Deploy Phoenix App on Seenode | Phoenix Hosting & Deployment Guide

This guide explains how to deploy your existing Phoenix application on seenode.

Prerequisites

Before you begin, ensure you have:

• A seenode account at cloud.seenode.com
• Git configured on your machine
• Existing Phoenix project ready to deploy

Configure for seenode Deployment

Production Configuration

In your config/prod.exs, ensure your endpoint is configured to listen on the port defined by an environment variable, defaulting to 80 if PORT is not set. This allows seenode to correctly route traffic to your application.

config/prod.exs

import Config

config :hello,
  generators: [timestamp_type: :utc_datetime]

# Configures the endpoint
config :hello, HelloWeb.Endpoint,
  url: [host: System.get_env("PHX_HOST") || "localhost", port: 80],
  adapter: Bandit.PhoenixAdapter,
  render_errors: [
    formats: [html: HelloWeb.ErrorHTML, json: HelloWeb.ErrorJSON],
    layout: false
  ],
  pubsub_server: Hello.PubSub,
  live_view: [signing_salt: "Kute9Cn2"],
  http: [port: String.to_integer(System.get_env("PORT") || "80")],
  server: true

Build Script

Create a build.sh script to streamline deployments:

build.sh

#!/usr/bin/env bash
# exit on error
set -o errexit

# Initial setup
mix local.hex --force
mix local.rebar --force

# Install dependencies
mix deps.get --only prod

# Compile and build assets
MIX_ENV=prod mix compile
MIX_ENV=prod mix assets.build
MIX_ENV=prod mix assets.deploy

Make the script executable: chmod +x build.sh

Deploy on seenode

1. Push to Git

   Commit your project and push it to GitHub or GitLab.

2. Create a Web Service

   From the seenode Dashboard, create a new Web Service and connect the Git repository for your Phoenix application.

   

   Port setting

   Our template listens on port 80 by default. If you need a different port, set it in the Port field on this screen (above Environment Variables). No need to add a PORT env var.

3. Configure Build & Start Commands

   seenode automatically detects an Elixir project. Configure the build and start commands:

   Build Command (choose one approach):

   Option A - Using build script:

   ./build.sh

   Option B - Direct commands:

   mix local.hex --force && mix local.rebar --force
   mix deps.get --only prod
   MIX_ENV=prod mix compile
   MIX_ENV=prod mix assets.build
   MIX_ENV=prod mix assets.deploy

   Start Command:

   MIX_ENV=prod mix phx.server

4. Configure Port and Environment Variables

   In the Configure Build & Start screen, set the Port field (above Environment Variables) to your desired value (e.g., 80 or 8080). You do not need to add a PORT environment variable. Then add any required environment variables, such as:

   • SECRET_KEY_BASE — generate locally with mix phx.gen.secret (required for production)

5. Choose Pricing Tier

   Select your preferred instance size and click Create Web Service.

6. Deploy

   Click Create Web Service and watch logs until your web service is live.

7. Success

   Once complete, your Phoenix app will be live and accessible at your service’s public URL.

   Alternative: Configure Later

   If you prefer to configure environment variables after deployment, navigate to the Environment tab in your service dashboard and add the SECRET_KEY_BASE there. However, configuring everything upfront in step 4 is more streamlined.

   Troubleshooting

   If your deployment fails, the first place to check is the Logs tab in your seenode service dashboard. Build and runtime logs often contain valuable information for diagnosing issues.

   Port configuration mismatch

   • Templates default to port 80. Ensure your application listens on the port you set in the Configure Build & Start screen.
   • Adjust in framework config if needed (e.g., in config/prod.exs, confirm http: [port: String.to_integer(System.get_env("PORT") || "80")]).
   • Seeing a 502 Bad Gateway? This often means your app is not listening on the configured port.

   Common Issues:

   OTP Version Problem (Linux-specific)

   • Error: Your system’s Erlang/OTP was too old and missing functions Phoenix needed (:public_key.cacerts_get/0).
   • Fix: Install a newer OTP (via asdf or manual build) so Phoenix and esbuild can work.

   Wrong Build Process

   • Error: You were building Phoenix but not doing it in a way that works for seenode’s deploy (wrong script, missing prod build steps).
   • Fix: Adjusted build command to properly compile dependencies, assets, and release for production.

   Missing SECRET_KEY_BASE

   • Error: Phoenix needs a secret key for signing and encryption. It wasn’t set in the deployment environment.
   • Fix: Generate one (mix phx.gen.secret) and set it as an environment variable in seenode before starting the app. :::

Starting from Scratch?

If you don’t have a Phoenix project yet:

Option 1: Use our Template (Recommended)

Phoenix Template

Deploy a minimal Phoenix application designed for zero-configuration deployment.

Option 2: Create from Phoenix Docs + seenode Setup

Follow the official Phoenix documentation to create a new project, then return here for seenode-specific deployment steps.

seenode-Specific Setup Steps:

1. Install Phoenix: mix archive.install hex phx_new
2. Create project: mix phx.new your_project
3. Configure production settings
4. Create build script

Next Steps

Now that your Phoenix app is deployed, here are some recommended next steps:

Set up a Custom Domain (Coming Soon)

Configure a custom domain to point to your new web service.

Connect to a Database

Instantly scaffold and connect PostgreSQL and MySQL databases