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Refactor backend handling #828

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Refactor backend handling #828

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0fe8639
Refactor backend handling
johananl Aug 21, 2020
332095c
Simplify backend handling
johananl Sep 4, 2020
025ec88
platform/aks: Fix whitespace in template
johananl Sep 4, 2020
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34 changes: 5 additions & 29 deletions cli/cmd/cluster.go
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Original file line number Diff line number Diff line change
Expand Up @@ -24,8 +24,6 @@ import (
"helm.sh/helm/v3/pkg/chart"
"sigs.k8s.io/yaml"

"github.com/kinvolk/lokomotive/pkg/backend"
"github.com/kinvolk/lokomotive/pkg/backend/local"
"github.com/kinvolk/lokomotive/pkg/components/util"
"github.com/kinvolk/lokomotive/pkg/config"
"github.com/kinvolk/lokomotive/pkg/platform"
Expand Down Expand Up @@ -58,52 +56,30 @@ func initialize(ctxLogger *logrus.Entry) (*terraform.Executor, platform.Platform
ctxLogger.Fatal("Errors found while loading cluster configuration")
}

// Get the configured backend for the cluster. Backend types currently supported: local, s3.
b, diags := getConfiguredBackend(lokoConfig)
if diags.HasErrors() {
for _, diagnostic := range diags {
ctxLogger.Error(diagnostic.Error())
}

ctxLogger.Fatal("Errors found while loading cluster configuration")
}

// Use a local backend if no backend is configured.
if b == nil {
b = local.NewLocalBackend()
if p == nil {
ctxLogger.Fatal("No cluster configured")
}

assetDir, err := homedir.Expand(p.Meta().AssetDir)
if err != nil {
ctxLogger.Fatalf("Error expanding path: %v", err)
}

// Validate backend configuration.
if err = b.Validate(); err != nil {
ctxLogger.Fatalf("Failed to validate backend configuration: %v", err)
}

ex := initializeTerraform(ctxLogger, p, b)
ex := initializeTerraform(ctxLogger, p)

return ex, p, lokoConfig, assetDir
}

// initializeTerraform initialized Terraform directory using given backend and platform
// and returns configured executor.
func initializeTerraform(ctxLogger *logrus.Entry, p platform.Platform, b backend.Backend) *terraform.Executor {
func initializeTerraform(ctxLogger *logrus.Entry, p platform.Platform) *terraform.Executor {
assetDir, err := homedir.Expand(p.Meta().AssetDir)
if err != nil {
ctxLogger.Fatalf("Error expanding path: %v", err)
}

// Render backend configuration.
renderedBackend, err := b.Render()
if err != nil {
ctxLogger.Fatalf("Failed to render backend configuration file: %v", err)
}

// Configure Terraform directory, module and backend.
if err := terraform.Configure(assetDir, renderedBackend); err != nil {
if err := terraform.Configure(assetDir); err != nil {
ctxLogger.Fatalf("Failed to configure Terraform : %v", err)
}

Expand Down
22 changes: 1 addition & 21 deletions cli/cmd/utils.go
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Expand Up @@ -25,7 +25,6 @@ import (
"github.com/sirupsen/logrus"
"github.com/spf13/viper"

"github.com/kinvolk/lokomotive/pkg/backend"
"github.com/kinvolk/lokomotive/pkg/config"
"github.com/kinvolk/lokomotive/pkg/platform"
)
Expand All @@ -36,25 +35,6 @@ const (
kubeconfigTerraformOutputKey = "kubeconfig"
)

// getConfiguredBackend loads a backend from the given configuration file.
func getConfiguredBackend(lokoConfig *config.Config) (backend.Backend, hcl.Diagnostics) {
if lokoConfig.RootConfig.Backend == nil {
// No backend defined and no configuration error
return nil, hcl.Diagnostics{}
}

backend, err := backend.GetBackend(lokoConfig.RootConfig.Backend.Name)
if err != nil {
diag := &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: err.Error(),
}
return nil, hcl.Diagnostics{diag}
}

return backend, backend.LoadConfig(&lokoConfig.RootConfig.Backend.Config, lokoConfig.EvalContext)
}

// getConfiguredPlatform loads a platform from the given configuration file.
func getConfiguredPlatform(lokoConfig *config.Config, require bool) (platform.Platform, hcl.Diagnostics) {
if lokoConfig.RootConfig.Cluster == nil && !require {
Expand All @@ -80,7 +60,7 @@ func getConfiguredPlatform(lokoConfig *config.Config, require bool) (platform.Pl
return nil, hcl.Diagnostics{diag}
}

return platform, platform.LoadConfig(&lokoConfig.RootConfig.Cluster.Config, lokoConfig.EvalContext)
return platform, platform.LoadConfig(lokoConfig)
}

// getKubeconfig finds the right kubeconfig file to use for an action and returns it's content.
Expand Down
74 changes: 48 additions & 26 deletions pkg/backend/backend.go
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Expand Up @@ -18,39 +18,61 @@ import (
"fmt"

"github.com/hashicorp/hcl/v2"
"github.com/kinvolk/lokomotive/pkg/backend/local"
"github.com/kinvolk/lokomotive/pkg/backend/s3"
"github.com/kinvolk/lokomotive/pkg/config"
)

// Backend describes the Terraform state storage location.
type Backend interface {
// LoadConfig loads the backend config provided by the user.
LoadConfig(*hcl.Body, *hcl.EvalContext) hcl.Diagnostics
// Render renders the backend template with user backend configuration.
Render() (string, error)
// Validate validates backend configuration.
Validate() error
const (
// Local represents a local backend.
Local = "local"
// S3 represents an S3 backend.
S3 = "s3"
)

// Backend describes a Terraform state storage location.
type Backend struct {
Type string
Config interface{}
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Why empty interface if we know all the types we deal with?

}

// backends is a collection in which all Backends get automatically registered.
var backends map[string]Backend
// New creates a new Backend from the provided config and returns a pointer to it.
func New(c *config.Config) (*Backend, hcl.Diagnostics) {
if c == nil && c.RootConfig.Backend == nil {
return nil, hcl.Diagnostics{
&hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "nil backend config",
},
}
}

// Initialize package's global variable on import.
func init() {
backends = make(map[string]Backend)
}
backendType := c.RootConfig.Backend.Type

// Register registers Backend b in the internal backends map.
func Register(name string, b Backend) {
if _, exists := backends[name]; exists {
panic(fmt.Sprintf("backend with name %q registered already", name))
var bc interface{}

var d hcl.Diagnostics

switch backendType {
case Local:
bc, d = local.NewConfig(&c.RootConfig.Backend.Config, c.EvalContext)
case S3:
bc, d = s3.NewConfig(&c.RootConfig.Backend.Config, c.EvalContext)
default:
return nil, hcl.Diagnostics{
&hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: fmt.Sprintf("unknown backend type %q", backendType),
},
}
}
backends[name] = b
}

// GetBackend returns the Backend referred to by name.
func GetBackend(name string) (Backend, error) {
backend, exists := backends[name]
if !exists {
return nil, fmt.Errorf("no backend with name %q found", name)
if d.HasErrors() {
return nil, d
}
return backend, nil

return &Backend{
Type: backendType,
Config: bc,
}, nil
}
36 changes: 11 additions & 25 deletions pkg/backend/local/local.go
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Expand Up @@ -17,38 +17,24 @@ package local
import (
"github.com/hashicorp/hcl/v2"
"github.com/hashicorp/hcl/v2/gohcl"

"github.com/kinvolk/lokomotive/internal/template"
"github.com/kinvolk/lokomotive/pkg/backend"
)

type local struct {
// Config represents the configuration of a local backend.
type Config struct {
Path string `hcl:"path,optional"`
}

// init registers local as a backend.
func init() {
backend.Register("local", NewLocalBackend())
}
// NewConfig creates a new Config and returns a pointer to it as well as any HCL diagnostics.
func NewConfig(b *hcl.Body, ctx *hcl.EvalContext) (*Config, hcl.Diagnostics) {
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Maybe FromHCL would be a better name for this function? So it reads pkg/backend/s3.FromHCL(...) ?

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Actually, I'd get rid of this code completely and do the reading only once somewhere, as reading is always exactly the same regardless of the backend type.

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That's what we had with LoadConfig(), however I don't think this is a good approach - see #828 (comment).

c := &Config{}

// LoadConfig loads the configuration for the local backend.
func (l *local) LoadConfig(configBody *hcl.Body, evalContext *hcl.EvalContext) hcl.Diagnostics {
if configBody == nil {
return hcl.Diagnostics{}
if b == nil {
return nil, hcl.Diagnostics{}
}
return gohcl.DecodeBody(*configBody, evalContext, l)
}

func NewLocalBackend() *local {
return &local{}
}

// Render renders the Go template with local backend configuration.
func (l *local) Render() (string, error) {
return template.Render(backendConfigTmpl, l)
}
if d := gohcl.DecodeBody(*b, ctx, c); len(d) != 0 {
return nil, d
}

// Validate validates the local backend configuration.
func (l *local) Validate() error {
return nil
return c, hcl.Diagnostics{}
}
23 changes: 0 additions & 23 deletions pkg/backend/local/template.go
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65 changes: 32 additions & 33 deletions pkg/backend/s3/s3.go
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Expand Up @@ -16,60 +16,59 @@ package s3

import (
"fmt"
"os"

"github.com/hashicorp/hcl/v2"
"github.com/hashicorp/hcl/v2/gohcl"

"github.com/kinvolk/lokomotive/internal/template"
"github.com/kinvolk/lokomotive/pkg/backend"
)

type s3 struct {
// Config represents the configuration of an S3 backend.
type Config struct {
Bucket string `hcl:"bucket"`
Key string `hcl:"key"`
Region string `hcl:"region,optional"`
Region string `hcl:"region"`
AWSCredsPath string `hcl:"aws_creds_path,optional"`
DynamoDBTable string `hcl:"dynamodb_table,optional"`
}

// init registers s3 as a backend.
func init() {
backend.Register("s3", NewS3Backend())
}
// NewConfig creates a new Config and returns a pointer to it as well as any HCL diagnostics.
func NewConfig(b *hcl.Body, ctx *hcl.EvalContext) (*Config, hcl.Diagnostics) {
diags := hcl.Diagnostics{}

c := &Config{}

// LoadConfig loads the configuration for the s3 backend.
func (s *s3) LoadConfig(configBody *hcl.Body, evalContext *hcl.EvalContext) hcl.Diagnostics {
if configBody == nil {
return hcl.Diagnostics{}
if b == nil {
return nil, diags
}
return gohcl.DecodeBody(*configBody, evalContext, s)
}

func NewS3Backend() *s3 {
return &s3{}
}
if d := gohcl.DecodeBody(*b, ctx, c); len(d) != 0 {
diags = append(diags, d...)
return nil, diags
}

if err := c.validate(); err != nil {
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: fmt.Sprintf("validating backend config: %v", err),
})

return nil, diags
}

// Render renders the Go template with s3 backend configuration.
func (s *s3) Render() (string, error) {
return template.Render(backendConfigTmpl, s)
return c, diags
}

// Validate validates the s3 backend configuration.
func (s *s3) Validate() error {
if s.Bucket == "" {
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return fmt.Errorf("no bucket specified")
// validate returns an error if the Config is invalid.
func (c *Config) validate() error {
if c.Bucket == "" {
return fmt.Errorf("bucket cannot be empty")
}

if s.Key == "" {
return fmt.Errorf("no key specified")
if c.Key == "" {
return fmt.Errorf("key cannot be empty")
}

if s.AWSCredsPath == "" && os.Getenv("AWS_SHARED_CREDENTIALS_FILE") == "" {
if s.Region == "" && os.Getenv("AWS_DEFAULT_REGION") == "" {
return fmt.Errorf("no region specified: use Region field in backend configuration or " +
"AWS_DEFAULT_REGION environment variable")
}
if c.Region == "" {
return fmt.Errorf("region cannot be empty")
}

return nil
Expand Down
29 changes: 0 additions & 29 deletions pkg/backend/s3/template.go
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