No way to pass Chromium launch args (e.g. --proxy-server) for PDF/PPTX export behind corporate proxy

[chirag127]

Problem

When exporting slide decks to PDF or PPTX on a corporate network, the internal Chromium/Edge browser used by @marp-team/marp-cli (via Puppeteer) must route traffic through a corporate proxy. There is currently no way to configure Chromium launch arguments in the extension settings.

Reproduction

1. Work behind a corporate HTTP/HTTPS proxy (e.g. http://proxy.corp.example.com:8080)
2. Create a Marp Markdown file that embeds images or web fonts loaded from external URLs
3. Run Marp: Export Slide Deck → PDF
4. Export either hangs (navigation timeout) or produces a PDF with missing resources

Expected behaviour

A setting such as markdown.marp.browserExtraArgs that accepts a list of additional Chromium/Firefox launch arguments, forwarded to marp-cli. Example configuration:

"markdown.marp.browserExtraArgs": [
  "--proxy-server=http://proxy.corp.example.com:8080",
  "--ignore-certificate-errors-spki-list=<fingerprint>"
]

Current workaround

None within the extension. Workaround is to run marp-cli from the terminal directly using PUPPETEER_EXTRA_LAUNCH_ARGS. This defeats the purpose of the VS Code extension.

Why this matters

Corporate environments are extremely common. marp-cli itself supports PUPPETEER_EXTRA_LAUNCH_ARGS and the underlying Puppeteer integration accepts arbitrary launch args. The VS Code extension is the missing link between the user's network configuration and the export pipeline.

Environment

• OS: Windows 11 Enterprise (also reproducible on Linux behind corporate proxy)
• VS Code: 1.100+
• Marp for VS Code: 3.5.1
• Network: Corporate HTTP/HTTPS proxy with TLS inspection (self-signed CA cert)

Related

• The existing markdown.marp.browserPath setting proves the extension already exposes browser configuration; extending it to launch args is a natural follow-on.
• marp-cli PUPPETEER_EXTRA_LAUNCH_ARGS documentation

[yhatt]

If support for Marp CLI is implemented, it might be worth adding configuration options to Marp for VS Code too. However, for general users (those not restricted by company policies), unnecessarily complicating the settings is undesirable. At first, we should consider to implement this via environment variables instead of the extension settings, to verify its effectiveness for the business users.

Workaround

The alternative workaround is already available: Make a proxy shell script for the browser binary to add extra arguments, and use it by setting as markdown.marp.browserPath.

#!/bin/sh

/usr/bin/google-chrome "$@" --proxy-server=http://proxy.corp.example.com:8080 --ignore-certificate-errors-spki-list=<fingerprint>

This idea is based on #451 (comment).

Warning

I'm not sure what you are referring to, but the workaround you described regarding the support for the PUPPETEER_EXTRA_LAUNCH_ARGS environment variable is incorrect. It has not been implemented in Marp CLI. A similar unresolved issue can be found at marp-team/marp-cli#671.