Use redis for caching

README.md

@@ -6,10 +6,26 @@ Node application that proxies requests to NASA's **A**stronomy **P**icture **O**
 
 An API key for `api.nasa.gov` is required. A key can be generated in about 5 seconds at: https://api.nasa.gov/#signUp
 
+Redis is running inside docker.
+
 ## Run
 
+Start up redis using `docker-compose`:
+
+```
+docker-compose up
+```
+
 To run the server on port 3000:
 
 ```
 NASA_API_KEY=<nasa-api-key-here> npm start
 ```
+
+## Use
+
+Hit the root endpoint with or without a date.  Any request made with a date will have its response cached for 60 minutes.
+
+```
+curl https://localhost:3000/?date=2019-10-28
+```

app.js

@@ -1,16 +1,18 @@
 const express = require('express');
+const redis = require('redis');
 const cookieParser = require('cookie-parser');
 const logger = require('morgan');
 
 const indexRouter = require('./routes/index');
 
 const app = express();
+const redisClient = redis.createClient();
 
 app.use(logger('dev'));
 app.use(express.json());
 app.use(express.urlencoded({ extended: false }));
 app.use(cookieParser());
 
-app.use('/', indexRouter(process.env.NASA_API_KEY));
+app.use('/', indexRouter(process.env.NASA_API_KEY, redisClient));
 
 module.exports = app;

docker-compose.yml

@@ -0,0 +1,7 @@
+version: "3.1"
+
+services:
+  redis:
+    image: "redis:alpine"
+    ports:
+    - 6379:6379

monitor.sh

@@ -2,7 +2,7 @@
 set -e
 
 while true; do
-  curl -s -o /dev/null -w "%{http_code}" http:https://apod-proxy.cfapps.io
+  curl -s -o /dev/null -w "%{http_code}" https:https://apod-proxy.apps.pcfone.io/
   printf "\n"
   sleep 1
 done

package.json

@@ -10,7 +10,8 @@
     "cookie-parser": "~1.4.4",
     "debug": "~2.6.9",
     "express": "~4.16.1",
-    "morgan": "~1.9.1"
+    "morgan": "~1.9.1",
+    "redis": "^2.8.0"
   },
   "engines": {
     "node": "13.1.0"

routes/index.js

@@ -10,13 +10,45 @@ function extractDate(date) {
   return date;
 }
 
-function index(nasaApiKey) {
-  router.get('/', async function(req, res, next) {
+function saveToCache(redisClient, key, value) {
+  redisClient.setex(key, 60 * 60, JSON.stringify(value));
+}
+
+function handleRequest(nasaApiKey, redisClient) {
+  return async (req, res, next) => {
     const date = extractDate(req.query.date);
     const desc = await client.getApodDesc(nasaApiKey, date);
+    const body = { desc };
+
+    await res.json(body);
+    saveToCache(redisClient, date, body);
+  }
+}
+
+function checkCache(redisClient) {
+  return (req, res, next) => {
+    const date = extractDate(req.query.date);
+
+    if (date === 'today') {
+      next();
+      return;
+    }
+
+    redisClient.get(date, (err, data) => {
+      if (data !== null) {
+        res.send(data);
+      } else {
+        next();
+      }
+    });
+  }
+}
 
-    await res.json({ desc });
-  });
+function index(nasaApiKey, redisClient) {
+  router.get('/',
+      checkCache(redisClient),
+      handleRequest(nasaApiKey, redisClient)
+  );
 
   return router;
 }