Add README file

Author: Consek

README.md

@@ -0,0 +1,66 @@
+# Devops example application
+
+This application serves as an example to show different methodologies for deployment and building in DevOps. 
+
+It consists of four services:
+- frontend
+- proxy
+- backend
+- redis
+
+## App diagram with request flow
+```
+  +--------------+                                      +--------------+
+  |              |                                      |              |
+  |   Frontend   |                                      |    Redis     |
+  |              |                                      |              |
+  +----------+---+                                      +----------+---+
+       ^     |                                               ^     |
+       |     |                                               |     |
+       1     2                                               5     6
+       |     |                                               |     |
+       |     v                                               |     v
+  +----+---------+             +-------------+          +----+---------+
+  |              +------3----->|             +----4---->|              |
+  |    Client    |             |    Proxy    |          |    Backend   |
+  |              |<-----8------+             |<---7-----+              |
+  +--------------+             +-------------+          +--------------+
+```
+
+## App UI
+
+The application displays proxy and backend instances with version and hostname. Also displays which instances handled the current connection by connecting them by an arrow.
+
+![App view](doc/images/app_view.png)
+
+## How to run the application
+
+To start the application `cd` into the **.deployment** folder and either run `dip provision` or `docker-compose up -d`. 
+
+In case of docker compose the command will need to be run multiple times because of dependencies, dip tool handles it automatically.
+
+## Folder and file structure
+
+#### Application folders
+
+Whole application is kept in **frontend**, **backend** and **proxy** folders. Each consists of service code, makefile for building and running the application, Dockerfile and files used to deploy to Google Cloud environment.
+
+#### Other folders
+
+- **.build** - builds all components using dip. Used by CI.
+- **.deployment** - deploys whole project using dip. Can be deployed locally or on external server
+- **.github** - stores workflows for Github Actions
+- **ansible** - configures Jenkins server and staging and production environments with auto deployment. To be used with **terraform** folder
+- **doc** - documentation related files
+- **jenkins** - container related files to deploy Jenkins locally
+- **terraform** - code for deploying infrastructure using [Hetzner Cloud](https://www.hetzner.com/) and [Cloudflare](https://www.cloudflare.com/)
+- **testing** - files for testing infrastructure (currently not used)
+
+#### Files
+
+- **Jenkinsfile** - different Jenkinsfiles used by Jenkins
+- **.travis.yml** - Travis CI pipeline
+
+## Author
+
+[Jan Kacik](https://github.com/Consek)