> ## Documentation Index
> Fetch the complete documentation index at: https://docs.fly.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Legacy pre v1.6.3 Phoenix App

Getting an application running on Fly.io is essentially working out how to package it as a deployable image and attach it to a database. Once packaged, it can be deployed to the Fly.io platform.

In this guide we’ll learn how to deploy an [Elixir Phoenix](https://www.phoenixframework.org/) application on Fly.io and connect it to a PostgreSQL database.

**This guide is for applications generated on Phoenix versions older than v1.6.3.**

If you're on 1.6.3 or higher, deployment setup is baked into the framework! Check out our [guide for
launching newer Elixir apps](/elixir/getting-started).

## *Running the Application Locally*

Let's walk through working with Phoenix locally and preparing it for deployment. We can start with a brand new Phoenix application.

```bash theme={null}
mix phx.new hello_elixir
```

**Tip:** Make sure you have a local [PostgreSQL server installed](https://wiki.postgresql.org/wiki/Detailed_installation_guides) and running.

Now, we setup the database and start the application.

<CodeGroup>
  ```bash cmd theme={null}
  mix ecto.setup
  ```

  ```output output theme={null}
  The database for HelloElixir.Repo has been created
  ```
</CodeGroup>

<CodeGroup>
  ```bash cmd theme={null}
  mix phx.server
  ```

  ```output output theme={null}
  [info] Running HelloElixirWeb.Endpoint with cowboy 2.8.0 at 0.0.0.0:4000 (http)
  [info] Access HelloElixirWeb.Endpoint at http://localhost:4000
  ```
</CodeGroup>

Connect to localhost:4000 to confirm that you have a working Elixir application.

### *Generate Release Config Files*

We use the `mix release.init` command to create some sample files in the `./rel` directory.

<CodeGroup>
  ```bash cmd theme={null}
  mix release.init
  ```

  ```output output theme={null}
  * creating rel/vm.args.eex
  * creating rel/remote.vm.args.eex
  * creating rel/env.sh.eex
  * creating rel/env.bat.eex
  ```
</CodeGroup>

## *Special Note on Fly Networking*

Internally Fly uses IPv6 networking. This enables some cool features, but legacy Elixir applications need to be configured to work smoothly with it.
These config changes tell Elixir, Phoenix, and the BEAM that we are using IPv6 addresses. The options look like `inet6` and `inet6_tcp`.
The next steps are how we configure that in our application.

We only need to configure `rel/env.sh.eex`. This file gets turned into a shell script that the release uses to set ENV values used when we run
any release commands. Here's the important parts.

```
#!/bin/sh

ip=$(grep fly-local-6pn /etc/hosts | cut -f 1)
export RELEASE_DISTRIBUTION=name
export ELIXIR_ERL_OPTIONS="-proto_dist inet6_tcp"
```

We configure the node to use a full node name when it runs. We get the Fly assigned IPv6 address and use that to name our node. Finally, we configure `inet6_tcp` for the BEAM as well.

Even if you don't care to cluster your nodes together, you still want to do this because it enables running an IEx shell in a running node.

## *Docker Setup*

### *Dockerfile*

You can find a good Dockerfile ready to build your application in the [hello\_elixir GitHub repo](https://github.com/fly-apps/hello_elixir/blob/main/Dockerfile). It is important to note that it uses a Debian-slim base image to build. This avoids DNS issues in Alpine images. The [base elixir image is maintained by the hexpm](https://hub.docker.com/r/hexpm/elixir/tags?page=1\&ordering=last_updated) org and is kept up to date. [Hex.pm](https://hex.pm/) is the official package repository for Elixir. There are other options instead of Debian there as well if you prefer.

The Dockerfile uses a two-stage approach. There are two `FROM` commands. The first stage pulls in the source and builds the release. The second stage takes the prepared release and sets it up in a minimal Docker image. The final deployed image contains only our release.

### *Docker Ignore File*

We add the file `.dockerignore` to the project with the following contents. Depending on how you `COPY` things into the Dockerfile, you may or may not need to configure this.

```
assets/node_modules/
deps/
```

This ensures we keep any natively compiled Elixir or Node packages from our development environments from causing a problem in the Linux container.

## *Launch the App on Fly*

To launch an app on fly, run `fly launch` in the directory with your source code. This creates and configures a fly app for you by inspecting your source code, then prompts you to deploy.

<CodeGroup>
  ```bash cmd theme={null}
  fly launch
  ```

  ```output output theme={null}
  $ fly launch
  Scanning source code
  Detected Dockerfile app
  ? Select region: sea (Seattle, Washington (US))
  Created app fly-elixir in organization personal
  Wrote config file fly.toml
  ? Would you like to deploy now? No
  ```
</CodeGroup>

Don't deploy it just yet. We're going to adjust the generated `fly.toml` file first.

The `fly launch` command scans your source code to determine how to build a deployment image as well as identify any other configuration your app needs, such as secrets and exposed ports.

After your source code is scanned and the results are printed, you'll be prompted for an organization. Organizations are a way of sharing applications and resources between Fly users. Every Fly account has a personal organization, called `personal`, which is only visible to your account. Let's select that for this guide.

Next, you'll be prompted to select a region to deploy in. The closest region to you is selected by default. You can use this or change to another region. You can find the [list of supported regions here](/reference/regions).

At this point, `flyctl` created an app for you and wrote your configuration to a `fly.toml` file. You'll then be prompted to build and deploy your app. Once complete, your app will be running on fly.

## *Inside `fly.toml`*

The `fly.toml` file now contains a default configuration for deploying your app. In the process of creating that file, `flyctl` has also generated a Fly-side application slot with a new name. In this case, it is `fly-elixir`. If we look at the `fly.toml` file we can see the name in there:

```toml theme={null}
app = "fly-elixir"

kill_signal = "SIGINT"
kill_timeout = 5
processes = []

[env]

[experimental]
  allowed_public_ports = []
  auto_rollback = true

[[services]]
  http_checks = []
  internal_port = 8080
  processes = ["app"]
  protocol = "tcp"
  script_checks = []

  [services.concurrency]
    hard_limit = 25
    soft_limit = 20
    type = "connections"

  [[services.ports]]
    handlers = ["http"]
    port = 80

  [[services.ports]]
    handlers = ["tls", "http"]
    port = 443

  [[services.tcp_checks]]
    grace_period = "1s"
    interval = "15s"
    restart_limit = 0
    timeout = "2s"
```

The `flyctl` command will always refer to this file in the current directory if it exists, specifically for the `app` name/value at the start. That name is used to identify the application to the Fly platform. The rest of the file contains settings to be applied to the application when it deploys.

We'll have more details about these properties as we progress, but for now, it's enough to say that they mostly configure which ports the application will be visible on.

## *Customizing `fly.toml`*

Elixir applications need a little customization to the generated `fly.toml` file.

```toml theme={null}
app = "fly-elixir"

kill_signal = "SIGTERM"
kill_timeout = 5
processes = []

[deploy]
  release_command = "/app/entry eval HelloElixir.Release.migrate"

[env]

[experimental]
  allowed_public_ports = []
  auto_rollback = true

[[services]]
  http_checks = []
  internal_port = 4000
  processes = ["app"]
  protocol = "tcp"
  script_checks = []

  [services.concurrency]
    hard_limit = 25
    soft_limit = 20
    type = "connections"

  [[services.ports]]
    handlers = ["http"]
    port = 80

  [[services.ports]]
    handlers = ["tls", "http"]
    port = 443

  [[services.tcp_checks]]
    grace_period = "30s"  # allow some time for startup
    interval = "15s"
    restart_limit = 0
    timeout = "2s"
```

There are two important changes here:

* We added the `[deploy]` setting. This tells Fly that on a new deploy, **run our database migrations**. The Dockerfile we're using creates a symlink to your app name called `entry`. This uses that symlink run the migrate command.
* The `kill_signal` is set to `SIGTERM`. An Elixir node does a clean shutdown when it receives a `SIGTERM` from the OS.
* The `internal_port` is set to 4000 for our Elixir application. The port value should match your application.

Some other values were tweaked as well.

## *Preparing to Deploy*

We're almost there! Before we can deploy our new app, we need to setup a few things in our Fly account first. Namely, we want to provide the needed secrets and we need a database!

### *Setting our Secrets on Fly*

Elixir has a mix task that can generate a new Phoenix key base secret. Let's use that.

```bash theme={null}
mix phx.gen.secret
```

It generates a long string of random text. Let's store that as a secret for our app. When we run this command in our project folder, `flyctl` uses the `fly.toml` file to know which app we are setting the value on.

```
fly secrets set SECRET_KEY_BASE=<GENERATED>
```

### *Creating our Fly Postgres Database*

<CodeGroup>
  ```bash cmd theme={null}
  fly postgres create
  ```

  ```output output theme={null}
  ? App name: hello-elixir-db
  Automatically selected personal organization: Mark Ericksen
  ? Select region: sea (Seattle, Washington (US))
  ? Select VM size: shared-cpu-1x - 256
  ? Volume size (GB): 10
  Creating postgres cluster hello-elixir-db in organization personal
  Postgres cluster hello-elixir-db created
    Username:    <USER>
    Password:    <PASSWORD>
    Hostname:    hello-elixir-db.internal
    Proxy Port:  5432
    PG Port: 5433
  Save your credentials in a secure place, you won't be able to see them again!

  Monitoring Deployment

  2 desired, 2 placed, 2 healthy, 0 unhealthy [health checks: 6 total, 6 passing]
  --> v0 deployed successfully

  Connect to postgres
  Any app within the personal organization can connect to postgres using the above credentials and the hostname "hello-elixir-db.internal."
  For example: postgres://<USER>:<PASSWORD>@hello-elixir-db.internal:5432

  See the postgres docs for more information on next steps, managing postgres, connecting from outside fly:  https://fly.io/docs/reference/postgres/
  ```
</CodeGroup>

We can take the defaults which select the lowest values for CPU, size, etc. This is perfect for getting started.

### *Attach our App to the Database*

We use `flyctl` to attach our app to the database which also sets our needed `DATABASE_URL` ENV value.

<CodeGroup>
  ```bash cmd theme={null}
  fly postgres attach hello-elixir-db
  ```

  ```output output theme={null}
  Postgres cluster hello-elixir-db is now attached to fly-elixir
  The following secret was added to fly-elixir:
    DATABASE_URL=postgres://<NEW_USER>:<NEW_PASSWORD>@hello-elixir-db.internal:5432/fly_elixir?sslmode=disable
  ```
</CodeGroup>

We can see the secrets that Fly is using for our app like this.

<CodeGroup>
  ```bash cmd theme={null}
  fly secrets list
  ```

  ```output output theme={null}
  NAME            DIGEST                           DATE
  DATABASE_URL    830d8769ff33cba6c8b29d1cd6a6fbac 1m10s ago
  SECRET_KEY_BASE 84c992ac7ef334c21f2aaecd41c43666 9m20s ago
  ```
</CodeGroup>

Looks like we're ready to deploy!

## *Deploying to Fly*

To deploy your app, just run just run:

```bash theme={null}
fly deploy
```

First, `flyctl` builds our Dockerfile and pushes it to a Fly container registry.

This will lookup our `fly.toml` file, and get the app name `fly-elixir` from there. Then `flyctl` will start the process of deploying our application to the Fly platform. Flyctl returns you to the command line when it's done.

## *Viewing the Deployed App*

Now that the application has been deployed, let's find out more about its deployment. The command `fly status` will give you all the essential details.

<CodeGroup>
  ```bash cmd theme={null}
  fly status
  ```

  ```output output theme={null}
  App
    Name     = fly-elixir
    Owner    = personal
    Version  = 3
    Status   = running
    Hostname = fly-elixir.fly.dev

  Deployment Status
    ID          = 9762642f-baa4-e4df-c683-13f2ce26a6bc
    Version     = v3
    Status      = successful
    Description = Deployment completed successfully
    Instances   = 1 desired, 1 placed, 1 healthy, 0 unhealthy

  Instances
  ID       VERSION REGION DESIRED STATUS  HEALTH CHECKS      RESTARTS CREATED
  f617e72a 3       sea    run     running 1 total, 1 passing 0        1m34s ago
  ```
</CodeGroup>

## *Connecting to the App*

The quickest way to browse your newly deployed application is with the `fly apps open` command.

<CodeGroup>
  ```bash cmd theme={null}
  fly apps open
  ```

  ```output output theme={null}
  Opening https://fly-elixir.fly.dev/
  ```
</CodeGroup>

Your browser will be sent to the displayed URL. Fly will auto-upgrade this URL to a HTTPS secured URL.

### *Special Note on Clustering*

To make clustering your Elixir applications easier on Fly, in the `env.sh.eex` file, the `RELEASE_NODE` is named using the `$FLY_APP_NAME` and
the IPv6 address. It will look something like this in practice.

```
fly-elixir@fdaa:0:1da8:a7b:ac2:216b:da3f:2
```

### *Runtime Config*

When we created the app, the file `config/runtime.exs` was created for us. Now we need to update it.

```elixir theme={null}
import Config

if config_env() == :prod do
  database_url =
    System.get_env("DATABASE_URL") ||
      raise """
      environment variable DATABASE_URL is missing.
      For example: ecto://USER:PASS@HOST/DATABASE
      """

  config :hello_elixir, HelloElixir.Repo,
    # IMPORTANT: Or it won't find the DB server
    socket_options: [:inet6],
    url: database_url,
    pool_size: String.to_integer(System.get_env("POOL_SIZE") || "10")

  secret_key_base =
    System.get_env("SECRET_KEY_BASE") ||
      raise """
      environment variable SECRET_KEY_BASE is missing.
      You can generate one by calling: mix phx.gen.secret
      """

  # IMPORTANT: Get the app_name we're using
  app_name =
    System.get_env("FLY_APP_NAME") ||
      raise "FLY_APP_NAME not available"

  config :hello_elixir, HelloElixirWeb.Endpoint,
    # IMPORTANT: tell our app about the host name to use when generating URLs
    url: [host: "#{app_name}.fly.dev", port: 80],
    http: [
      ip: {0, 0, 0, 0, 0, 0, 0, 0},
      port: String.to_integer(System.get_env("PORT") || "4000")
    ],
    secret_key_base: secret_key_base

  # IMPORTANT: Enable the endpoint for releases
  config :hello_elixir, HelloElixirWeb.Endpoint, server: true
end
```

This code expects to receive some ENV values at runtime. We're expecting `SECRET_KEY_BASE` with our Phoenix secret, our `FLY_APP_NAME` from Fly, and the `DATABASE_URL` for connecting to a Fly hosted Postgres database.

Also, you don't need to turn on TLS for connecting to the Postgres instance. Fly private networks operate over an encrypted WireGuard mesh, so traffic between application servers and PostgreSQL is already encrypted and there's no need to TLS.

## *Bonus Sections*

With your application up and running, there are some additional things you can do to go further. Using some `flyctl` commands, we can easily do some powerful things with our application.

These bonus tips cover:

* Getting an IEx shell into your running node. This helps you manage and work with your running system.
* Clustering multiple Elixir nodes together. Say "Hello!" to the power of Distributed Computing!
* Scaling your application out to more machines and even distant regions (with or without clustering).

### *What is the IP Address?*

If you want to know what IP addresses the app is using, try `fly ips list`:

<CodeGroup>
  ```bash cmd theme={null}
  fly ips list
  ```

  ```output output theme={null}
  TYPE ADDRESS                              CREATED AT
  v4   213.188.199.124                      24m5s ago
  v6   2a09:8280:1:ce56:c80f:5071:6e94:6688 24m5s ago
  ```
</CodeGroup>