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Platform Support

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Platform Support

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The bloqr-backend includes a platform abstraction layer that enables running in any JavaScript runtime, including:

  • Deno (default)
  • Node.js (via npm compatibility)
  • Cloudflare Workers
  • Deno Deploy
  • Vercel Edge Functions
  • AWS Lambda@Edge
  • Web Workers (browser)
  • Browsers (with server-side proxy for CORS)

The platform layer is designed to be pluggable - you can easily add or remove fetchers without modifying the core compiler.

Core Concepts

The platform layer provides:

  • WorkerCompiler - A platform-agnostic compiler that works without file system access
  • PreFetchedContentFetcher - Supply source content directly instead of fetching from URLs
  • HttpFetcher - Standard Fetch API-based content fetching (works everywhere)
  • CompositeFetcher - Chain multiple fetchers together (pre-fetched takes priority)
  • PlatformDownloader - Handles !#include directives and conditional compilation

Edge Runtimes (Generic)

The WorkerCompiler works in any edge runtime or serverless environment that supports the standard Fetch API. The pattern is the same across all platforms:

  1. Pre-fetch source content on the server (avoids CORS and network restrictions)
  2. Pass content to the compiler via preFetchedContent
  3. Configure and compile using the standard API
import { CompositeFetcher, HttpFetcher, type IConfiguration, PreFetchedContentFetcher, WorkerCompiler } from '@jk-com/bloqr-compiler';


// Option 1: Use pre-fetched content (recommended for edge)
async function compileWithPreFetched(sourceUrls: string[]): Promise<string[]> {
    // Fetch all sources
    const preFetched = new Map<string, string>();
    for (const url of sourceUrls) {
        const response = await fetch(url);
        preFetched.set(url, await response.text());
    }


    const compiler = new WorkerCompiler({ preFetchedContent: preFetched });
    const config: IConfiguration = {
        name: 'My Filter List',
        sources: sourceUrls.map((url) => ({ source: url })),
        transformations: ['Deduplicate', 'RemoveEmptyLines'],
    };


    return compiler.compile(config);
}


// Option 2: Build a custom fetcher chain
function createCustomCompiler() {
    const preFetched = new PreFetchedContentFetcher(
        new Map([
            ['local://rules', 'my-custom-rule'],
        ]),
    );
    const http = new HttpFetcher();
    const composite = new CompositeFetcher([preFetched, http]);


    return new WorkerCompiler({ customFetcher: composite });
}

Cloudflare Workers

The compiler runs natively in Cloudflare Workers. A production-ready implementation is available at the repository root in the worker/ directory with a comprehensive web UI in public/.

Quick Start:

Terminal window
# Install dependencies
npm install


# Run locally
deno task wrangler:dev


# Deploy to Cloudflare
deno task wrangler:deploy

Deployment: A wrangler.toml configuration file is provided in the repository root for easy deployment via Cloudflare’s Git integration or using wrangler deploy.

⚠️ Important: This project uses wrangler deploy for Cloudflare Workers, NOT deno deploy. While this is a Deno-based project, it deploys to Cloudflare Workers runtime. See the Cloudflare Pages Deployment Guide for Pages-specific configuration.

The production worker (worker/worker.ts) includes:

  • Interactive Web UI at / (see public/index.html)
  • API Testing Interface at /test.html
  • JSON API at POST /compile
  • Streaming API at POST /compile/stream with Server-Sent Events
  • Batch API at POST /compile/batch
  • Async API at POST /compile/async for queue-based processing
  • Batch Async API at POST /compile/batch/async for queue-based batch processing
  • Metrics at GET /metrics
  • Pre-fetched content support to bypass CORS restrictions
  • Caching with KV storage
  • Rate limiting
  • Request body size limits (DoS protection)
  • Request deduplication
  • Cloudflare Queue integration for async compilation

Request Body Size Limits:

The worker validates request body sizes to prevent denial-of-service attacks via large payloads. The default limit is 1MB.

Terminal window
# Configure in environment (megabytes)
MAX_REQUEST_BODY_MB="2"  # Set to 2MB limit

Requests exceeding the limit receive a 413 Payload Too Large response:

{
    "error": "Request body size (2097152 bytes) exceeds maximum allowed size (1048576 bytes)"
}

Cloudflare Queue Support:

The worker supports asynchronous compilation through Cloudflare Queues, allowing you to:

  • Offload long-running compilations to background processing
  • Process batch operations without blocking
  • Pre-warm the cache with popular filter lists
  • Bypass rate limits for queued requests

📚 Queue Support Documentation - Complete guide for using async compilation

Tail Worker for Observability:

A Cloudflare Tail Worker is included for advanced logging and monitoring. The tail worker captures logs, exceptions, and events from the main worker in real-time.

Terminal window
# Deploy the tail worker
deno task wrangler:tail:deploy


# View tail worker logs
deno task wrangler:tail:logs

Features:

  • Log Persistence: Store logs in Cloudflare KV
  • Error Forwarding: Send critical errors to webhooks (Slack, Discord, etc.)
  • Structured Events: Format logs for external systems
  • Automatic Cleanup: Configurable log retention

📚 Tail Worker Documentation - Complete guide for setup and configuration

import { type IConfiguration, WorkerCompiler } from '@jk-com/bloqr-compiler';


export default {
    async fetch(request: Request): Promise<Response> {
        // Pre-fetch content on the server where there are no CORS restrictions
        const sourceContent = await fetch('https://example.com/filters.txt').then((r) => r.text());


        const compiler = new WorkerCompiler({
            preFetchedContent: {
                'https://example.com/filters.txt': sourceContent,
            },
        });


        const configuration: IConfiguration = {
            name: 'My Filter List',
            sources: [
                { source: 'https://example.com/filters.txt' },
            ],
            transformations: ['Deduplicate', 'RemoveEmptyLines'],
        };


        const result = await compiler.compile(configuration);


        return new Response(result.join('\n'), {
            headers: { 'Content-Type': 'text/plain' },
        });
    },
};

Using the Web UI:

  1. Visit the root URL of your deployed worker
  2. Use Simple Mode for quick filter list compilation
  3. Use Advanced Mode for JSON configuration
  4. Use Test Page to test API endpoints directly
  5. View real-time progress with streaming compilation

Web Workers

Use WorkerCompiler in Web Workers for background compilation:

worker.ts
import { type IConfiguration, WorkerCompiler } from '@jk-com/bloqr-compiler';


self.onmessage = async (event) => {
    const { configuration, preFetchedContent } = event.data;


    const compiler = new WorkerCompiler({
        preFetchedContent,
        events: {
            onProgress: (progress) => {
                self.postMessage({ type: 'progress', progress });
            },
        },
    });


    const result = await compiler.compile(configuration);
    self.postMessage({ type: 'complete', rules: result });
};

Browser Usage

For browser environments, pre-fetch all source content server-side to avoid CORS issues:

import { type IConfiguration, WorkerCompiler } from '@jk-com/bloqr-compiler';


// Fetch sources through your server proxy to avoid CORS
async function fetchSources(urls: string[]): Promise<Map<string, string>> {
    const content = new Map<string, string>();
    for (const url of urls) {
        const response = await fetch(`/api/proxy?url=${encodeURIComponent(url)}`);
        content.set(url, await response.text());
    }
    return content;
}


// Usage
const sources = await fetchSources([
    'https://example.com/filters.txt',
]);


const compiler = new WorkerCompiler({
    preFetchedContent: Object.fromEntries(sources),
});


const configuration: IConfiguration = {
    name: 'Browser Compiled List',
    sources: [
        { source: 'https://example.com/filters.txt' },
    ],
};


const rules = await compiler.compile(configuration);

Platform API Reference

WorkerCompiler

interface WorkerCompilerOptions {
    // Pre-fetched content (Map or Record)
    preFetchedContent?: Map<string, string> | Record<string, string>;


    // Custom content fetcher (for advanced use cases)
    customFetcher?: IContentFetcher;


    // Options for the default HTTP fetcher (timeout, user agent, custom headers)
    httpOptions?: IHttpFetcherOptions;


    // Tracing context for diagnostics and OpenTelemetry integration
    tracingContext?: TracingContext;


    // Injectable dependencies (for testing/customization)
    dependencies?: WorkerCompilerDependencies;
}


class WorkerCompiler {
    constructor(options?: WorkerCompilerOptions);


    // Compile and return rules
    compile(configuration: IConfiguration): Promise<string[]>;


    // Compile with optional benchmarking metrics
    compileWithMetrics(
        configuration: IConfiguration,
        benchmark?: boolean,
    ): Promise<WorkerCompilationResult>;
}

IContentFetcher

Implement this interface to create custom content fetchers:

interface IContentFetcher {
    canHandle(source: string): boolean;
    fetch(source: string): Promise<string>;
}

Custom Fetchers

You can implement custom fetchers for specialized use cases:

import { CompositeFetcher, HttpFetcher, type IContentFetcher, WorkerCompiler } from '@jk-com/bloqr-compiler';


// Example: Redis-backed cache fetcher
class RedisCacheFetcher implements IContentFetcher {
    constructor(private redis: RedisClient, private ttl: number) {}


    canHandle(source: string): boolean {
        return source.startsWith('http://') || source.startsWith('https://');
    }


    async fetch(source: string): Promise<string> {
        const cached = await this.redis.get(`filter:${source}`);
        if (cached) return cached;


        const response = await fetch(source);
        const content = await response.text();


        await this.redis.setex(`filter:${source}`, this.ttl, content);
        return content;
    }
}


// Example: S3/R2-backed storage fetcher
class S3StorageFetcher implements IContentFetcher {
    constructor(private bucket: S3Bucket) {}


    canHandle(source: string): boolean {
        return source.startsWith('s3://');
    }


    async fetch(source: string): Promise<string> {
        const key = source.replace('s3://', '');
        const object = await this.bucket.get(key);
        return object?.text() ?? '';
    }
}


// Chain fetchers together - first match wins
const compiler = new WorkerCompiler({
    customFetcher: new CompositeFetcher([
        new RedisCacheFetcher(redis, 3600),
        new S3StorageFetcher(bucket),
        new HttpFetcher(),
    ]),
});

This pluggable architecture allows you to:

  • Add caching layers (Redis, KV, memory)
  • Support custom protocols (S3, R2, database)
  • Implement authentication/authorization
  • Add logging and metrics
  • Mock sources for testing