Make it easier to expose Sentry API and tree shake at the same time

[rchl]

Problem Statement

In Sentry Nuxt Module, there is a "Nuxt Context" object on which the module exposes the whole Sentry SDK API. It did that with a code like:

import * as Sentry from '@sentry/vue'
// ...
ctx.$sentry = Sentry

The problem with that was that it would import everything from @sentry/vue which includes a bunch of stuff that shouldn't need to be exposed to module users or stuff like @sentry/replay that users are not even using (user would have to manually import this one to use it).

That bloated the client bundle (build by webpack 4) which I haven't noticed until recently.

So my solution that I have already implemented (but I'm not entirely happy about) was to do more targeted importing like:

import { init, Integrations, vueRouterInstrumentation } from '~@sentry/vue'
import * as CoreSdk from '~@sentry/core'
import * as BrowserSdk from '~@sentry/browser-sdk'  // resolves to `@sentry/browser/esm/sdk.js`
// ...
const SentrySdk = { ...CoreSdk, ...BrowserSdk }
ctx.$sentry = Sentry

And that works to keep the bundle at bay.

The potential problem with that is that I'm just guessing here in regards to which APIs should actually be exported to the user. I've picked the ones from @sentry/core and exports from a specific file in @sentry/browser. This doesn't seem that future proof as Sentry could export new important APIs somewhere else and I wouldn't know about those.

Solution Brainstorm

Create some official list of APIs (methods/properties) that the user should have access to. Ideally have a specific export in the package (like @sentry/vue in this case) that lists all exports that should be exposed at runtime. Not including things like @sentry/replay, of course.

[lforst]

I will discuss this with the team but I think it is unlikely that we will maintain a lookup of "guaranteed" API in the future. My suggestion would be for you to do export * from '@sentry/vue'. We follow semver so as long as you pin the minor this should never break. This means however that it is very likely that you have to do major bumps whenever we decide to do one. Does this make sense?

[rchl]

Exporting from the Sentry Vue package is what I have been doing. The problem with that is that it pulls in a lot of exports that don't have to or even should be in the client bundle.

See my recent PR for the sentry Nuxt module to see how much difference it makes to not export all: nuxt-community/sentry-module#547

[Lms24]

The problem with that is that it pulls in a lot of exports that don't have to or even should be in the client bundle.

Can you elaborate which exports from @sentry/vue shouldn't end up in the client bundle in your opinion? I think it should be noted that just because certain e.g. integrations are exported from @sentry/vue, like Replay or BrowserTracingin recent versions, doesn't mean that they automatically end up in any bundle. For instance, both of the mentioned integrations should be tree-shaken out as long as users don't import and use them in their code (i.e. put it in Sentry.init). If this doesn't work, I suggest to take a look at your bundler setup. Perhaps it is not configured correctly for tree-shaking?

[rchl]

Please have a look at the initial comment again, especially at the first code block:

import * as Sentry from '@sentry/vue'
// ...
ctx.$sentry = Sentry

Webpack is not gonna be able to treeshake anything here because we are importing everything from the package and attaching it to the context which is exposed in user code.

I can give more details later on which specific exports i think should not be needed in user code but i don't have access to the code right now

[lforst]

We are aware that this will prevent Sentry from being tree-shakable. My question is why are you attaching it to the context instead of letting users import API directly?

The consensus in the team is that we will not maintain "essential API" for various reasons.

[rchl]

I suppose there are both philosophical and technical reasons for that.

Nuxt modules' approach is to provide a simple experience so that the user doesn't have to think where to import stuff from.

On the technical side, Nuxt is an universal framework so same Vue files are rendered both on the server and client side. So if the user would import from @sentry/node in a Vue file then that import would then be also included in the client bundle.

User could do some gymnastics and use async imports but that has drawbacks (separate network requests) and it's just not straight forward.

Nuxt module automatically exposes Vue exports on the client side and node exports on the server side on the same context object.

I understand that you don't want to add more complexity to your packages. I will just have to manually pick and choose the exports to expose then.

[rchl]

Btw. The Next Sentry package is probably the closest to the Nuxt module I'm maintaining so maybe someone from that team has some good tips for me? I wonder how does it handle the case of "universally" rendered react files.

[lforst]

@rchl I am currently more or less the owner of the Next.js SDK. For that SDK we hook into the bundling process and decide for the user which code to import depending on whether we're building server or client bundles.

This works by resolving "@sentry/nextjs" differently depending on what bundle is built. I elegantly (but at the cost of my team ridiculing me) named this process "SDK multiplexer". I guess since you're using webpack you could do the same thing. The "multiplexer" is just a very simple webpack loader.

[rchl]

But that sounds more or less like what I'm doing - picking and choosing specific exports to expose. Just in a slightly different way 🙂.

The advantage for you is that you work at Sentry so you are constantly aware of things changing and can adjust appropriately. ;)