SSL - Automatic Certificate Management Environment (ACME)

The Automatic Certificate Management Environment (ACME) protocol allow automating interactions between certificate authorities and their users' servers, allowing the automated deployment of public key infrastructure.

Most of the issuers offers Automatic Issuing free of cost.

Supported ACME Challenge Methods

Easy HAProxy supports the following ACME challenge types:

• HTTP-01 Challenge (Default and Only)
  The ACME server validates ownership by making an HTTP request to a temporary endpoint served on port 80. Easy HAProxy provisions a standalone Certbot responder on an internal port and routes /.well-known/acme-challenge/ traffic to it.

Challenge Support

• HTTP-01: Fully supported (default)
• TLS-ALPN-01: Not supported natively by Easy HAProxy
• DNS-01: Not supported natively. If you need DNS-01 for wildcard certificates, obtain certificates externally and mount them via sslcert as static certificates.

How ACME works with Easy HAProxy

At a high level, ACME with Easy HAProxy works in two stages:

1. Global ACME/Certbot setup (one-time per EasyHAProxy instance)

   • Choose your Certificate Authority (CA) either by:
     • Using AUTOCONFIG with EASYHAPROXY_CERTBOT_AUTOCONFIG (e.g., zerossl, letsencrypt_test, google, etc.), or
     • Manually setting EASYHAPROXY_CERTBOT_SERVER (and EASYHAPROXY_CERTBOT_EAB_KID / EASYHAPROXY_CERTBOT_EAB_HMAC_KEY when your CA requires EAB).
   • Always set your contact email via EASYHAPROXY_CERTBOT_EMAIL.
   • Ensure ports 80 and 443 are publicly reachable on the EasyHAProxy host.
   • Persist the folder /certs/certbot on a durable volume so issued/renewed certificates survive container restarts and avoid hitting CA rate limits.
   • Challenge method is HTTP-01 only; EasyHAProxy configures a standalone Certbot responder internally.

2. Enable ACME per domain (per service/app)

   • Add the label easyhaproxy.<definition>.certbot=true to the service you want a certificate for.
   • Ensure the service is exposed on HTTP port 80 from EasyHAProxy’s perspective (e.g., easyhaproxy.<definition>.port=80). ACME HTTP-01 will not work if the front port is not 80.
   • Provide the domain via easyhaproxy.<definition>.host=yourdomain.tld (and additional labels per your install method).

What happens under the hood

• When a labeled domain is detected and a certificate is needed, EasyHAProxy runs Certbot with --preferred-challenges http and a standalone responder bound to internal port 2080.
• HAProxy temporarily routes /.well-known/acme-challenge/ for that domain to the Certbot responder, allowing the CA to validate via HTTP-01.
• On success, EasyHAProxy merges the issued cert and key and stores them under /certs/certbot (one PEM per domain), then reloads HAProxy to serve HTTPS for that domain.
• Certificates are monitored and renewed automatically before expiry.

Tips

• Do not map port 443 for your backend app; EasyHAProxy will terminate TLS at the proxy once the certificate is issued.
• If you do not set EASYHAPROXY_CERTBOT_EMAIL, EasyHAProxy will not request certificates.
• DNS-01 is not supported natively; for wildcards or DNS-only environments, issue certificates externally and mount them via sslcert as static certificates.

Environment Variables

To enable the ACME protocol we need to enable Certbot in EasyHAProxy by setting up to the following environment variables:

Environment Variable	Required?	Description
EASYHAPROXY_CERTBOT_EMAIL	YES	Your email in the certificate authority.
EASYHAPROXY_CERTBOT_AUTOCONFIG	-	Will use pre-sets for your Certificate Authority (CA). See table below.
EASYHAPROXY_CERTBOT_SERVER	-	The ACME Endpoint of your certificate authority. If you use AUTOCONFIG, it is set automatically. See table below.
EASYHAPROXY_CERTBOT_EAB_KID	-	External Account Binding (EAB) Key Identifier (KID) provided by your certificate authority. Some CA require it. See table below.
EASYHAPROXY_CERTBOT_EAB_HMAC_KEY	-	External Account Binding (EAB) HMAC Key provided by your certificate authority. Some CA require it. See table below.
EASYHAPROXY_CERTBOT_RETRY_COUNT	-	Wait 'n' requests before retrying issue invalid requests. Default 60.
EASYHAPROXY_CERTBOT_PREFERRED_CHALLENGES	-	The preferred challenges for Certbot. Available: http
EASYHAPROXY_CERTBOT_MANUAL_AUTH_HOOK	-	The path to a script that will be executed (default: None)

Auto Config Certificate Authority (CA)

Here are detailed instructions per Certificate Authority (CA). If anyone is missing, please let's know.

Possible values for: EASYHAPROXY_CERTBOT_AUTOCONFIG

CA	Auto Config	Free?	Account Required?	EAB KID?	EAB HMAC Key?	More Info
Let's Encrypt	letsencrypt	Yes	No	No	No	Default when no AUTOCONFIG is set
Let's Encrypt (Test)	letsencrypt_test	Yes	No	No	No	-
ZeroSSL	zerossl	Yes	No	No	No	Link
BuyPass	buypass	Yes	No	No	No	Link
BuyPass (test)	buypass_test	Yes	No	No	No	Link
Google	google	Yes	Yes	Yes	Yes	Link
Google Test	google_test	Yes	Yes	Yes	Yes	Link
SSLCOM RCA	sslcom_rca	Trial	EAB Keys by email.	Yes	Yes	Link
SSLCOM ECC	sslcom_ecc	Trial	EAB Keys by email.	Yes	Yes	Link
Digicert	-	No	Yes	Yes	Yes	Link
Entrust	-	No	Yes	Yes	Yes	Link
Sectigo	-	No	Yes	Yes	Yes	Link

This configuration is global. After set up ACME properly, is necessary enable for each domain the certificate request.

To do that add the label: easyhaproxy.<definition>.certbot=true. See the method of installation you are using to learn how to set up properly.

Example

Setting up EasyHAProxy

Run the EasyHAProxy container:

docker run \
    ... \
    -e EASYHAPROXY_CERTBOT_AUTOCONFIG=zerossl \
    -e EASYHAPROXY_CERTBOT_EMAIL=john@doe.com \
    -p 80:80 \
    -p 443:443 \
    -v /path/to/guest/certbot/certs:/certs/certbot \
    ... \
    byjg/easy-haproxy

Configuration Notes

• The EASYHAPROXY_CERTBOT_AUTOCONFIG is not required for Let's Encrypt (it's the default). In this example, the certificate will be issued by ZeroSSL.
• If you don't set the EASYHAPROXY_CERTBOT_EMAIL environment variable, EasyHAProxy will fail silently and will not request certificates.
• Ports 80 and 443 must be accessible through the internet as a Let's Encrypt requirement

Important: Persist Certbot Certificates

To avoid hitting rate limits and certificate issuing problems:

• You must persist the container folder /certs/certbot outside the container
• Never delete or modify its contents manually
• If you don't persist this folder, or if you delete/modify its contents, certificate issuing may not work properly and you may hit rate limits

If you are using Let's Encrypt, be aware of it rate limits:

• https://letsencrypt.org/docs/duplicate-certificate-limit/
• https://letsencrypt.org/docs/rate-limits/

Setting up your container to use the ACME CA

docker run \
    ... \
    --label easyhaproxy.express.port=80 \
    --label easyhaproxy.express.localport=3000 \
    --label easyhaproxy.express.host=example.org \
    --label easyhaproxy.express.certbot=true \
    ... \
    some/myimage

ACME Requirements

• Your container must be configured to listen on port 80 (easyhaproxy.<definition>.port=80). The CA will not issue certificates if using another port, and EasyHAProxy will fail silently.
• Do not set port 443 for the container when using ACME, because EasyHAProxy will create the HTTPS binding automatically once the certificate is issued.

---

Open source ByJG