replit-migration-deep-dive

Replit Migration Deep Dive

Current State

!cat .replit 2>/dev/null | head -10 || echo 'No .replit found' !cat Procfile 2>/dev/null || echo 'No Procfile (not Heroku)' !cat Dockerfile 2>/dev/null | head -10 || echo 'No Dockerfile' !cat railway.json 2>/dev/null || echo 'No railway.json'

Overview

Comprehensive guide for migrating existing applications to Replit from Heroku, Railway, Vercel, Render, or local development. Covers converting configuration files, migrating databases, adapting to Replit's Nix-based environment, and setting up Replit-native features.

Prerequisites

• Source application with working deployment
• Access to current database for export
• Git repository with application code
• Replit Core or Teams plan

Migration Paths

From	Complexity	Duration	Key Changes
Local dev	Low	1-2 hours	Add .replit + replit.nix
Heroku	Medium	2-4 hours	Procfile to .replit, addons to Replit services
Railway	Low-Medium	1-3 hours	railway.json to .replit
Vercel	Low	1-2 hours	Usually frontend-only, use Static deploy
Docker	Medium	3-6 hours	Dockerfile to replit.nix

Instructions

Step 1: Import from GitHub

1. Go to replit.com > Create Repl > Import from GitHub
2. Paste your repository URL
3. Replit auto-detects language and creates default config
4. Review and adjust .replit and replit.nix

Step 2: Convert from Heroku

Procfile to .replit:

# Heroku Procfile
web: npm start
worker: node worker.js
release: node migrate.js

# Equivalent .replit
run = "npm start"
entrypoint = "index.js"

[deployment]
run = ["sh", "-c", "node migrate.js && npm start"]
build = ["sh", "-c", "npm ci --production"]
deploymentTarget = "autoscale"

[env]
NODE_ENV = "production"

Heroku addons to Replit services:

Heroku Addon	Replit Equivalent
Heroku Postgres	Replit PostgreSQL (Database pane)
Heroku Redis	Upstash Redis (external) or Replit KV
Heroku Scheduler	Replit Automations or external cron
Papertrail	Replit deployment logs + external
SendGrid	Same (use API key in Secrets)
Cloudinary	Replit Object Storage or same

Environment variables:

# Export from Heroku
heroku config -s > heroku-env.txt

# Import to Replit: copy each line into Secrets tab
# Or use Replit Secrets tool (lock icon in sidebar)

Step 3: Convert from Railway

railway.json to .replit:

// railway.json
{
  "build": { "builder": "NIXPACKS" },
  "deploy": {
    "startCommand": "npm start",
    "healthcheckPath": "/health"
  }
}

# Equivalent .replit
run = "npm start"

[deployment]
run = ["sh", "-c", "npm start"]
build = ["sh", "-c", "npm ci"]
deploymentTarget = "autoscale"

Step 4: Convert from Docker

Dockerfile to replit.nix:

# Dockerfile
FROM node:20-slim
RUN apt-get update && apt-get install -y python3 postgresql-client
WORKDIR /app
COPY package*.json ./
RUN npm ci --production
COPY . .
CMD ["node", "dist/index.js"]

# Equivalent replit.nix
{ pkgs }: {
  deps = [
    pkgs.nodejs-20_x
    pkgs.python311
    pkgs.postgresql
  ];
}

# .replit
run = "node dist/index.js"

[deployment]
run = ["sh", "-c", "node dist/index.js"]
build = ["sh", "-c", "npm ci --production && npm run build"]
deploymentTarget = "autoscale"

Step 5: Database Migration

Export from source:

# From Heroku Postgres
heroku pg:backups:capture
heroku pg:backups:download
pg_restore -d LOCAL_DB latest.dump

# From Railway
railway run pg_dump > backup.sql

# From any PostgreSQL
pg_dump --format=custom DATABASE_URL > backup.dump

Import to Replit PostgreSQL:

# In Replit Shell, after provisioning PostgreSQL in Database pane:

# Option 1: SQL file
psql "$DATABASE_URL" < backup.sql

# Option 2: Custom format dump
pg_restore -d "$DATABASE_URL" backup.dump

# Option 3: Schema only (recreate, then migrate data app-level)
psql "$DATABASE_URL" < schema.sql
node scripts/migrate-data.js

Migrate from non-PostgreSQL (MongoDB, etc.):

// scripts/migrate-from-mongo.ts
import { MongoClient } from 'mongodb';
import { Pool } from 'pg';

const mongo = new MongoClient(process.env.MONGO_URL!);
const pg = new Pool({ connectionString: process.env.DATABASE_URL });

async function migrate() {
  await mongo.connect();
  const users = await mongo.db('app').collection('users').find().toArray();

  await pg.query(`
    CREATE TABLE IF NOT EXISTS users (
      id TEXT PRIMARY KEY,
      email TEXT UNIQUE,
      name TEXT,
      data JSONB,
      created_at TIMESTAMPTZ
    )
  `);

  for (const user of users) {
    await pg.query(
      'INSERT INTO users (id, email, name, data, created_at) VALUES ($1, $2, $3, $4, $5)',
      [user._id.toString(), user.email, user.name, JSON.stringify(user), user.createdAt]
    );
  }

  console.log(`Migrated ${users.length} users`);
  await mongo.close();
  await pg.end();
}

migrate();

Step 6: Post-Migration Checklist

## After Migration

### Configuration
- [ ] .replit configured with correct run and build commands
- [ ] replit.nix includes all system dependencies
- [ ] All env vars moved to Replit Secrets
- [ ] PORT reads from environment variable
- [ ] App listens on 0.0.0.0 (not localhost)

### Database
- [ ] PostgreSQL provisioned in Database pane
- [ ] Data imported and verified
- [ ] Connection string uses DATABASE_URL env var
- [ ] SSL configured: { rejectUnauthorized: false }

### Testing
- [ ] App runs successfully in Workspace ("Run")
- [ ] Health endpoint works: /health returns 200
- [ ] All API endpoints functional
- [ ] Auth flow works (if using Replit Auth)
- [ ] File uploads work (if using Object Storage)

### Deployment
- [ ] Deployed successfully (Autoscale or Reserved VM)
- [ ] Custom domain configured (if applicable)
- [ ] SSL certificate provisioned
- [ ] Post-deploy health check passes

### Cleanup
- [ ] Old platform deprovisioned after verification period
- [ ] DNS records updated (if custom domain)
- [ ] CI/CD updated to point to Replit
- [ ] Team notified of new deployment URL

Error Handling

Issue	Cause	Solution
Missing system package	Not in replit.nix	Add to deps (e.g., pkgs.openssl)
Build failure	Different build env	Adapt build command for Replit
DB connection refused	Wrong SSL config	Add ssl: { rejectUnauthorized: false }
Port binding error	Hardcoded port	Read from process.env.PORT
Static files not served	Wrong public directory	Set publicDir in deployment config

Resources

• Import from GitHub
• Import from Bolt
• Import from Lovable
• Nix on Replit
• Replit Deployments

Next Steps

For advanced troubleshooting after migration, see replit-advanced-troubleshooting.