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Switch Traefik to DNS Challenge ​

By default, Coolify configures Traefik to obtain SSL certificates using the HTTP challenge (httpChallenge), which requires port 80 to be publicly reachable. There are two common reasons to switch to the DNS challenge (dnsChallenge) instead:

  • You want wildcard SSL certificates (e.g., *.example.com) — these require DNS challenge.
  • Your server does not have a public port 80 (e.g., internal network, behind a firewall, or a Tailscale-only node).

How It Works ​

Instead of proving domain ownership over HTTP, Traefik asks your DNS provider to create a temporary TXT record under _acme-challenge.<your-domain>. Let's Encrypt reads that record to confirm ownership, then issues the certificate. Traefik (via the Lego library) handles the whole process automatically.

Prerequisites ​

  • A domain managed by a supported DNS provider.
  • An API token / key for that provider with permission to create and delete DNS records.
Finding your provider's required variables

Each provider needs different environment variables. Open the Lego provider list, click your provider, and note the required env vars listed at the top.

Configuration ​

Go to Servers → your server → Proxy and replace the default Traefik configuration with the one below.

The highlighted lines show exactly what changes from the default HTTP-challenge setup.

yaml
name: coolify-proxy
networks:
  coolify:
    external: true
services:
  traefik:
    container_name: coolify-proxy
    image: 'traefik:v3.6'
    restart: unless-stopped
    environment: 
      - HETZNER_API_TOKEN=<Hetzner API Token>
    extra_hosts:
      - 'host.docker.internal:host-gateway'
    networks:
      - coolify
    ports:
      - '80:80'
      - '443:443'
      - '443:443/udp'
      - '8080:8080'
    healthcheck:
      test: 'wget -qO- http://localhost:80/ping || exit 1'
      interval: 4s
      timeout: 2s
      retries: 5
    volumes:
      - '/var/run/docker.sock:/var/run/docker.sock:ro'
      - '/data/coolify/proxy/:/traefik'
    command:
      - '--ping=true'
      - '--ping.entrypoint=http'
      - '--api.dashboard=true'
      - '--api.insecure=false'
      - '--entrypoints.http.address=:80'
      - '--entrypoints.https.address=:443'
      - '--entrypoints.http.http.encodequerysemicolons=true'
      - '--entryPoints.http.http2.maxConcurrentStreams=250'
      - '--entrypoints.https.http.encodequerysemicolons=true'
      - '--entryPoints.https.http2.maxConcurrentStreams=250'
      - '--entrypoints.https.http3'
      - '--providers.docker.exposedbydefault=false'
      - '--providers.file.directory=/traefik/dynamic/'
      - '--providers.file.watch=true'
      - '--certificatesresolvers.letsencrypt.acme.httpchallenge=true'
      - '--certificatesresolvers.letsencrypt.acme.httpchallenge.entrypoint=http'
      - '--certificatesresolvers.letsencrypt.acme.dnschallenge.provider=hetzner'
      - '--certificatesresolvers.letsencrypt.acme.dnschallenge.delaybeforecheck=0'
      - '--certificatesresolvers.letsencrypt.acme.storage=/traefik/acme.json'
      - '--providers.docker=true'
    labels:
      - traefik.enable=true
      - traefik.http.routers.traefik.entrypoints=http
      - traefik.http.routers.traefik.service=api@internal
      - traefik.http.services.traefik.loadbalancer.server.port=8080
      - coolify.managed=true
      - coolify.proxy=true
yaml
name: coolify-proxy
networks:
  coolify:
    external: true
services:
  traefik:
    container_name: coolify-proxy
    image: 'traefik:v3.6'
    restart: unless-stopped
    environment: 
      - CF_DNS_API_TOKEN=<Cloudflare API Token>
    extra_hosts:
      - 'host.docker.internal:host-gateway'
    networks:
      - coolify
    ports:
      - '80:80'
      - '443:443'
      - '443:443/udp'
      - '8080:8080'
    healthcheck:
      test: 'wget -qO- http://localhost:80/ping || exit 1'
      interval: 4s
      timeout: 2s
      retries: 5
    volumes:
      - '/var/run/docker.sock:/var/run/docker.sock:ro'
      - '/data/coolify/proxy/:/traefik'
    command:
      - '--ping=true'
      - '--ping.entrypoint=http'
      - '--api.dashboard=true'
      - '--api.insecure=false'
      - '--entrypoints.http.address=:80'
      - '--entrypoints.https.address=:443'
      - '--entrypoints.http.http.encodequerysemicolons=true'
      - '--entryPoints.http.http2.maxConcurrentStreams=250'
      - '--entrypoints.https.http.encodequerysemicolons=true'
      - '--entryPoints.https.http2.maxConcurrentStreams=250'
      - '--entrypoints.https.http3'
      - '--providers.docker.exposedbydefault=false'
      - '--providers.file.directory=/traefik/dynamic/'
      - '--providers.file.watch=true'
      - '--certificatesresolvers.letsencrypt.acme.httpchallenge=true'
      - '--certificatesresolvers.letsencrypt.acme.httpchallenge.entrypoint=http'
      - '--certificatesresolvers.letsencrypt.acme.dnschallenge.provider=cloudflare'
      - '--certificatesresolvers.letsencrypt.acme.dnschallenge.delaybeforecheck=0'
      - '--certificatesresolvers.letsencrypt.acme.storage=/traefik/acme.json'
      - '--providers.docker=true'
    labels:
      - traefik.enable=true
      - traefik.http.routers.traefik.entrypoints=http
      - traefik.http.routers.traefik.service=api@internal
      - traefik.http.services.traefik.loadbalancer.server.port=8080
      - coolify.managed=true
      - coolify.proxy=true
yaml
name: coolify-proxy
networks:
  coolify:
    external: true
services:
  traefik:
    container_name: coolify-proxy
    image: 'traefik:v3.6'
    restart: unless-stopped
    environment: 
      - AWS_ACCESS_KEY_ID=<Access Key ID>
      - AWS_SECRET_ACCESS_KEY=<Secret Access Key>
      - AWS_REGION=<Region>
    extra_hosts:
      - 'host.docker.internal:host-gateway'
    networks:
      - coolify
    ports:
      - '80:80'
      - '443:443'
      - '443:443/udp'
      - '8080:8080'
    healthcheck:
      test: 'wget -qO- http://localhost:80/ping || exit 1'
      interval: 4s
      timeout: 2s
      retries: 5
    volumes:
      - '/var/run/docker.sock:/var/run/docker.sock:ro'
      - '/data/coolify/proxy/:/traefik'
    command:
      - '--ping=true'
      - '--ping.entrypoint=http'
      - '--api.dashboard=true'
      - '--api.insecure=false'
      - '--entrypoints.http.address=:80'
      - '--entrypoints.https.address=:443'
      - '--entrypoints.http.http.encodequerysemicolons=true'
      - '--entryPoints.http.http2.maxConcurrentStreams=250'
      - '--entrypoints.https.http.encodequerysemicolons=true'
      - '--entryPoints.https.http2.maxConcurrentStreams=250'
      - '--entrypoints.https.http3'
      - '--providers.docker.exposedbydefault=false'
      - '--providers.file.directory=/traefik/dynamic/'
      - '--providers.file.watch=true'
      - '--certificatesresolvers.letsencrypt.acme.httpchallenge=true'
      - '--certificatesresolvers.letsencrypt.acme.httpchallenge.entrypoint=http'
      - '--certificatesresolvers.letsencrypt.acme.dnschallenge.provider=route53'
      - '--certificatesresolvers.letsencrypt.acme.dnschallenge.delaybeforecheck=0'
      - '--certificatesresolvers.letsencrypt.acme.storage=/traefik/acme.json'
      - '--providers.docker=true'
    labels:
      - traefik.enable=true
      - traefik.http.routers.traefik.entrypoints=http
      - traefik.http.routers.traefik.service=api@internal
      - traefik.http.services.traefik.loadbalancer.server.port=8080
      - coolify.managed=true
      - coolify.proxy=true
yaml
name: coolify-proxy
networks:
  coolify:
    external: true
services:
  traefik:
    container_name: coolify-proxy
    image: 'traefik:v3.6'
    restart: unless-stopped
    environment: 
      - HOSTINGER_API_TOKEN=<Hostinger API Token>
    extra_hosts:
      - 'host.docker.internal:host-gateway'
    networks:
      - coolify
    ports:
      - '80:80'
      - '443:443'
      - '443:443/udp'
      - '8080:8080'
    healthcheck:
      test: 'wget -qO- http://localhost:80/ping || exit 1'
      interval: 4s
      timeout: 2s
      retries: 5
    volumes:
      - '/var/run/docker.sock:/var/run/docker.sock:ro'
      - '/data/coolify/proxy/:/traefik'
    command:
      - '--ping=true'
      - '--ping.entrypoint=http'
      - '--api.dashboard=true'
      - '--api.insecure=false'
      - '--entrypoints.http.address=:80'
      - '--entrypoints.https.address=:443'
      - '--entrypoints.http.http.encodequerysemicolons=true'
      - '--entryPoints.http.http2.maxConcurrentStreams=250'
      - '--entrypoints.https.http.encodequerysemicolons=true'
      - '--entryPoints.https.http2.maxConcurrentStreams=250'
      - '--entrypoints.https.http3'
      - '--providers.docker.exposedbydefault=false'
      - '--providers.file.directory=/traefik/dynamic/'
      - '--providers.file.watch=true'
      - '--certificatesresolvers.letsencrypt.acme.httpchallenge=true'
      - '--certificatesresolvers.letsencrypt.acme.httpchallenge.entrypoint=http'
      - '--certificatesresolvers.letsencrypt.acme.dnschallenge.provider=hostinger'
      - '--certificatesresolvers.letsencrypt.acme.dnschallenge.delaybeforecheck=0'
      - '--certificatesresolvers.letsencrypt.acme.storage=/traefik/acme.json'
      - '--providers.docker=true'
    labels:
      - traefik.enable=true
      - traefik.http.routers.traefik.entrypoints=http
      - traefik.http.routers.traefik.service=api@internal
      - traefik.http.services.traefik.loadbalancer.server.port=8080
      - coolify.managed=true
      - coolify.proxy=true

You can also use env_file instead of environment — create a .env file on the server and reference it. This is useful for keeping secrets out of the UI.

Change --certificatesresolvers.letsencrypt.acme.dnschallenge.provider=<name> to match your provider's identifier from the Lego provider list.

Restart the proxy after making these changes. Traefik will now use the DNS challenge to obtain and renew SSL certificates.

Troubleshooting ​

Certificate not issuing / DNS record not found

DNS propagation can be slow. If the challenge fails immediately, increase delaybeforecheck to give your provider time to propagate the TXT record:

- '--certificatesresolvers.letsencrypt.acme.dnschallenge.delaybeforecheck=30'

CNAME records interfering with challenge

If your domain uses CNAME delegation and challenges fail on renewal, set this environment variable to disable CNAME following:

yaml
environment:
  - LEGO_DISABLE_CNAME_SUPPORT=true

Rate limits

Let's Encrypt enforces rate limits. While testing, add the staging CA flag to avoid burning your quota:

- '--certificatesresolvers.letsencrypt.acme.caserver=https://acme-staging-v02.api.letsencrypt.org/directory'

Remove this flag once everything works.

Next Steps ​

Now that Traefik uses the DNS challenge, you can issue wildcard SSL certificates that cover all subdomains under your domain with a single certificate.