---
title: "Migrate from Fly.io"
description: "Move a Fly.io app to dply: build the same Dockerfile, set the port, copy secrets, replace Fly databases with dply resources, and switch the domain."
---

This guide is for apps that run on Fly Machines today. dply doesn't read `fly.toml`, but it builds your `Dockerfile` as it is, so most Fly apps run unchanged as [container apps](/docs/containers) that sleep when idle.

## How the pieces map

| Fly.io | dply |
|---|---|
| App | A container app |
| `Dockerfile` | Built as it is |
| `fly.toml` | Not read. Move the settings you need by hand (see below) |
| `[http_service] internal_port` | The `EXPOSE` port in your `Dockerfile` |
| `[deploy] release_command` | The release command: `build.release` in `dply.yaml` ([Configuration files](/docs/configuration-files)) |
| `[env]` | **Environment** ([Environment variables](/docs/environment-variables)) |
| Secrets | **Environment** |
| `[processes]` | The web process is the app; others become **Queue workers** ([Queue workers](/docs/queue-workers)) |
| Machines, `auto_stop_machines`, `min_machines_running` | Instances, **Sleeps after** and **Min instances** ([Scaling & sleep](/docs/scaling-and-sleep)) |
| Regions | [Data regions](/docs/data-regions) |
| Volumes | Not available. Use [object storage](/docs/resources/object-storage) |
| Managed Postgres | dply Postgres ([Postgres, MySQL & MongoDB](/docs/resources/databases)) |
| Upstash Redis | dply Valkey ([Valkey (Redis)](/docs/resources/valkey)) |
| `fly ssh console` | The app's **Console**, or `dply-edge ssh` from the [CLI](/docs/cli) |
| `*.fly.dev` | The app's `*.on-dply.live` hostname ([Domains](/docs/domains)) |

## 1. Check the port

dply sends traffic to the first `EXPOSE` port in your `Dockerfile`, or `8080` when there isn't one. Fly uses `internal_port` from `fly.toml` instead, so many Fly Dockerfiles have no `EXPOSE`. Add one with the port your app listens on:

```dockerfile
EXPOSE 3000
```

A `Procfile` `web:` line doesn't change the start command of your own `Dockerfile`; its `CMD` is used. A `release:` line still runs. See [Procfile](/docs/configuration-files#procfile).

## 2. Deploy the app

1. Choose **New app**, connect your source control, and select the repository and branch.
2. Check that dply found the `Dockerfile` and shows **App**, then choose **Deploy**.

If `fly.toml` has a `release_command`, add it to `dply.yaml`:

```yaml
build:
  release: bin/rails db:migrate
```

## 3. Copy secrets and environment

`fly secrets list` shows only names and digests, not values. Take the values from where you keep them, or print them from a running Machine:

```bash
fly ssh console -C printenv
```

Copy the `[env]` values from `fly.toml` too. Paste everything into **Environment** on dply as `KEY=value` lines. Leave out `DATABASE_URL` and `REDIS_URL`: dply sets them from the resources you attach next.

## 4. Attach resources

On the app's **Overview**, choose **Add resource** and add a **Database** for Postgres and **dply Valkey** for Redis. Add **Queue workers** for each extra process group. Redeploy so the app receives the new variables.

## 5. Move the database

1. Stop writes to the Fly app.
2. Open a tunnel with `fly proxy` (or use your managed database's connection string) and export:

   ```bash
   pg_dump --no-owner --no-acl -Fc "$FLY_DATABASE_URL" > app.dump
   ```

3. Open the database from the app's **Overview**. Under **Export and import**, choose **Get upload command**, run it where `app.dump` is, then choose **Load it**.

See [Postgres, MySQL & MongoDB](/docs/resources/databases#export-and-import).

## 6. Switch the domain

1. Check the app on its `on-dply.live` address.
2. Add the domain under **Routing**, **Domains**.
3. Lower the TTL on the existing record, then replace the A and AAAA records pointing at Fly with the CNAME target dply shows. Apex domains need an ALIAS, ANAME or flattened CNAME at most DNS providers.
4. Choose **Verify DNS** and wait for TLS to be active.
5. Remove the certificate from Fly with `fly certs remove`, then scale the app to zero.

See [Domains](/docs/domains).

## Next steps

- [Container apps](/docs/containers)
- [Scaling & sleep](/docs/scaling-and-sleep)
- [Troubleshooting builds](/docs/guides/troubleshooting-builds)