terraform: plugin manager with provisioner support and tests

Signed-off-by: Máximo Cuadros <mcuadros@gmail.com>

cmd/ascode-doc/doc/provider_test.go

@@ -28,7 +28,7 @@ func TestDocumentation(t *testing.T) {
 func TestDo(t *testing.T) {
 
 	pm := &terraform.PluginManager{".providers"}
-	cli, meta := pm.Get("ignition", "1.1.0")
+	cli, meta := pm.Provider("ignition", "1.1.0")
 	fmt.Println(meta)
 
 	rpc, err := cli.Client()

starlark/types/provider.go

@@ -49,7 +49,11 @@ type Provider struct {
 }
 
 func MakeProvider(pm *terraform.PluginManager, name, version string) (*Provider, error) {
-	cli, meta := pm.Get(name, version)
+	cli, meta, err := pm.Provider(name, version, false)
+	if err != nil {
+		return nil, err
+	}
+
 	rpc, err := cli.Client()
 	if err != nil {
 		return nil, err

terraform/plugins.go

@@ -3,25 +3,62 @@ package terraform
 import (
 	"os"
 	"os/exec"
+	"strings"
 
 	"github.com/hashicorp/go-hclog"
 	"github.com/hashicorp/go-plugin"
+	"github.com/hashicorp/terraform/command"
 	tfplugin "github.com/hashicorp/terraform/plugin"
 	"github.com/hashicorp/terraform/plugin/discovery"
 	"github.com/mitchellh/cli"
 )
 
+// PluginManager is a wrapper arround the terraform tools to download and execute
+// terraform plugins, like providers and provisioners.
 type PluginManager struct {
 	Path string
 }
 
-func (m *PluginManager) Get(provider, version string) (*plugin.Client, discovery.PluginMeta) {
-	meta, ok := m.getLocal(provider, version)
-	if !ok {
-		meta, ok = m.getRemote(provider, version)
+// Provider returns a client and the metadata for a given provider and version,
+// first try to locate the provider in the local  path, if not found, it
+// downloads it from terraform registry. If forceLocal just tries to find
+// the binary in the local filesystem.
+func (m *PluginManager) Provider(provider, version string, forceLocal bool) (*plugin.Client, discovery.PluginMeta, error) {
+	meta, ok := m.getLocal("provider", provider, version)
+	if !ok && !forceLocal {
+		var err error
+		meta, ok, err = m.getProviderRemote(provider, version)
+		if err != nil {
+			return nil, discovery.PluginMeta{}, err
+		}
+
 	}
 
-	return client(meta), meta
+	return client(meta), meta, nil
+}
+
+// Provisioner returns a client and the metadata for a given provisioner, it
+// try to locate it at the local Path, if not try to execute it from the
+// built-in plugins in the terraform binary.
+func (m *PluginManager) Provisioner(provisioner string) (*plugin.Client, discovery.PluginMeta, error) {
+	meta, ok := m.getLocal("provisioner", provisioner, "")
+	if ok {
+		return client(meta), meta, nil
+	}
+
+	// fallback to terraform internal provisioner.
+	cmdLine, _ := command.BuildPluginCommandString("provisioner", provisioner)
+	cmdArgv := strings.Split(cmdLine, command.TFSPACE)
+
+	// override the internal to the terraform binary.
+	cmdArgv[0] = "terraform"
+
+	meta = discovery.PluginMeta{
+		Name: provisioner,
+		Path: strings.Join(cmdArgv, command.TFSPACE),
+	}
+
+	return client(meta), meta, nil
 }
 
 func client(m discovery.PluginMeta) *plugin.Client {
@@ -31,8 +68,10 @@ func client(m discovery.PluginMeta) *plugin.Client {
 		Output: os.Stderr,
 	})
 
+	cmdArgv := strings.Split(m.Path, command.TFSPACE)
+
 	return plugin.NewClient(&plugin.ClientConfig{
-		Cmd:              exec.Command(m.Path),
+		Cmd:              exec.Command(cmdArgv[0], cmdArgv[1:]...),
 		HandshakeConfig:  tfplugin.Handshake,
 		VersionedPlugins: tfplugin.VersionedPlugins,
 		Managed:          true,
@@ -44,7 +83,7 @@ func client(m discovery.PluginMeta) *plugin.Client {
 
 const defaultVersionContraint = "> 0"
 
-func (m *PluginManager) getRemote(provider, v string) (discovery.PluginMeta, bool) {
+func (m *PluginManager) getProviderRemote(provider, v string) (discovery.PluginMeta, bool, error) {
 	if v == "" {
 		v = defaultVersionContraint
 	}
@@ -55,16 +94,16 @@ func (m *PluginManager) getRemote(provider, v string) (discovery.PluginMeta, boo
 		Ui:                    cli.NewMockUi(),
 	}
 
-	pm, _, err := installer.Get(provider, discovery.ConstraintStr(v).MustParse())
+	meta, _, err := installer.Get(provider, discovery.ConstraintStr(v).MustParse())
 	if err != nil {
-		panic(err)
+		return discovery.PluginMeta{}, false, err
 	}
 
-	return pm, true
+	return meta, true, nil
 }
 
-func (m *PluginManager) getLocal(provider, version string) (discovery.PluginMeta, bool) {
-	set := discovery.FindPlugins("provider", []string{m.Path})
+func (m *PluginManager) getLocal(kind, provider, version string) (discovery.PluginMeta, bool) {
+	set := discovery.FindPlugins(kind, []string{m.Path})
 	set = set.WithName(provider)
 	if len(set) == 0 {
 		return discovery.PluginMeta{}, false

terraform/plugins_test.go

@@ -0,0 +1,64 @@
+package terraform
+
+import (
+	"fmt"
+	"io/ioutil"
+	"strings"
+	"testing"
+
+	"github.com/hashicorp/terraform/plugin/discovery"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestPluginManager_Provider(t *testing.T) {
+	path, err := ioutil.TempDir("", "provider")
+	assert.NoError(t, err)
+
+	pm := &PluginManager{Path: path}
+	cli, meta, err := pm.Provider("github", "2.1.0", false)
+	assert.NoError(t, err)
+	assert.NotNil(t, cli)
+	assert.Equal(t, meta.Version, discovery.VersionStr("2.1.0"))
+
+	cli, meta, err = pm.Provider("github", "2.1.0", true)
+	assert.NoError(t, err)
+	assert.NotNil(t, cli)
+	assert.Equal(t, meta.Version, discovery.VersionStr("2.1.0"))
+
+	cli, meta, err = pm.Provider("github", "2.1.0", false)
+	assert.NoError(t, err)
+	assert.NotNil(t, cli)
+	assert.Equal(t, meta.Version, discovery.VersionStr("2.1.0"))
+}
+
+func TestPluginManager_ProviderDefault(t *testing.T) {
+	path, err := ioutil.TempDir("", "provider")
+	assert.NoError(t, err)
+
+	pm := &PluginManager{Path: path}
+	cli, meta, err := pm.Provider("github", "", false)
+	assert.NoError(t, err)
+	assert.NotNil(t, cli)
+	assert.NotEqual(t, meta.Version, discovery.VersionStr("2.1.0"))
+
+	cli, meta, err = pm.Provider("github", "", true)
+	assert.NoError(t, err)
+	assert.NotNil(t, cli)
+	assert.NotEqual(t, meta.Version, discovery.VersionStr("2.1.0"))
+
+	fmt.Println(meta.Path)
+	assert.Equal(t, strings.Index(meta.Path, path), 0)
+}
+
+func TestPluginManager_ProvisionerDefault(t *testing.T) {
+	path, err := ioutil.TempDir("", "provisioner")
+	assert.NoError(t, err)
+
+	pm := &PluginManager{Path: path}
+	cli, meta, err := pm.Provisioner("file")
+	assert.NoError(t, err)
+
+	assert.NotNil(t, cli)
+	assert.Equal(t, strings.Index(meta.Path, "terraform-TFSPACE-internal-plugin-"), 0)
+
+}