Launch a New App on Fly.io
We'll be migrating all V1 apps in phases. Learn more about how and why we're getting off Nomad.
You can also migrate your V1 app yourself using our migration tool or manually.
To create a brand new app on Fly.io, run
from the root directory of your project.
If you're in a hurry to try your first launch, we also have a condensed Hands-on. You may also be interested in our language- and framework-specific launch guides.
Ingredients of a Ready-to-deploy Fly App
Here are the components of a successful launch, ready for the first deployment:
- a way to get a Docker image that Fly.io can use to boot up a VM with your app running
- Fly.io-specific configuration for the app, in the form of a
- platform resources such as public IP addresses, Fly Volumes, app secrets, Fly Postgres clusters, integrated resources like Redis by Upstash
Framework Launch Scanners
Depending on your project,
fly launch may be able to look at your app's source code and get through that list, straight to a deployed Fly App, in one swoop. This is most likely for frameworks on which Fly.io has people specializing full time. Right now that's Elixir/Phoenix, Laravel, Rails, and Django, but we have launch guides for various other languages and frameworks.
Our best scanners furnish a Dockerfile from which your app's image will be built. Some of our terrible older scanners may invoke buildpacks, which tend to be slow and brittle.
fly launch in a directory containing a working Django app (it happens to be the one from our Django getting-started example):
Creating app in /Users/chris/FlyTests/django Scanning source code Detected a Django app ? Choose an app name (leave blank to generate one): ...
The flyctl Django scanner has taken ownership of my launch. Visit our Django guide to see how that story will end. (Spoiler: it has a happy ending.)
You can nudge
fly launch to better suit your project.
Choose How the Docker Image Is Built
fly launch how you want to get the Docker image for your app, using either the
--dockerfile option, or by catching the Dockerfile launch scanner's attention with the presence of a Dockerfile in your app's root directory. The Dockerfile scanner doesn't do a lot of configuration, but it prevents other scanners from taking over.
The actual Docker image build (or image pull) for a Fly App takes place during deployment.
fly launch sets the stage by recording how to build, or get, the image, and both the first and all later deploys use that information.
Customize the Configuration File
You can provide your own
fly launch will offer to read it in, in lieu of the default config. That sets a starting point for the app configuration, and under some circumstances a framework launch scanner may overwrite parts of it.
There are also a number of other options you can use to exert control over
fly launch doesn't have a scanner that can set up your app automatically, it will still initialize a new Fly App in your Fly.io organization and provide you with a default app configuration that's a reasonable starting point for a simple web app.
It's also possible to perform an entirely manual "launch", skipping all the launch scanners and full-service resource provisioning, using
fly apps create, a hand-crafted (or copied)
fly.toml, and step-by-step resource provisioning, followed by
Here's me launching my Flask app that I've written and tested using the local dev server:
Creating app in /Users/chris/FlyTests/hello-gunicorn-flask Scanning source code Detected a Python app Using the following build configuration: Builder: paketobuildpacks/builder:base ? Choose an app name (leave blank to generate one):
If I carry on with this buildpack-based build, this story does not end with a working Flask app. Dockerfile-based deployments are much simpler and faster anyway, so I decide to use a Dockerfile. (I hit ctrl-C to stop the launch.)
Conveniently, there's also already a Dockerfile that works with this app.
With a Dockerfile in my working directory, if I run
fly launch again, the Dockerfile launcher takes over before the generic Python buildpack one has a chance to.
An existing fly.toml file was found for app testrun ? Would you like to copy its configuration to the new app? No
I have a
fly.toml in my working directory from cloning the
fly-apps/hello-gunicorn-flask repo to my local machine, but I want to use whatever config
fly launch gives me, so I answer
No to that question.
Creating app in /Users/chris/FlyTests/hello-gunicorn-flask Scanning source code Detected a Dockerfile app
There's the Dockerfile scanner taking over. Now some general app configuration:
? Choose an app name (leave blank to generate one): testrun ? Select Organization: Chris (personal) Some regions require a paid plan (fra, maa). See https://fly.io/plans to set up a plan. ? Choose a region for deployment: Toronto, Canada (yyz)
This is the region where flyctl will start Machines for this app if not otherwise specified. The first deployment will put its Machine(s) in that region.
Created app 'testrun' in organization 'personal' Admin URL: https://fly.io/apps/testrun Hostname: testrun.fly.dev ? Would you like to set up a Postgresql database now? No ? Would you like to set up an Upstash Redis database now? No
fly launch offers to provision Fly Postgres and Redis by Upstash databases. I don't need them for my very simple web app.
Wrote config file fly.toml ? Would you like to deploy now? Yes ==> Building image Remote builder fly-builder-crimson-dew-6190 ready ...
It's downloaded the new app's configuration into
fly.toml and offered to deploy straight away. I accept. By default, the Docker build happens on one of Fly.io's remote builder Machines.
fly launch always rewrites
fly.toml even if it's just writing an identical config back into the file.
Aside: In the case of my Dockerfile app, I ended up with the default
fly.toml, configured with an HTTP service suitable for a basic web app, but with one small tweak. My Dockerfile contains the line:
My Flask app listens on port 4999, not the more common (and default for
fly.toml) port 8080.
Fly.io doesn't care about EXPOSE statements in Dockerfiles directly, because we don't actually run containers, and services via our proxy are configured in
fly.toml, not in the Dockerfile. But as a convenience, the Dockerfile
fly launch scanner catches EXPOSE if it's there, and fills in
internal_port on the public HTTP
[[services]] section accordingly.
Coming back to the deployment, skipping some of the build output:
... --> Pushing image done image: registry.fly.io/testrun:deployment-01GWAPGQWQ5N1HY5651D5DX5B0 image size: 141 MB Provisioning ips for testrun Dedicated ipv6: 2a09:8280:1::5b:297 Shared ipv4: 188.8.131.52 Add a dedicated ipv4 with: fly ips allocate-v4
Because I had an HTTP service configured, and no public IP addresses, these were provisioned on deployment.
Process groups have changed. This will: * create 1 "app" machine No machines in group 'app', launching one new machine Machine 17811122f5d089 [app] update finished: success Finished deploying
The first deployment has finished!
I haven't explicitly configured process groups, so my app gets a single Machine assigned to the default
app process. With
fly status I can see that this machine is running in
yyz (Toronto), where I told
fly launch I wanted my app to be deployed.
App Name = testrun Owner = personal Hostname = testrun.fly.dev Image = testrun:deployment-01GWAPGQWQ5N1HY5651D5DX5B0 Platform = machines Machines ID PROCESS VERSION REGION STATE HEALTH CHECKS LAST UPDATED 17811122f5d089 app 1 yyz started 2023-03-24T20:56:45Z
I can scale out by adding Machines in other regions if I want to get close to users in more corners of the world.
To check that my new web app is actually working, I run
to visit my app in the browser!
If you've run
fly launch but haven't deployed yet, want to change your configuration, update your app source, or change or provision platform resources such as public IP addresses, Fly Volumes, app secrets, Fly Postgres clusters, or integrated resources like Redis by Upstash, you can go ahead and do so, and (re)deploy with
Once your app is deployed you'll probably want to check up on it using one or more of the techniques in Get Information About an App. When you're ready to go to production, scale up to two or more Machines for high availability.