feat: Allow setting asset_host separately from api_host

[frankh]

Changes

Currently we fetch static assets from the api_host. This has a bunch of issues and we'd like to separate these (so that e.g. static assets can be behind a CDN but not the API)

Checklist

• Tests for new code (see advice on the tests we use)
• Accounted for the impact of any changes across different browsers

[benjackwhite]

Not sure if this is the way to go... if we ever wanted it to be a universal change, we would have to get every user to add an additional config item. 🤔

Could we write out the various configurations we expect to get to and what they solve first? (Just trying to reduce the work and confusing setups that users have to implement as we end up stuck with them for basically forever...)

[benjackwhite]

Follow up thought - part of the thing here is to make sure that blockers don't add blocks to non-tracking domains (leading to our web app or other parts being broken).

I feel like adding a new assets host will just make it clear "oh these are more hosts we should block" which just exacerbates the problem right?

In my mind best would be to have tracking assets and tracking endpoints linked together as a default. That way tracker-blockers (that we have to live with) don't block anything they shouldn't, and if someone uses a reverse proxy, then the chances of successful tracking increase as both assets and tracking goes via that route?

Which again comes down to my general thought - how does a separate assets host actually benefit us at all? 😅

[frankh]

the idea is:

1. it defaults to how it is now, so nobody has to update config for things to continue working
2. we automatically map asset_host for our api_hosts (app.posthog.com -> app-static-prod.posthog.com)
3. we allow people to optionally pass in asset_host if they're proxying api host (but by default we'll just use api_host like we do now)

the main reason for separate hosts is to have a CDN on static assets but not the api endpoints

[github-actions]

Size Change: +968 B (0%)

Total Size: 753 kB

Filename	Size	Change
dist/array.full.js	177 kB	+242 B (0%)
dist/array.js	118 kB	+242 B (0%)
dist/es.js	118 kB	+242 B (0%)
dist/module.js	119 kB	+242 B (0%)

ℹ️ View Unchanged

Filename	Size
dist/exception-autocapture.js	12 kB
dist/recorder-v2.js	104 kB
dist/recorder.js	58.4 kB
dist/surveys.js	46.8 kB

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[benjackwhite]

the idea is:

1. it defaults to how it is now, so nobody has to update config for things to continue working
2. we automatically map asset_host for our api_hosts (app.posthog.com -> app-static-prod.posthog.com)
3. we allow people to optionally pass in asset_host if they're proxying api host (but by default we'll just use api_host like we do now)

the main reason for separate hosts is to have a CDN on static assets but not the api endpoints

1. Sure
2. This is the bit I feel is going to be an issue (for the reasons I outlined in the other comment)
3. Reading the code again I see what you mean - if you reverse proxy then it won't be any different

I still feel like we need a tracking-specific CDN for those assets, otherwise eventually it will get added to a block list and then our whole app will be broken again

[posthog-bot]

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[posthog-bot]

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