Support configuring cache-control for index.html when using BP_WEB_SERVER

[uqix]

Before using this buildpack, we use the nginx configuration below to disable cache for index.html:

        # https://stackoverflow.com/a/41635866
        location / {
          try_files $uri $uri/ /index.html;
          gzip_static on;
        }
        location = /index.html {
          add_header cache-control {{ .Values.indexHtmlCacheControl | squote }};
          add_header last-modified '';
          etag off;
        }

it seems this buildpack doesn't provide such option.

Describe the Enhancement

Possible Solution

Motivation

Explicit cache-control for index.html page is more controllable.

[arjun024]

BP_WEB_SERVER is designed for an application to serve the most basic static file applications. See the RFC https://github.com/paketo-buildpacks/rfcs/blob/main/text/web-servers/0004-zero-config.md#detailed-explanation

For your use case, I would suggest you to provide your own nginx.conf.
See example https://github.com/paketo-buildpacks/samples/tree/main/web-servers/nginx-sample

[uqix]

Thanks, just realized the root cause is the normalized image date, will try to fix that by SOURCE_DATE_EPOCH as described in https://github.com/buildpacks/rfcs/blob/main/text/0103-source-date-epoch.md

[uqix]

Same problem as #447