Let's Encrypt Lexicon Service
Multiple domains, as well as SANs, are supported. Certificates will be renewed automatically, and obtained automatically as soon as new domains are added.
Accepting Let's Encrypt's terms
In order to issue certificates with Let's Encrypt, you must agree to the
Let's Encrypt terms of service. You can do this by running the command
/dehydrated --register --accept-terms from within the container.
For ease of automation, you can define the
ACCEPT_CA_TERMS env var
(with any non-empty value) to automatically accept the terms. Be warned
that doing so will automatically accept any future changes to the terms
The container defines one volume at
/letsencrypt, and expects there to be
a list of domains in
/letsencrypt/domains.txt. Certificates are output to
domains.txt should contain one line per certificate. If you want alternate names on the cert, these should be listed after the primary domain. e.g.
example.com www.example.com admin.example.com
This will request two certificates: one for example.com with a SAN of www.example.com, and a separate one for admin.example.com.
To obtain a wildcard certificate you must alias the domain:
*.example.com > star_example_com
This will request the wildcard certificate and store it under
star_example_com. For more information see
The container uses inotify to monitor the domains.txt file for changes, so you can update it while the container is running and changes will be automatically applied.
To verify that you own the domain, a TXT record needs to be automatically created for it. The Lexicon library handles this, and comes with support for a variety of providers including CloudFlare, EasyDNS, DigitalOcean and Vultr.
Lexicon takes its configuration from environment variables. For full instructions, see its README.
To configure Lexicon to update DNS hosted by CloudFlare, for example, you would pass in:
docker run ... \ -e "PROVIDER=cloudflare" \ -e "LEXICON_CLOUDFLARE_USERNAMEfirstname.lastname@example.org" \ -e "LEXICON_CLOUDFLARE_TOKEN=api-key-here"
For testing purposes, you can set the
STAGING environment variable to
a non-empty value. This will use the Let's Encrypt staging server, which
has much more relaxed limits.
You should pass in a contact e-mail address by setting the
Here's a full worked example:
# The directory we'll use to store the domain list and certificates. # You could use a docker volume instead. mkdir /tmp/letsencrypt echo "domain.com www.domain.com" > /tmp/letsencrypt/domains.txt docker run -d --restart=always \ -e "EMAILemail@example.com" \ -e "STAGING=true" \ -e "PROVIDER=cloudflare" \ -e "LEXICON_CLOUDFLARE_USERNAMEfirstname.lastname@example.org" \ -e "LEXICON_CLOUDFLARE_TOKEN=api-key-here" \ -v /tmp/letsencrypt:/letsencrypt \ csmith/letsencrypt-lexicon:latest