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workspace.go
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/
workspace.go
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// Copyright 2018 the Service Broker Project Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package wrapper
import (
"encoding/json"
"errors"
"fmt"
"io/ioutil"
"os"
"os/exec"
"path"
"strings"
"sync"
"code.cloudfoundry.org/lager"
"github.com/GoogleCloudPlatform/gcp-service-broker/utils"
)
// DefaultInstanceName is the default name of an instance of a particular module.
const (
DefaultInstanceName = "instance"
)
var (
FsInitializationErr = errors.New("Filesystem must first be initialized.")
)
// TerraformExecutor is the function that shells out to Terraform.
// It can intercept, modify or retry the given command.
type TerraformExecutor func(*exec.Cmd) error
// NewWorkspace creates a new TerraformWorkspace from a given template and variables to populate an instance of it.
// The created instance will have the name specified by the DefaultInstanceName constant.
func NewWorkspace(templateVars map[string]interface{}, terraformTemplate string) (*TerraformWorkspace, error) {
tfModule := ModuleDefinition{
Name: "brokertemplate",
Definition: terraformTemplate,
}
inputList, err := tfModule.Inputs()
if err != nil {
return nil, err
}
limitedConfig := make(map[string]interface{})
for _, name := range inputList {
limitedConfig[name] = templateVars[name]
}
workspace := TerraformWorkspace{
Modules: []ModuleDefinition{tfModule},
Instances: []ModuleInstance{
{
ModuleName: tfModule.Name,
InstanceName: DefaultInstanceName,
Configuration: limitedConfig,
},
},
}
return &workspace, nil
}
// DeserializeWorkspace creates a new TerraformWorkspace from a given JSON
// serialization of one.
func DeserializeWorkspace(definition string) (*TerraformWorkspace, error) {
ws := TerraformWorkspace{}
if err := json.Unmarshal([]byte(definition), &ws); err != nil {
return nil, err
}
return &ws, nil
}
// TerraformWorkspace represents the directory layout of a Terraform execution.
// The structure is strict, consiting of several Terraform modules and instances
// of those modules. The strictness is artificial, but maintains a clear
// separation between data and code.
//
// It manages the directory structure needed for the commands, serializing and
// deserializing Terraform state, and all the flags necessary to call Terraform.
//
// All public functions that shell out to Terraform maintain the following invariants:
// - The function blocks if another terraform shell is running.
// - The function updates the tfstate once finished.
// - The function creates and destroys its own dir.
type TerraformWorkspace struct {
Modules []ModuleDefinition `json:"modules"`
Instances []ModuleInstance `json:"instances"`
State []byte `json:"tfstate"`
// Executor is a function that gets invoked to shell out to Terraform.
// If left nil, the default executor is used.
Executor TerraformExecutor `json:"-"`
dirLock sync.Mutex
dir string
}
// String returns a human-friendly representation of the workspace suitable for
// printing to the console.
func (workspace *TerraformWorkspace) String() string {
var b strings.Builder
b.WriteString("# Terraform Workspace\n")
fmt.Fprintf(&b, "modules: %d\n", len(workspace.Modules))
fmt.Fprintf(&b, "instances: %d\n", len(workspace.Instances))
fmt.Fprintln(&b)
for _, instance := range workspace.Instances {
fmt.Fprintf(&b, "## Instance %q\n", instance.InstanceName)
fmt.Fprintf(&b, "module = %q\n", instance.ModuleName)
for k, v := range instance.Configuration {
fmt.Fprintf(&b, "input.%s = %#v\n", k, v)
}
if outputs, err := workspace.Outputs(instance.InstanceName); err != nil {
for k, v := range outputs {
fmt.Fprintf(&b, "output.%s = %#v\n", k, v)
}
}
fmt.Fprintln(&b)
}
return b.String()
}
// Serialize converts the TerraformWorkspace into a JSON string.
func (workspace *TerraformWorkspace) Serialize() (string, error) {
ws, err := json.Marshal(workspace)
if err != nil {
return "", err
}
return string(ws), nil
}
// initializeFs initializes the filesystem directory necessary to run Terraform.
func (workspace *TerraformWorkspace) initializeFs() error {
workspace.dirLock.Lock()
// create a temp directory
if dir, err := ioutil.TempDir("", "gsb"); err != nil {
return err
} else {
workspace.dir = dir
}
// write the modulesTerraformWorkspace
for _, module := range workspace.Modules {
parent := path.Join(workspace.dir, module.Name)
if err := os.Mkdir(parent, 0755); err != nil {
return err
}
if err := ioutil.WriteFile(path.Join(parent, "definition.tf"), []byte(module.Definition), 0755); err != nil {
return err
}
}
// write the instances
for _, instance := range workspace.Instances {
contents, err := instance.MarshalDefinition()
if err != nil {
return err
}
if err := ioutil.WriteFile(path.Join(workspace.dir, instance.InstanceName+".tf"), contents, 0755); err != nil {
return err
}
}
// write the state if it exists
if len(workspace.State) > 0 {
if err := ioutil.WriteFile(workspace.tfStatePath(), workspace.State, 0755); err != nil {
return err
}
}
// run "terraform init"
if err := workspace.runTf("init", "-no-color"); err != nil {
return err
}
return nil
}
// TeardownFs removes the directory we executed Terraform in and updates the
// state from it.
func (workspace *TerraformWorkspace) teardownFs() error {
bytes, err := ioutil.ReadFile(workspace.tfStatePath())
if err != nil {
return err
}
workspace.State = bytes
if err := os.RemoveAll(workspace.dir); err != nil {
return err
}
workspace.dir = ""
workspace.dirLock.Unlock()
return nil
}
// Outputs gets the Terraform outputs from the state for the instance with the
// given name. This function DOES NOT invoke Terraform and instead uses the stored state.
// If no instance exists with the given name, it could be that Terraform pruned it due
// to having no contents so a blank map is returned.
func (workspace *TerraformWorkspace) Outputs(instance string) (map[string]interface{}, error) {
state, err := NewTfstate(workspace.State)
if err != nil {
return nil, err
}
// All root project modules get put under the "root" namespace
module := state.GetModule("root", instance)
// Terraform prunes modules with no contents, so we return blank results.
if module == nil {
return map[string]interface{}{}, nil
}
return module.GetOutputs(), nil
}
// Validate runs `terraform Validate` on this workspace.
// This funciton blocks if another Terraform command is running on this workspace.
func (workspace *TerraformWorkspace) Validate() error {
err := workspace.initializeFs()
defer workspace.teardownFs()
if err != nil {
return err
}
return workspace.runTf("validate", "-no-color")
}
// Apply runs `terraform apply` on this workspace.
// This funciton blocks if another Terraform command is running on this workspace.
func (workspace *TerraformWorkspace) Apply() error {
err := workspace.initializeFs()
defer workspace.teardownFs()
if err != nil {
return err
}
return workspace.runTf("apply", "-auto-approve", "-no-color")
}
// Destroy runs `terraform destroy` on this workspace.
// This funciton blocks if another Terraform command is running on this workspace.
func (workspace *TerraformWorkspace) Destroy() error {
err := workspace.initializeFs()
defer workspace.teardownFs()
if err != nil {
return err
}
return workspace.runTf("destroy", "-auto-approve", "-no-color")
}
func (workspace *TerraformWorkspace) tfStatePath() string {
return path.Join(workspace.dir, "terraform.tfstate")
}
func (workspace *TerraformWorkspace) runTf(subCommand string, args ...string) error {
sub := []string{subCommand}
sub = append(sub, args...)
c := exec.Command("terraform", sub...)
c.Env = os.Environ()
c.Dir = workspace.dir
executor := DefaultExecutor
if workspace.Executor != nil {
executor = workspace.Executor
}
return executor(c)
}
// CustomEnvironmentExecutor sets custom environment variables on the Terraform
// execution.
func CustomEnvironmentExecutor(environment map[string]string, wrapped TerraformExecutor) TerraformExecutor {
return func(c *exec.Cmd) error {
for k, v := range environment {
c.Env = append(c.Env, fmt.Sprintf("%s=%s", k, v))
}
return wrapped(c)
}
}
// CustomTerraformExecutor executes a custom Terraform binary that uses plugins
// from a given plugin directory rather than the Terraform that's on the PATH
// which will download provider binaries from the web.
func CustomTerraformExecutor(tfBinaryPath, tfPluginDir string, wrapped TerraformExecutor) TerraformExecutor {
return func(c *exec.Cmd) error {
// Add the -get-plugins=false and -plugin-dir={tfPluginDir} after the
// sub-command to force Terraform to use a particular plugin.
subCommand := c.Args[1]
subCommandArgs := c.Args[2:]
if subCommand == "init" {
subCommandArgs = append([]string{"-get-plugins=false", fmt.Sprintf("-plugin-dir=%s", tfPluginDir)}, subCommandArgs...)
}
allArgs := append([]string{subCommand}, subCommandArgs...)
newCmd := exec.Command(tfBinaryPath, allArgs...)
newCmd.Dir = c.Dir
newCmd.Env = c.Env
return wrapped(newCmd)
}
}
// DefaultExecutor is the default executor that shells out to Terraform
// and logs results to stdout.
func DefaultExecutor(c *exec.Cmd) error {
logger := utils.NewLogger("terraform@" + c.Dir)
logger.Info("starting process", lager.Data{
"path": c.Path,
"args": c.Args,
"dir": c.Dir,
})
output, err := c.CombinedOutput()
logger.Info("results", lager.Data{
"output": string(output),
"error": err,
})
return err
}