Reddit sentiment

Use Beneath, Kubernetes, Next.js, and Netlify to build and deploy an analytics website


In this walk-through, we’ll create a real-time, data-driven web app to monitor sentiment of Reddit posts. The following things are needed for dashboards like this one:

  • Subscribe to a data feed and store it
  • Apply an NLP model for sentiment analysis
  • Visualize the data in real-time
  • Build and deploy a web app so we can share our work

To accomplish these tasks, our full stack includes:

  • Beneath, our data system.
  • Kubernetes, a to orchestrate the compute that subscribes to Reddit and writes data to Beneath.
  • Next.js, a minimalistic React framework. The latest and greatest way to build Single Page Applications.
  • Recharts.js, a React-native graphing library.
  • MaterialUI, a library for design aesthetics.
  • Netlify, a tool to build and deploy our web app.

Given our objectives and stack, why is Beneath a good choice for data storage?

  • Little code!
  • Store the data in a data warehouse to enable efficient SQL queries
  • Store the data in a log to quickly fetch the latest records.
  • Very easy React library to fetch data into our frontend
  • No need to build an API server if we want to share data with others
  • No need to configure or maintain a database(s)

What we’ll build

For reference, here’s all the frontend code and the backend code.


In the interest of getting-to-the-point and focusing on Beneath, we’ll assume you can set yourself up with the following:

Alright, let’s start!

Write real-time data to Beneath

Initialize a Nextjs + MaterialUI site

Run create next-app

From the Next.js Getting Started docs, in our command line:

yarn create next-app

Add files for MaterialUI

Next.js provides a fantastic repository of examples. Here’s their Next.js example for MaterialUI.

We add the MaterialUI package:

yarn add @material-ui/core

Copied files into my project directory:

  • pages/_app.js
  • pages/_document.js
  • src/theme.js

Now we’re all ready to use React components and Material UI.

Read data from Beneath into frontend

Add the Beneath dependency

From your command line:

yarn add beneath-react

Read data into your frontend

import { useRecords } from "beneath-react";

const { records, error, loading, fetchMore, fetchMoreChanges, subscription, truncation } = useRecords({
    stream: "epg/reddit/coronavirus-posts-sentiment",
    query: {type: "log", peek: "true"},
    pageSize: 500,

Use Recharts to display the data

Recharts has great documentatation. And it’s very intuitive to use for anyone with React component experience.

Here’s our full code:

<ResponsiveContainer width={"100%"} height={400}>
  <LineChart data={sortedRecords} margin={{ top: 30, right: 30, left: 30, bottom: 30 }}>
    <CartesianGrid />
      domain={["dataMin", "dataMax"]}
      tickFormatter={(unixTime) => moment(unixTime).format("MMMM Do YYYY, h:mm:ss a")}
      <Label value={"Date"} position="bottom" style={{ textAnchor: "middle" }} />
    <YAxis dataKey="polarity" domain={[-1, 1]}>
      <Label value={"Polarity"} position="left" angle={-90} style={{ textAnchor: "middle" }} />
      formatter={(value) => value.toFixed(2)}
      labelFormatter={(unixTime) => moment(unixTime).format("MMMM Do YYYY, h:mm:ss a")}
    <Line dataKey="polarity" stroke="#8884d8" />
    <ReferenceLine y={0} stroke="black" />

Notes for working with Rechart:

Build and deploy site with Netlify