Fly.io lets you deploy Docker containers that will be compiled as a Firecracker VM and run in locations around the world.
\nFly offer a number of ways to build and deploy apps. For many frameworks you can run fly launch and it will detect the framework and configure a container for you. For others you can pass it a Dockerfile which will be built and deployed. But you can also push your own images to a Docker registry and deploy them to Fly.
Today I figured out how to use Fly's own registry to deploy an app.
\nFly's registry is called registry.fly.io. To use it, you need to tag your Docker images with a tag that begins with that string.
Every Fly app gets its own registry subdomain. You can create apps in a number of ways, but the easiest is to use the Fly CLI:
\nflyctl apps create datasette-demo\nFly app names must be globally unique across all of Fly - you will get an error if the app name is already taken.
\nYou can create an app with a random, freely available name using the --generate-name option:
~ % flyctl apps create --generate-name\n? Select Organization: Simon Willison (personal)\nNew app created: rough-dew-1296\nNow that you have an app name, you can tag your Docker image using:
\nregistry.fly.io/your-app-name:unique-tag-for-your-image\nIf you are building an image using Docker on your machine, you can run this command in the same directory as your Dockerfile:
docker build -t registry.fly.io/datasette-demo:datasette-demo-v0 .\nIn order to push your image to Fly, you will first need to authenticate.
\nThe flyctl auth docker command will do this for you:
~ % flyctl auth docker\nAuthentication successful. You can now tag and push images to registry.fly.io/{your-app}\nThis works by hooking into Docker's own authentication mechanism. You can see what it has done by looking at your ~/.docker/config.json file. Mine looks like this:
{\n \"auths\": {\n \"registry.fly.io\": {\n \"auth\": \"... secret token here ...\"\n }\n ,\n \"experimental\": \"disabled\",\n \"stackOrchestrator\": \"swarm\"\n}Now you can push your image to the registry like this:
\ndocker push registry.fly.io/datasette-demo:datasette-demo-v0\nNow that your image is pushed, you can deploy an instance of it like this:
\nflyctl deploy --app datasette-demo \\\n --image registry.fly.io/datasette-demo:datasette-demo-v0\nA few seconds later your app will be running at:
\nhttps://name-of-your-app.fly.dev/\n