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Built-in Middlewares

Arkos comes with a set of built-in middlewares that handle common tasks like compression, security, and parsing. This document outlines each middleware, its purpose, and how to configure it.

note

The following code snippets are Arkos behind the scenes implementation of each built-in middleware.

Compression​

The compression middleware reduces the size of HTTP responses sent to clients.

app.use(compression(arkosConfig?.compressionOptions));

Configuration Options:

  • Pass custom compression options via arkosConfig.compressionOptions
  • Accepts all options from the compression package

Customization:

Global Rate Limiting​

Protects your API from abuse by limiting the number of requests per client.

app.use(
  rateLimit({
    windowMs: 60 * 1000, // 1 minute
    limit: 1000, // 1000 requests per windowMs
    standardHeaders: "draft-7",
    legacyHeaders: false,
  })
);

Configuration Options:

  • Override default settings via arkosConfig.globalRequestRateLimitOptions
  • Default: 1000 requests per minute

Customization:

CORS​

Configures Cross-Origin Resource Sharing policy for your API.

Configuration Options:

  • Set allowed origins via arkosConfig.cors.allowedOrigins (array, string, or "*")
  • Provide custom options via arkosConfig.cors.options
  • Replace entire handler with arkosConfig.cors.customHandler

Customization:

JSON Body Parser​

Parses incoming JSON request bodies.

app.use(express.json(arkosConfig?.jsonBodyParserOptions));

Configuration Options:

  • Override with custom options via arkosConfig.jsonBodyParserOptions
  • Accepts all options from Express's json method

Customization:

Parses Cookie header and populates req.cookies.

app.use(cookieParser(...[...(arkosConfig?.cookieParserParameters || [])]));

Configuration Options:

  • Provide custom parameters via arkosConfig.cookieParserParameters

Customization:

Query Parser​

Parses query string parameters into appropriate JavaScript types.

app.use(
  queryParser({
    parseNull: true,
    parseUndefined: true,
    parseBoolean: true,
  })
);

Configuration Options:

  • Override default settings via arkosConfig.queryParserOptions
  • Default: parses null values, undefined values, and booleans

Customization:

Database Connection Check​

Validates database connectivity before request processing.

app.use(checkDatabaseConnection);

Customization:

Request Logger​

Logs incoming requests for debugging and monitoring.

app.use(handleRequestLogs);

Customization:

Global Error Handler​

Captures and formats errors thrown during request processing.

app.use(errorHandler);

Customization:

Adding Custom Middlewares​

To add your own middlewares to the stack:

// src/app.ts
import arkos from "arkos";

arkos.init({
  middlewares: {
    additional: [myCustomMiddleware, anotherMiddleware],
  },
  // other configs
});
warning

This will not override the built-in middlewares because they will be placed right after the whole built-in middleware stack, if you would like to replace or disable any built-in middleware see Modifying Built-in Middlewares Guide.

Where Custom Middlewares Are Placed​

Bear in mind that these stack of middlewares will be passed right after all built-in middlewares mentioned above. If you want to put custom middlewares before all Arkos built-in configurations pass a function to configureApp under configs to have acess to express app before any Arkos configurations, see the Acessing The Express App Guide.

Next Steps:​