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Last pushed: 2 months ago
Short Description
A daemon to create and renew letsencrypt certs in a professional setup (e.g. with load balancer)
Full Description


This was useful for some time but I now use docker swarm with traefik for loadbalancing which has support for letsencrypt baked in. I suggest you start using this today too.


I opened a Gitter room

Bugs go to issues please.

Docker service

Available on docker hub.


This service can be run on a webserver to obtain letsencrypt certificates.
It can be run on the server that the A record of the domain points to, but the major benefit of this service is, that it can be run in a professional setup
with loadbalancers and in this scenario be deployed on any node behind the loadbalancer without
interrupting the live deployment.

This service has been tested in a deployment orchestrated with Docker Cloud and their haproxy image but
should work fine in other setups too.


The problem with the default letsencrypt tool is that it expects to be run on port 80 on the root domain.
Or at least the server where all http traffic to the domain ends up. This
means that you can either "inject" it into your one instance apache or nginx server. If you have another setup
which involves for example some node http servers and path based http routing + loadbalancing you need to take down
your live deployment, start a new webserver, get the certificates on port 80 and then start your deployment
again. It goes without saying that this cannot be a "workflow".

Intent of this service

To provide a solution to the above problem, we suggest this service.

  • It can be run as an additional service in any load balanced setup.
  • It can run forever and permanently runs a http server on port 80 (important for
    load balancers that check whether the service is "alive" before routing traffic to it).
  • One can securely connect to the service at any time and create or renew certificates with a simple command.

Setup and certificate creation

I made a stackfile to get you going. Available on


  • You have exactly one node "loadbalancer" in docker cloud that has the tag "loadbalancer". You can change "loadbalancer" to whatever floats your boat, it just needs to match the "tag" in the stackfile.
  • You want to issue certs for and have and properly registered and
    the DNS entries resolve to the node with the tag "loadbalancer"<sup>1</sup>.


  1. Copy the stackfile and change the content (like domain names, passwords and such).
  2. Deploy the stackfile to docker cloud. Wait for the services to start.
  3. Check whether shows the correct success message ("Letsencrypt cert service reporting in! Load balancing seems to work.")
  4. Check whether shows the correct success message ("Letsencrypt cert service reporting in! Load balancing seems to work.")
  5. Check whether shows success message
  6. Open<sup>2</sup>(wait a little, if you get an error, check the server logs to debug or open an issue here).
  7. On success go to and authenticate (Please check that it is properly encrypted traffic!)
  8. Then do one of these:
    1. Get your certificate from
    2. Get your private key from
    3. Get you Docker Cloud Haproxy certificate string from (:D)
  9. Change the stackfile and put the certificate in the environment of the lb to enable encryption. See here
  10. Check that gives you correctly encrypted responses.


<a name="myfootnote1"><sup>1</sup></a>: Two ways to achieve this. For (root domain) you need an A-Record with the ip address of the node. Do not set a CNAME for the root domain, you will break stuff, for example MX records.
For you can either put an A record with the ip address or you create a CNAME for certs and point it to the endpoint of the loadbalancer which will be something like

<a name="myfootnote2"><sup>2</sup></a>: There are no checks on rate limit and so on. Please do not hit /makecert too often.

Certificat renewal

With private service enabled and certificates in place you can hit to renew certs. On success you can retrieve the new extended certificate as above.

Container configuration

As this is a docker container image, all configuration of the running container is done by setting appropriate environment variables.
These are as follows:

General environment variables

Variable Explanation Example value
CERT_DOMAINS Domains the certificate should be issued for, comma separated,
CERT_EMAIL Email for notifications (like imminent certificate expiry) ````
CERT_SERVICE_PRIVATE Flag to run private part of app (certificate hosting) true
CERT_SERVICE_PASSWORD Pass to authenticate against private certificate service SomeGoodPassword
CERT_SERVICE_USERNAME Username to authenticate against private certificate service michael

Docker Cloud HAProxy specific

Variable Explanation Example value
VIRTUAL_HOST Routing all acme queries to the service http://*/.well-known/*
VIRTUAL_HOST_WEIGHT Taking over queries. You need to set a value that is higher than the one of the "catch all" service 1
EXCLUDE_PORTS Don't route traffic to port 443 443

Usually you would want the newly generated certificates to be stored in the hosts file system
so make sure to link the container dir /etc/letsencrypt to the host.

Node package

The docker image is running a node service. It can also be used standalone if you need it. Documentation comes below.

API Reference

<a name="module_letsencrypt-cert-service"></a>



var CertService = require("letsencrypt-cert-service");
var certService = new CertService(config);

<a name="module_letsencrypt-cert-service..LetsEncryptCertService"></a>


Kind: inner class of <code>letsencrypt-cert-service</code>
<a name="new_module_letsencrypt-cert-service..LetsEncryptCertService_new"></a>

new LetsEncryptCertService(config)

Param Type Description
config <code>Array.<string></code> The hostnames which the certificate is to be created for <code>string</code> Letsencrypt notification email
[config.private] <code>boolean</code> Set to true when you want private service to be running
[config.password] <code>string</code> Strong password to protect private parts - required when private true
[config.username] <code>string</code> Username of choice - required when private true


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Released under the Unlicense. See the Unlicense

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