Handlebars "The partial include could not be found" inside Lambda function

Question

I have an express application that I want to port to AWS Lambda. It uses handlebars as middleware. I started out following this guide: https://dev.to/brightdevs/how-to-convert-an-express-app-to-aws-lambda--44gc

The difference between this and my code is handlebars. When I try to GET / for example, I get:

Error: /var/task/views/index.hbs: The partial include could not be found at Object.invokePartial (/var/task/node_modules/handlebars/dist/cjs/handlebars/runtime.js:266:11) at Object.invokePartialWrapper [as invokePartial] (/var/task/node_modules/handlebars/dist/cjs/handlebars/runtime.js:68:39) at Object.eval [as main] (eval at createFunctionContext (/var/task/node_modules/handlebars/dist/cjs/handlebars/compiler/javascript-compiler.js:254:23), <anonymous>:8:28) at main (/var/task/node_modules/handlebars/dist/cjs/handlebars/runtime.js:173:32) at ret (/var/task/node_modules/handlebars/dist/cjs/handlebars/runtime.js:176:12) at ret (/var/task/node_modules/handlebars/dist/cjs/handlebars/compiler/compiler.js:525:21) at /var/task/node_modules/hbs/lib/hbs.js:63:19 at FSReqWrap.readFileAfterClose [as oncomplete] (fs.js:511:3)

My folder structure looks like this: /server.js /views/index.hbs /views/partials/include.hbs

The relevant parts of server.js:

const express = require('express'),
    hbs = require('hbs'),
    app = express();

hbs.registerPartials(__dirname +'/views/partials');
app.set('view-engine', 'hbs');

app.get("/", (req, res) => {
    res.render('index.hbs', {});
});

const PORT = process.env.PORT || 8080;

const isInLambda = !!process.env.LAMBDA_TASK_ROOT;
if (isInLambda) {
    const serverlessExpress = require('aws-serverless-express');
    const server = serverlessExpress.createServer(app);
    exports.main = (event, context) => serverlessExpress.proxy(server, event, context)
} else {
    app.listen(PORT, ()=>{
        console.log('Server is up, listening on port ' + PORT);
    });
}

I would expect index.hbs to be rendered as it does if I run the code locally with node .\server.js. Instead I got the could not be found error I pasted above. Any clues are appreciated.

Answer 1

I ended up solving it, but wanted to post the resolution since I spent a lot of time with this issue and putting the question together.

What did it: Requiring the "express-handlebars" instead of "hbs". I don't know why it did not work with hbs, but I don't want to spend any more time on investigating this.

I hope this might be useful for someone in the future.