feat: skip terraform destroy if there is no state when deleting (#1594)

deansheather · web-flow · commit adb7d20c1619 · 2022-05-20T14:07:23.000+10:00
diff --git a/provisioner/terraform/provision.go b/provisioner/terraform/provision.go
@@ -9,6 +9,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"regexp"
 	"runtime"
 	"strings"
 
@@ -22,6 +23,11 @@ import (
 	"github.com/coder/coder/provisionersdk/proto"
 )
 
+var (
+	// noStateRegex is matched against the output from `terraform state show`
+	noStateRegex = regexp.MustCompile(`(?i)State read error.*no state`)
+)
+
 // Provision executes `terraform apply`.
 func (t *terraform) Provision(stream proto.DRPCProvisioner_ProvisionStream) error {
 	shutdown, shutdownFunc := context.WithCancel(stream.Context())
@@ -190,6 +196,43 @@ func (t *terraform) Provision(stream proto.DRPCProvisioner_ProvisionStream) erro
 		}
 	}()
 
+	// If we're destroying, exit early if there's no state. This is necessary to
+	// avoid any cases where a workspace is "locked out" of terraform due to
+	// e.g. bad template param values and cannot be deleted. This is just for
+	// contingency, in the future we will try harder to prevent workspaces being
+	// broken this hard.
+	if start.Metadata.WorkspaceTransition == proto.WorkspaceTransition_DESTROY {
+		_, err := getTerraformState(shutdown, terraform, statefilePath)
+		if xerrors.Is(err, os.ErrNotExist) {
+			_ = stream.Send(&proto.Provision_Response{
+				Type: &proto.Provision_Response_Log{
+					Log: &proto.Log{
+						Level:  proto.LogLevel_INFO,
+						Output: "The terraform state does not exist, there is nothing to do",
+					},
+				},
+			})
+
+			return stream.Send(&proto.Provision_Response{
+				Type: &proto.Provision_Response_Complete{
+					Complete: &proto.Provision_Complete{},
+				},
+			})
+		}
+		if err != nil {
+			err = xerrors.Errorf("get terraform state: %w", err)
+			_ = stream.Send(&proto.Provision_Response{
+				Type: &proto.Provision_Response_Complete{
+					Complete: &proto.Provision_Complete{
+						Error: err.Error(),
+					},
+				},
+			})
+
+			return err
+		}
+	}
+
 	planfilePath := filepath.Join(start.Directory, "terraform.tfplan")
 	var args []string
 	if start.DryRun {
@@ -378,23 +421,11 @@ func parseTerraformApply(ctx context.Context, terraform *tfexec.Terraform, state
 	_, err := os.Stat(statefilePath)
 	statefileExisted := err == nil
 
-	statefile, err := os.OpenFile(statefilePath, os.O_CREATE|os.O_RDWR, 0600)
-	if err != nil {
-		return nil, xerrors.Errorf("open statefile %q: %w", statefilePath, err)
-	}
-	defer statefile.Close()
-	// #nosec
-	cmd := exec.CommandContext(ctx, terraform.ExecPath(), "state", "pull")
-	cmd.Dir = terraform.WorkingDir()
-	cmd.Stdout = statefile
-	err = cmd.Run()
-	if err != nil {
-		return nil, xerrors.Errorf("pull terraform state: %w", err)
-	}
-	state, err := terraform.ShowStateFile(ctx, statefilePath)
+	state, err := getTerraformState(ctx, terraform, statefilePath)
 	if err != nil {
-		return nil, xerrors.Errorf("show terraform state: %w", err)
+		return nil, xerrors.Errorf("get terraform state: %w", err)
 	}
+
 	resources := make([]*proto.Resource, 0)
 	if state.Values != nil {
 		rawGraph, err := terraform.Graph(ctx)
@@ -557,6 +588,37 @@ func parseTerraformApply(ctx context.Context, terraform *tfexec.Terraform, state
 	}, nil
 }
 
+// getTerraformState pulls and merges any remote terraform state into the given
+// path and reads the merged state. If there is no state, `os.ErrNotExist` will
+// be returned.
+func getTerraformState(ctx context.Context, terraform *tfexec.Terraform, statefilePath string) (*tfjson.State, error) {
+	statefile, err := os.OpenFile(statefilePath, os.O_CREATE|os.O_RDWR, 0600)
+	if err != nil {
+		return nil, xerrors.Errorf("open statefile %q: %w", statefilePath, err)
+	}
+	defer statefile.Close()
+
+	// #nosec
+	cmd := exec.CommandContext(ctx, terraform.ExecPath(), "state", "pull")
+	cmd.Dir = terraform.WorkingDir()
+	cmd.Stdout = statefile
+	err = cmd.Run()
+	if err != nil {
+		return nil, xerrors.Errorf("pull terraform state: %w", err)
+	}
+
+	state, err := terraform.ShowStateFile(ctx, statefilePath)
+	if err != nil {
+		if noStateRegex.MatchString(err.Error()) {
+			return nil, os.ErrNotExist
+		}
+
+		return nil, xerrors.Errorf("show terraform state: %w", err)
+	}
+
+	return state, nil
+}
+
 type terraformProvisionLog struct {
 	Level   string `json:"@level"`
 	Message string `json:"@message"`
diff --git a/provisioner/terraform/provision_test.go b/provisioner/terraform/provision_test.go
@@ -8,6 +8,7 @@ import (
 	"os"
 	"path/filepath"
 	"sort"
+	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -509,4 +510,50 @@ provider "coder" {
 			}
 		})
 	}
+
+	t.Run("DestroyNoState", func(t *testing.T) {
+		t.Parallel()
+
+		const template = `resource "null_resource" "A" {}`
+
+		directory := t.TempDir()
+		err := os.WriteFile(filepath.Join(directory, "main.tf"), []byte(template), 0600)
+		require.NoError(t, err)
+
+		request := &proto.Provision_Request{
+			Type: &proto.Provision_Request_Start{
+				Start: &proto.Provision_Start{
+					State:     nil,
+					Directory: directory,
+					Metadata: &proto.Provision_Metadata{
+						WorkspaceTransition: proto.WorkspaceTransition_DESTROY,
+					},
+				},
+			},
+		}
+
+		response, err := api.Provision(ctx)
+		require.NoError(t, err)
+		err = response.Send(request)
+		require.NoError(t, err)
+
+		gotLog := false
+		for {
+			msg, err := response.Recv()
+			require.NoError(t, err)
+			require.NotNil(t, msg)
+
+			if msg.GetLog() != nil && strings.Contains(msg.GetLog().Output, "nothing to do") {
+				gotLog = true
+				continue
+			}
+			if msg.GetComplete() == nil {
+				continue
+			}
+
+			require.Empty(t, msg.GetComplete().Error)
+			require.True(t, gotLog, "never received 'nothing to do' log")
+			break
+		}
+	})
 }
