We use this internally for automating our certificate management using dehydrated. We do not support this further than needed for our usage, but feel free to use it if you want.

We have short tutorials for two different modi operandi: The dns-01 and http-01 challenge. Both are fairly easy to use. The dns-01 challenge requires less effort if your DNS provider is supported by lexicon, the http-01 challenge otherwise.

For a short tutorial of getting a certificate with this container and the dns-01 challenge, go here, for the same using the http-01 challenge, go here.

By default the container will attempt to generate a config as /data/config with the default values for all the environment variables. The defaults are explicitly meant to not work. Things you need to change:

• set DEHYDRATED_ACCEPT_TERMS to yes, after reading letsencrypts ToS
• set DEHYDRATED_EMAIL to an email address you own
• set DEHYDRATED_CA to a production ACME CA, for example letsencrypt's ACME v2 endpoint, "https://acme-v02.api.letsencrypt.org/directory"
  • Only do this after you have tried it with the default staging endpoint and it worked and you got the certificates you want. If this fails too often, letsencrypt will block your IP and domain for a week, so do your experiments on the staging endpoint.

• DEHYDRATED_CA: This controls which ACME endpoint dehydrated contacts. The most common value for production environments is "https://acme-v02.api.letsencrypt.org/directory", while you should use "https://acme-staging-v02.api.letsencrypt.org/directory" for experiments.
• DEHYDRATED_CHALLENGE: You can either put dns-01 or http-01 here, depending on how you want letsencrypt to verify that you are allowed to obtain this certificate.
• DEHYDRATED_KEYSIZE: This defaults to 4096, but you could also put 2048 or 3072 here, if you want less secure but slightly faster keys. This only makes sense if your host or your clients are very slow.
• DEHYDRATED_KEY_ALGO: This defaults to rsa but you could also put prime256v1 or secp384r1 here. DEHYDRATED_KEYSIZE is only relevant for rsa certs, but still controls the acocunt key size.
• DEHYDRATED_HOOK: If you use the dns-01 challenge, you need to supply a hook script, which dehydrated will use to set dns records. The container ships with lexicon installed and a lexicon hook in /usr/local/bin/lexicon-hook. Apart from the dns-01 challenge, you can also use hooks to deploy newly created certificates. For more info see dehydrated's project page.
• DEHYDRATED_RENEW_DAYS: When dehydrated runs, it will check if any certificates need renewal and renew those. All certificates which expire in the next n days will be renewed, where n is the number you set here. Default is 30
• DEHYDRATED_KEY_RENEW: Set this to yes to make dehydrated renew keys too when renewing certificates, or to no to keep the keys.
• DEHYDRATED_ACCEPT_TERMS: For the first run this needs to be set to yes, else dehydrated will not work. Read the terms of service of letsencrypt before setting this to yes.
• DEHYDRATED_EMAIL: Set your email address here.
• DEHYDRATED_GENERATE_CONFIG: Set to yes by default. If you want to use a config supplied by you, change this to no and put your own config in /data/config
• UID and GID: You can set the UID and GID of the things run in the docker container here.s