Remove unused net/rpc based plugin implementations (#147)

Author: wata727

README.md

@@ -10,7 +10,7 @@ NOTE: This plugin system is experimental. This means that API compatibility is f
 
 ## Requirements
 
-- TFLint v0.30+
+- TFLint v0.35+
 - Go v1.18
 
 ## Usage
@@ -23,6 +23,8 @@ For more details on the API, see [tflint](https://pkg.go.dev/github.com/terrafor
 
 ![architecture](architecture.png)
 
-This plugin system uses [go-plugin](https://github.com/hashicorp/go-plugin). TFLint launches the plugin as a sub-process and communicates with the plugin over RPC. The plugin acts as a server, while TFLint acts as a client that sends inspection requests to the plugin.
+This plugin system uses [go-plugin](https://github.com/hashicorp/go-plugin). TFLint launches the plugin as a sub-process and communicates with the plugin over gRPC. The plugin acts as a server, while TFLint acts as a client that sends inspection requests to the plugin.
 
 On the other hand, the plugin sends various requests to a server (TFLint) to get detailed runtime contexts (e.g. variables and expressions). This means that TFLint and plugins can act as both a server and a client.
+
+These implementations are included in the [plugin/host2plugin](https://pkg.go.dev/github.com/terraform-linters/tflint-plugin-sdk/plugin/host2plugin) and [plugin/plugin2host]((https://pkg.go.dev/github.com/terraform-linters/tflint-plugin-sdk/plugin/plugin2host)) packages.

go.mod

@@ -6,9 +6,7 @@ require (
 	github.com/google/go-cmp v0.5.7
 	github.com/hashicorp/go-hclog v1.2.0
 	github.com/hashicorp/go-plugin v1.4.3
-	github.com/hashicorp/go-version v1.4.0
 	github.com/hashicorp/hcl/v2 v2.11.1
-	github.com/hashicorp/terraform-svchost v0.0.0-20200729002733-f050f53b9734
 	github.com/zclconf/go-cty v1.10.0
 	google.golang.org/grpc v1.45.0
 	google.golang.org/protobuf v1.27.1

go.sum

@@ -60,19 +60,13 @@ github.com/google/go-cmp v0.5.7 h1:81/ik6ipDQS2aGcBfIN5dHDB36BwrStyeAQquSYCV4o=
 github.com/google/go-cmp v0.5.7/go.mod h1:n+brtR0CgQNWTVd5ZUFpTBC8YFBDLK/h/bpaJ8/DtOE=
 github.com/google/uuid v1.1.2/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/grpc-ecosystem/grpc-gateway v1.16.0/go.mod h1:BDjrQk3hbvj6Nolgz8mAMFbcEtjT1g+wF4CSlocrBnw=
-github.com/hashicorp/go-cleanhttp v0.5.1/go.mod h1:JpRdi6/HCYpAwUzNwuwqhbovhLtngrth3wmdIIUrZ80=
 github.com/hashicorp/go-hclog v0.14.1/go.mod h1:whpDNt7SSdeAju8AWKIWsul05p54N/39EeqMAyrmvFQ=
 github.com/hashicorp/go-hclog v1.2.0 h1:La19f8d7WIlm4ogzNHB0JGqs5AUDAZ2UfCY4sJXcJdM=
 github.com/hashicorp/go-hclog v1.2.0/go.mod h1:whpDNt7SSdeAju8AWKIWsul05p54N/39EeqMAyrmvFQ=
 github.com/hashicorp/go-plugin v1.4.3 h1:DXmvivbWD5qdiBts9TpBC7BYL1Aia5sxbRgQB+v6UZM=
 github.com/hashicorp/go-plugin v1.4.3/go.mod h1:5fGEH17QVwTTcR0zV7yhDPLLmFX9YSZ38b18Udy6vYQ=
-github.com/hashicorp/go-version v1.2.0/go.mod h1:fltr4n8CU8Ke44wwGCBoEymUuxUHl09ZGVZPK5anwXA=
-github.com/hashicorp/go-version v1.4.0 h1:aAQzgqIrRKRa7w75CKpbBxYsmUoPjzVm1W59ca1L0J4=
-github.com/hashicorp/go-version v1.4.0/go.mod h1:fltr4n8CU8Ke44wwGCBoEymUuxUHl09ZGVZPK5anwXA=
 github.com/hashicorp/hcl/v2 v2.11.1 h1:yTyWcXcm9XB0TEkyU/JCRU6rYy4K+mgLtzn2wlrJbcc=
 github.com/hashicorp/hcl/v2 v2.11.1/go.mod h1:FwWsfWEjyV/CMj8s/gqAuiviY72rJ1/oayI9WftqcKg=
-github.com/hashicorp/terraform-svchost v0.0.0-20200729002733-f050f53b9734 h1:HKLsbzeOsfXmKNpr3GiT18XAblV0BjCbzL8KQAMZGa0=
-github.com/hashicorp/terraform-svchost v0.0.0-20200729002733-f050f53b9734/go.mod h1:kNDNcF7sN4DocDLBkQYz73HGKwN1ANB1blq4lIYLYvg=
 github.com/hashicorp/yamux v0.0.0-20180604194846-3520598351bb h1:b5rjCoWHc7eqmAS4/qyk21ZsHyb6Mxv/jykxvNTkU4M=
 github.com/hashicorp/yamux v0.0.0-20180604194846-3520598351bb/go.mod h1:+NfK9FKeTrX5uv1uIXGdwYDTeHna2qgaIlx54MXqjAM=
 github.com/jhump/protoreflect v1.6.0 h1:h5jfMVslIg6l29nsMs0D8Wj17RDVdNYti0vDN/PZZoE=
@@ -113,7 +107,6 @@ github.com/vmihailenco/msgpack/v4 v4.3.12 h1:07s4sz9IReOgdikxLTKNbBdqDMLsjPKXwvC
 github.com/vmihailenco/msgpack/v4 v4.3.12/go.mod h1:gborTTJjAo/GWTqqRjrLCn9pgNN+NXzzngzBKDPIqw4=
 github.com/vmihailenco/tagparser v0.1.1 h1:quXMXlA39OCbd2wAdTsGDlK9RkOk6Wuw+x37wVyIuWY=
 github.com/vmihailenco/tagparser v0.1.1/go.mod h1:OeAg3pn3UbLjkWt+rN9oFYB6u/cQgqMEUPoW2WPyhdI=
-github.com/zclconf/go-cty v1.1.0/go.mod h1:xnAOWiHeOqg2nWS62VtQ7pbOu17FtxJNW8RLEih+O3s=
 github.com/zclconf/go-cty v1.2.0/go.mod h1:hOPWgoHbaTUnI5k4D2ld+GRpFJSCe6bCM7m1q/N4PQ8=
 github.com/zclconf/go-cty v1.8.0/go.mod h1:vVKLxnk3puL4qRAv72AO+W99LUD4da90g3uUAzyuvAk=
 github.com/zclconf/go-cty v1.10.0 h1:mp9ZXQeIcN8kAwuqorjH+Q+njbJKjLrvB2yIh4q7U+0=
@@ -136,12 +129,10 @@ golang.org/x/net v0.0.0-20190213061140-3a22650c66bd/go.mod h1:mL1N/T3taQHkDXs73r
 golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190603091049-60506f45cf65/go.mod h1:HSz+uSET+XFnRR8LxR5pz3Of3rY3CfYBVs4xY44aLks=
-golang.org/x/net v0.0.0-20191009170851-d66e71096ffb/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.0.0-20200301022130-244492dfa37a/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.0.0-20200822124328-c89045814202 h1:VvcQYSHwXgi7W+TpUR6A9g6Up98WAHf3f/ulnJ62IyA=
 golang.org/x/net v0.0.0-20200822124328-c89045814202/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
 golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
-golang.org/x/oauth2 v0.0.0-20190604053449-0f29369cfe45/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
 golang.org/x/oauth2 v0.0.0-20200107190931-bf48bf16ab8d/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
 golang.org/x/sync v0.0.0-20180314180146-1d60e4601c6f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20181108010431-42b317875d0f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=

helper/doc.go

@@ -1,7 +1,7 @@
 // Package helper contains implementations for plugin testing.
 //
 // You can test the implemented rules using the mock Runner that is not
-// an RPC client. It is similar to TFLint's Runner, but is implemented
+// an gRPC client. It is similar to TFLint's Runner, but is implemented
 // from scratch to avoid Terraform dependencies.
 //
 // Some implementations of the mock Runner have been simplified. As a result,

helper/runner.go

@@ -6,7 +6,6 @@ import (
 
 	"github.com/hashicorp/hcl/v2"
 	"github.com/terraform-linters/tflint-plugin-sdk/hclext"
-	"github.com/terraform-linters/tflint-plugin-sdk/terraform/configs"
 	"github.com/terraform-linters/tflint-plugin-sdk/tflint"
 	"github.com/zclconf/go-cty/cty"
 	"github.com/zclconf/go-cty/cty/convert"
@@ -15,11 +14,18 @@ import (
 
 // Runner is a mock that satisfies the Runner interface for plugin testing.
 type Runner struct {
-	files  map[string]*hcl.File
 	Issues Issues
 
-	tfconfig *configs.Config
-	config   Config
+	files     map[string]*hcl.File
+	config    Config
+	variables map[string]*Variable
+}
+
+// Variable is an implementation of variables in Terraform language
+type Variable struct {
+	Name      string
+	Default   cty.Value
+	DeclRange hcl.Range
 }
 
 // Config is a pseudo TFLint config file object for testing from plugins.
@@ -141,7 +147,7 @@ func (r *Runner) EvaluateExpr(expr hcl.Expression, ret interface{}, opts *tflint
 	}
 
 	variables := map[string]cty.Value{}
-	for _, variable := range r.tfconfig.Module.Variables {
+	for _, variable := range r.variables {
 		variables[variable.Name] = variable.Default
 	}
 	workspace, success := os.LookupEnv("TF_WORKSPACE")
@@ -203,12 +209,6 @@ func (r *Runner) AddLocalFile(name string, file *hcl.File) bool {
 }
 
 func (r *Runner) initFromFiles() error {
-	r.tfconfig = &configs.Config{
-		Module: &configs.Module{
-			Variables: map[string]*configs.Variable{},
-		},
-	}
-
 	for _, file := range r.files {
 		content, _, diags := file.Body.PartialContent(configFileSchema)
 		if diags.HasErrors() {
@@ -218,11 +218,11 @@ func (r *Runner) initFromFiles() error {
 		for _, block := range content.Blocks {
 			switch block.Type {
 			case "variable":
-				variable, diags := simpleDecodeVariableBlock(block)
+				variable, diags := decodeVariableBlock(block)
 				if diags.HasErrors() {
 					return diags
 				}
-				r.tfconfig.Module.Variables[variable.Name] = variable
+				r.variables[variable.Name] = variable
 			default:
 				continue
 			}
@@ -232,8 +232,8 @@ func (r *Runner) initFromFiles() error {
 	return nil
 }
 
-func simpleDecodeVariableBlock(block *hcl.Block) (*configs.Variable, hcl.Diagnostics) {
-	v := &configs.Variable{
+func decodeVariableBlock(block *hcl.Block) (*Variable, hcl.Diagnostics) {
+	v := &Variable{
 		Name:      block.Labels[0],
 		DeclRange: block.DefRange,
 	}

helper/runner_test.go

@@ -283,7 +283,7 @@ func (r *dummyRule) Enabled() bool             { return true }
 func (r *dummyRule) Severity() tflint.Severity { return tflint.ERROR }
 func (r *dummyRule) Check(tflint.Runner) error { return nil }
 
-func Test_EmitIssueOnExpr(t *testing.T) {
+func Test_EmitIssue(t *testing.T) {
 	src := `
 resource "aws_instance" "foo" {
   instance_type = "t2.micro"

plugin/client.go

@@ -1,11 +1,8 @@
 // Package plugin contains the implementations needed to make
 // the built binary act as a plugin.
 //
-// A plugin is implemented as an RPC server and the host acts
+// A plugin is implemented as an gRPC server and the host acts
 // as the client, sending analysis requests to the plugin.
-// Note that the server-client relationship here is the opposite of
-// the communication that takes place during the checking phase.
 //
-// Implementation details are hidden in go-plugin. This package is
-// essentially a wrapper for go-plugin.
+// See host2plugin for implementation details.
 package plugin

plugin/doc.go

@@ -1,38 +1,15 @@
 package plugin
 
 import (
-	"encoding/gob"
-	"net/rpc"
-
-	plugin "github.com/hashicorp/go-plugin"
-	"github.com/terraform-linters/tflint-plugin-sdk/tflint"
+	"github.com/terraform-linters/tflint-plugin-sdk/plugin/host2plugin"
 
 	// Import this package to initialize the global logger
 	_ "github.com/terraform-linters/tflint-plugin-sdk/logger"
 )
 
-// handShakeConfig is used for UX. ProcotolVersion will be updated by incompatible changes.
-var handshakeConfig = plugin.HandshakeConfig{
-	ProtocolVersion:  9,
-	MagicCookieKey:   "TFLINT_RULESET_PLUGIN",
-	MagicCookieValue: "5adSn1bX8nrDfgBqiAqqEkC6OE1h3iD8SqbMc5UUONx8x3xCF0KlPDsBRNDjoYDP",
-}
-
-// RuleSetPlugin is a wrapper to satisfy the interface of go-plugin.
-type RuleSetPlugin struct {
-	impl tflint.RPCRuleSet
-}
-
-// Server returns an RPC server acting as a plugin.
-func (p *RuleSetPlugin) Server(b *plugin.MuxBroker) (interface{}, error) {
-	return &Server{impl: p.impl, broker: b}, nil
-}
-
-// Client returns an RPC client for the host.
-func (RuleSetPlugin) Client(b *plugin.MuxBroker, c *rpc.Client) (interface{}, error) {
-	return &Client{rpcClient: c, broker: b}, nil
-}
+// ServeOpts is an option for serving a plugin.
+// Each plugin can pass a RuleSet that represents its own functionality.
+type ServeOpts = host2plugin.ServeOpts
 
-func init() {
-	gob.Register(tflint.Error{})
-}
+// Serve is a wrapper of plugin.Serve. This is entrypoint of all plugins.
+var Serve = host2plugin.Serve