feat: add sgpython3 and sgpoetry tools

For Python projects managed by Poetry.

tools/sgpoetry/command.go

@@ -0,0 +1,48 @@
+package sgpoetry
+
+import (
+	"context"
+	"os"
+	"os/exec"
+	"path/filepath"
+
+	"go.einride.tech/sage/sg"
+	"go.einride.tech/sage/sgtool"
+	"go.einride.tech/sage/tools/sgpython3"
+)
+
+const (
+	name    = "poetry"
+	version = "1.5.1"
+)
+
+func Command(ctx context.Context, args ...string) *exec.Cmd {
+	sg.Deps(ctx, PrepareCommand)
+	return sg.Command(ctx, sg.FromBinDir(name), args...)
+}
+
+func PrepareCommand(ctx context.Context) error {
+	toolDir := sg.FromToolsDir(name, version)
+	poetry := filepath.Join(toolDir, "bin", name)
+	if _, err := os.Stat(poetry); err == nil {
+		if _, err := sgtool.CreateSymlink(poetry); err != nil {
+			return err
+		}
+		return nil
+	}
+	// See: https://python-poetry.org/docs/#installing-manually
+	if err := sgpython3.Command(ctx, "-m", "venv", toolDir).Run(); err != nil {
+		return err
+	}
+	pip := filepath.Join(toolDir, "bin", "pip")
+	if err := sg.Command(ctx, pip, "install", "-U", "pip", "setuptools").Run(); err != nil {
+		return err
+	}
+	if err := sg.Command(ctx, pip, "install", name+"poetry=="+version).Run(); err != nil {
+		return err
+	}
+	if _, err := sgtool.CreateSymlink(poetry); err != nil {
+		return err
+	}
+	return nil
+}

tools/sgpython3/command.go

@@ -0,0 +1,29 @@
+package sgpython3
+
+import (
+	"context"
+	"fmt"
+	"os/exec"
+
+	"go.einride.tech/sage/sg"
+	"go.einride.tech/sage/sgtool"
+)
+
+const name = "python3"
+
+func Command(ctx context.Context, args ...string) *exec.Cmd {
+	sg.Deps(ctx, PrepareCommand)
+	return sg.Command(ctx, sg.FromBinDir(name), args...)
+}
+
+func PrepareCommand(context.Context) error {
+	// Make sure python3 is available.
+	if binary, err := exec.LookPath("python3"); err == nil {
+		if _, err := sgtool.CreateSymlink(binary); err != nil {
+			return err
+		}
+		return nil
+	}
+	// TODO: If needed, check if `python` is Python 3.
+	return fmt.Errorf("python3 is not available in $PATH")
+}