feat: set default Cache-Control header with max-age of 1 year

[nathanchase]

🔗 Linked issue

#762, nuxt/nuxt#15465

❓ Type of change

• 📖 Documentation (updates to the documentation or readme)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

For all public static assets, we can define a best practice value for the Cache-Control header, to fall in line with the Google Lighthouse scoring of serving assets with an efficient cache policy.

Cache-Control: max-age=31536000, immutable

This checks if the asset is public, and not already defined, and sets the header accordingly.

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

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Name	Status	Preview	Updated
unjs-nitro	🔄 Building (Inspect)		Dec 17, 2022 at 7:10PM (UTC)

[danielroe]

for a public asset base of / (which would be the case with Nuxt's /public directory) this will cache all html/assets, including things like robots.txt, favico.ico or even /about/index.html. I think that is probably too broad a net to cast.

[danielroe]

I think @pi0 has some thoughts about this, but maybe allow cache headers to be set per asset folder? So Nuxt could push in /_nuxt, for example, with the appropriate long cache headers.

[nathanchase]

Agreed. I have this accomplished in Nuxt 3 using routeRules currently:

routeRules: {
  '/assets/**': { headers: { 'Cache-Control': 'max-age=31536000, immutable' } },
  '/images/**': { headers: { 'Cache-Control': 'max-age=31536000, immutable' } },
  '/_nuxt/**': { headers: { 'Cache-Control': 'max-age=31536000, immutable' } },
  '/**/*.js': { headers: { 'Cache-Control': 'max-age=31536000, immutable' } },
  '/**/*.css': { headers: { 'Cache-Control': 'max-age=31536000, immutable' } },
  '/**/*.json': { headers: { 'Cache-Control': 'max-age=31536000, immutable' } },
  '/**/*.html': { headers: { 'Cache-Control': 'max-age=31536000, immutable' } },
  '/**/*.xml': { headers: { 'Cache-Control': 'max-age=31536000, immutable' } },
  '/**/*.svg': { headers: { 'Cache-Control': 'max-age=31536000, immutable' } },
}

Perhaps nitro's scope is too broad to set any cache defaults since it could be used by things other than Nuxt 3? Maybe these defaults (or something perhaps more targeted) could be done on the Nuxt config side, rather than here in Nitro?

[pi0]

Thanks for PR dear @nathanchase

As of above discussion, i think using route rules indeed makes much better sense and makes it possible to also support via CDN native configurations without hitting the server.

I think we can still support it in nitro via publicDir.maxAge option mapping to (auto) route rules. Making a PR shortly. (#860)