POC of image service

src/api/image/README.md

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+# Image Service
+
+The Image Service can optimize images at a URL, or provide optimized backgrounds.
+
+## Install
+
+```
+npm install
+```
+
+## Usage
+
+By default the server is running on http://localhost:4444/.
+
+You can use any/all the following optional query params:
+
+1. `w` - the desired width. Must be between `200` and `4592`. Defaults to `800` if missing.
+1. `t` - the desired image type. Must be one of `jpeg`, `jpg`, `webp`, `png`, or `avif`. Defaults to `jpeg`.
+1. `u` - an image URL to use as the source. Must be an absolute HTTP/HTTPS encoded URL.
+
+### Examples
+
+- `GET /` - returns the default background JPEG with width = 800px
+- `GET /?w=1024`- returns the default background JPEG with width = 1024px
+- `GET /?t=png`- returns the default background JPEG with width = 800px as a PNG
+- `GET /?u=https://example.com/image` - returns the image at the given URL as a JPEG at 800px
+- `GET /?w=500&t=webp&u=https://example.com/image` - returns the image at the given URL as a WebP at 500px

src/api/image/app.js

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+const express = require('express');
+const cors = require('cors');
+const helmet = require('helmet');
+const service = require('./service');
+
+const app = express();
+app.use(helmet());
+app.use(cors());
+
+// TODO: figure out how to do logging for each service...
+// app.set('logger', logger);
+// app.use(logger);
+
+// Include our router with all endpoints
+app.use('/', service);
+
+// TODO: what to do with default error handler...
+// app.use(errorHandler);
+
+module.exports = app;

src/api/image/image.js

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+const sharp = require('sharp');
+
+// TODO: logging
+
+// https://sharp.pixelplumbing.com/api-resize
+const resize = (width) => {
+  const s = sharp({ failOnError: false });
+  // Only resize if we're given a width
+  return width > 0 ? s.resize({ width }) : s;
+};
+
+const transformers = {
+  // https://sharp.pixelplumbing.com/api-output#jpeg
+  jpeg: (width) => resize(width).jpeg(),
+  // https://sharp.pixelplumbing.com/api-output#avif
+  avif: (width) => resize(width).avif(),
+  // https://sharp.pixelplumbing.com/api-output#png
+  png: (width) => resize(width).png(),
+  // https://sharp.pixelplumbing.com/api-output#webp
+  webp: (width) => resize(width).webp(),
+};
+
+/**
+ * OptDownloads and reduces the image at `url` to the given `width`, sending
+ * the response back on the `res` stream.
+ */
+function optimize({ imgStream, width, imageType, res }) {
+  const transformer = transformers[imageType](width);
+
+  // TODO: build more error handling on this...
+  const transformErrorHandler = (err) => {
+    console.error(err);
+    // 400 or 500? The image at the given URL isn't valid
+    res.status(500).end();
+  };
+
+  // TODO: better logging/errors
+  return imgStream.pipe(transformer).on('error', transformErrorHandler);
+}
+
+function setType(type = 'jpeg', res) {
+  switch (type.toLowerCase()) {
+    case 'avif':
+      res.type('image/avif');
+      return 'avif';
+    case 'webp':
+      res.type('image/webp');
+      return 'webp';
+    case 'png':
+      res.type('image/png');
+      return 'png';
+    case 'jpeg':
+    case 'jpg':
+    default:
+      res.type('image/jpeg');
+      return 'jpeg';
+  }
+}
+
+module.exports.setType = setType;
+module.exports.optimize = optimize;

src/api/image/index.js

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+const app = require('./app.js');
+
+const server = app.listen(process.env.PORT || 4444);
+
+module.exports = server;

src/api/image/package.json

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+{
+  "name": "@seneca/telescope-image",
+  "private": true,
+  "version": "0.0.1",
+  "description": "A service for optimizing images",
+  "scripts": {
+    "start": "node index.js"
+  },
+  "repository": "Seneca-CDOT/telescope",
+  "license": "BSD-2-Clause",
+  "bugs": {
+    "url": "https://github.com/Seneca-CDOT/telescope/issues"
+  },
+  "homepage": "https://github.com/Seneca-CDOT/telescope#readme",
+  "dependencies": {
+    "body-parser": "1.19.0",
+    "celebrate": "^13.0.4",
+    "cors": "2.8.5",
+    "express": "4.17.1",
+    "express-handlebars": "5.1.0",
+    "got": "^11.8.1",
+    "helmet": "4.1.1",
+    "sharp": "^0.27.1"
+  },
+  "engines": {
+    "node": ">=12.0.0"
+  }
+}

src/api/image/service.js

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+const path = require('path');
+const fs = require('fs');
+const express = require('express');
+const got = require('got');
+const { celebrate, Joi, errors, Segments } = require('celebrate');
+
+const { optimize, setType } = require('./image');
+
+const router = express.Router();
+
+const defaultImagePath = path.join(__dirname, 'default.jpg');
+
+const defaultImageStream = () => fs.createReadStream(defaultImagePath);
+
+const urlImageStream = (url) => got.stream(url);
+
+/**
+ * Support the following query params, all optional:
+ *
+ *  - u: the image URL to download and resize. Must be absolute http/https
+ *  - w: the width to resize the image to. Must be 200-4592. Defaults to 800.
+ *  - t: the image type to render, one of: jpeg/jpeg, png, webp, avif. Defaults to jpeg.
+ */
+const schema = {
+  [Segments.QUERY]: Joi.object().keys({
+    t: Joi.string(),
+    w: Joi.number().integer().min(200).max(4592),
+    u: Joi.string().uri({
+      scheme: ['http', 'https'],
+    }),
+  }),
+};
+
+const optimizeImage = (req, res) => {
+  const { t, w, u } = req.query;
+
+  // We use 800 for the width if none is given
+  const width = w ? parseInt(w, 10) : 800;
+
+  // Set the header and normalize the image type we'll stream
+  const imageType = setType(t, res);
+
+  // Use the provided URL or fall-back to our default image
+  const stream = u ? urlImageStream(u) : defaultImageStream();
+
+  // Deal with URL not being resolvable
+  stream.on('error', (err) => {
+    console.error(err);
+    // 400 or 500?  The client is asking for a URL we can't get...
+    res.status(500).end();
+  });
+
+  // Optimize this image and stream back to the client
+  optimize({
+    imgStream: stream,
+    width,
+    imageType,
+    res,
+  }).pipe(res);
+};
+
+router.use('/', celebrate(schema), optimizeImage);
+router.use(errors());
+
+module.exports = router;