Setting/Accessing Nunjucks global variables within a NodeJS/KeystoneJS project - node.js

Question

I've spent all of this morning searching for how to do this, and have come up stumped.
The project I'm working on is built on KeystoneJS/NodeJS. It's using Nunjucks which I've only got a few days basic experience of.
My issue is that after loading the config vars that sets the URI's/Ports of the services, I then want to set these up as Nunjucks variables, so within the html views, I can use those as the src locations.
I can't share all the code here, as I'm working on a government (UK) project but here's enough I hope.
Keystone.js
// Require keystone
var keystone = require('keystone');
var cons = require('consolidate');
var nunjucks = require('nunjucks');
var env = new nunjucks.Environment(null);
env.addGlobal('provision_uri', 3);
This loads initially, after routing it calls:
Login.js
var keystone = require('keystone');
var nunjucks = require('nunjucks');
exports = module.exports = function (req, res) {
var view = new keystone.View(req, res);
var locals = res.locals;
// locals.section is used to set the currently selected
// item in the header navigation.
locals.section = 'home';
var env = new nunjucks.Environment(null);
var provision_uri = env.getGlobal('provision_uri',3);
console.log(`Uri ${provision_uri}`); **<-- ERRORS HERE**
// Render the view
view.render('login', {
title: 'User Login',
description: 'Login to your Account',
provision_uri: provision_uri
});
};
Login.html
<br>
<form action="{{provision_uri}}/session" method="post" name="user">
<div class="container">
When I then start the project, the landing page loads, click on the login page and within console I get:
GET /provision/ 304 74.147 ms
Error thrown for request: /login
Error: global not found: provision_uri
I've checked this Question however it doesn't answer what I need but I looked up the environment.addGlobal given as an answer. That did seem to be what I wanted, but still it wouldn't work. I found this question which provided hope.
Any ideas would be great, I do have a work-around but would like to learn how to use these.
Thanks,
Colin

Answer 1

You don't need to create new instance of nunjucks environment on each render call. The new scope (environment) has empty global space.
var nunjucks = require('nunjucks');
var env = new nunjucks.Environment(null);
env.addGlobal('provision_uri', 3);
...
exports = module.exports = function (req, res) {
...
var provision_uri = env.getGlobal('provision_uri',3);
console.log(provision_uri);
view.render('login', {
title: 'User Login',
description: 'Login to your Account',
// provision_uri: provision_uri // it's not necessary
});
}