stats lambda: better caching (or lack thereof) & error handling

functions/send_view.js

@@ -1,60 +1,80 @@
 const axios = require("axios");
 
 exports.handler = function (event, context, callback) {
-  // if triggered as an image without JS (i.e. from AMP pages) set `?noscript=true`
-  const noScript = event.queryStringParameters["noscript"] === "true";
+  try {
+    // if triggered as an image without JS (i.e. from AMP pages) set `?noscript=true`
+    const noScript = event.queryStringParameters["noscript"] === "true";
 
-  // https://docs.simpleanalytics.com/without-javascript
-  const endpointPath = noScript ? "noscript.gif" : "simple.gif";
-  const endpointUrl = "https://queue.simpleanalyticscdn.com/" + endpointPath;
+    // https://docs.simpleanalytics.com/without-javascript
+    const endpointHost = "queue.simpleanalyticscdn.com";
+    const endpointPath = noScript ? "noscript.gif" : "simple.gif";
+    const endpointUrl = "https://" + endpointHost + "/" + endpointPath;
 
-  // pass these headers along to SA
-  const reqHeaders = {
-    referer: event.headers["referer"] || "",
-    "user-agent": event.headers["user-agent"] || "",
-  };
+    // pass these headers along to SA
+    const reqHeaders = {
+      referer: event.headers["referer"] || "",
+      "user-agent": event.headers["user-agent"] || "",
+    };
 
-  // pass these URL parameters along to SA
-  const reqQuery = event.queryStringParameters;
-  reqQuery["ignore-dnt"] = "true"; // this isn't nefarious, we're not tracking in the first place!
+    // pass these URL parameters along to SA
+    const reqQuery = event.queryStringParameters;
+    reqQuery["ignore-dnt"] = "true"; // this isn't nefarious, we're not tracking in the first place!
 
-  const reqConfig = {
-    method: "GET",
-    url: endpointUrl,
-    headers: reqHeaders,
-    params: reqQuery,
-    responseType: "arraybuffer",
-    timeout: 3000,
-  };
+    const reqConfig = {
+      method: "GET",
+      url: endpointUrl,
+      headers: reqHeaders,
+      params: reqQuery,
+      responseType: "arraybuffer",
+      timeout: 2000,
+    };
 
-  console.info(`Proxying ${reqQuery["type"]} to ${endpointPath} ...`);
+    console.info(`Proxying ${reqQuery["type"]} to ${endpointPath} ...`);
 
-  axios
-    .request(reqConfig)
-    .then(function (response) {
-      console.info(response.status, response.headers["simple-analytics-feedback"]);
+    axios
+      .request(reqConfig)
+      .then(function (response) {
+        // parse the feedback message from SA
+        const apiFeedback = response.headers["simple-analytics-feedback"] || "No feedback from Simple Analytics.";
+        const shortFeedback = apiFeedback.toLowerCase().includes("thanks for sending") ? "OK" : `ERROR: ${apiFeedback}`;
 
-      // imitate the headers that would normally be sent back from SA's pixel
-      const resHeaders = {
-        "cache-control": "no-cache, no-store, must-revalidate",
-        "content-type": response.headers["content-type"],
-        "x-api-feedback": response.headers["simple-analytics-feedback"],
-        "x-api-destination": response.headers["simple-analytics-location"],
-      };
+        console.info(response.status, apiFeedback);
 
-      callback(null, {
-        statusCode: response.status,
-        headers: resHeaders,
-        body: response.data.toString("base64"),
-        isBase64Encoded: true,
+        // imitate the headers that would normally be sent back from SA's pixel
+        const resHeaders = {
+          "Content-Type": "image/gif",
+          "Cache-Control": "private, no-cache, no-store, must-revalidate",
+          Expires: "0",
+          Pragma: "no-cache",
+          "X-API-Response": shortFeedback,
+          "X-API-Endpoint": endpointHost,
+        };
+
+        // reasoning for base64 encoding:
+        // https://community.netlify.com/t/debugging-a-function-returns-502/429/12
+        callback(null, {
+          statusCode: response.status,
+          headers: resHeaders,
+          body: response.data.toString("base64"),
+          isBase64Encoded: true,
+        });
+      })
+      .catch(function (error) {
+        // this indicates a function error, NOT an error returned from SA
+        throw error;
       });
-    })
-    .catch(function (error) {
-      // this indicates a function error, NOT an error returned from SA
-      console.log(error);
+  } catch (error) {
+    // something went VERY wrong...
+    console.log(error.message);
 
-      callback(null, {
-        statusCode: 500,
-      });
+    callback(null, {
+      statusCode: 500,
+      headers: {
+        "Content-Type": "application/json",
+      },
+      body: JSON.stringify({
+        error: error.message,
+      }),
     });
+  }
 };