Feature Request: Allow Custom Puppeteer Launch Arguments

[bobbui]

Problem Description

Currently, marp-cli uses a predefined set of Puppeteer launch arguments that work well for most environments but fail when running inside AWS Lambda runtime. The hardcoded browser arguments don't account for the specific requirements and limitations of serverless environments like AWS Lambda.

Current Behavior

When running marp-cli in AWS Lambda, the PDF/image generation fails because:

The default Puppeteer launch arguments are not compatible with Lambda's sandboxed environment
Lambda requires specific Chrome/Chromium flags for proper execution
There's no way to customize or override the browser launch arguments

Expected Behavior

Users should be able to pass additional or custom Puppeteer launch arguments to make marp-cli work in restricted environments like AWS Lambda.

Proposed Solution

Add support for customizing Puppeteer launch arguments through one of these methods:

Option 1: Environment Variable

bashMARP_PUPPETEER_ARGS="--no-sandbox,--disable-setuid-sandbox,--disable-dev-shm-usage" marp --pdf presentation.md

Option 2: CLI Flag

bashmarp --pdf --puppeteer-args="--no-sandbox,--disable-setuid-sandbox" presentation.md

Option 3: Configuration File

json{
"puppeteer": {
"args": ["--no-sandbox", "--disable-setuid-sandbox", "--disable-dev-shm-usage"]
}
}
AWS Lambda Requirements
For AWS Lambda compatibility, these arguments are typically needed:
javascript{
args: [
'--no-sandbox',
'--disable-setuid-sandbox',
'--disable-dev-shm-usage',
'--disable-background-timer-throttling',
'--disable-backgrounding-occluded-windows',
'--disable-renderer-backgrounding',
'--single-process' // Sometimes needed depending on Lambda configuration
]
}

[yhatt]

Marp CLI has already supported a few environment variables to control Puppeteer arguments (PUPPETEER_HEADLESS_MODE, CHROME_NO_SANDBOX, CHROME_DISABLE_GPU, CHROME_ENABLE_EXTENSIONS, etc) so it would be natural to add as one of them, to allow overriding Puppeteer args with fully custom arguments. I think it would be helpful for limited serverless environments such as AWS Lambda, Cloudflare, Vercel, etc.

Requirements

• Setting custom arguments for Puppeteer is available through the environment value, like CHROME_ARGUMENTS.
  • The naming rule should be matched to existing environment values CHROME_xxx.
  • CHROME_ARGUMENTS for Chrome and Chromium-flavored browsers like Microsoft Edge, and FIREFOX_ARGUMENTS for Firefox.
  • Custom arguments are considered an advanced feature of the CLI. To prevent users who are not familiar with the details from accidentally misconfiguring, we will limit configuration to environment variables for the time being.
• If the environment value has been set, Marp CLI should use custom arguments as much as possible.
  • Some of arguments for working Marp CLI correctly cannot override. e.g. --user-data-dir
• The custom arguments can contain allowed by Puppeteer.
  • Overriding some of custom args may be disallowed by Puppeteer, such as arguments provided by puppeteer.defaultArgs()
• Marp CLI's Browser class is used for 2 purposes: converting Markdown to other formats, and opening the preview window through Chrome/Chromium-flavored browser. xxx_ARGUMENTS environment value should be allowed only for converting.
  • We believe overloading Puppeteer arguments for opening a preview window (--preview/-p option) is distinctly rare, and it may break the window management by Marp CLI.

[yhatt]

• Some of arguments for working Marp CLI correctly cannot override. e.g. --user-data-dir

That limitation might want to mitigate to resolve an edge case similar to #678. This issue points out that Marp CLI generates a unique data directory in the temporary folder whenever the process is started. Allowing the custom --user-data-dir, Puppeteer may possibly reduce file I/O by using the custom data directory located on a RAM disk.