Use a template for our simplest nginx configs

[acozine]

DRAFT ONLY - includes changes for testing that must not be merged.

This approach would convert a majority of our nginx config files to variables that run through a template. Currently addresses our two most common use cases:

• public/production sites with a single location definition
• private/staging sites with a single location definition that are restricted to the VPN

[acozine]

A quick look at a few config files uncovers a few differences among sites. Known needed changes:

• add a var for the HTTP load-balancing technique (see annotations-prod)
• add a section for enabling/disabling app_protect (see abid-staging)
• allow more than one included restrict file (see bibdata-qa)
• regularize an ansible-managed comment

With these changes done, we can try using the template for these sites:

• abid
• annotations
• ansible-tower
• approvals
• bibdata
• byzantine-tsp
• cicognara
• eal-apps
  . . . and probably more.

Once the changes are ready, we can put the vars in place and create the templated files in /tmp/, then diff the files against the actual nginxplus config files to identify any changes/drift.

[acozine]

Add a variable for the health check page (see Drupal sites for examples).

[acozine]

Current CI failure is:

  TASK [nginxplus : Setup | Upload NGINX HTTP Configuration Files] ***************
  fatal: [instance]: FAILED! => {"msg": "Invalid data passed to 'loop', it requires a list, got this instead: conf/http/*.conf. Hint: If you passed a list/dict of just one element, try adding wantlist=True to your lookup invocation or use q/query instead of lookup."}

[acozine]

Closing in favor of #4397