs, background jobs, workflows and UIs

Windmill is fully open-sourced (AGPLv3) and Windmill Labs offers dedicated instance and commercial support and licenses.

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• Windmill - Developer platform for APIs, background jobs, workflows and UIs
  • Main Concepts
  • Show me some actual script code
  • CLI
    • Running scripts locally
  • Stack
  • Fastest Self-Hostable Workflow Engine
  • Security
    • Sandboxing
    • Secrets, credentials and sensitive values
  • Performance
  • Architecture
  • How to self-host
    • Docker compose
    • Kubernetes (k8s) and Helm charts
    • Run from binaries
    • OAuth, SSO & SMTP
    • Commercial license
    • Integrations
  • Environment Variables
  • Run a local dev setup
    • only Frontend
    • Backend + Frontend
  • Contributors
  • Copyright

Main Concepts

1. Define a minimal and generic script in Python, TypeScript, Go or Bash that solves a specific task. The code can be defined in the provided Web IDE or synchronized with your own GitHub repo (e.g. through VS Code extension):

   

2. Your scripts parameters are automatically parsed and generate a frontend.

3. Make it flow! You can chain your scripts or scripts made by the community shared on WindmillHub.

   

4. Build complex UIs on top of your scripts and flows.

   

Scripts and flows can also be triggered by a cron schedule (e.g. '_/5 _ * * *') or through webhooks.

You can build your entire infra on top of Windmill!

Show me some actual script code

//import any dependency  from npm
import * as wmill from "windmill-client"
import * as cowsay from '[email protected]';

// fill the type, or use the +Resource type to get a type-safe reference to a resource
type Postgresql = {
  host: string;
  port: number;
  user: string;
  dbname: string;
  sslmode: string;
  password: string;
};

export async function main(
  a: number,
  b: "my" | "enum",
  c: Postgresql,
  d = "inferred type string from default arg",
  e = { nested: "object" }
  //f: wmill.Base64
) {
  const email = process.env["WM_EMAIL"];
  // variables are permissioned and by path
  let variable = await wmill.getVariable("f/company-folder/my_secret");
  const lastTimeRun = await wmill.getState();
  // logs are printed and always inspectable
  console.log(cowsay.say({ text: "hello " + email + " " + lastTimeRun }));
  await wmill.setState(Date.now());

  // return is serialized as JSON
  return { foo: d, variable };
}

CLI

We have a powerful CLI to interact with the windmill platform and sync your scripts from local files, GitHub repos and to run scripts and flows on the instance from local commands. See more details.

Running scripts locally

You can run your script locally easily, you simply need to pass the right environment variables for the wmill client library to fetch resources and variables from your instance if necessary. See more: https://www.windmill.dev/docs/advanced/local_development.

To develop & test locally scripts & flows, we recommend using the Windmill VS Code extension: https://www.windmill.dev/docs/cli_local_dev/vscode-extension.

Stack

• Postgres as the database.
• Backend in Rust with the following highly-available and horizontally scalable. Architecture:
  • Stateless API backend.
  • Workers that pull jobs from a queue in Postgres (and later, Kafka or Redis. Upvote #173 if interested).
• Frontend in Svelte.
• Scripts executions are sandboxed using Google's nsjail.
• Javascript runtime is the deno_core rust library (which itself uses the rusty_v8 and hence V8 underneath).
• TypeScript runtime is Bun and deno.
• Python runtime is python3.
• Golang runtime is 1.19.1.

Fastest Self-Hostable Workflow Engine

We have compared Windmill to other self-hostable workflow engines (Airflow, Prefect & Temporal) and Windmill is the most performant solution for both benchmarks: one flow composed of 40 lightweight tasks & one flow composed of 10 long-running tasks.

All methodology & results on our Benchmarks page.

Security

Sandboxing

Windmill can use nsjail. It is production multi-tenant grade secure. Do not take our word for it, take fly.io's one.

Secrets, credentials and sensitive values

There is one encryption key per workspace to encrypt the credentials and secrets stored in Windmill's K/V store.

In addition, we strongly recommend that you encrypt the whole Postgres database. That is what we do at https://app.windmill.dev.

Performance

Once a job started, there is no overhead compared to running the same script on the node with its corresponding runner (Deno/Go/Python/Bash). The added latency from a job being pulled from the queue, started, and then having its result sent back to the database is ~50ms. A typical lightweight deno job will take around 100ms total.

Architecture

How to self-host

We only provide docker-compose setup here. For more advanced setups, like compiling from source or using without a postgres super user, see Self-Host documentation.

Docker compose

Windmill can be deployed using 3 files: (docker-compose.yml, Caddyfile and a .env) in a single command.

Make sure Docker is started, and run:

curl https://raw.githubusercontent.com/windmill-labs/windmill/main/docker-compose.yml -o docker-compose.yml
curl https://raw.githubusercontent.com/windmill-labs/windmill/main/Caddyfile -o Caddyfile
curl https://raw.githubusercontent.com/windmill-labs/windmill/main/.env -o .env

docker compose up -d

Go to http://localhost et voilà :)

The default super-admin user is: [email protected] / changeme.

From there, you can follow the setup app and create other users.

More details in Self-Host Documention.

Kubernetes (k8s) and Helm charts

We publish helm charts at: https://github.com/windmill-labs/windmill-helm-charts.

Run from binaries

Each release includes the corresponding binaries for x86_64. You can simply download the latest windmill binary using the following set of bash commands.

BINARY_NAME='windmill-amd64' # or windmill-ee-amd64 for the enterprise edition
LATEST_RELEASE=$(curl -L -s -H 'Accept: application/json' https://github.com/windmill-labs/windmill/releases/latest)
LATEST_VERSION=$(echo $LATEST_RELEASE | sed -e 's/.*"tag_name":"\([^"]*\)".*/\1/')
ARTIFACT_URL="https://github.com/windmill-labs/windmill/releases/download/$LATEST_VERSION/$BINARY_NAME"
wget "$ARTIFACT_URL" -O windmill

OAuth, SSO & SMTP

Windmill Community Edition allows to configure the OAuth, SSO (including Google Workspace SSO, Microsoft/Azure and Okta) directly from the UI in the superadmin settings. Do note that there is a limit of 10 SSO users on the community edition.

See documentation.

Commercial license

To self-host Windmill, you must respect the terms of the AGPLv3 license which you do not need to worry about for personal uses. For business uses, you should be fine if you do not re-expose Windmill in any way to your users and are comfortable with AGPLv3.

To re-expose any Windmill parts to your users as a feature of your product, or to build a feature on top of Windmill, to comply with AGPLv3 your product must be AGPLv3 or you must get a commercial license. Contact us at [email protected] if you have any doubts.

In addition, a commercial license grants you a dedicated engineer to transition your current infrastructure to Windmill, support with tight SLA, and our global cache sync for high-performance/no dependency cache miss of cluster from 10+ nodes to 200+ nodes.

Integrations

In Windmill, integrations are referred to as resources and resource types. Each Resource has a Resource Type that defines the schema that the resource needs to implement.

On self-hosted instances, you might want to import all the approved resource types from WindmillHub. A setup script will prompt you to have it being synced automatically everyday.

Environment Variables

Environment Variable name	Default	Description	Api Server/Worker/All
DATABASE_URL		The Postgres database url.	All
WORKER_GROUP	default	The worker group the worker belongs to and get its configuration pulled from	Worker
MODE	standalone	The mode if the binary. Possible values: standalone, worker, server	All
METRICS_ADDR	None	(ee only) The socket addr at which to expose Prometheus metrics at the /metrics path. Set to "true" to expose it on port 8001	All
JSON_FMT	false	Output the logs in json format instead of logfmt	All
BASE_URL	http://localhost:8000	The base url that is exposed publicly to access your instance. Is overriden by the instance settings if any.	Server
SCRIPT_TOKEN_EXPIRY	900	The default duration period of the ephemeral-token generated at the beginning of a script	Worker
ZOMBIE_JOB_TIMEOUT	30	The timeout after which a job is considered to be zombie if the worker did not send pings about processing the job (every server check for zombie jobs every 30s)	Server
RESTART_ZOMBIE_JOBS	true	If true then a zombie job is restarted (in-place with the same uuid and some logs), if false the zombie job is failed	Server
SLEEP_QUEUE	50	The number of ms to sleep in between the last check for new jobs in the DB. It is multiplied by NUM_WORKERS such that in average, for one worker instance, there is one pull every SLEEP_QUEUE ms.	Worker
MAX_LOG_SIZE	500000	The maximum number of characters a job can emit (log + result)	Worker
DISABLE_NUSER	false	If Nsjail is enabled, disable the nsjail's clone_newuser setting	Worker
KEEP_JOB_DIR	false	Keep the job directory after the job is done. Useful for debugging.	Worker
LICENSE_KEY (EE only)	None	License key checked at startup for the Enterprise Edition of Windmill	Worker
S3_CACHE_BUCKET (EE only)	None	The S3 bucket to sync the cache of the workers to	Worker
SLACK_SIGNING_SECRET	None	The signing secret of your Slack app. See Slack documentation	Server
COOKIE_DOMAIN	None	The domain of the cookie. If not set, the cookie will be set by the browser based on the full origin	Server
DENO_PATH	/usr/bin/deno	The path to the deno binary.	Worker
PYTHON_PATH	/usr/local/bin/python3	The path to the python binary.	Worker
GO_PATH	/usr/bin/go	The path to the go binary.	Worker
GOPRIVATE		The GOPRIVATE env variable to use private go modules	Worker
GOPROXY		The GOPROXY env variable to use	Worker
NETRC		The netrc content to use a private go registry	Worker
PIP_INDEX_URL	None	The index url to pass for pip.	Worker
PIP_EXTRA_INDEX_URL	None	The extra index url to pass to pip.	Worker
PIP_TRUSTED_HOST	None	The trusted host to pass to pip.	Worker
PATH	None	The path environment variable, usually inherited	Worker
HOME	None	The home directory to use for Go and Bash , usually inherited	Worker
DATABASE_CONNECTIONS	50 (Server)/3 (Worker)	The max number of connections in the database connection pool	All
SUPERADMIN_SECRET	None	A token that would let the caller act as a virtual superadmin [email protected]	Server
TIMEOUT_WAIT_RESULT	20	The number of seconds to wait before timeout on the 'run_wait_result' endpoint	Worker
QUEUE_LIMIT_WAIT_RESULT	None	The number of max jobs in the queue before rejecting immediately the request in 'run_wait_result' endpoint. Takes precedence on the query arg. If none is specified, there are no limit.	Worker
DENO_AUTH_TOKENS	None	Custom DENO_AUTH_TOKENS to pass to worker to allow the use of private modules	Worker
DISABLE_RESPONSE_LOGS	false	Disable response logs	Server

Run a local dev setup

See the ./frontend/README_DEV.md file for all running options.

only Frontend

This will use the backend of https://app.windmill.dev but your own frontend with hot-code reloading. Note that you will need to use a username / password login due to CSRF checks using a different auth provider.

In the frontend/ directory:

1. install the dependencies with npm install (or pnpm install or yarn)
2. generate the windmill client:

npm run generate-backend-client
## on mac use
npm run generate-backend-client-mac

3. Run your dev server with npm run dev
4. Et voilà, windmill should be available at http://localhost/

Backend + Frontend

See the ./frontend/README_DEV.md file for all running options.

1. Create a Postgres Database for Windmill and create an admin role inside your Postgres setup. The easiest way to get a working db is to run

   cargo install sqlx-cli
   env DATABASE_URL=<YOUR_DATABASE_URL> sqlx migrate run
   

   This will also avoid compile time issue with sqlx's query! macro
2. Install nsjail and have it accessible in your PATH
3. Install deno and python3, have the bins at /usr/bin/deno and /usr/local/bin/python3
4. Install caddy
5. Install the lld linker
6. Go to frontend/:
   1. npm install, npm run generate-backend-client then npm run dev
   2. You might need to set some extra heap space for the node runtime export NODE_OPTIONS="--max-old-space-size=4096"
   3. In another shell npm run build otherwise the backend will not find the frontend/build folder and will not compile.
   4. In another shell sudo caddy run --config Caddyfile
7. Go to backend/: env DATABASE_URL=<DATABASE_URL_TO_YOUR_WINDMILL_DB> RUST_LOG=info cargo run
8. Et voilà, windmill should be available at http://localhost/

Contributors

Copyright

Windmill Labs, Inc 2023