Setting Up Coolify on Hetzner with a Custom Domain

Coolify is an open-source self-hosting platform that lets you deploy applications, databases, and services with a developer-friendly workflow—similar to platforms like Vercel or Netlify, but fully under your control.

This post summarizes how we set up Coolify on a Hetzner Cloud server, connected it to a custom subdomain, and enabled HTTPS via Let's Encrypt.

What we built

At the end of this setup, Coolify is accessible at:

https://coolify.therkiller.dev

with:

a dedicated SSH key for the project
Coolify installed on a Hetzner Cloud VPS
DNS configured at hosttech
a valid Let's Encrypt certificate

Prerequisites

Hetzner Cloud account
A registered domain (here: therkiller.dev) managed at hosttech
Local machine with SSH (macOS)
Basic terminal knowledge

Step 1: Create a dedicated SSH key

To keep this project isolated from existing keys, we created a separate keypair:

ssh-keygen -t ed25519 -f ~/.ssh/id_ed25519_therkiller -C "therkiller.dev"

The private key stays on your machine.

The public key (.pub) gets added to Hetzner.

We intentionally skipped a passphrase for this private project.

Step 2: Add the key to your SSH config (SSH Config Editor)

Because multiple keys already existed, we configured an explicit host entry (via SSH Config Editor) to avoid SSH trying random keys.

Conceptually, the entry looks like this:

Host therkiller-coolify
    HostName 46.224.144.135
    User root
    IdentityFile ~/.ssh/id_ed25519_therkiller
    IdentitiesOnly yes

Then we connected using:

ssh therkiller-coolify

On first login, we confirmed the server fingerprint (normal behavior for a new host).

Step 3: Create the Hetzner Cloud server

We created a new server with:

Ubuntu 24.04 LTS
CX23 (2 vCPU, 4 GB RAM)
SSH key: id_ed25519_therkiller
Name: therkiller-coolify

We skipped optional features like Volumes, Placement Groups, and Cloud-Init to keep things simple. Backups are optional, but recommended.

Step 4: Install Coolify

On the server, we ran the official install script:

curl -fsSL https://cdn.coollabs.io/coolify/install.sh | bash

This installs Docker, Docker Compose, and all required Coolify containers.

After installation, Coolify was reachable via the server IP (initially on port 8000).

Step 5: Choose the server type in Coolify

In the Coolify onboarding, we selected:

This Machine

This is the correct choice for a single-server setup where Coolify and all apps run on the same server.

Step 6: Create a project in Coolify

Next, we created the first project (a logical container for apps, databases, services, and environments). We kept the default production environment.

Step 7: Point a subdomain to the server (DNS at hosttech)

The domain therkiller.dev is managed at hosttech and already had existing records:

an A record for the apex domain
a wildcard *.therkiller.dev record

To attach Coolify without breaking anything else, we added one additional A record:

Type	Host	Target	TTL
A	coolify	46.224.144.135	3600

Important: we did not change the existing apex / wildcard / MX / TXT records.

Step 8: Configure the Coolify instance domain

In Coolify:

Settings → Instance → General

we set:

Domain: https://coolify.therkiller.dev

In newer Coolify versions, SSL is handled automatically once the HTTPS domain is set.

Step 9: Fix DNS validation and SSL issues

Because the wildcard record existed, DNS propagation and caching caused temporary issues:

nslookup coolify.therkiller.dev initially returned the wildcard IP (76.76.21.21)
Coolify failed DNS validation (Validating DNS failed)

Once DNS propagated correctly, nslookup returned the right server IP:

nslookup coolify.therkiller.dev

After that, saving the instance settings again triggered SSL issuance successfully.

Chrome still showed a temporary certificate warning (ERR_CERT_AUTHORITY_INVALID) due to caching, but it resolved once the valid certificate was active.

Final result

Coolify is now running and secured with HTTPS:

https://coolify.therkiller.dev

with:

Hetzner VPS (Ubuntu 24.04)
dedicated SSH key and explicit SSH config entry
DNS configured at hosttech
Let's Encrypt SSL managed by Coolify

Conclusion

This setup is a great sweet spot for private projects: simple, inexpensive, and powerful. The biggest gotcha was DNS propagation due to an existing wildcard record, but once DNS resolved correctly, SSL setup was fully automatic.