pompelmi — ClamAV Antivirus Scanning for Node.js

ClamAV antivirus scanning for Node.js — clean, typed, zero dependencies.

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Documentation

Guide	Description
Getting Started	Installation, prerequisites, quickstart examples
API Reference	Full function signatures, options, verdicts, error conditions
Docker / Remote Scanning	TCP sidecar, UNIX socket mount, docker-compose patterns
GitHub Action	CI scanning, inputs/outputs, caching, example workflows

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Overview

pompelmi is a minimal Node.js wrapper around ClamAV that exposes a single async function — scan() — and returns one of three typed verdict Symbols: Verdict.Clean, Verdict.Malicious, or Verdict.ScanError. Full documentation at pompelmi.app.

It supports two scanning modes:

• Local — spawns clamscan as a child process and maps its exit code to a verdict. No stdout parsing, no regex.
• Remote / Docker / UNIX socket — streams the file to a running clamd daemon over TCP or a UNIX domain socket using the ClamAV INSTREAM protocol.

No cloud. No daemon required for local mode. No native bindings. Zero runtime dependencies.

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Why pompelmi

If you need to scan file uploads for viruses in Node.js, integrate ClamAV with Express or Fastify, or add antivirus scanning to any upload pipeline, pompelmi is the simplest path.

Most integrations require parsing ClamAV's stdout with regex, managing a clamd daemon, or working around unmaintained packages. pompelmi does none of that: one function call, exit-code-mapped verdicts, zero dependencies.

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Features

• Single scan(filePath, [options]) function — works locally or against a remote clamd instance
• scanBuffer(buffer, [options]) — scan in-memory Buffers directly, no temp file required in TCP mode
• scanStream(stream, [options]) — scan a Readable stream directly. In TCP mode, streamed to clamd with no disk I/O.
• scanDirectory(dirPath, [options]) — recursively scan every file in a directory, returns clean/malicious/errors arrays
• Symbol-based verdicts (Verdict.Clean / Verdict.Malicious / Verdict.ScanError) — typo-proof comparisons
• Full clamd support via the INSTREAM protocol — TCP (host/port) or UNIX socket (socket) with configurable timeout
• Built-in helpers to install ClamAV and update virus definitions programmatically
• Works with Express, Fastify, and any other Node.js HTTP framework
• Zero runtime dependencies — ships nothing but source code
• Tested with EICAR standard antivirus test files
• CommonJS module; TypeScript type declarations available inline

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Requirements

• Node.js — any LTS release (no native addons, no C++ bindings)
• ClamAV — must be installed on the host or reachable over TCP

pompelmi does not bundle or automatically download ClamAV. Install it once per machine (see Installing ClamAV).

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Installation

See pompelmi.app for the full getting-started guide.

# npm
npm install pompelmi

# yarn
yarn add pompelmi

# pnpm
pnpm add pompelmi

Docker

Run ClamAV as a sidecar and point pompelmi at it — no local install needed on the application host.

# docker-compose.yml
services:
  clamav:
    image: clamav/clamav:stable
    ports:
      - "3310:3310"

const result = await scan('/path/to/upload.zip', {
  host: '127.0.0.1',
  port: 3310,
});

See Docker / remote scanning for details.

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Usage

Basic scan

const { scan, Verdict } = require('pompelmi');

const result = await scan('/path/to/file.pdf');

if (result === Verdict.Clean)     console.log('File is safe.');
if (result === Verdict.Malicious) throw new Error('Malware detected — file rejected.');
if (result === Verdict.ScanError) console.warn('Scan incomplete — treat file as untrusted.');

Express file upload

const express = require('express');
const multer  = require('multer');
const fs      = require('fs');
const { scan, Verdict } = require('pompelmi');

const upload = multer({ dest: './uploads' });
const app    = express();

app.post('/upload', upload.single('file'), async (req, res) => {
  const filePath = req.file.path;

  try {
    const result = await scan(filePath);

    if (result === Verdict.Malicious) {
      fs.unlinkSync(filePath);
      return res.status(422).json({ error: 'Malicious file rejected.' });
    }
    if (result === Verdict.ScanError) {
      fs.unlinkSync(filePath);
      return res.status(422).json({ error: 'Scan incomplete — file rejected as precaution.' });
    }

    return res.json({ ok: true, file: req.file.filename });
  } catch (err) {
    fs.unlink(filePath, () => {});
    return res.status(500).json({ error: `Scan failed: ${err.message}` });
  }
});

app.listen(3000);

Fastify file upload

const Fastify  = require('fastify');
const { pipeline } = require('stream/promises');
const fs       = require('fs');
const path     = require('path');
const { scan, Verdict } = require('pompelmi');

const app = Fastify({ logger: true });
app.register(require('@fastify/multipart'));

app.post('/upload', async (req, reply) => {
  const data     = await req.file();
  const filePath = path.join('./uploads', `${Date.now()}-${data.filename}`);

  await pipeline(data.file, fs.createWriteStream(filePath));

  const result = await scan(filePath);

  if (result !== Verdict.Clean) {
    fs.unlinkSync(filePath);
    return reply.code(422).send({ error: result.description });
  }

  return reply.send({ ok: true });
});

Full error handling

const { scan, Verdict } = require('pompelmi');
const path = require('path');

async function safeScan(filePath) {
  try {
    const result = await scan(path.resolve(filePath));

    if (result === Verdict.ScanError) {
      // clamscan exited with code 2 — I/O error, encrypted archive, etc.
      console.warn('Scan could not complete — rejecting file as precaution.');
      return null;
    }

    return result; // Verdict.Clean or Verdict.Malicious
  } catch (err) {
    // filePath not a string, file not found, clamscan not in PATH, etc.
    console.error('Scan failed:', err.message);
    return null;
  }
}

Scan multiple files concurrently

const { scan } = require('pompelmi');
const files    = ['/uploads/a.pdf', '/uploads/b.zip', '/uploads/c.png'];

const results = await Promise.all(files.map((f) => scan(f)));

Scan a Directory

const fs = require('fs');
const { scanDirectory } = require('pompelmi');

const results = await scanDirectory('/uploads');

console.log('Clean:', results.clean);
console.log('Malicious:', results.malicious);
console.log('Errors:', results.errors);

// Delete all malicious files
results.malicious.forEach(f => fs.unlinkSync(f));

Scan a Buffer

const { scanBuffer, Verdict } = require('pompelmi');

// Useful with multer memoryStorage or any in-memory upload
const result = await scanBuffer(req.file.buffer);

if (result === Verdict.Malicious) throw new Error('Malware detected.');
if (result === Verdict.ScanError) console.warn('Scan incomplete.');

Scan a Stream

const { scanStream, Verdict } = require('pompelmi');
const { Readable } = require('stream');

// Useful for S3 getObject, HTTP downloads, or any piped source
const stream = s3.getObject({ Bucket, Key }).createReadStream();
const result = await scanStream(stream);

if (result === Verdict.Malicious) throw new Error('Malware detected.');
if (result === Verdict.ScanError) console.warn('Scan incomplete.');

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Docker / Remote Scanning

Pass host and port (or socket) to switch from the local clamscan CLI to the clamd daemon. Everything else — the returned verdicts, error types — is identical.

TCP:

const result = await scan('/path/to/file.zip', { host: '127.0.0.1', port: 3310 });

UNIX socket:

const result = await scan('/path/to/file.zip', { socket: '/run/clamav/clamd.sock' });

See docs/docker.md for Docker Compose examples, UNIX socket volume mounts, scanBuffer / scanStream in clamd mode, and connection retry patterns.

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Configuration

pompelmi has no configuration file or environment variables. All options are passed directly to scan().

Option	Type	Default	Description
socket	string	—	Path to a clamd UNIX domain socket (e.g. /run/clamav/clamd.sock). Takes precedence over host/port when set.
host	string	—	clamd hostname. Enables TCP mode when set.
port	number	3310	clamd port.
timeout	number	15000	Socket idle timeout in milliseconds (clamd mode only).

When none of socket, host, or port is provided, pompelmi spawns clamscan --no-summary <filePath> locally.

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API Reference

See docs/api.md for the full reference: function signatures, options table, verdict Symbols, error conditions, and error handling patterns.

Quick summary:

Function	Input	clamd mode disk I/O
scan(filePath, [options])	File path on disk	None (streamed)
scanBuffer(buffer, [options])	Buffer	None (streamed)
scanStream(stream, [options])	Node.js Readable	None (streamed)
scanDirectory(dirPath, [options])	Directory path	None (streamed)

All four functions accept the same options object and resolve to the same three verdict Symbols:

Symbol	Meaning
Verdict.Clean	No threats found
Verdict.Malicious	Known signature matched
Verdict.ScanError	Scan could not complete — treat as untrusted

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Installing ClamAV

# macOS
brew install clamav && freshclam

# Linux (Debian / Ubuntu)
sudo apt-get install -y clamav clamav-daemon && sudo freshclam

# Windows (Chocolatey)
choco install clamav -y

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Examples

The examples/ directory contains standalone runnable scripts and framework-specific starters.

Framework starters

Directory	Description
examples/express/	Full Express app with multer + pompelmi middleware
examples/nextjs/	Next.js API route that scans raw upload bytes
examples/nestjs/	NestJS guard wrapping pompelmi for route-level protection

Standalone scripts

Each can be run with node examples/<name>.js.

File	Description
basic-scan.js	Scan a single file and log the verdict
scan-on-upload-express.js	Express route: scan before saving
scan-on-upload-fastify.js	Fastify route: same pattern
scan-with-options.js	Remote clamd with custom host, port, timeout
handle-scan-error.js	Handle every verdict including hard rejections
delete-on-malicious.js	Auto-delete file if malicious
quarantine-on-malicious.js	Move infected file to a quarantine folder
scan-multiple-files.js	Concurrent scans with Promise.all
scan-directory.js	Recursively scan every file in a directory
scan-buffer.js	Scan an in-memory Buffer (multer memoryStorage)
scan-stream.js	Scan a Readable stream (S3, HTTP, pipes)
rest-api-server.js	Minimal HTTP server exposing POST /scan
s3-scan-before-upload.js	Scan locally, then upload to S3 only if clean
cli-scan.js	CLI tool: scan file paths, exit non-zero on threats
scan-with-timeout.js	Timeout patterns for local and remote scanning
scan-pdf.js	PDF upload with extension validation
scan-image.js	Image upload with extension validation
scan-zip.js	ZIP archive scan (ClamAV recurses automatically)
install-clamav.js	Programmatic ClamAV installation
update-virus-database.js	Programmatic virus DB update
typescript-usage.ts	TypeScript example with full type declarations

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GitHub Action

Scan any repository for viruses on every push or pull request — ClamAV is bundled inside a Docker container, virus definitions are auto-updated at runtime, and no external services are required.

Minimal usage

- uses: actions/checkout@v4

- name: Virus scan
  uses: pompelmi/pompelmi@v1.7.0

Full example

- uses: actions/checkout@v4

- name: Virus scan
  id: scan
  uses: pompelmi/pompelmi@v1.7.0
  with:
    path: 'uploads/'        # scan a subdirectory instead of the whole workspace
    fail-on-virus: 'true'   # fail the workflow step on detection (default)

- name: Print infected files
  if: always()
  run: echo "${{ steps.scan.outputs.infected-files }}"

Inputs

Input	Description	Default
path	Directory or file to scan	. (full workspace)
fail-on-virus	Fail the workflow step when infected files are found	true
comment-on-pr	Post a PR comment listing infected files (requires GITHUB_TOKEN)	true

Outputs

Output	Description
infected-files	Newline-separated list of infected file paths (empty when clean)
status	"clean" or "infected"

A ready-to-copy workflow is available at .github/workflows/action-example.yml. Full reference — inputs, outputs, layer caching, and more examples — in docs/github-action.md.

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Contributing

Full documentation and guides are available in the Wiki.

# 1. Clone and install dev dependencies
git clone https://github.com/pompelmi/pompelmi.git
cd pompelmi
npm install

# 2. Run the test suite
npm test

# 3. Lint
npm run lint

Tests

• test/unit.test.js — runs with Node's built-in test runner. Mocks nativeSpawn and platform dependencies; ClamAV is not required.
• test/scan.test.js — integration tests that spawn real clamscan against EICAR test files. Skipped automatically when clamscan is not in PATH.

Submitting changes

1. Fork the repository.
2. Create a feature branch: git checkout -b feat/your-change.
3. Make your changes and confirm npm test passes.
4. Open a pull request against main.

Please read CODE_OF_CONDUCT.md before contributing. To report a security vulnerability, see SECURITY.md.

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Coming soon

• AWS S3 integration — scan objects directly from S3 without downloading
• Cloudflare Workers support — edge-native scanning via the clamd TCP protocol
• NestJS official module — PompelmiModule.forRoot() with injectable PompelmiService

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License

ISC — © pompelmi contributors

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pompelmi.app · npm · GitHub