Managing HANA Service automatically. Scheduled Start/Stop. Part.1

Today, I published a library for managing HANA Service. I write to this blog why I needed this library.

Background of this article

Our customer contracts a consumption-based commercial model for SAP Cloud Platform. In the case of a CPEA contract, the HANA Service is pay-per-use based on start-up time, which can be very costly if it has been running 24 hours a day.

For example, a 24-hour running with HANA Service 32GB memory costs about 700 EUR per month. If it can be stopped for 12 hours a day, it is possible to compress the cost to about half.
In particular, isn’t it necessary to keep the development environment DB running for 24 hours?

However, manually starting and stopping the HANA Service is very cumbersome and is likely to be forgotten.
I wrote this article, thinking that I could somehow automate the startup / shutdown of the HANA Service Instances.

There are two existing ways to start / stop HANA Service.

1. HANA Service Dashboard. (existing ways)
2. Start / Stop Command with CF CLI. (existing ways)
3. My library (new ways)

Certainly, if you write a script for batch execution of CF CLI and register it in the Windows Task Scheduler, it seems that you can automatically start / stop the HANA Service. However, I can not afford to keep my PC running for 24 hours.

So, I needed to manage the HANA Service from Node.js.

Roughly speaking, CF CLI is just running the REST API in the background.

Appendix: CF CLI TRACE

If you want to check whether what I’m saying (it can replace “CF commands” to “REST API”) is true, try setting the environment variable CF_TRACE to true and executing the CF commands.

In Windows:

set CF_TRACE=true
cf login

You can inspect the HTTP requests of a CLI command by setting CF_TRACE=true.

How to use cf-nodejs-client? What can it do?

cf-nodejs-client is a CF client library for Node.js.
I modified it by adding methods required to operate HANA Service. I will show you how to use it.

Prerequirements

• SAP HANA Service instance in CF environment.
• Install Node.js on your PC

Outline of the procedure

1. Create a Node.js project.
2. Run the app locally.
3. Deploy the app to CF. (Next blog)

1.Create a Node.js project.

Open Command Prompt and move to your workspace directory. In my case, the workspace is “D:\html5”.

cd /d D:\html5

Make project folder. In this time, I named “hana_controller”.

mkdir hana_controller
cd hana_controller

Create package.json file like following.

{
  "name": "hana_controller",
  "version": "0.0.1",
  "private": true,
  "scripts": {
    "start": "node app.js"
  },
  "dependencies": {
    "cf-nodejs-client": "git+https://github.com/unosistema/cf-nodejs-client.git"
  }
}

Then install the library.

npm install

Create app.js file like following.

■app.js

"use-strict";

const endpoint = "https://api.cf.eu10.hana.ondemand.com";  // Change here if you're not use CF-frankfurt.
const username = "SAPCP_USERNAME"; // Change here
const password = "SAPCP_PASSWORD"; // Change here

const CloudController = new (require("cf-nodejs-client")).CloudController(endpoint);
const UsersUAA = new (require("cf-nodejs-client")).UsersUAA;
//const Apps = new (require("cf-nodejs-client")).Apps(endpoint);
const ServiceInstances = new (require("cf-nodejs-client")).ServiceInstances(endpoint);

CloudController.getInfo().then( (result) => {
    UsersUAA.setEndPoint(result.authorization_endpoint);
    return UsersUAA.login(username, password);
}).then( (result) => {
    
    ServiceInstances.setToken(result);
    return ServiceInstances.start("YOUR_HANA_SERVICE_ID"); // Change here
    //return ServiceInstances.stop("YOUR_HANA_SERVICE_ID");
    
}).then( (result) => {
    console.log(result);
}).catch( (reason) => {
    console.error("Error: " + reason);
});

Please refer to the HANA dashboard for the “YOUR_HANA_SERVICE_ID” as shown below.

2.Run the app locally.

Run the application by

node app.js

Your HANA DB should have started.

In the next article, I will write about how to deploy this application to the cloud and how to schedule the start / stop of HANA DB.

Also, if there is extra capacity, the library will be updated and all commands for HANA Service operation will be supported.