acme-client

A simple and unopinionated ACME client.

This module is written to handle communication with a Boulder/Let's Encrypt-style ACME API.

• RFC 8555 - Automatic Certificate Management Environment (ACME): https://tools.ietf.org/html/rfc8555
• Boulder divergences from ACME: https://github.com/letsencrypt/boulder/blob/master/docs/acme-divergences.md

Compatibility

Table of contents

• Installation
• Usage
• Cryptography
• Auto mode
  • Challenge priority
  • Internal challenge verification
• API
• HTTP client defaults
• Debugging
• License

Installation

$ npm install acme-client

Usage

const acme = require('acme-client');

const accountPrivateKey = '<PEM encoded private key>';

const client = new acme.Client({
    directoryUrl: acme.directory.letsencrypt.staging,
    accountKey: accountPrivateKey
});

Directory URLs

acme.directory.letsencrypt.staging;
acme.directory.letsencrypt.production;

Cryptography

For key pair generation and Certificate Signing Requests, acme-client uses node-forge, a pure JavaScript implementation of the TLS protocol.

These utility methods are exposed through .forge.

API documentation: docs/forge.md

Example

const privateKey = await acme.forge.createPrivateKey();

const [certificateKey, certificateCsr] = await acme.forge.createCsr({
    commonName: '*.example.com',
    altNames: ['example.com']
});

Auto mode

For convenience an auto() method is included in the client that takes a single config object. This method will handle the entire process of getting a certificate for one or multiple domains.

A full example can be found at examples/auto.js.

Documentation: docs/client.md#AcmeClient+auto

Example

const autoOpts = {
    csr: '<PEM encoded CSR>',
    email: '[email protected]',
    termsOfServiceAgreed: true,
    challengeCreateFn: async (authz, challenge, keyAuthorization) => {},
    challengeRemoveFn: async (authz, challenge, keyAuthorization) => {}
};

const certificate = await client.auto(autoOpts);

Challenge priority

When ordering a certificate using auto mode, acme-client uses a priority list when selecting challenges to respond to. Its default value is ['http-01', 'dns-01'] which translates to "use http-01 if any challenges exist, otherwise fall back to dns-01".

While most challenges can be validated using the method of your choosing, please note that wildcard certificates can only be validated through dns-01. More information regarding Let's Encrypt challenge types can be found here.

To modify challenge priority, provide a list of challenge types in challengePriority:

await client.auto({
    ...,
    challengePriority: ['http-01', 'dns-01']
});

Internal challenge verification

When using auto mode, acme-client will first validate that challenges are satisfied internally before completing the challenge at the ACME provider. In some cases (firewalls, etc) this internal challenge verification might not be possible to complete.

If internal challenge validation needs to travel through an HTTP proxy, see HTTP client defaults.

To completely disable acme-clients internal challenge verification, enable skipChallengeVerification:

await client.auto({
    ...,
    skipChallengeVerification: true
});

API

For more fine-grained control you can interact with the ACME API using the methods documented below.

A full example can be found at examples/api.js.

API documentation: docs/client.md

Example

const account = await client.createAccount({
    termsOfServiceAgreed: true,
    contact: ['mailto:[email protected]']
});

const order = await client.createOrder({
    identifiers: [
        { type: 'dns', value: 'example.com' },
        { type: 'dns', value: '*.example.com' }
    ]
});

HTTP client defaults

This module uses axios when communicating with the ACME HTTP API, and exposes the client instance through .axios.

For example, should you need to change the default axios configuration to route requests through an HTTP proxy, this can be achieved as follows:

const acme = require('acme-client');

acme.axios.defaults.proxy = {
    host: '127.0.0.1',
    port: 9000
};

A complete list of axios options and documentation can be found at:

• https://github.com/axios/axios#request-config
• https://github.com/axios/axios#custom-instance-defaults

Debugging

acme-client uses debug for debugging which can be enabled by running

DEBUG=acme-client node index.js

License

MIT