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/terraform.go

@@ -0,0 +1,203 @@
+/*
+Copyright (c) Edgeless Systems GmbH
+
+SPDX-License-Identifier: AGPL-3.0-only
+*/
+
+package terraform
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"github.com/edgelesssys/constellation/v2/internal/cloud/cloudprovider"
+	"github.com/edgelesssys/constellation/v2/internal/file"
+	"github.com/edgelesssys/constellation/v2/internal/state"
+	"github.com/hashicorp/go-version"
+	install "github.com/hashicorp/hc-install"
+	"github.com/hashicorp/hc-install/fs"
+	"github.com/hashicorp/hc-install/product"
+	"github.com/hashicorp/hc-install/releases"
+	"github.com/hashicorp/hc-install/src"
+	"github.com/hashicorp/terraform-exec/tfexec"
+	tfjson "github.com/hashicorp/terraform-json"
+	"github.com/spf13/afero"
+)
+
+const (
+	tfVersion         = ">= 1.2.0"
+	terraformVarsFile = "terraform.tfvars"
+)
+
+// Client manages interaction with Terraform.
+type Client struct {
+	tf tfInterface
+
+	provider cloudprovider.Provider
+
+	file   file.Handler
+	state  state.ConstellationState
+	remove func()
+}
+
+// New sets up a new Client for Terraform.
+func New(ctx context.Context, provider cloudprovider.Provider) (*Client, error) {
+	tf, remove, err := GetExecutable(ctx, ".")
+	if err != nil {
+		return nil, err
+	}
+
+	file := file.NewHandler(afero.NewOsFs())
+
+	return &Client{
+		tf:       tf,
+		provider: provider,
+		remove:   remove,
+		file:     file,
+	}, nil
+}
+
+// CreateCluster creates a Constellation cluster using Terraform.
+func (c *Client) CreateCluster(ctx context.Context, name string, input CreateClusterInput) error {
+	if err := prepareWorkspace(c.file, c.provider); err != nil {
+		return err
+	}
+
+	if err := c.tf.Init(ctx); err != nil {
+		return err
+	}
+
+	if err := writeUserConfig(c.file, c.provider, name, input); err != nil {
+		return err
+	}
+
+	if err := c.tf.Apply(ctx); err != nil {
+		return err
+	}
+
+	tfState, err := c.tf.Show(ctx)
+	if err != nil {
+		return err
+	}
+
+	ipOutput, ok := tfState.Values.Outputs["ip"]
+	if !ok {
+		return errors.New("no IP output found")
+	}
+	ip, ok := ipOutput.Value.(string)
+	if !ok {
+		return errors.New("invalid type in IP output: not a string")
+	}
+	c.state = state.ConstellationState{
+		CloudProvider:  c.provider.String(),
+		LoadBalancerIP: ip,
+	}
+
+	return nil
+}
+
+// DestroyInstances destroys a Constellation cluster using Terraform.
+func (c *Client) DestroyCluster(ctx context.Context) error {
+	return c.tf.Destroy(ctx)
+}
+
+// RemoveInstaller removes the Terraform installer, if it was downloaded for this command.
+func (c *Client) RemoveInstaller() {
+	c.remove()
+}
+
+// CleanUpWorkspace removes terraform files from the current directory.
+func (c *Client) CleanUpWorkspace() error {
+	if err := cleanUpWorkspace(c.file, c.provider); err != nil {
+		return err
+	}
+
+	if err := ignoreFileNotFoundErr(c.file.Remove("terraform.tfvars")); err != nil {
+		return err
+	}
+	if err := ignoreFileNotFoundErr(c.file.Remove("terraform.tfstate")); err != nil {
+		return err
+	}
+	if err := ignoreFileNotFoundErr(c.file.Remove("terraform.tfstate.backup")); err != nil {
+		return err
+	}
+	if err := ignoreFileNotFoundErr(c.file.Remove(".terraform.lock.hcl")); err != nil {
+		return err
+	}
+	if err := ignoreFileNotFoundErr(c.file.RemoveAll(".terraform")); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// GetState returns the state of the cluster.
+func (c *Client) GetState() state.ConstellationState {
+	return c.state
+}
+
+// writeUserConfig writes the user config file for Terraform.
+func writeUserConfig(file file.Handler, provider cloudprovider.Provider, name string, input CreateClusterInput) error {
+	var userConfig string
+	switch provider {
+	case cloudprovider.QEMU:
+		userConfig = fmt.Sprintf(`
+constellation_coreos_image = "%s"
+image_format = "%s"
+control_plane_count = %d
+worker_count = %d
+vcpus = %d
+memory = %d
+state_disk_size = %d
+ip_range_start = %d
+metadata_api_image = "%s"
+name = "%s"
+`,
+			input.QEMU.ImagePath, input.QEMU.ImageFormat,
+			input.CountControlPlanes, input.CountWorkers,
+			input.QEMU.CPUCount, input.QEMU.MemorySizeMiB, input.QEMU.StateDiskSizeGB,
+			input.QEMU.IPRangeStart,
+			input.QEMU.MetadataAPIImage,
+			name,
+		)
+	}
+
+	return file.Write(terraformVarsFile, []byte(userConfig))
+}
+
+// GetExecutable returns a Terraform executable either from the local filesystem,
+// or downloads the latest version fulfilling the version constraint.
+func GetExecutable(ctx context.Context, workingDir string) (terraform *tfexec.Terraform, remove func(), err error) {
+	inst := install.NewInstaller()
+
+	version, err := version.NewConstraint(tfVersion)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	downloadVersion := &releases.LatestVersion{
+		Product:     product.Terraform,
+		Constraints: version,
+	}
+	localVersion := &fs.Version{
+		Product:     product.Terraform,
+		Constraints: version,
+	}
+
+	execPath, err := inst.Ensure(ctx, []src.Source{localVersion, downloadVersion})
+	if err != nil {
+		return nil, nil, err
+	}
+
+	tf, err := tfexec.NewTerraform(workingDir, execPath)
+
+	return tf, func() { _ = inst.Remove(context.Background()) }, err
+}
+
+type tfInterface interface {
+	Apply(context.Context, ...tfexec.ApplyOption) error
+	Destroy(context.Context, ...tfexec.DestroyOption) error
+	Init(context.Context, ...tfexec.InitOption) error
+	Show(context.Context, ...tfexec.ShowOption) (*tfjson.State, error)
+}