Deploying the Undeployable: How I Engineered the First Dockerized n8n for Heroku

When I set out to automate Plant-for-the-Planet’s internal workflows, I had a simple requirement: I needed n8n (a powerful workflow automation tool), but I didn’t want to manage a server.

We were already using Heroku for our main stack, so deploying n8n there seemed like the logical step. I thought it would be a quick afternoon task: write a Dockerfile, push it, and go home.

I was wrong. What followed was a week of relentless trial and error, staring at CrashLoopBackOff logs, and hacking around Heroku’s strict security model.

Here is the story of how I built the first stable, one-click Docker deployment for n8n on Heroku—and the specific technical hurdles I had to break to get there.

Phase 1: The “Permissions” Hell

The first wall I hit was immediate. I tried deploying the standard n8n Docker image, and the app crashed instantly.

The logs were cryptic but pointing to a permissions failure:

Bash

su-exec: setgroups: Operation not permitted
[WARN tini (3)] Tini is not running as PID 1

The Engineering Conflict:

The official n8n image at the time relied on su-exec to switch users at runtime. It expected to start as root, set up permissions, and then drop down to the node user.

Heroku, however, is a locked-down PaaS. It runs containers with a random, non-root user ID for security. It strictly forbids setgroups calls. Basically, the container was trying to say “I am root,” and Heroku was saying “No, you are not.”

The Fix:

I had to rebuild the image from scratch. I wrote a custom Dockerfile that stripped out the su-exec logic entirely. Instead of trying to switch users at runtime, I configured the image to run natively as the node user from the start, ensuring it never requested privileges Heroku wouldn’t grant.

Phase 2: The Random Port Lottery

Once I fixed the user permissions, the app started—but nobody could reach it.

Heroku reported: Error R10 (Boot timeout) -> Web process failed to bind to $PORT.

The Engineering Conflict:

n8n defaults to listening on port 5678.

Heroku doesn’t care about your defaults. It assigns a random port to your application every time the dyno restarts (e.g., 12345, 54321) and passes it via the $PORT environment variable. If your app doesn’t listen on exactly that port within 60 seconds, Heroku kills the process.

The Fix:

I couldn’t hardcode the port in a config file because it changed every 24 hours. I had to write a dynamic entrypoint script (docker-entrypoint.sh) to bridge the gap:

Bash

#!/bin/sh
if [ -z ${PORT+x} ]; then
    echo "PORT variable not defined, leaving N8N to default port."
else
    # Inject Heroku's random port into n8n's expected variable
    export N8N_PORT=$PORT
    echo "N8N will start on '$PORT'"
fi

# Execute the command
n8n start

This script acts as the translator between Heroku’s infrastructure and n8n’s runtime.

Phase 3: The “Deploy to Heroku” Button

Fixing the code was only half the battle. I wanted this to be reusable for my team (and others). I didn’t want anyone else to have to manually configure Heroku Postgres or Redis just to get this running.

I introduced an app.json manifest to the repository. This file tells Heroku exactly what the app needs before it even builds:

JSON

"env": {
    "DB_TYPE": {
        "description": "The type of database to use.",
        "value": "postgresdb"
    },
    "N8N_ENCRYPTION_KEY": {
        "description": "The encryption key for n8n.",
        "generator": "secret"
    }
},
"addons": [
    "heroku-postgresql",
    "heroku-redis"
]

By defining the addons and environment generation in code, I turned a complex manual deployment into a literal “One-Click” install.

The Result

After dozens of commits (you can scroll through the initial commit history to see the struggle), I finally had a stable architecture.

This solution allowed Plant-for-the-Planet to run critical automation pipelines on a zero-maintenance infrastructure. But beyond our use case, it took on a life of its own. The repository sarveshpro/n8n-heroku has since been starred and forked hundreds of times by other developers facing the exact same constraints.

Open source isn’t always about inventing a new framework. Sometimes, it’s just about banging your head against a wall until you find the door—and then holding that door open for everyone else.

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If you need to deploy n8n on Heroku today, you don’t need to repeat my trial and error. You can just fork the solution here:

GitHub – sarveshpro/n8n-heroku