tar1090 config: add arbitrary config options

README.md

@@ -330,6 +330,27 @@ All of the variables below are optional.
 | `TAR1090_RANGERINGSDISTANCES` | Distances to display range rings, in miles, nautical miles, or km (depending settings value '`TAR1090_DISPLAYUNITS`'). Accepts a comma separated list of numbers (no spaces, no quotes).                                          | `100,150,200,250` |
 | `TAR1090_RANGERINGSCOLORS`    | Colours for each of the range rings specified in `TAR1090_RANGERINGSDISTANCES`. Accepts a comma separated list of hex colour values, each enclosed in single quotes (eg `TAR1090_RANGERINGSCOLORS='#FFFFF','#00000'`). No spaces. | Blank             |
 
+#### `tar1090` `config.js` Configuration - Expert
+
+| Environment Variable         | Purpose                                              | Default   |
+| ---------------------------- | ---------------------------------------------------- | --------- |
+| `TAR1090_CONFIG_JS_APPEND`   | Append arbitrary javascript code to config.js        | Unset     |
+
+- In case a setting is available in tar1090 but not exposed via environment variable for this container
+- For a list of possible settings, see <https://github.com/wiedehopf/tar1090/blob/master/html/config.js>
+- Incorrect syntax or any capitalization errors will cause the map to not load, you have been warned!
+- Example: `TAR1090_CONFIG_JS_APPEND= MapDim=false; nexradOpacity=0.2;`
+- In the environment section of a compose file you can generally use multiple lines like this:
+```yaml
+    environment:
+    ...
+      - TAR1090_CONFIG_JS_APPEND=
+        MapDim=false;
+        nexradOpacity=0.2;
+    ...
+```
+
+
 ### `tar1090` Route Display Configuration
 
 | Environment Variable  | Purpose                                            | Default                               |

rootfs/etc/s6-overlay/startup.d/04-tar1090-configure

@@ -184,6 +184,10 @@ if [[ -n "$TAR1090_ROUTEAPIURL" ]]; then
   echo "routeApiUrl = ${TAR1090_ROUTEAPIURL};"
 fi
 
+if [[ -n "$TAR1090_CONFIG_JS_APPEND" ]]; then
+  echo "$TAR1090_CONFIG_JS_APPEND"
+fi
+
 } >> "${TAR1090_INSTALL_DIR}/html-webroot/config.js"
 
 if chk_enabled "$TAR1090_LABEL_GROUND_SHOWALL"; then