Docker-compose with Let's Encrypt: DNS Challenge¶
This guide aims to demonstrate how to create a certificate with the Let's Encrypt DNS challenge to use https on a simple service exposed with Traefik.
Please also read the basic example for details on how to expose such a service.
Prerequisite¶
For the DNS challenge, you'll need:
- A working provider along with the credentials allowing to create and remove DNS records.
Variables may vary depending on the Provider.
Please note this guide may vary depending on the provider you use.
The only things changing are the names of the variables you will need to define in order to configure your provider so it can create DNS records.
Please refer the list of providers given right above and replace all the environment variables with the ones described in this documentation.
Setup¶
- Create a
docker-compose.yml
file with the following content:
version: "3.3"
services:
traefik:
image: "traefik:v3.1"
container_name: "traefik"
command:
#- "--log.level=DEBUG"
- "--api.insecure=true"
- "--providers.docker=true"
- "--providers.docker.exposedbydefault=false"
- "--entryPoints.web.address=:80"
- "--entryPoints.websecure.address=:443"
- "--certificatesresolvers.myresolver.acme.dnschallenge=true"
- "--certificatesresolvers.myresolver.acme.dnschallenge.provider=ovh"
#- "--certificatesresolvers.myresolver.acme.caserver=https://acme-staging-v02.api.letsencrypt.org/directory"
- "--certificatesresolvers.myresolver.acme.email=postmaster@example.com"
- "--certificatesresolvers.myresolver.acme.storage=/letsencrypt/acme.json"
ports:
- "80:80"
- "443:443"
- "8080:8080"
environment:
- "OVH_ENDPOINT=xxx"
- "OVH_APPLICATION_KEY=xxx"
- "OVH_APPLICATION_SECRET=xxx"
- "OVH_CONSUMER_KEY=xxx"
volumes:
- "./letsencrypt:/letsencrypt"
- "/var/run/docker.sock:/var/run/docker.sock:ro"
whoami:
image: "traefik/whoami"
container_name: "simple-service"
labels:
- "traefik.enable=true"
- "traefik.http.routers.whoami.rule=Host(`whoami.example.com`)"
- "traefik.http.routers.whoami.entrypoints=websecure"
- "traefik.http.routers.whoami.tls.certresolver=myresolver"
-
Replace the environment variables by your own:
environment: - "OVH_ENDPOINT=[YOUR_OWN_VALUE]" - "OVH_APPLICATION_KEY=[YOUR_OWN_VALUE]" - "OVH_APPLICATION_SECRET=[YOUR_OWN_VALUE]" - "OVH_CONSUMER_KEY=[YOUR_OWN_VALUE]"
-
Replace
[email protected]
by your own email within thecertificatesresolvers.myresolver.acme.email
command line argument of thetraefik
service. - Replace
whoami.example.com
by your own domain within thetraefik.http.routers.whoami.rule
label of thewhoami
service. -
Optionally uncomment the following lines if you want to test/debug:
#- "--log.level=DEBUG" #- "--certificatesresolvers.myresolver.acme.caserver=https://acme-staging-v02.api.letsencrypt.org/directory"
-
Run
docker-compose up -d
within the folder where you created the previous file. - Wait a bit and visit
https://your_own_domain
to confirm everything went fine.
Note
If you uncommented the acme.caserver
line, you will get an SSL error, but if you display the certificate and see it was emitted by Fake LE Intermediate X1
then it means all is good.
(It is the staging environment intermediate certificate used by Let's Encrypt).
You can now safely comment the acme.caserver
line, remove the letsencrypt/acme.json
file and restart Traefik to issue a valid certificate.
Explanation¶
What changed between the initial setup:
- We configure a second entry point for the https traffic:
command:
# Traefik will listen to incoming request on the port 443 (https)
- "--entryPoints.websecure.address=:443"
ports:
- "443:443"
- We configure the DNS Let's Encrypt challenge:
command:
# Enable a dns challenge named "myresolver"
- "--certificatesresolvers.myresolver.acme.dnschallenge=true"
# Tell which provider to use
- "--certificatesresolvers.myresolver.acme.dnschallenge.provider=ovh"
# The email to provide to Let's Encrypt
- "--certificatesresolvers.myresolver.acme.email=postmaster@example.com"
- We provide the required configuration to our provider via environment variables:
environment:
- "OVH_ENDPOINT=xxx"
- "OVH_APPLICATION_KEY=xxx"
- "OVH_APPLICATION_SECRET=xxx"
- "OVH_CONSUMER_KEY=xxx"
Note
This is the step that may vary depending on the provider you use. Just define the variables required by your provider. (see the prerequisite for a list)
- We add a volume to store our certificates:
volumes:
# Create a letsencrypt dir within the folder where the docker-compose file is
- "./letsencrypt:/letsencrypt"
command:
# Tell to store the certificate on a path under our volume
- "--certificatesresolvers.myresolver.acme.storage=/letsencrypt/acme.json"
- We configure the
whoami
service to tell Traefik to use the certificate resolver namedmyresolver
we just configured:
labels:
- "traefik.http.routers.whoami.tls.certresolver=myresolver" # Uses the Host rule to define which certificate to issue
Use Secrets¶
To configure the provider, and avoid having the secrets exposed in plaintext within the docker-compose environment section,
you could use docker secrets.
The point is to manage those secret files by another mean, and read them from the docker-compose.yml
file making the docker-compose file itself less sensitive.
- Create a directory named
secrets
, and create a file for each parameters required to configure you provider containing the value of the parameter:
for example, theovh_endpoint.secret
file containovh-eu
./secrets
├── ovh_application_key.secret
├── ovh_application_secret.secret
├── ovh_consumer_key.secret
└── ovh_endpoint.secret
Note
You could store those secrets anywhere on the server,
just make sure to use the proper path for the file
directive for the secrets definition in the docker-compose.yml
file.
- Use this
docker-compose.yml
file:
version: "3.3"
secrets:
ovh_endpoint:
file: "./secrets/ovh_endpoint.secret"
ovh_application_key:
file: "./secrets/ovh_application_key.secret"
ovh_application_secret:
file: "./secrets/ovh_application_secret.secret"
ovh_consumer_key:
file: "./secrets/ovh_consumer_key.secret"
services:
traefik:
image: "traefik:v3.1"
container_name: "traefik"
command:
#- "--log.level=DEBUG"
- "--api.insecure=true"
- "--providers.docker=true"
- "--providers.docker.exposedbydefault=false"
- "--entryPoints.web.address=:80"
- "--entryPoints.websecure.address=:443"
- "--certificatesresolvers.myresolver.acme.dnschallenge=true"
- "--certificatesresolvers.myresolver.acme.dnschallenge.provider=ovh"
#- "--certificatesresolvers.myresolver.acme.caserver=https://acme-staging-v02.api.letsencrypt.org/directory"
- "--certificatesresolvers.myresolver.acme.email=postmaster@example.com"
- "--certificatesresolvers.myresolver.acme.storage=/letsencrypt/acme.json"
ports:
- "80:80"
- "443:443"
- "8080:8080"
secrets:
- "ovh_endpoint"
- "ovh_application_key"
- "ovh_application_secret"
- "ovh_consumer_key"
environment:
- "OVH_ENDPOINT_FILE=/run/secrets/ovh_endpoint"
- "OVH_APPLICATION_KEY_FILE=/run/secrets/ovh_application_key"
- "OVH_APPLICATION_SECRET_FILE=/run/secrets/ovh_application_secret"
- "OVH_CONSUMER_KEY_FILE=/run/secrets/ovh_consumer_key"
volumes:
- "./letsencrypt:/letsencrypt"
- "/var/run/docker.sock:/var/run/docker.sock:ro"
whoami:
image: "traefik/whoami"
container_name: "simple-service"
labels:
- "traefik.enable=true"
- "traefik.http.routers.whoami.rule=Host(`whoami.example.com`)"
- "traefik.http.routers.whoami.entrypoints=websecure"
- "traefik.http.routers.whoami.tls.certresolver=myresolver"
Note
Still think about changing [email protected]
& whoami.example.com
by your own values.
Let's explain a bit what we just did:
- The following section allow to read files on the docker host, and expose those file under
/run/secrets/[NAME_OF_THE_SECRET]
within the container:
secrets:
# secret name also used to name the file exposed within the container
ovh_endpoint:
# path on the host
file: "./secrets/ovh_endpoint.secret"
ovh_application_key:
file: "./secrets/ovh_application_key.secret"
ovh_application_secret:
file: "./secrets/ovh_application_secret.secret"
ovh_consumer_key:
file: "./secrets/ovh_consumer_key.secret"
services:
traefik:
# expose the predefined secret to the container by name
secrets:
- "ovh_endpoint"
- "ovh_application_key"
- "ovh_application_secret"
- "ovh_consumer_key"
- The environment variable within our
traefik
service are suffixed by_FILE
which allow us to point to files containing the value, instead of exposing the value itself.
The acme client will read the content of those file to get the required configuration values.
environment:
# expose the path to file provided by docker containing the value we want for OVH_ENDPOINT.
- "OVH_ENDPOINT_FILE=/run/secrets/ovh_endpoint"
- "OVH_APPLICATION_KEY_FILE=/run/secrets/ovh_application_key"
- "OVH_APPLICATION_SECRET_FILE=/run/secrets/ovh_application_secret"
- "OVH_CONSUMER_KEY_FILE=/run/secrets/ovh_consumer_key"