feat: add python/appsync-graphql-dynamodb/README.md (#124)

* feat: add python/appsync-graphql-dynamodb/README.md

* feat: add python/appsync-graphql-dynamodb/README.md

Author: jocoandonov

README.md

@@ -84,6 +84,7 @@ $ cdk destroy
 |---------|-------------|
 | [api-cors-lambda](https://github.com/aws-samples/aws-cdk-examples/tree/master/python/api-cors-lambda/) | Shows creation of Rest API (GW) with an /example GET endpoint, with CORS enabled |
 | [application-load-balancer](https://github.com/aws-samples/aws-cdk-examples/tree/master/python/application-load-balancer/) | Using an AutoScalingGroup with an Application Load Balancer |
+| [appsync-graphql-dynamodb](https://github.com/aws-samples/aws-cdk-examples/tree/master/python/appsync-graphql-dynamodb/) | Creating a single GraphQL API with an API Key, and four Resolvers doing CRUD operations over a single DynamoDB |
 | [classic-load-balancer](https://github.com/aws-samples/aws-cdk-examples/tree/master/python/classic-load-balancer/) | Using an AutoScalingGroup with a Classic Load Balancer |
 | [custom-resource](https://github.com/aws-samples/aws-cdk-examples/tree/master/python/custom-resource/) | Shows adding a Custom Resource to your CDK app |
 | [ecs-cluster](https://github.com/aws-samples/aws-cdk-examples/tree/master/python/ecs/cluster/) | Provision an ECS Cluster with custom Autoscaling Group configuration |

python/appsync-graphql-dynamodb/README.md

@@ -0,0 +1,58 @@
+# AppSync GraphQL API Acting on DynamoDB
+<!--BEGIN STABILITY BANNER-->
+---
+
+![Stability: Experimental](https://img.shields.io/badge/stability-Experimental-important.svg?style=for-the-badge)
+
+> **This is an experimental example. It may not build out of the box**
+>
+> This examples does is build on Construct Libraries marked "Experimental" and may not be updated for latest breaking changes.
+>
+> If build is unsuccessful, please create an [issue](https://github.com/aws-samples/aws-cdk-examples/issues/new) so that we may debug the problem 
+
+---
+<!--END STABILITY BANNER-->
+
+This an example of an AppSync GraphQL API, pointing to four resolvers doing CRUD operations with a single DynamoDB table.
+
+## Build
+
+To build this app, you need to be in this example's root folder. Then run the following:
+
+```bash
+$ python3 -m venv .env
+$ source .env/bin/activate
+$ pip install -r requirements.txt
+```
+
+This will install the necessary CDK, then this example's dependencies, and then build your Python files and your CloudFormation template.
+
+Install the latest version of the AWS CDK CLI:
+
+```shell
+$ npm i -g aws-cdk
+```
+
+## Deploy
+
+Run `cdk deploy`. This will deploy / redeploy your Stack to your AWS Account.
+
+After the deployment you will see the API's URL, which represents the url you can then use.
+
+## Synthesize Cloudformation Template
+
+To see the Cloudformation template generated by the CDK, run `cdk synth`, then check the output file in the "cdk.out" directory.
+
+## The Component Structure
+
+This Stack contains:
+
+- a __GraphQL API__ with an API Key (Use with caution, each key is only valid for 7 days.)
+- a __GraphQL Schema__ with Queries to get one and all items and two mutations to save and delete an item
+- a __DynamoDB table__ `items` that stores the data with a Pay Per Request Billing Mode
+- an __IAM Role__ that allows AppSync to invoke your DynamoDB table.
+- an __AppSync DataSource__, connecting your API to the DynamoDB table with the previously specified role.
+- a __AppSync Resolver__ for a Query `getOne` to get one item from the DynamoDB table.
+- a __AppSync Resolver__ for a Query `all` to get all items from the DynamoDB table.
+- a __AppSync Resolver__ for a Mutation `save` to put an item into the DynamoDB table (the id is autogenerated, you need only name).
+- a __AppSync Resolver__ for a Mutation `delete` to delete one item from the DynamoDB table.