[APM] New platform migration: replace injected vars

[ogupte]

We rely on injected var in a number of places:

• apmUiEnabled - in public/hacks/toggle_app_link_in_nav.ts, public/register_feature.js
• apmIndexPatternTitle - in public/components/app/ServiceDetails/ServiceIntegrations/WatcherFlyout.tsx
• apmServiceMapEnabled in public/components/app/ServiceDetails/ServiceDetailTabs.tsx, public/components/app/Main/route_config/index.tsx, public/components/app/Home/index.tsx

Related Platform Issue: #41990

Follow the details outlined in the platform PR #50641 to define a set of whitelisted configs that can be referenced from the client.

[elasticmachine]

Pinging @elastic/apm-ui

[smith]

There's some additions in #46497. Search for apmServiceMapEnabled.

[smith]

Asked @joshdover about what we should use to replace this. He wrote:

We don’t currently have a replacement ready yet, but our plans are here: #41990.

I’d recommend just leaving it as-is until we complete this

Looking at where we have this on our backlog, I’d guess this is about 3-4 weeks out from getting done.

Putting this ticket back in the backlog.

[smith]

Labelling as blocked by #41990.

[joshdover]

Want to point out that we have exposed the old getInjectedVar API on core.injectedMetadata.getInjectedVar for now. This only enables getting vars injected from the server-side legacy plugin, but can be consumed by a NP plugin. It will still be replaced by #41990, but could help out in the meantime if you're blocked.

[sorenlouv]

@joshdover Instead of using the inject stuff we might just make an endpoint like GET /api/apm/config that returns a whitelist of config options. WDYT?

[joshdover]

That's certainly an option, but will slow down the startup of Kibana or your application. In fact, if you're doing this in setup or start, this may become impossible depending on if we accept this RFC: #45796 I think if you're blocked right now, it's significantly less work to use `getInjectedVar` until the real solution is finished.

…

On Mon, Nov 11, 2019 at 1:27 PM Søren Louv-Jansen ***@***.***> wrote: @joshdover <https://github.com/joshdover> Instead of using the inject stuff we might just make an endpoint like GET /api/apm/config that returns a whitelist of config options. WDYT? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#44232?email_source=notifications&email_token=AAN2UEBL7PGVJILG4QCOBDLQTGWZ5A5CNFSM4IRCBK62YY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOEDX3FLY#issuecomment-552579759>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAN2UECHLL6RD5JR2EC7IELQTGWZ5ANCNFSM4IRCBK6Q> .

[dgieselaar]

PR: Expose whitelisted config values to client-side plugin #50641