feat: make ftl build et al work with Go (#775)

- `ftl-go` has been deleted.
- There must be a 1:1 mapping between FTL modules and Go modules.
- Updated `ftl init go` to generate a valid module.
- Updated all of the Go examples, including online-boutique, which can
now be trivially started with `ftl dev ./examples/online-boutique`
- The tooling is quite restrictive about code layout at the moment, but
we can come back to that later.

eg. Create, deploy and call a new module.

```
🐚 ~/dev/ftl $ ftl init go examples echo2
info: Initializing FTL Go module echo2 in examples
info: Running go mod tidy
🐚 ~/dev/ftl $ ftl deploy examples/echo2
info: Creating deployment for module echo2
info: Building Go module 'echo2'
info: Generating external modules
info: Extracting schema
info: Generating main module
info: Compiling
info: Uploading 1/1 files
info: Uploaded examples/echo2/_ftl/main as ba6f7f20ee5dac4e97197633348b5bb41e68e63c7e2d9b1da614d0a011b83872:main
info: Created deployment echo2-0a1cebbfcc
🐚 ~/dev/ftl $ ftl call echo2.echo
{"message":"Hello, anonymous!"}
```

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

.gitignore

@@ -5,7 +5,6 @@
 target/
 build/
 deploy/
-.ftl*/
 .DS_Store
 reflex.conf
 /logs/
@@ -14,3 +13,5 @@ reflex.conf
 generated_ftl_module.go
 *.zip
 dist/
+examples/**/_ftl/
+go.work*

Bitfile

@@ -90,6 +90,14 @@ go-runtime/scaffolding.zip: go-runtime/scaffolding/**/*
   cd go-runtime/scaffolding
   build: zip -q --symlinks -r ../scaffolding.zip .
 
+go-runtime/compile/build-template.zip: go-runtime/compile/build-template/**/*
+  cd go-runtime/compile/build-template
+  build: zip -q --symlinks -r ../build-template.zip .
+
+go-runtime/compile/external-module-template.zip: go-runtime/compile/external-module-template/**/* 
+  cd go-runtime/compile/external-module-template
+  build: zip -q --symlinks -r ../external-module-template.zip .
+
 kotlin-runtime/scaffolding.zip: kotlin-runtime/scaffolding/**/*
   cd kotlin-runtime/scaffolding
   build: zip -q --symlinks -r ../scaffolding.zip .

Justfile

@@ -15,11 +15,11 @@ install-runtime-jar:
 
 # Deploy the Go time module
 deploy-time:
-  cd examples && ftl-go deploy time
+  ftl deploy examples/time
 
 # Deploy the Kotlin echo module
 deploy-echo-kotlin:
-  cd examples/echo-kotlin && mvn compile && ftl deploy target
+  ftl deploy examples/echo-kotlin
 
 regen-schema:
   bit protos/xyz/block/ftl/v1/schema/schema.proto

backend/common/moduleconfig/config.go

@@ -1,11 +1,21 @@
 package moduleconfig
 
 import (
+	"fmt"
 	"path/filepath"
+	"strings"
 
 	"github.com/BurntSushi/toml"
 )
 
+// GoConfig is language-specific configuration for Go modules.
+type GoConfig struct {
+}
+
+// KotlinConfig is language-specific configuration for Kotlin modules.
+type KotlinConfig struct {
+}
+
 // ModuleConfig is the configuration for an FTL module.
 //
 // Module config files are currently TOML.
@@ -17,6 +27,9 @@ type ModuleConfig struct {
 	DeployDir string   `toml:"deploy-dir"`
 	Schema    string   `toml:"schema"`
 	Watch     []string `toml:"watch"`
+
+	Go     GoConfig     `toml:"go,optional"`
+	Kotlin KotlinConfig `toml:"kotlin,optional"`
 }
 
 // LoadConfig from a directory.
@@ -27,11 +40,16 @@ func LoadConfig(dir string) (ModuleConfig, error) {
 	if err != nil {
 		return ModuleConfig{}, err
 	}
-	setConfigDefaults(&config)
+	if err := setConfigDefaults(dir, &config); err != nil {
+		return config, fmt.Errorf("%s: %w", path, err)
+	}
 	return config, nil
 }
 
-func setConfigDefaults(config *ModuleConfig) {
+func setConfigDefaults(moduleDir string, config *ModuleConfig) error {
+	if config.Schema == "" {
+		config.Schema = "schema.pb"
+	}
 	switch config.Language {
 	case "kotlin":
 		if config.Build == "" {
@@ -43,18 +61,40 @@ func setConfigDefaults(config *ModuleConfig) {
 		if len(config.Deploy) == 0 {
 			config.Deploy = []string{"main", "classes", "dependency", "classpath.txt"}
 		}
-		if config.Schema == "" {
-			config.Schema = "schema.pb"
-		}
 		if len(config.Watch) == 0 {
 			config.Watch = []string{"pom.xml", "src/**", "target/generated-sources"}
 		}
+
 	case "go":
 		if config.DeployDir == "" {
-			config.DeployDir = "build"
+			config.DeployDir = "_ftl"
 		}
 		if len(config.Deploy) == 0 {
-			config.Deploy = []string{"main", "schema.pb"}
+			config.Deploy = []string{"main"}
+		}
+		if len(config.Watch) == 0 {
+			config.Watch = []string{"**/*.go", "go.mod", "go.sum"}
+		}
+	}
+
+	// Do some validation.
+	if !isBeneath(moduleDir, config.DeployDir) {
+		return fmt.Errorf("deploy-dir must be relative to the module directory")
+	}
+	for _, deploy := range config.Deploy {
+		if !isBeneath(moduleDir, deploy) {
+			return fmt.Errorf("deploy files must be relative to the module directory")
 		}
 	}
+	for _, watch := range config.Watch {
+		if !isBeneath(moduleDir, watch) {
+			return fmt.Errorf("watch files must be relative to the module directory")
+		}
+	}
+	return nil
+}
+
+func isBeneath(moduleDir, path string) bool {
+	resolved := filepath.Clean(filepath.Join(moduleDir, path))
+	return strings.HasPrefix(resolved, strings.TrimSuffix(moduleDir, "/")+"/")
 }

backend/schema/builtin.go

@@ -1,7 +1,11 @@
 package schema
 
+import (
+	"golang.design/x/reflect"
+)
+
 // BuiltinsSource is the schema source code for built-in types.
-var BuiltinsSource = `
+const BuiltinsSource = `
 // Built-in types for FTL.
 builtin module builtin {
   // HTTP request structure used for HTTP ingress verbs.
@@ -23,11 +27,15 @@ builtin module builtin {
 }
 `
 
-// Builtins returns a [Module] containing built-in types.
-func Builtins() *Module {
-	module, err := ParseModuleString("builtins.ftl", BuiltinsSource)
+var builtinsModuleParsed = func() *Module {
+	module, err := moduleParser.ParseString("", BuiltinsSource)
 	if err != nil {
-		panic("failed to parse builtins: " + err.Error())
+		panic(err)
 	}
 	return module
+}()
+
+// Builtins returns a [Module] containing built-in types.
+func Builtins() *Module {
+	return reflect.DeepCopy(builtinsModuleParsed)
 }

backend/schema/schema_test.go

@@ -218,8 +218,8 @@ func TestParsing(t *testing.T) {
 		{name: "InvalidRequestRef",
 			input: `module test { verb test(InvalidRequest) InvalidResponse}`,
 			errors: []string{
-				"1:25: reference to unknown data structure \"InvalidRequest\"",
-				"1:41: reference to unknown data structure \"InvalidResponse\""}},
+				"1:25: unqualified reference to unknown data structure \"InvalidRequest\"",
+				"1:41: unqualified reference to unknown data structure \"InvalidResponse\""}},
 		{name: "InvalidDataRef",
 			input: `module test { data Data { user user.User }}`,
 			errors: []string{
@@ -234,7 +234,7 @@ func TestParsing(t *testing.T) {
 			input: `module test { data Data {} calls verb }`,
 			errors: []string{
 				"1:28: metadata \"calls verb\" is not valid on data structures",
-				"1:34: reference to unknown Verb \"verb\"",
+				"1:34: unqualified reference to unknown Verb \"verb\"",
 			}},
 		{name: "KeywordAsName",
 			input:  `module int { data String { name String } verb verb(String) String }`,