Update README.md add architecture diagram

Author: mehr74

README.md

@@ -27,3 +27,78 @@
 ](./LICENSE)
 
 </div>
+
+The repository contains the terraform code to deploy Grafana and PostgreSql 
+on Amazon Elastic Container Service (ECS). 
+
+## Table of Contents
+* [Architecture](#architecture)
+* [Code Structure](#code-structure)
+* [Usage](#usage)
+* [References](#references)
+
+
+## Cloud Architecture
+
+The following diagram shows the architecture of the deployment. It consists of 
+two services `grafana` and `postgres` running on ECS. The `grafana` service
+is connected to the `postgres` service using the official Grafana PostgreSql
+plugin. Through this connection, Grafana can visualize the data stored in the
+PostgreSql database. Furthermore, the `grafana` service is exposed to the
+internet using an Elastic Load Balancer (ELB).
+
+![Architecture](./docs/images/deployment.dark.png)
+
+## Code Structure
+
+The repository contains the following files and directories:
+
+```plaintext
+├── LICENSE
+├── README.md
+├── docs
+├── ops
+│   ├── ecs
+│   │   ├── README.md
+│   │   ├── main.tf
+│   │   ├── modules
+│   │   │   ├── cluster
+│   │   │   ├── grafana
+│   │   │   ├── postgres
+│   │   │   └── vpc
+│   │   ├── provider.tf
+│   │   └── variables.tf
+│   └── repository
+│       └── ecr.tf
+└── src
+    ├── docker-compose.yaml
+    ├── grafana
+    │   ├── Dockerfile
+    │   ├── grafana.ini
+    │   └── provisioning
+    │       ├── dashboards
+    │       │   └── dashboards.yaml
+    │       └── datasources
+    │           └── postgres.yaml
+    └── postgres
+        ├── Dockerfile
+        └── init.sql
+```
+
+* `src` contains the source code for the `grafana` and `postgres` services.
+* `ops/repository` contains the terraform code to create the Elastic Container
+  Registry (ECR) repository, and required IAM roles.
+* `ops/ecs` contains the terraform code to create the ECS cluster, services,
+
+## Usage 
+
+1. Follow the instructions in the [ops/repository/README.md](./ops/repository/README.md)
+   to create the Elastic Container Registry (ECR) repository and required IAM roles.
+2. Follow the instruction in the [ops/ecs/README.md](./ops/ecs/README.md) to deploy
+   the `grafana` and `postgres` services on Amazon Elastic Container Service (ECS).
+
+
+## References
+* [Grafana](https://grafana.com/)
+* [PostgreSql](https://www.postgresql.org/)
+* [Amazon Elastic Container Service](https://aws.amazon.com/ecs/)

docs/images/deployment.dark.png

@@ -1,7 +1,5 @@
 # Elastic Container Service (ECS) Stack
 
-![Architecture](./docs/architecture.svg)
-
 ## Usage
 
 1. Create a secret name `grafana-postgres-on-ecs` in AWS Secret Manager with the following secrets.
@@ -10,17 +8,18 @@
 | --- | --- |
 | `DATABASE_USERNAME` | Username for database (e.g. postgres) |
 | `DATABASE_PASSWORD` | Password for database (e.g. passw0rd) |
-| `DATABASE_HOST` | `database.service.local` |
-| `DATABASE_NAME` | Name of the database (e.g. sylla) |
+| `DATABASE_HOST` | `postgres.service.local` |
+| `DATABASE_NAME` | Name of the database (e.g. postgres) |
 
-2. We need to have two ECR repositories `grafana` and `postgres`. Set the variables 
-set the `repository_name` variable in `modules/grafana/variables.tf` and `modules/postgres/variables.tf` 
-respectively. The subdirectory `repo/ops/repository` contains the 
-terraform code to create the ECR repositories.
+2. We need to have two ECR repositories `grafana` and `postgres`. Set the variable 
+`repository_name` in `modules/grafana/variables.tf` and `modules/postgres/variables.tf`. 
+The subdirectory `repo/ops/repository` contains the 
+terraform code to create the ECR repositories, and the subdirectory `repo/src/`
+contains the Dockerfile and the code for the services.
 
 
 3. Add your public key to `main.tf` to allow ssh access to the EC2 instances.
 
 
 ## References 
-* [How to Deploy an AWS ECS Cluster with Terraform](https://spacelift.io/blog/terraform-ecs)]
+* [Amazon Elastic Container Service (ECS)](https://aws.amazon.com/ecs/)