Appkata: MinIO - S3 Compatible Storage

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As you build out your applications, the need for storage of larger unstructured data, such as web assets, images, or any kind of large file, may become essential. Software compatible with Amazon's S3 is one of the ways people address this issue - the other, obviously being using third party services such as Amazon's S3 to store data on. MinIO is an object storage system available under the AGPLv3 which can provide such an S3 compatible service.

We're going to set up MinIO on Fly, backed by Fly's disk Volume storage, so we can use it as part of a digital asset delivery system.


For this app, we'll use the official minio/minio Docker image. We'll use a Dockerfile, a very minimal Dockerfile:

FROM minio/minio

CMD [ "server", "/data" ]

This just takes the MinIO image and runs it with the command server /data, so that the server runs using the /data directory. We'll get to that directory in a moment.


This image uses port 9000 to communicate with the world. We have a Dockerfile. We're now ready to initialize our Fly app. Using fly init we create an app called appkata-minio. We then add the --dockerfile flag to tell it to use the Dockerfile we created, --org personal to deploy it to our personal organization, and --port 9000 to set the default internal port to 9000.

fly init appkata-minio --dockerfile --org personal --port 9000
Selected App Name: appkata-minio

New app created
  Name         = appkata-minio
  Organization = personal
  Version      = 0
  Status       =
  Hostname     = <empty>

App will initially deploy to lhr (London, United Kingdom) region

Wrote config file fly.toml

The generated configuration in fly.toml will now send connections over HTTP (port 80) and HTTPS (port 443) to port 9000 of the running image. Make a note of where the app will initially deploy, we'll need that in a moment.

Disk Storage

The application's VM and image are ephemeral. When the app is stopped of moved it loses any data written to its file system. That's why there are Volumes, storage that is independent of the VM and image. All we need to do is create a Volume with a name and a size in the region where the app is.

❯ fly vol create miniodata --region lhr
        ID: L5365X5p7QRzxfv6eJZ8
      Name: miniodata
    Region: lhr
   Size GB: 10
Created at: 09 Nov 20 14:34 UTC

If not specified, the size defaults to the minimum: 10GB. Now we have that volume, we need to let out app know about it. Back to the fly.toml and append to the file:


This mounts the volume we just created onto the '/data' directory of the running app. With this in place, it's now time to set some secrets.


MinIO uses two environment variables that can be set to provide an access key and secret key which are used to log into the server as admin. To pass these values to the server, we'll use fly secrets set which will encrypt the values being passed and only decrypt them at runtime, using the key names to set similarly named environment variables.

fly secrets set MINIO_ACCESS_KEY=appkataaccesskey MINIO_SECRET_KEY=appkatasecretkey


With our configuration complete, we can now deploy the app:

fly deploy

When the deployment is complete, run fly open to browse to the server. MinIO has a web interface for creating buckets and opening files. You'll need to log in first with the access key and secret key you saved into secrets.

If you have the MinIO Client installed, you can also set this up as an alias to connect to with:

mc alias set appkata appkataaccesskey appkatasecretkey

And proceed to administer the server.


  • You can discuss this example on its dedicated Fly Community topic.