This docs show how to issuing wildcard cert(by Let's Encrypt) with docker and DNS challenge. no need to install any software.

get-letsencrypt-wildcard-cert.sh

EMAIL="foo@barcom"
DOMAINS="example.com"

###################################################################
# Renewing
docker run \
  -it --rm \
  -v /opt/letsencrypt/:/etc/letsencrypt/ \
  -v /opt/letsencrypt/logs/:/var/log/letsencrypt/ \
  certbot/certbot \
  renew

exit 0
###################################################################
# 1st issuing
# - cert will locate at /opt/letsencrypt/live/*
# - logs are at /opt/letsencrypt/logs/
docker run \
  -it --rm \
  -v /opt/letsencrypt/:/etc/letsencrypt/ \
  -v /opt/letsencrypt/logs/:/var/log/letsencrypt/ \
  certbot/certbot \
  --manual \
  --agree-tos \
  --email "${EMAIL}" \
  --preferred-challenges dns-01 \
  -d ${DOMAINS} -d *.${DOMAINS} \
  --server https://acme-v02.api.letsencrypt.org/directory \
  certonly

issue-about-txt-record.md

TL;DR

This docs show how to issuing wildcard cert(by Let's Encrypt) with docker and DNS challenge. no need to install any software.

Issues

• for wildcard cert, you have to add record both of not wildcarded and wildcarded one.
• for example, if your domain is foo.com, you have to add foo.com and *.foo.com
• That means DNS challenges are tried at each of, so you have dual TXT recoard for it.

DNS challenges

• if such message shown, add TXT recoard for dual.

-------------------------------------------------------------------------------
Please deploy a DNS TXT record under the name
_acme-challenge.example.com with the following value:

asdf-asdf-asdf

Before continuing, verify the record is deployed.
-------------------------------------------------------------------------------
Press Enter to Continue

-------------------------------------------------------------------------------
Please deploy a DNS TXT record under the name
_acme-challenge.example.com with the following value:

qqqq-qqqq-qqqq

Before continuing, verify the record is deployed.
-------------------------------------------------------------------------------

• shown as below

C:\Users\ziozzang>nslookup -q=TXT _acme-challenge.example.com 8.8.8.8
Server:    google-public-dns-a.google.com
Address:  8.8.8.8

Response:
_acme-challenge.example.com        text =

        "asdf-asdf-asdf"
_acme-challenge.example.com        text =

        "qqqq-qqqq-qqqq"

zz-free-domain-and-cert.md

TL;DR

• you can get free Domain and Cert :)

Free Domain

• you can get domains at https://dot.tk.

• if domains remaining day under 1month, notification mail will arrived at your mail box. You can extend freely.

• dns challenges are using with TXT recoard, and add twice TXT recoard with same name.

• all other things are same process. enjoy yourself.