Use terraform in CLI to create QEMU cluster (#172)

* Use terraform in CLI to create QEMU cluster

* Dont allow qemu creation on os/arch other than linux/amd64

* Allow usage of --name flag for QEMU resources

Signed-off-by: Daniel Weiße <dw@edgeless.systems>

cli/internal/terraform/loader.go

@@ -0,0 +1,64 @@
+/*
+Copyright (c) Edgeless Systems GmbH
+
+SPDX-License-Identifier: AGPL-3.0-only
+*/
+
+package terraform
+
+import (
+	"embed"
+	"errors"
+	"io/fs"
+	"path"
+	"strings"
+
+	"github.com/edgelesssys/constellation/v2/internal/cloud/cloudprovider"
+	"github.com/edgelesssys/constellation/v2/internal/file"
+	"github.com/spf13/afero"
+)
+
+//go:embed terraform/*
+var terraformFS embed.FS
+
+// prepareWorkspace loads the embedded Terraform files,
+// and writes them into the workspace.
+func prepareWorkspace(fileHandler file.Handler, provider cloudprovider.Provider) error {
+	// use path.Join to ensure no forward slashes are used to read the embedded FS
+	rootDir := path.Join("terraform", strings.ToLower(provider.String()))
+	return fs.WalkDir(terraformFS, rootDir, func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		if d.IsDir() {
+			return nil
+		}
+
+		content, err := terraformFS.ReadFile(path)
+		if err != nil {
+			return err
+		}
+		fileName := strings.TrimPrefix(path, rootDir+"/")
+		return fileHandler.Write(fileName, content, file.OptMkdirAll)
+	})
+}
+
+// cleanUpWorkspace removes files that were loaded into the workspace.
+func cleanUpWorkspace(fileHandler file.Handler, provider cloudprovider.Provider) error {
+	rootDir := path.Join("terraform", strings.ToLower(provider.String()))
+	return fs.WalkDir(terraformFS, rootDir, func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		fileName := strings.TrimPrefix(path, rootDir+"/")
+		return ignoreFileNotFoundErr(fileHandler.RemoveAll(fileName))
+	})
+}
+
+// ignoreFileNotFoundErr ignores the error if it is a file not found error.
+func ignoreFileNotFoundErr(err error) error {
+	if errors.Is(err, afero.ErrFileNotFound) {
+		return nil
+	}
+	return err
+}