Genkit Express Plugin

This plugin provides utilities for conveninetly exposing Genkit flows and actions via Express HTTP server as REST APIs.

import { expressHandler } from '@genkit-ai/express';
import express from 'express';

const simpleFlow = ai.defineFlow(
  'simpleFlow',
  async (input, streamingCallback) => {
    const { text } = await ai.generate({
      model: gemini15Flash,
      prompt: input,
      streamingCallback,
    });
    return text;
  }
);

const app = express();
app.use(express.json());

app.post('/simpleFlow', expressHandler(simpleFlow));

app.listen(8080);
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You can also set auth policies:

// middleware for handling auth headers.
const authMiddleware = async (req, resp, next) => {
  // parse auth headers and convert to auth object.
  (req as RequestWithAuth).auth = {
    user:
      req.header('authorization') === 'open sesame' ? 'Ali Baba' : '40 thieves',
  };
  next();
};

app.post(
  '/simpleFlow',
  authMiddleware,
  expressHandler(simpleFlow, {
    authPolicy: ({ auth }) => {
      if (auth.user !== 'Ali Baba') {
        throw new Error('not authorized');
      }
    },
  })
);
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Flows and actions exposed using the expressHandler function can be accessed using genkit/client library:

import { runFlow, streamFlow } from 'genkit/client';

const result = await runFlow({
  url: `http://localhost:${port}/simpleFlow`,
  input: 'say hello',
});

console.log(result); // hello

// set auth headers (when using auth policies)
const result = await runFlow({
  url: `http://localhost:${port}/simpleFlow`,
  headers: {
    Authorization: 'open sesame',
  },
  input: 'say hello',
});

console.log(result); // hello

// and streamed
const result = streamFlow({
  url: `http://localhost:${port}/simpleFlow`,
  input: 'say hello',
});
for await (const chunk of result.stream()) {
  console.log(chunk);
}
console.log(await result.output());
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The sources for this package are in the main Genkit repo. Please file issues and pull requests against that repo.

Usage information and reference details can be found in Genkit documentation.

License: Apache 2.0