Add Cache-Control header to knockout partials

[paveq]

Description (*)

This PR adds Cache-Control headers to knockout partials (.html static content files). Previous PR #8000 failed to add this.

Fixed Issues

Without Cache-Control header in same cases when using caching proxies such as Cloudflare to serve files, end user browser does 304 check each time on every page. This highly depends on proxy configuration, but there should not be any reason not to set Cache-Control header. Is seems with just Expires header set, there's different interpretations what logic should be used for revalidation.

In this PR we set Cache-Control to public, which is same value for all static content files. There is no need for browser to revalidate these requests, as invalidation is handled by static content versioning.

Manual testing scenarios (*)

1. Open category page
2. Open browser inspector
3. Verify that returned response to .html static content file has Cache-Control header
4. Open another category page
5. Verify that the same .html file is retrieved from browser disk cache

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• [not applicable] All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds are green)

[m2-assistant]

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[rodrigowebjump]

Hi @paveq Thanks for your contribution

[magento-engcom-team]

Hi @rodrigowebjump, thank you for the review.
ENGCOM-6189 has been created to process this Pull Request
✳️ @rodrigowebjump, could you please add one of the following labels to the Pull Request?

Label	Description
Auto-Tests: Covered	All changes in Pull Request is covered by auto-tests
Auto-Tests: Not Covered	Changes in Pull Request requires coverage by auto-tests
Auto-Tests: Not Required	Changes in Pull Request does not require coverage by auto-tests

[ihor-sviziev]

Hi @paveq,
Could you also add this change to nginx.conf.sample to make both installations consistent?

[paveq]

Hi @paveq,
Could you also add this change to nginx.conf.sample to make both installations consistent?

This is now added.

[magento-engcom-team]

Hi @ihor-sviziev, thank you for the review.
ENGCOM-6189 has been created to process this Pull Request
✳️ @ihor-sviziev, could you please add one of the following labels to the Pull Request?

Label	Description
Auto-Tests: Covered	All changes in Pull Request is covered by auto-tests
Auto-Tests: Not Covered	Changes in Pull Request requires coverage by auto-tests
Auto-Tests: Not Required	Changes in Pull Request does not require coverage by auto-tests

[engcom-Bravo]

Hello @paveq. Thank You for Your contribution. Could You please help us a bit with Manual Testing and give us some more details on it so that we can be sure we do everything correctly. For example in "Verify that returned response to .html static content file has Cache-Control header" please specify some concrete .html file. Also "Open another category page" means another page of the same category or a page of some other category? Besides do we need to switch to Developer or to Production mode for executing all of that. There also may be some other details will help us to correctly reproduce the scenario. Thank You in advance.

[ihor-sviziev]

@magento give me test instance

[magento-engcom-team]

Hi @ihor-sviziev. Thank you for your request. I'm working on Magento instance for you

[ihor-sviziev]

@magento give me 2.3-develop instance

[magento-engcom-team]

Hi @ihor-sviziev. Thank you for your request. I'm working on Magento 2.3-develop instance for you

[magento-engcom-team]

Hi @ihor-sviziev, here is your new Magento instance.
Admin access: https://pr-25325.instances.magento-community.engineering/admin
Login: admin Password: 123123q

[ihor-sviziev]

@engcom-Bravo,
Steps to reproduce:

1. Open Google Chrome developer tools
2. Navigate to homepage
3. In Google Chrome dev tools looks at any .js file (I checked on domReady.js file), look at "Response Headers" section

On 2.3-develop:
❌ Cache-Control header is missin

On this PR:
✔ Cache-Control header is present

In order to make full testing - you need to setup Magento with CDN, for instance CloudFlare or CloudFront and re-check that requests are cached in browser and no requests for .html files were sent to server.

I just tried to test it on test instances and found another issue - #25578.
But anyway that's separate issue that need to be fixed

[engcom-Bravo]

Thank You, @ihor-sviziev. Before proceeding to full testing, can You tell me please if this fix is supposed to be detected on the local environment. Yes, I see it works on the instances You requested above. But I can't see it working on my local instance. In fact Cache-Control header is present only for the main requested recourse, i.e. for example for the testcategory.html if we talk about category page with testcategory url key. Besides it appears only in developer mode and looks differently meaning it contains more information than just "public".

[engcom-Bravo]

✔️ QA Passed

[m2-assistant]

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