Ability to run code on server start

[benmccann]

@aewing on Discord couldn't figure out how to do database setup. Was requesting:

Some mechanism to intercept the request before it goes to snowpack.handleRequest or some startup function I can introduce in my adapter config that runs before createServer and can populate context...

I ignore most of the help requests, but this one seemed like it might be a feature gap rather than a usage / documentation issue. Feel free to close if this use case is already supported in some way

[Rich-Harris]

Depends on the specifics. We already have this...

// src/setup/index.js
export function prepare(headers) {
  // this function runs before every page/endpoint request
  return {
    context: {...}, // this object is passed to endpoints, and used to derive session
    headers: {...} // this object is mixed in with response headers
  };
}

export function getSession(context) {
  return {
    user: context.user && {
      name: user.name
    }
  };
}

...but without knowing more about the problem it's hard to know if that's the solution

[benmccann]

I followed up with the user. It seems they were conflating a couple different issues. Their main complaint was around Snowpack's bundling of Node dependencies. I've opened a new issue for that (#210)

But anyway, it does seem like it'd be a nice API to support one-time setup stuff somewhere. You can probably work around it using the per-request method and setting a global flag to have it executed only on the first call, but it's a little messy to do it that way and if it takes a long time you might have requests that are hanging or failing whereas if it were done separately it might be able to be better handled

[Rich-Harris]

Still not totally sure what the suggestion is — what does 'one-time setup' mean in the context of a serverless deployment (for example)?

[benmccann]

Yeah, I guess it wouldn't mean much in that context, which is an interesting call out. I'll close this for now and let that thought bounce around in my head for awhile