Add a terraform provider (#13)

Using https://github.com/dikhan/terraform-provider-openapi,
building a Terraform provider.

The built-in gRPC-gateway openapi support has some differences
from what the provider expects. Build our own for now.

List of known additions that have to be added:

- required Get method for Terraform resources.
- added Apply (PUT) method for updating resources (could probably be
  replaced with json merge-patch).
- Addition of an "id" field, since the provider generator does not have
  a first-class understanding of path fields.

Expected follow-up work includes:

- figuring out how to require the "id" parameter during resource create.
  - especially nested resources: probably have to use the resource model
    to extract parent information and pass that via reference,
constructing resource paths by reading the parents.

.gitignore

@@ -1,2 +1,2 @@
-.idea
 main
+terraform-provider-bookstore

README.md

@@ -25,6 +25,14 @@ flowchart LR
 
 ## User Guide
 
+Building the proto and openapi files:
+
 ```
 go run main.go -i ./example/bookstore/bookstore.yaml -o ./example/bookstore/bookstore.yaml.output.proto
 ```
+
+Building the Terraform provider:
+
+```
+go run example/terraform/main.go
+```

cmd/root.go

@@ -26,6 +26,7 @@ import (
 	"github.com/aep-dev/aepc/parser"
 	"github.com/aep-dev/aepc/schema"
 	"github.com/aep-dev/aepc/validator"
+	"github.com/aep-dev/aepc/writer/openapi"
 	"github.com/aep-dev/aepc/writer/proto"
 	"github.com/spf13/cobra"
 	"google.golang.org/protobuf/encoding/protojson"
@@ -72,13 +73,19 @@ func ProcessInput(inputFile, outputFile string) error {
 		return fmt.Errorf("error parsing service: %w", err)
 	}
 	proto, _ := proto.WriteServiceToProto(ps)
-
-	err = WriteFile(outputFile, proto)
+	protoFile := fmt.Sprintf("%s.proto", outputFile)
+	err = WriteFile(protoFile, proto)
+	if err != nil {
+		return fmt.Errorf("error writing file: %w", err)
+	}
+	fmt.Printf("output proto file: %s\n", protoFile)
+	openapi, _ := openapi.WriteServiceToOpenAPI(ps)
+	openapiFile := fmt.Sprintf("%s.openapi.json", outputFile)
+	err = WriteFile(openapiFile, openapi)
 	if err != nil {
 		return fmt.Errorf("error writing file: %w", err)
 	}
-	fmt.Printf("output file: %s\n", outputFile)
-	fmt.Printf("output proto: %s\n", proto)
+	fmt.Printf("output openapi file: %s\n", openapiFile)
 	return nil
 }
 

writer/proto/constants.go → constants/constants.go

@@ -11,7 +11,7 @@
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
-package proto
+package constants
 
 const FIELD_NAME_PARENT = "parent"
 const FIELD_NAME_PATH = "path"

example/README.md

@@ -22,8 +22,48 @@ graph TD
     OpenAPI("OpenAPI Definition")
     client("Client")
     resource -- aepc --> serviceProto
+    resource -- aepc --> OpenAPI
     serviceProto -- protoc --> gService
     serviceProto -- protoc --> httpService
-    httpService -- protoc --> OpenAPI
-    OpenAPI -- openapi-generator et al --> client
+    OpenAPI -- terraform-provider-openapi --> terraform provider
+    OpenAPI -- openapi-generator et al --> clients
+```
+
+## Terraform Provider
+
+This example provides an example of generating a terraform provider using
+[terraform-provider-openapi](https://github.com/dikhan/terraform-provider-openapi/blob/master/docs/publishing_provider.md).
+
+### Building and installing the provider
+
+To build the provider, run the following:
+
+```sh
+go build -o terraform-provider-bookstore github.com/aep-dev/aepc/example/terraform/
+```
+
+### Installing
+
+See [scripts/terraform-provider-regenerate-and-install.sh]
+for an example.
+
+
+### Using
+
+See example/terraform/example_usage/main.tf for an example.
+
+You could do something like:
+
+```sh
+$ cd example/terraform/example_usage/
+$ terraform init
+# - uncomment resource "book" in main.tf
+$ terraform apply -auto-approve
+# - observe the resource has been created.
+# - modify the resource isbn
+$ terraform apply -auto-approve
+# - observe the resource has been updated.
+# - comment the resource out
+$ terraform apply -auto-approve
+# - observe the resource has been deleted.
 ```

example/bookstore/bookstore.yaml

@@ -1,29 +1,33 @@
 name: "bookstore.example.com"
 resources:
   - kind: "Book"
+    plural: "books"
     properties:
       isbn:
         type: STRING
         number: 1
-    parents:
-      - "bookstore.example.com/Publisher"
+        required: true
+    # parents:
+    #   - "bookstore.example.com/Publisher"
     methods:
       create: {}
       read: {}
       update: {}
       delete: {}
       list: {}
-      global_list: {}
-  - kind: "Publisher"
-    methods:
-      read: {}
-      list: {}
-  - kind: "Author"
-    properties:
-      name:
-        type: STRING
-        number: 1
-    parents:
-      - "Publisher"
-    methods:
-      read: {}
+      apply: {}
+#   - kind: "Publisher"
+#     plural: "publishers"
+#     methods:
+#       read: {}
+#       list: {}
+#   - kind: "Author"
+#     plural: "authors"
+#     properties:
+#       name:
+#         type: STRING
+#         number: 1
+#     parents:
+#       - "Publisher"
+#     methods:
+#       read: {}

example/bookstore/bookstore.yaml.output.openapi.json

@@ -0,0 +1,131 @@
+{
+  "swagger": "2.0",
+  "info": {
+    "title": "bookstore.example.com",
+    "version": "version not set"
+  },
+  "schemes": [
+    "http"
+  ],
+  "paths": {
+    "/books": {
+      "get": {
+        "responses": {
+          "200": {
+            "schema": {
+              "items": {
+                "$ref": "#/definitions/Book"
+              }
+            }
+          }
+        },
+        "parameters": null
+      },
+      "post": {
+        "responses": {
+          "200": {
+            "schema": {
+              "$ref": "#/definitions/Book"
+            }
+          }
+        },
+        "parameters": [
+          {
+            "in": "body",
+            "name": "body",
+            "schema": {
+              "$ref": "#/definitions/Book"
+            }
+          },
+          {
+            "in": "path",
+            "name": "id",
+            "schema": {},
+            "required": true,
+            "type": "string"
+          }
+        ]
+      }
+    },
+    "/books/{id}": {
+      "delete": {
+        "responses": {
+          "200": {
+            "schema": {
+              "$ref": "#/definitions/Book"
+            }
+          }
+        },
+        "parameters": null
+      },
+      "get": {
+        "responses": {
+          "200": {
+            "schema": {
+              "$ref": "#/definitions/Book"
+            }
+          }
+        },
+        "parameters": null
+      },
+      "patch": {
+        "responses": {
+          "200": {
+            "schema": {
+              "$ref": "#/definitions/Book"
+            }
+          }
+        },
+        "parameters": [
+          {
+            "in": "body",
+            "name": "body",
+            "schema": {
+              "$ref": "#/definitions/Book"
+            }
+          }
+        ]
+      },
+      "put": {
+        "responses": {
+          "200": {
+            "schema": {
+              "$ref": "#/definitions/Book"
+            }
+          }
+        },
+        "parameters": [
+          {
+            "in": "body",
+            "name": "body",
+            "schema": {
+              "$ref": "#/definitions/Book"
+            }
+          }
+        ]
+      }
+    }
+  },
+  "definitions": {
+    "Book": {
+      "type": "object",
+      "required": [
+        "isbn"
+      ],
+      "properties": {
+        "id": {
+          "type": "string",
+          "readOnly": true,
+          "x-terraform-id": true
+        },
+        "isbn": {
+          "type": "string"
+        },
+        "path": {
+          "type": "string",
+          "readOnly": true
+        }
+      }
+    }
+  }
+}