feat(log): Log structured data about Placeholder requests

Structured logs allow later analysis with details like query parameters,
request time, etc.

controller/placeholder.js

@@ -228,8 +228,17 @@ function setup(placeholderService, do_geometric_filters_apply, should_execute) {
       return next();
     }
     const initialTime = debugLog.beginTimer(req);
+    const start = Date.now();
 
     placeholderService(req, (err, results) => {
+      logger.info('placeholder', {
+        response_time: Date.now() - start,
+        params: req.clean,
+        result_count: _.defaultTo(res.data, []).length,
+        text_length: _.get(req, 'clean.text.length', 0),
+        controller: 'placeholder',
+      });
+
       if (err) {
         // push err.message or err onto req.errors
         req.errors.push( _.get(err, 'message', err));

middleware/changeLanguage.js

@@ -32,6 +32,7 @@ function setup(service, should_execute) {
       return next();
     }
 
+    const start = Date.now();
     service(req, res, (err, translations) => {
       // if there's an error, log it and bail
       if (err) {
@@ -40,6 +41,12 @@ function setup(service, should_execute) {
         return next();
       }
 
+      logger.info('language', {
+        response_time: Date.now() - start,
+        language: req.clean.lang.iso6391,
+        controller: 'language', //technically middleware, but this is consistent with other log lines
+      });
+
       // otherwise, update all the docs with translations
       updateDocs(req, res, _.defaultTo(translations, []));
       next();