Handle event versions in the SDK (#37)

* Handle event versions in the SDK

Change CDEventType to be a struct to allow for one-time parsing
of the type string. The event type is still stored as string in
the context so that it may unmarshal without the need for a
custom unmarshaller.

When producing events, the SDK produces the latest version of an
event, the only one know to the SDK.
When consuming events, the SDK allows for versions different from
the SDK ones, as long as they are compatible with the SDK one,
according to the versioning rules from the spec.

The spec submodule has been moved into pkg/api so that we may use
go embed to embed the schemas from the spec into the event modules
which allows to embed the schema definitions in the SDK module.

Signed-off-by: Andrea Frittoli <[email protected]>

Author: afrittoli

.github/workflows/ci.yml

@@ -17,14 +17,18 @@ jobs:
     steps:
     - name: Checkout
       uses: actions/checkout@v3
+      with:
+        submodules: recursive
     - name: Setup Go
       uses: actions/setup-go@v3
       with:
         go-version: 1.19
     - name: Format check
       run: make fmt
-    - name: Linting check
-      run: make lint
+    - name: golangci-lint
+      uses: golangci/golangci-lint-action@v3
+      with:
+        version: v1.52
 
   test:
     runs-on: ubuntu-latest

.gitmodules

@@ -1,3 +1,3 @@
-[submodule "spec"]
-	path = spec
+[submodule "pkg/api/spec"]
+	path = pkg/api/spec
 	url = https://github.com/cdevents/spec

go.mod

@@ -30,6 +30,7 @@ require (
 	go.uber.org/atomic v1.7.0 // indirect
 	go.uber.org/multierr v1.6.0 // indirect
 	go.uber.org/zap v1.17.0 // indirect
+	golang.org/x/mod v0.9.0
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 	gopkg.in/yaml.v3 v3.0.0 // indirect
 )

go.sum

@@ -74,6 +74,8 @@ go.uber.org/zap v1.17.0 h1:MTjgFu6ZLKvY6Pvaqk97GlxNBuMpV4Hy/3P6tRGlI2U=
 go.uber.org/zap v1.17.0/go.mod h1:MXVU+bhUf/A7Xi2HNOnopQOrmycQ5Ih87HtOu4q5SSo=
 golang.org/x/crypto v0.0.0-20211215153901-e495a2d5b3d3 h1:0es+/5331RGQPcXlMfP+WrnIIS6dNnNRe0WB02W0F4M=
 golang.org/x/crypto v0.0.0-20211215153901-e495a2d5b3d3/go.mod h1:IxCIyHEi3zRg3s0A5j5BB6A9Jmi73HwBIUl50j+osU4=
+golang.org/x/mod v0.9.0 h1:KENHtAZL2y3NLMYZeHY9DW8HW8V+kQyJsY/V9JlKvCs=
+golang.org/x/mod v0.9.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
 golang.org/x/net v0.0.0-20211112202133-69e39bad7dc2/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=

hack/add-event.sh

@@ -46,10 +46,16 @@ import (
 	"time"
 )
 
-const (
-	// ${SUBJECT_UPPER_CAMEL}${PREDICATE_UPPER_CAMEL} event
-	${SUBJECT_UPPER_CAMEL}${PREDICATE_UPPER_CAMEL}EventV1    CDEventType = "dev.cdevents.${SUBJECT_LOWER}.${PREDICATE_LOWER}.0.1.0"
-	${SUBJECT_LOWER_CAMEL}${PREDICATE_UPPER_CAMEL}SchemaFile string      = "${SUBJECT_LOWER}${PREDICATE_LOWER}"
+//go:embed spec/schemas/${SUBJECT_LOWER}${PREDICATE_LOWER}.json
+var ${SUBJECT_LOWER}${PREDICATE_LOWER}schema string
+
+var (
+	// ${SUBJECT_UPPER_CAMEL}${PREDICATE_UPPER_CAMEL} event v0.1.0
+	${SUBJECT_UPPER_CAMEL}${PREDICATE_UPPER_CAMEL}EventV1 CDEventType CDEventType = CDEventType{
+		Subject:   "${SUBJECT_LOWER}",
+		Predicate: "${PREDICATE_LOWER}",
+		Version:   "0.1.0",
+	}
 )
 
 type ${SUBJECT_UPPER_CAMEL}${PREDICATE_UPPER_CAMEL}SubjectContent struct{}
@@ -159,8 +165,9 @@ func (e *${SUBJECT_UPPER_CAMEL}${PREDICATE_UPPER_CAMEL}Event) SetCustomData(cont
 	return nil
 }
 
-func (e ${SUBJECT_UPPER_CAMEL}${PREDICATE_UPPER_CAMEL}Event) GetSchema() string {
-	return ${SUBJECT_LOWER_CAMEL}${PREDICATE_UPPER_CAMEL}SchemaFile
+func (e ${SUBJECT_UPPER_CAMEL}${PREDICATE_UPPER_CAMEL}Event) GetSchema() (string, string) {
+	eType := e.GetType()
+	return fmt.Sprintf(CDEventsSchemaURLTemplate, CDEventsSpecVersion, eType.Subject, eType.Predicate), schema${SUBJECT_LOWER}${PREDICATE_LOWER}schema
 }
 
 func New${SUBJECT_UPPER_CAMEL}${PREDICATE_UPPER_CAMEL}Event() (*${SUBJECT_UPPER_CAMEL}${PREDICATE_UPPER_CAMEL}Event, error) {