Deploy your applications with Dokku on a VPS

Where other PaaS solutions bundle a web interface and a full orchestrator, Dokku stays deliberately minimalist: it is a set of shell scripts that drive Docker. You push your code with git push dokku main, Dokku detects the language via Heroku buildpacks or a Dockerfile, builds the image and brings the application online. Everything is managed from the command line, which makes it extremely lightweight and predictable.

Compared to Dokku, CapRover, Coolify and Easypanel all offer a graphical interface, but at the cost of a much heavier memory footprint. CapRover reserves Docker Swarm and its supervision daemon; it recommends 2 GB of RAM as a minimum configuration. Coolify 4 relies on Nixpacks and an embedded PostgreSQL database: expect 2 GB of RAM at idle. Easypanel integrates Traefik and a Nixpacks builder, which also requires 2 GB of RAM as soon as a build is active. Dokku, on the other hand, runs comfortably from 512 MB of RAM for a lightweight application and adds no permanent control component. It is the natural choice for developers who want a Heroku-like workflow on a small VPS, without memory overhead and without consuming resources for a dashboard they will use only a few minutes per week.

Dokku is the most resource-efficient PaaS in this series.

RAM. 512 MB is enough for a lightweight application without an active build. Plan for 1 GB of RAM for everyday use and 2 GB as soon as your builds use buildpacks (Node, Ruby, Python compile in memory during image construction) or you host a database on the same VPS. For several applications in parallel with PostgreSQL, target 4 GB.

CPU. 1 vCPU is sufficient for lightweight applications. Buildpack build phases are CPU-intensive and occur on the fly during each git push: a shared vCPU may slow the deployment but does not block it.

Disk. Count on 20 GB of SSD minimum. Buildpack Docker images can weigh several hundred megabytes; add space for your data volumes (database, uploads).

Swap. On a VPS with 1 or 2 GB of RAM, always add 2 GB of swap. Without swap, the Linux kernel OOM killer can terminate a Node or Ruby build during compilation.

System. Ubuntu 22.04 LTS or 24.04 LTS freshly installed, without pre-installed Docker or Nginx. Dokku installs its own versions. Ports 22 (SSH), 80 and 443 must be open.

DNS. Configure either one domain per application or a wildcard domain *.your-domain.com pointing to the VPS IP address.

Dokku manages each application in an isolated container. You can host as many applications as your VPS can handle, each on its own subdomain or custom domain.

Environment variables. Use dokku config:set to inject secrets or configuration parameters:

dokku config:set my-app NODE_ENV=production \
  SECRET_KEY=changeme \
  MAIL_HOST=smtp.your-domain.com

Staging vs production. The common practice is to create two applications on the same server:

dokku apps:create my-app-staging
dokku apps:create my-app-production

Each Git remote points to its own application with separately defined environment variables.

Custom domains. To associate an existing domain with an application:

dokku domains:add my-app your-domain.com
dokku domains:add my-app www.your-domain.com

Dokku handles zero-downtime via a health check mechanism before switching. By default, it waits for the new container to respond on the application port before redirecting traffic. You can refine this behavior with a CHECKS file at the root of your project:

WAIT=10
TIMEOUT=60
/healthz Application is up

Tags and rollback. Dokku keeps Docker images of previous deployments as tags. List them:

dokku tags:list my-app

To revert to a previous version, deploy the desired tag:

dokku tags:deploy my-app v3

This command switches traffic to the image tagged v3 without any rebuild — the rollback is near-instant. To explicitly create a backup tag before a risky deployment:

dokku tags:create my-app stable-before-migration

Dokku draws its richness from its ecosystem of official plugins.

PostgreSQL. The most used. Additional useful commands: dokku postgres:backup my-db for a manual dump, dokku postgres:connect my-db for interactive psql access.

Redis.

dokku plugin:install https://github.com/dokku/dokku-redis.git
dokku redis:create my-cache
dokku redis:link my-cache my-app

Injects the REDIS_URL variable into the container.

Cron (scheduler). Create an app.json file at the root of your project:

{
  "cron": [
    { "command": "php artisan schedule:run", "schedule": "* * * * *" }
  ]
}

Dokku 0.26+ reads this file and automatically creates a cron task in the container.

error: failed to push some refs — permission denied.
Check that your SSH key is registered: dokku ssh-keys:list. If absent, add it with dokku ssh-keys:add admin < ~/.ssh/id_ed25519.pub.

! [remote rejected] main -> main (pre-receive hook declined).
This error indicates a build failure on the Dokku side. Check the detailed logs with dokku logs my-app.

The application returns 502 Bad Gateway.
Nginx receives the request but the container does not respond. Check the process status: dokku ps:report my-app. Common cause: the application is not listening on the port declared in the Procfile or the PORT variable injected by Dokku.

letsencrypt:enable fails — HTTP-01 challenge timeout.
The ACME challenge requires the domain to resolve to the VPS IP before activation. Check DNS propagation (dig +short my-app.your-domain.com). If behind a proxy (Cloudflare), temporarily disable the proxy (DNS-only) while the certificate is being issued.

Build killed by the kernel (OOM) — Killed.
The OOM killer intervened due to lack of memory. Add swap or migrate to a VPS with 2 GB of RAM.

Dokku covers the deployment of single-container applications on a VPS. If your architecture evolves toward multiple interdependent services, several alternatives in the same family complement this approach. CapRover adds a graphical interface and a Docker Swarm cluster mode. Easypanel simplifies multi-service management with Nixpacks and an application marketplace. For a standalone reverse proxy without a full PaaS, Caddy or Nginx Proxy Manager integrate natively with Docker. Each of these tools runs on a ServOrbit Cloud VPS under Ubuntu LTS.