Limit catalog-proxy traffic to only from Cloudfront

[nickumia-reisys]

User Story

In order to complete #4059, the Data.gov O&M team wants to implement a new solution to track whether requests are coming from cloudfront or not.

Acceptance Criteria

• GIVEN the nginx config has been updated and deployed
  AND Forward User-Agent from AWS CloudFront to catalog app #4059 is implemented
  WHEN I visit catalog.data.gov
  THEN I am able to visit the site without issues

Background

• Hide/Redirect cloud.gov url for catalog app if it is behind CDN #3909
  • Nginx conf rework catalog.data.gov#512
  • allow health check catalog.data.gov#515

Security Considerations (required)

...

Sketch

See @FuhuXia

• Preliminary work has been started, Use HOST know whether we are from CDN catalog.data.gov#1014

[nickumia-reisys]

Completed manually, assisted by

• Add PUBLIC_ROUTE into nginx server_name catalog.data.gov#1046