osm-vector-maps/README.md & osm_vector_maps_enabled experiment for IIAB 7.2 RC2

roles/osm-vector-maps/README.md

@@ -2,14 +2,16 @@
 
 1. Some variables have newer meanings:
     1. `osm_vector_maps_install` in `/etc/iiab/local_vars.yml` means install the map program (about 40MB).
-    2. `osm_vector_maps_enabled` in `/etc/iiab/local_vars.yml` is not currently in use.  [why if so?]
-    3. `osm_vector_maps_installed` in `/etc/iiab/iiab_state.yml` means it's been installed.  [no longer means "install a functioning world map to zoom 10 (about 2.8GB)" right?]
-2. There's an "Install IIAB Maps" page (http://box/osm-vector-maps/installer/) separate from the Admin Console, to help you download Map Pack(s) for your favorite continents, and Hi-Res Satellite Photo Imagery for (square) local regions.  This lets you to add satellite photos with 4 more levels of zoom (i.e. zoom level 10-13) to get 16X the resolution (i.e. 19 x 19 m pixels) — as compared to zoom level 9 (i.e. 306 x 306 m pixels) everywhere else.
+    2. `osm_vector_maps_enabled` in `/etc/iiab/local_vars.yml` was not in use.  [CAN WE SPELL OUT WHY?  SEE tasks/nginx.yml AND TKTS BELOW]
+    3. `osm_vector_maps_installed` in `/etc/iiab/iiab_state.yml` means a functioning world map to with 7 levels of zoom (z0-z6) has been installed.  [NO LONGER 2.8GB & HOURLONG WAIT TO DOWNLOAD 10 ZOOM LEVELS PER #2484, PR #2486, PR #2487 ETC]
+2. There's an "Install IIAB Maps" page (http://box/osm-vector-maps/installer/) separate from the Admin Console, to help you download Map Pack(s) for your favorite continents, and Hi-Res Satellite Photo Regions serving local communities.
+    1. Hi-Res Satellite Photo Regions are 'squares' with 4 more levels of satellite photo zoom (i.e. zoom levels 10-13) giving you 16X the resolution (i.e. 19 x 19 m pixels) and 256X more photographic information density.
+    2. As compared to Lo-Res Satellite Photos i.e. zooms level 0-9 (306 x 306 m pixels) everywhere else on the planet.
 3. OpenStreetMap Vector Maps: multiple Map Packs can be installed (one "continent" at a time).
 4. Hi-Res Satellite Photos: multiple local regions can be installed (one "square" at a time).
 5. Hi-Res Satellite Photos can be downloaded for any 100 x 100 km, 300 x 300 km, or 1000 x 1000 km square region (around a selected map point).
-6. More recent OSM data is used in the vector tiles (2017 => 2019).  [is this included in all 12 Map Packs? who did the 2019 updates?]
-7. The base install (world view) increases zoom levels from 0-9 to 0-10, so that city search is successful more of the time.  [is this included in all 12 Map Packs?]
-8. There is a new drag-and-drop feature which permits the student to add descriptions and pictures about local points of interest, and then save and restore them using their local browser.  [by right clicking? any teacher tips and/or hints as to how this works?]
+6. Map Packs' OSM vector tile data (from 2017) was updated to 2019 data.  [WHO GENERATED THE 2019 VECTOR TILES?  WHEN IN 2019?]
+7. The base install (world view) increases zoom levels from 0-9 to 0-10, so that city search is successful more of the time.
+8. There is a new drag-and-drop feature which permits the student to add descriptions and pictures about local points of interest, and then save and restore them using their local browser.  [BY RIGHT CLICKING?  ANY TEACHER TIPS AND/OR HINTS AS TO HOW THIS WORKS?]
 
 #### Please also see our IIAB Maps doc: https://github.com/iiab/iiab/wiki/IIAB-Maps

roles/osm-vector-maps/tasks/install.yml

@@ -192,7 +192,8 @@
     - iiab-make-init.py
     - iiab-update-map
 
-# nginx.yml handles this, right?
+# nginx.yml handles this.  Please see discussion/question in tasks/nginx.yml
+#
 #- name: Install /etc/nginx/osm-vector-maps-nginx.conf from template
 #  template:
 #    src: osm-vector-maps-nginx.conf.j2

roles/osm-vector-maps/tasks/main.yml

@@ -18,7 +18,7 @@
 
 - name: Enable/Disable/Reload NGINX for OSM, if nginx_enabled
   include_tasks: nginx.yml
-  #when: nginx_enabled | bool
+  #when: nginx_enabled | bool    # NGINX is mandatory starting with IIAB 7.2
 
 
 - name: Add 'osm-vector-maps' variable values to {{ iiab_ini_file }}

roles/osm-vector-maps/tasks/nginx.yml

@@ -2,14 +2,26 @@
   template:
     src: osm-vector-maps-nginx.conf.j2
     dest: "{{ nginx_conf_dir }}/osm-vector-maps-nginx.conf"    # /etc/nginx/conf.d
-  when: osm_vector_maps_install | bool
+  when: osm_vector_maps_enabled | bool
+  #when: osm_vector_maps_install | bool
+
 # Note that the above change from enabled->install is required by the OSM command line installer
 
+# 2020-09-29: @georgejhunt can u explain more the PR #2486 comment just above ?
+#
+# osm_vector_maps_install is _always_ true here, so doesn't serve a purpose in
+# when: conditions.  What underlying issue are we trying to solve?  If this is
+# to enable a functioning world map to zoom level 7-or-10, can we be honest in
+# saying "enablement" IS essentially required...in most/all situations?  @holta
+#
+# SEE: #2484, PR #2486, #2487 mentioned @ roles/osm-vector-maps/README.md
+
 - name: Disable http://box/maps & http://box/osm-vector-maps via NGINX, by removing {{ nginx_conf_dir }}/osm-vector-maps-nginx.conf
   file:
     path: "{{ nginx_conf_dir }}/osm-vector-maps-nginx.conf"    # /etc/nginx/conf.d
     state: absent
-  when: not osm_vector_maps_install
+  when: not osm_vector_maps_enabled
+  #when: not osm_vector_maps_install
 
 - name: Reload 'nginx' systemd service
   systemd: