[Draft] Trying to make HTTP backend work

Author: gaelL

src/terraform-resource/helper/helper.go

@@ -0,0 +1,31 @@
+package helper
+
+import (
+	"net/url"
+	"path"
+	"strings"
+)
+
+func PlanAddressForHTTPBackend(BackendConfig map[string]interface{}) (string, error) {
+
+	if planAddress, ok := BackendConfig["plan_address"]; ok {
+		return planAddress.(string), nil
+	}
+
+	address := BackendConfig["address"].(string)
+	// As Terraform HTTP backend don't implement workspaces, we need to define a
+	// different URL to store the plan file.
+	u, err := url.Parse(address)
+	if err != nil {
+		return "", err
+	}
+
+	// Parse the URL and add -plan suffix to the filename
+	baseURL, fFullName := path.Split(u.Path)
+	fExt := path.Ext(u.Path)
+	fName := strings.TrimSuffix(fFullName, fExt)
+
+	fFullName = fName + "-plan" + fExt
+	u.Path = path.Join(baseURL, fFullName)
+	return u.String(), nil
+}

src/terraform-resource/in/in.go

@@ -13,6 +13,7 @@ import (
 	"strings"
 
 	"github.com/ljfranklin/terraform-resource/encoder"
+	"github.com/ljfranklin/terraform-resource/helper"
 	"github.com/ljfranklin/terraform-resource/logger"
 	"github.com/ljfranklin/terraform-resource/models"
 	"github.com/ljfranklin/terraform-resource/storage"
@@ -101,11 +102,29 @@ func (r Runner) inWithBackend(req models.InRequest, tmpDir string) (models.InRes
 
 	targetEnvName := req.Version.EnvName
 
+	// If plan and http backend, use plan URL
+	origBackendConfig := terraformModel.BackendConfig
+	if req.Version.IsPlan() && terraformModel.BackendType == "http" {
+		planAddress, err := helper.PlanAddressForHTTPBackend(terraformModel.BackendConfig)
+		if err != nil {
+			return models.InResponse{}, err
+		}
+		terraformModel.BackendConfig["address"] = planAddress
+	}
+
 	client := terraform.NewClient(
 		terraformModel,
 		r.LogWriter,
 	)
 
+	// Rollback address change in case of http backend and tfplan
+	defer func() {
+		if req.Version.IsPlan() && terraformModel.BackendType == "http" {
+			terraformModel.BackendConfig = origBackendConfig
+			client.SetModel(terraformModel)
+		}
+	}()
+
 	if err := client.InitWithBackend(); err != nil {
 		return models.InResponse{}, err
 	}
@@ -138,8 +157,16 @@ func (r Runner) inWithBackend(req models.InRequest, tmpDir string) (models.InRes
 }
 
 func (r Runner) writeBackendOutputs(req models.InRequest, targetEnvName string, client terraform.Client) (models.InResponse, error) {
-	if err := r.ensureEnvExistsInBackend(targetEnvName, client); err != nil {
-		return models.InResponse{}, err
+	terraformModel := req.Source.Terraform.Merge(req.Params.Terraform)
+	if err := terraformModel.Validate(); err != nil {
+		return models.InResponse{}, fmt.Errorf("Failed to validate terraform Model: %s", err)
+	}
+	terraformModel.Source = "."
+
+	if terraformModel.BackendType != "http" {
+		if err := r.ensureEnvExistsInBackend(targetEnvName, client); err != nil {
+			return models.InResponse{}, err
+		}
 	}
 
 	tfOutput, err := client.Output(targetEnvName)

src/terraform-resource/terraform/client.go

@@ -16,6 +16,7 @@ import (
 	"path/filepath"
 	"strings"
 
+	"github.com/ljfranklin/terraform-resource/helper"
 	"github.com/ljfranklin/terraform-resource/models"
 	"github.com/ljfranklin/terraform-resource/runner"
 )
@@ -115,7 +116,16 @@ func (c *client) InitWithBackend() error {
 }
 
 func (c *client) writeBackendConfig(outputDir string) (string, error) {
-	configContents, err := json.Marshal(c.model.BackendConfig)
+	bc := make(map[string]interface{})
+	for key, value := range c.model.BackendConfig {
+		bc[key] = value
+	}
+
+	if _, ok := c.model.BackendConfig["plan_address"]; ok && c.model.BackendType == "http" {
+		delete(bc, "plan_address")
+	}
+
+	configContents, err := json.Marshal(bc)
 	if err != nil {
 		return "", err
 	}
@@ -389,6 +399,9 @@ func (c *client) Output(envName string) (map[string]map[string]interface{}, erro
 		"output",
 		"-json",
 	}
+	if c.model.BackendType == "http" {
+		envName = defaultWorkspace
+	}
 	outputCmd, err := c.terraformCmd(outputArgs, []string{
 		fmt.Sprintf("TF_WORKSPACE=%s", envName),
 	})
@@ -537,6 +550,9 @@ func (c *client) ImportWithLegacyStorage() error {
 }
 
 func (c *client) WorkspaceList() ([]string, error) {
+	if c.model.BackendType == "http" {
+		return []string{defaultWorkspace}, nil
+	}
 	cmd, err := c.terraformCmd([]string{
 		"workspace",
 		"list",
@@ -563,6 +579,9 @@ func (c *client) WorkspaceList() ([]string, error) {
 }
 
 func (c *client) WorkspaceSelect(envName string) error {
+	if c.model.BackendType == "http" {
+		return nil
+	}
 	cmd, err := c.terraformCmd([]string{
 		"workspace",
 		"select",
@@ -580,6 +599,10 @@ func (c *client) WorkspaceSelect(envName string) error {
 }
 
 func (c *client) WorkspaceNewIfNotExists(envName string) error {
+	if c.model.BackendType == "http" {
+		return nil
+	}
+
 	workspaces, err := c.WorkspaceList()
 
 	if err != nil {
@@ -614,6 +637,9 @@ func (c *client) WorkspaceNewIfNotExists(envName string) error {
 }
 
 func (c *client) WorkspaceNewFromExistingStateFile(envName string, localStateFilePath string) error {
+	if c.model.BackendType == "http" {
+		return nil
+	}
 	cmd, err := c.terraformCmd([]string{
 		"workspace",
 		"new",
@@ -644,7 +670,7 @@ func (c *client) WorkspaceNewFromExistingStateFile(envName string, localStateFil
 }
 
 func (c *client) WorkspaceDelete(envName string) error {
-	if envName == defaultWorkspace {
+	if envName == defaultWorkspace || c.model.BackendType == "http" {
 		return nil
 	}
 
@@ -667,7 +693,7 @@ func (c *client) WorkspaceDelete(envName string) error {
 }
 
 func (c *client) WorkspaceDeleteWithForce(envName string) error {
-	if envName == defaultWorkspace {
+	if envName == defaultWorkspace || c.model.BackendType == "http" {
 		return nil
 	}
 
@@ -691,6 +717,9 @@ func (c *client) WorkspaceDeleteWithForce(envName string) error {
 }
 
 func (c *client) StatePull(envName string) ([]byte, error) {
+	if c.model.BackendType == "http" {
+		envName = defaultWorkspace
+	}
 	cmd, err := c.terraformCmd([]string{
 		"state",
 		"pull",
@@ -762,6 +791,7 @@ func (c *client) SavePlanToBackend(planEnvName string) error {
 	}
 	origSource := c.model.Source
 	origLogger := c.logWriter
+	origBackendConfig := c.model.BackendConfig
 
 	err = os.Chdir(tmpDir)
 	if err != nil {
@@ -781,6 +811,7 @@ func (c *client) SavePlanToBackend(planEnvName string) error {
 		os.Chdir(origDir)
 		c.model.Source = origSource
 		c.logWriter = origLogger
+		c.model.BackendConfig = origBackendConfig
 	}()
 
 	// The /tmp/tf-plan.log file can contain credentials, so we tell the user to
@@ -791,6 +822,15 @@ func (c *client) SavePlanToBackend(planEnvName string) error {
 		return fmt.Errorf(errPrefix, logPath, err)
 	}
 
+	// Override the backendConfig for HTTP type in order to target a different "-plan"
+	if c.model.BackendType == "http" {
+		planAddress, err := helper.PlanAddressForHTTPBackend(c.model.BackendConfig)
+		if err != nil {
+			return err
+		}
+		c.model.BackendConfig["address"] = planAddress
+	}
+
 	err = c.InitWithBackend()
 	if err != nil {
 		return fmt.Errorf(errPrefix, logPath, err)
@@ -810,6 +850,46 @@ func (c *client) SavePlanToBackend(planEnvName string) error {
 }
 
 func (c *client) GetPlanFromBackend(planEnvName string) error {
+	tmpDir, err := ioutil.TempDir("", "tf-resource-plan")
+	if err != nil {
+		return err
+	}
+	defer os.RemoveAll(tmpDir)
+
+	// TODO: this stateful set and reset isn't great
+	origDir, err := os.Getwd()
+	if err != nil {
+		return err
+	}
+	origSource := c.model.Source
+	origBackendConfig := c.model.BackendConfig
+
+	err = os.Chdir(tmpDir)
+	if err != nil {
+		return err
+	}
+	c.model.Source = tmpDir
+	defer func() {
+		os.Chdir(origDir)
+		c.model.Source = origSource
+		c.model.BackendConfig = origBackendConfig
+	}()
+	// Override the backendConfig for HTTP type in order to target a different "-plan"
+	if c.model.BackendType == "http" {
+		planAddress, err := helper.PlanAddressForHTTPBackend(c.model.BackendConfig)
+		if err != nil {
+			return err
+		}
+		c.model.BackendConfig["address"] = planAddress
+	}
+
+	// Run again the init as we change directory.
+	// This should init to get the tfplan, then let the regular workflow get back on the previously init dir due to the defer func()
+	err = c.InitWithBackend()
+	if err != nil {
+		return fmt.Errorf("init failed %s", err)
+	}
+
 	if err := c.WorkspaceSelect(planEnvName); err != nil {
 		return err
 	}
@@ -843,6 +923,9 @@ func (c *client) SetModel(model models.Terraform) {
 }
 
 func (c *client) resourceExists(tfID string, envName string) (bool, error) {
+	if c.model.BackendType == "http" {
+		envName = defaultWorkspace
+	}
 	cmd, err := c.terraformCmd([]string{
 		"state",
 		"list",