Deploy with your own Dockerfile

A Dockerfile gives you full control over the language version, system packages and start command. If a Dockerfile is present in your root folder, DployHub builds it as-is, before checking for Node.js, Python or static files. You can also choose Use my Dockerfile explicitly when creating the app.

How the port is chosen

We read the first EXPOSE line in your Dockerfile and use that port. If there is no EXPOSE, we use 3000 and show a note so you can check it. You can always change the port in the app Settings. We also set the PORT environment variable to the same value.

Example: Node.js

FROM node:22-alpine AS build
WORKDIR /app
COPY package*.json ./
RUN npm ci
COPY . .
RUN npm run build

FROM node:22-alpine
WORKDIR /app
ENV NODE_ENV=production
COPY --from=build /app/package*.json ./
RUN npm ci --omit=dev
COPY --from=build /app/dist ./dist
EXPOSE 8080
CMD ["node", "dist/server.js"]

Example: Python

FROM python:3.11-slim
WORKDIR /app
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt
COPY . .
EXPOSE 8000
CMD ["gunicorn", "mysite.wsgi", "--bind", "0.0.0.0:8000"]

Dockerfile path and monorepos

The Dockerfile path defaults to Dockerfile and is relative to Folder with your app. In a monorepo set the folder to, for example, services/api, and the path to Dockerfile or docker/Dockerfile.prod. Keep COPY paths consistent with that layout.

Rules your container must follow

• Listen on 0.0.0.0 on the configured port, and answer HTTP with a status below 500 on the health check path within 90 seconds.
• Stay within the memory you chose. A process that exceeds it is killed with exit code 137.
• Keep to 512 processes or fewer. Containers run with no-new-privileges.
• Write persistent files under /data only. Everything else is reset on deploy or restart.
• Log to stdout and stderr. Container logs are rotated at 10 MB, keeping 3 files.
• Finish the build within 30 minutes.

Secrets and environment variables

Do not bake secrets into the image with ENV or ARG. Add them in the Environment variables tab instead; they are encrypted at rest and injected when the container starts, separately for staging and live.

Already building images in CI? You can skip our build and deploy a public Docker image directly. The quick guide is at /deploy/docker. If a Dockerfile build behaves differently than on your machine, raise a ticket with the deployment attached.