Using GitHub Copilot in RStudio (Behind Zscaler)

Purpose

This tutorial explains how to use GitHub Copilot effectively in RStudio, with specific attention to the IMF computing environment, which operates behind Zscaler.

What GitHub Copilot Does in RStudio

GitHub Copilot is an AI-powered code completion tool. In RStudio, it:

  • Suggests complete lines or blocks of R code while you type
  • Translates comments or natural-language prompts into code
  • Assists with refactoring, documentation, and debugging
  • Is particularly useful for repetitive tasks such as data wrangling, plotting, and simulations

Copilot does not run code and does not replace understanding. It should be treated as a drafting assistant whose suggestions must always be evaluated.

Prerequisites

Before starting, ensure that you have:

  • A GitHub account with Copilot enabled
  • A recent version of RStudio (2023.06 or newer recommended)
  • Internet access that allows GitHub Copilot traffic

In corporate environments, the last point is often the binding constraint.

Zscaler at the IMF

At the IMF, all outbound internet traffic is routed through Zscaler. Zscaler is a cloud-based security platform used to enforce the Fund’s cybersecurity policies, including protection against malware, data exfiltration, and unauthorized external connections.

A key feature of Zscaler is SSL inspection. Encrypted HTTPS traffic is intercepted and re-signed using an IMF corporate certificate so that traffic can be inspected securely.

This setup is essential for security, but it has implications for developer tools.

GitHub Copilot in RStudio runs on Node.js. Unlike web browsers, Node.js does not automatically trust the IMF’s corporate certificate. As a result, Copilot may appear enabled but fail to function.

Typical symptoms include:

  • Copilot options appear in RStudio, but no suggestions appear
  • Copilot is marked as enabled, yet nothing happens when typing

When this occurs, the issue is not with R, RStudio, or Copilot itself. It is a consequence of how Zscaler performs SSL inspection and how Node.js handles certificate trust.

Enabling Copilot in RStudio

  1. Open RStudio
  2. Go to Tools → Global Options → Code → Completion
  3. Ensure GitHub Copilot is checked
  4. Sign in to GitHub when prompted

Restart RStudio once after enabling Copilot.

If you are behind Zscaler, Copilot will still not work until the workaround below is applied.

Workaround: Configure Node.js to Trust the IMF Certificate

The most reliable fix is to explicitly tell Node.js to trust the IMF corporate root certificate using the environment variable NODE_EXTRA_CA_CERTS.

Step 1: Export the IMF corporate root certificate (Windows)

  1. Press Win + R, type certmgr.msc, press Enter
  2. Navigate to:

Trusted Root Certification Authorities
└─ Certificates
  1. Locate the IMF/Zscaler root CA
    (often labeled Zscaler, Corp Root CA, or similar)
  2. Right-click → All Tasks → Export
  3. Choose Base-64 encoded X.509 (.CER)
  4. Save the file, for example:

C:\certs\imf-corp-root-ca.cer

Step 2: Register the certificate with Node.js

Open PowerShell as a normal user (administrator rights are not required) and run:

setx NODE_EXTRA_CA_CERTS "C:\certs\imf-corp-root-ca.cer"

This writes the variable to your user environment, which is what RStudio and Copilot use.

Step 3: Restart properly

After running setx:

  1. Close RStudio completely
  2. (Safest) Log out of Windows and log back in
  3. Start RStudio again

Copilot will not pick up the change without a full restart of the user session.

Step 4: Confirm the variable is set

Open a new PowerShell window and run:

echo $env:NODE_EXTRA_CA_CERTS

You should see:

C:\certs\imf-corp-root-ca.cer

If nothing is returned, the variable did not apply.

Step 5: Verify in Copilot diagnostics

Open Copilot Diagnostics in RStudio and check Reachability.

You want to see entries such as:

default.exp-tas.com: HTTP 200

and not:

unable to get local issuer certificate

Once the certificate error disappears, Copilot suggestions should begin appearing within seconds.

How to Use Copilot Effectively in R

Write Comments First

Copilot responds best to clear, descriptive comments.

# Load Penn World Table data and keep only GDP per worker

Pause briefly after typing the comment; Copilot will often propose the full code block.

Let Copilot Continue Patterns

Copilot is strongest when continuing existing structure.

library(dplyr)

df <- df %>%
  filter(year >= 2000) %>%

Use Copilot for ggplot2 Boilerplate

Copilot performs well with ggplot2 syntax, including:

  • Repetitive aesthetics
  • Faceting and labeling
  • Standard theme components

You retain control over design choices while saving typing time.

Ask for Explanations in Comments

You can prompt Copilot to explain code logic:

# Explain what this regression is estimating
lm(y ~ x + z, data = df)

This is useful for teaching materials and self-checking.

What Copilot Is Bad At

Be cautious when:

  • Working with highly specialized or proprietary datasets
  • Implementing novel econometric or identification strategies
  • Writing theory-heavy code where correctness depends on assumptions

Copilot will often sound confident even when it is wrong. Verification is essential.

Summary

  • GitHub Copilot integrates well with RStudio once enabled
  • At the IMF, Zscaler’s SSL inspection requires explicit certificate trust
  • Setting NODE_EXTRA_CA_CERTS resolves Copilot connectivity issues
  • Copilot is best used as a drafting and acceleration tool