Deployment Guide

How a project gets onto rethink-net — our Ubuntu 26.x servers. Get your container to follow a few consistent rules and deploying is mostly handing us a compose.yaml.

What can run here

APIs, websites, applets, bots, monitors.

Docker — the services account

Every service runs containerized as the shared services account: uid/gid 1337, fixed fleet-wide. Build your image to be uid-agnostic so it runs cleanly as that account.

FROM python:3.12-slim
ENV HOME=/tmp                                  # (1)!

WORKDIR /app
RUN apt-get update \
    && apt-get install -y --no-install-recommends git \
    && rm -rf /var/lib/apt/lists/*            # (2)!

COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt   # (3)!

COPY . .
RUN chmod -R a+rwX /app                        # (4)!
CMD ["python", "-m", "yourapp"]

1. HOME=/tmp — the services account has no home dir; anything writing to $HOME (caches, configs) needs a writable target.
2. Include git only if the container itself needs it — e.g. you pip install from git, or the app shells out to git at runtime. The build and host always have git; this line is about what's inside the image.
3. Install deps before copying the code (see layer caching).
4. chmod -R a+rwX /app makes the app tree writable by any uid — that's what "uid-agnostic" means.

services:
  yourapp:
    build: .
    user: "1337:1337"                          # (1)!
    environment:
      HOME: /tmp
    volumes:
      - /srv/configs/<project>:/app/config:ro  # (2)!
      - /srv/logs/<dev>/<project>:/app/logs    # (3)!
      - yourapp-data:/app/data                 # (4)!

volumes:
  yourapp-data:

1. Run as the shared account. No in-container user/useradd — don't bake a user into the image; set it here.
2. Configs: host-managed bind mount, mounted read-only.
3. Logs: bind mount — live and rolled, scraped for monitoring.
4. Everything else: a named volume. Docker owns it, so there are no host permissions to fiddle with.

Paths and mounts

What	Where	How
Configs	/srv/configs/<project>/	bind mount, host-managed, read-only
Logs	/srv/logs/<dev>/<project>/	bind mount; live + rolled, scraped
Caches, profiles, scratch	named volume	Docker manages ownership

If your service won't start or its logs aren't persisting

That's usually a host-side bind-mount ownership thing — the kind of detail we sort out at deploy time, not something you need to chown or provision. If a bot won't come up or logs/caches keep vanishing, flag it and we'll fix the mount perms. Stick to a clean compose.yaml and let us handle the host.

Layer caching

Copy requirements.txt and pip install before COPY . .. Docker caches layers in order, so deps only reinstall when requirements.txt changes — not on every code edit. Get this backwards and every one-line change triggers a full dependency reinstall.

COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt   # cached until deps change
COPY . .                                             # changes every build

Subprocess and browser workloads

Bots that spawn Chrome, Xvfb, ffmpeg, or other child processes need three extra knobs in compose:

services:
  yourbot:
    build: .
    user: "1337:1337"
    init: true              # (1)!
    shm_size: "2gb"         # (2)!
    mem_limit: "4g"         # (3)!

1. Runs tini as PID 1 to reap zombie subprocesses and forward signals. Without it, spawned Chrome/Xvfb processes leak as zombies.
2. Chrome and most headless browsers crash on Docker's default 64 MB /dev/shm. Bump it for any browser workload.
3. Bound memory — especially when each worker spawns a browser. Raise it as worker count grows.

The PID-1 gotcha with shell-wrapper CMDs

If your CMD is a shell-script wrapper (e.g. xvfb-run ...), it must not be PID 1, or the real process dies on startup. init: true is exactly what fixes this — tini takes PID 1, and your wrapper runs as a normal child.

What your compose / Dockerfile needs

• user: "1337:1337"
• bind mounts for configs + logs
• named volumes for the rest
• secrets bind-mounted :ro
• HOME=/tmp
• chmod -R a+rwX /app
• deps installed before the code copy (layer caching)
• git in the image if the container needs it
• for browser/subprocess workloads: init: true, shm_size, mem_limit

Secrets

Secrets never go in the image

We do not commit secrets (usually, lol). They stay gitignored, live on the host at /srv/configs/<project>/, and are bind-mounted read-only at runtime. Add them to .dockerignore so a COPY . . can't sweep them into a layer.

Rotating a secret = edit the host file and restart. No rebuild.

vim /srv/configs/<project>/secrets.env   # edit on the host
docker compose restart yourapp           # pick up the change — no rebuild