Allow one file sources

We currently only support specifying a directory as a custom source like this:

{
   name: 'fa-ir',
   prefix: '/fa', // All contents inside this source will be prefixed with `/fa`
   driver: 'fs',
   base: resolve(__dirname, 'content-fa') // Path for source directory
}

Would it be possible to support specifying a complete file path as a source?

It would be useful for cases like:

• Adding nuxt and @nuxt/content dependencies to a repository
• Only have a nuxt.config.ts at the root of the project
• Render a single file like README.md with a custom theme as a website for the repository

[pi0]

Content can create a virtual or overlay driver for single soures with a nested unstorage instance. There is a performance side-effect since with single file mounts, we want to avoid listing operations on those mountpoints that this driver can do. I would suggest instead of extending driver key, introduce a new option such as fileName: 'README.md' that enables this behavior.

[farnabaz]

There is two way to create single-file drivers for unstorage:

1 - Allow unstorage to expose storage instance into drivers and create a simple alias driver

// simple aliasing
export default defineDriver((_opts: DriverOptions) => {
  const opts = { ..._opts, ...defaultOptions }
  return {
    getKeys () {
      return Promise.resolve([opts.alias as string])
    },
    hasItem (key) {
      return Promise.resolve(key === opts.alias)
    },
    getItem (key) {
      if (key === opts.alias) {
        return storageInstance.getItem(opts.source)
      }
      return Promise.resolve(null)
    },
    setItem (key, value) {
      if (key === opts.alias) {
        return storageInstance.setItem(opts.source, value)
      }
      return Promise.resolve(undefined)
    }
  }
})

Pros

• With aliases we do not need to create separate drivers for each file source (fs-single, github-single, cloudflare-kv-single, …)
• With aliases, we don’t need to mount multiple drivers for the same source, For example, we can simple alias root:README.md into content:index.md without the need for any extra fs-driver

Cons

• The storage instance should expose to drivers, it might not be safe to expose the whole storage to drivers.
• In some cases, the user might need to define two sources. (for example for reading README.md from GitHub source, she needs to define two sources, one for the GitHub repo and the other for README.md alias

2 - Create a separate single driver for each driver

Pros

• This approach is straightforward and it does not require any change in unstorage core.

Cons

• We need to create multiple drivers for this purpose (fs-single, github-single, cloudflare-kv-single, …)
• Performance-wise, it is slow. For example, reading content and README.md from github require two drivers that both tries to fetch repo