We knode you would want NodeJS on Singularity so we you made a recipe.
On your host, create a folder called “node” where we will store our files:
$ mkdir nodeTo create our recipe and test file run:
$ touch node/nodejs.def
$ touch node/Hello-world.jsAt this point, your host’s “node” folder will contain the following files:
node/
|-- nodejs.def
|-- Hello-world.jsEdit your nodejs.def recipe file with the following content: (you can paste using nano if you’d like– “$ nano node/node.js“)
Bootstrap: docker
From: node:10.11.0-alpine
%environment
HOSTNAME=127.0.0.1
PORT=3000
YARN_VERSION=1.9.4
export HOSTNAME PORT YARN_VERSION
%setup
# We make the directory where we will store our NodeJS file
mkdir -p $SINGULARITY_ROOTFS/node
%files
# Copy the file in the local directory to the /node location in the Image
Hello-world.js /node/Hello-world.js
%runscript
# What is executed with "singularity run"
# Pass any arguments to the node binary directly
node "$@"
%startscript
# what is executed with "singularity instance start"
# Run node on our Hello-world.js file
node /node/Hello-world.jsIn our recipe file we specify to pull node v.10.11.0 Alpine from a DockerHub base. The environment variables defined in %environment are needed for defining the dependencies (like in the case of YARN_VERSION) or for reference later in our Hello-world.js test script (below). Remember that these variables need to be defined in the %environment section to be exported. The %files section will copy the Hello-world.js we created before from the host to the container. The %startscript section will be run after starting an instance of our created container.
To test, we will need to define the contents of the Hello-world.js file. Use the editor of your choice. (ex. vim, emacs, nano) In this case we will use nano:
$ nano Hello-world.jsThen add the following content to the file:
const http = require('http');
const hostname = process.env.HOSTNAME||’127.0.0.1’;
const port = process.env.PORT||3000;
const server = http.createServer((req, res) => {
res.statusCode = 200;
res.setHeader('Content-Type', 'text/plain');
res.end('Hello World from node in a Singularity container!\n');
});
server.listen(port, hostname, () => {
console.log(`Server running at https://${hostname}:${port}/`);
});Make sure you have the correct code by running:
$ cat Hello-world.jsHello-world.js runs the “process.env” directive to obtain every environment variable from javascript. In this case we obtain process.env.HOSTNAME and process.env.PORT – the variables we set in the recipe definition file.
After this, we are ready to build our Singularity container.
$ cd node
$ sudo singularity build nodejs.sif nodejs.defWe are naming the Singularity image “nodejs.sif”
We can start an instance of our container to check that our server is up and running. In the same “node/” directory on your host run:
$ singularity instance start nodejs.sif nodeSince the Hello-world.js was referenced on the %startscript section from the definition file, after starting an instance you can open your browser at https://localhost:3000 to see the server up and running. For development you can specify new files to copy from node/ on your host system by editing %files in your recipe file. Then quickly rebuild only the files section by running:
$ sudo singularity build --section files nodejs.sif node.defOr to rebuild both %environment and %files:
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