main.go

package main

import (
	"context"
	"fmt"
	"math/rand"
	"time"

	"dagger/book/internal/dagger"
)

func New(
	// +defaultPath="."
	source *dagger.Directory,
) *Book {
	return &Book{
		Source: source,
	}
}

type Book struct {
	// The source directory of the app
	Source *dagger.Directory
}

// Env sets up a Python environment with dependencies installed.
func (b *Book) Env(ctx context.Context) (*dagger.Container, error) {
	return dag.Container().
		From("python:3.11").
		WithDirectory("/app", b.Source).
		WithWorkdir("/app").
		WithMountedCache("/root/.cache/pip", dag.CacheVolume("python-pip")).
		WithExec([]string{"pip", "install", "-r", "requirements.txt"}), nil
}

// Test spins up a Postgres service, sets up the environment, and runs pytest.
func (b *Book) Test(ctx context.Context) (string, error) {
	postgres := dag.Container().
		From("postgres:alpine").
		WithEnvVariable("POSTGRES_DB", "app_test").
		WithEnvVariable("POSTGRES_PASSWORD", "secret").
		WithExposedPort(5432).
		AsService()

	env, err := b.Env(ctx)
	if err != nil {
		return "", err
	}

	testContainer := env.
		WithServiceBinding("db", postgres).
		WithEnvVariable("DATABASE_URL", "postgresql://postgres:secret@db/app_test").
		WithExec([]string{"pytest"})

	return testContainer.Stdout(ctx)
}

// Publish runs tests and publishes the FastAPI app container.
func (b *Book) Publish(ctx context.Context) (string, error) {
	// Run tests first
	if _, err := b.Test(ctx); err != nil {
		return "", err
	}

	env, err := b.Env(ctx)
	if err != nil {
		return "", err
	}

	r := rand.New(rand.NewSource(time.Now().UnixNano()))
	tag := fmt.Sprintf("ttl.sh/my-fastapi-app-%d", r.Intn(1e8))

	return env.
		WithExposedPort(8000).
		WithEntrypoint([]string{"fastapi", "run", "main.py"}).
		Publish(ctx, tag)
}