Improvements to our RUM implimentation

[Nooshu]

These apply to both static and govuk_publishing_components.

Make sure LUX data is captured when a user first accepts the cookie banner

Iniitial data is currently discarded and the beacon only fires on the 2nd page load. SpeedCurve have guidence on how to handle with cookie banners here.

Remove the CSP workarounds connect-src etc

SC support have stated that they will change the content type of the image early next week so they match, this workaround will then no longer be required.

Double check hard-coded sample rate is set to 1%

I believe we may have a 100% sample rate hard-coded somewhere. e.g. LUX.sampleRate(100). What is currently happening is the JS is sending 100% traffic to SC, the UI is set to 1% so 99% of the beacons are being rejected by the server.

Note on sample rates:

if we want 1% across all pages then it’s best to remove sampleRate() from the JS in our pages and set 1% in the UI settings. Or if we want different sample rates on different pages set targeted sample rates per page using sampleRate() and then use 100% in the settings.

For the moment we should remove the hard-coded sampleRate() and rely on the SC UI to set to 1%.

Todo List:

• Make sure LUX data is captured when a user first accepts the cookie banner
• Remove the CSP workarounds connect-src etc
• Double check hard-coded sample rate is set to 1%

[injms]

It looks as if LUX defaults to 100% if LUX.samplerate isn't set:

static/app/assets/javascripts/libs/lux/lux.js

Line 75 in 28b60ee

_samplerate = void 0 !== LUX.samplerate ? LUX.samplerate : 100;

This can be fixed by setting the samplerate variable inside the main LUX function - I'll raise a pull request to do that.

[injms]

With the release of v24.15.0 of the components gem, the sampling rate for LUX has been now set to 1% instead of the default 100%.

As the gem verison of LUX is now being used by Static, the bump to v24.15.0 of the gem should fix the sampling rate issue across all of the frontend apps regardless of the template that is being used.

[injms]

When running LUX.forceSample() locally the response has a content type of image/webp - I haven't been able to verify this on production as I'm not being sampled, but I think it'd be the same as the change is on SpeedCurve's server.

I've checked and the response now has an image content-type when on production as well - we should be able to remove connect-src from the content security policy safely now.

[injms]

A user's first page visit is now measured after (and only after) they've consented to the appropriate cookies.

This was released in v24.18.1 of the components gem, which was then bumped in Static in #2539.

[injms]

I've raised a pull request to remove the lux.speedcurve.com domain from the connect-src content security policy: alphagov/govuk_app_config#216

[injms]

I've raised a pull request to remove the lux.speedcurve.com domain from the connect-src content security policy: alphagov/govuk_app_config#216

This pull request to sort out govuk_app_config has been merged in and released (alphagov/govuk_app_config#220) - this will be winging its way to all of the frontend applications over the next day or so thanks to dependabot.

[Nooshu]

Awesome work as always @injms! Closing issue as all fixed!