To introduce the concepts and foundations within OpenShift we are going to start with some simple source and tests of a NodeJS application.
Start by cloning the repo and using the files needed in this first step. In a terminal window:
git clone https://github.com/jeremycaine/hello-world
cd hello-world
cp ./src/server-v1.js ./server.js
npm install
npm run start
The output will show the build description infromation and the process id the app is running as.
> [email protected] start /Users/jeremycaine/Documents/code/github.com/jeremycaine/hello-world
> node server.js
Build:
-version: v1
-description: Simple server; No Signal intercept
Process ID: 8891
Server version is running on http://localhost:3000
From another terminal check the application is running
$ curl http://localhost:3000
Hello World ! (version v1)
and observe the log output in the original terminal window
...
Server version is running on http://localhost:3000
hello-world called
...
Next we want to add signal handling to the NodeJS application so it can respond to graceful and unexpected termination signals.
cp ./src/server-v2.js ./server.js
npm install
npm run start
Output has changed to
> [email protected] start /Users/jeremycaine/Documents/code/github.com/jeremycaine/hello-world
> node server.js
Build:
-version: v2
-description: Simple server; With Signal intercept
Server version is running on http://localhost:3000
And if you call curl http://localhost:3000 you see the message Hello World ! (version v2).
But now, the app will respond to a kill action.
Keystroke Ctrl+C is interrupt triggering SIGINT.
...
Process ID: 8891
Server version is running on http://localhost:3000
hello-world called
^CSIGINT signal received
HTTP server closed
hello-world app shutting down
Or if you find the process id (PID) and issue a Kill (SIGTERM) command e.g. kill 9098
Process ID: 9098
Server version is running on http://localhost:3000
SIGTERM signal received
HTTP server closed
hello-world app shutting down
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