add following handler cloud run service

packages/following-handler/.dockerignore

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+node_modules
+build
+.env*
+Dockerfile
+.dockerignore

packages/following-handler/.eslintignore

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+node_modules/
+build/

packages/following-handler/.eslintrc

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+{
+  "extends": "../../.eslintrc",
+  "parserOptions": {
+    "project": "tsconfig.json"
+  }
+}

packages/following-handler/.gcloudignore

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+# This file specifies files that are *not* uploaded to Google Cloud Platform
+# using gcloud. It follows the same syntax as .gitignore, with the addition of
+# "#!include" directives (which insert the entries of the given .gitignore-style
+# file at that point).
+#
+# For more information, run:
+#   $ gcloud topic gcloudignore
+#
+.gcloudignore
+# If you would like to upload your .git directory, .gitignore file or files
+# from your .gitignore file, remove the corresponding line
+# below:
+.git
+.gitignore
+
+node_modules

packages/following-handler/Dockerfile

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+FROM node:18.16-alpine
+
+# Run everything after as non-privileged user.
+WORKDIR /app
+
+COPY package.json .
+COPY yarn.lock .
+COPY tsconfig.json .
+COPY .eslintrc .
+
+COPY /packages/following-handler/package.json ./packages/following-handler/package.json
+
+RUN yarn install --pure-lockfile
+
+COPY /packages/following-handler ./packages/following-handler
+RUN yarn workspace @omnivore/rss-handler build
+
+# After building, fetch the production dependencies
+RUN rm -rf /app/packages/following-handler/node_modules
+RUN rm -rf /app/node_modules
+RUN yarn install --pure-lockfile --production
+
+EXPOSE 8080
+
+CMD ["yarn", "workspace", "@omnivore/following-handler", "start"]
+

packages/following-handler/mocha-config.json

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+{
+    "extension": ["ts"],
+    "spec": "test/**/*.test.ts",
+    "require": "test/babel-register.js"
+  }

packages/following-handler/package.json

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+{
+  "name": "@omnivore/following-handler",
+  "version": "1.0.0",
+  "main": "build/src/index.js",
+  "files": [
+    "build/src"
+  ],
+  "license": "Apache-2.0",
+  "scripts": {
+    "test": "yarn mocha -r ts-node/register --config mocha-config.json",
+    "test:typecheck": "tsc --noEmit",
+    "lint": "eslint src --ext ts,js,tsx,jsx",
+    "compile": "tsc",
+    "build": "tsc",
+    "start": "functions-framework --target=followingHandler",
+    "dev": "concurrently \"tsc -w\" \"nodemon --watch ./build/ --exec npm run start\""
+  },
+  "devDependencies": {
+    "chai": "^4.3.6",
+    "eslint-plugin-prettier": "^4.0.0",
+    "mocha": "^10.0.0"
+  },
+  "dependencies": {
+    "@google-cloud/functions-framework": "3.1.2",
+    "@sentry/serverless": "^7.77.0",
+    "dotenv": "^16.0.1"
+  },
+  "volta": {
+    "extends": "../../package.json"
+  }
+}

packages/following-handler/src/index.ts

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+import * as Sentry from '@sentry/serverless'
+import * as dotenv from 'dotenv' // see https://github.com/motdotla/dotenv#how-do-i-use-dotenv-with-import
+
+dotenv.config()
+Sentry.GCPFunction.init({
+  dsn: process.env.SENTRY_DSN,
+  tracesSampleRate: 0,
+})
+
+export const followingHandler = Sentry.GCPFunction.wrapHttpFunction(
+  (req, res) => {
+    if (req.query.token !== process.env.PUBSUB_VERIFICATION_TOKEN) {
+      console.log('query does not include valid token')
+      return res.sendStatus(403)
+    }
+
+    res.send('ok')
+  }
+)

packages/following-handler/test/babel-register.js

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+const register = require('@babel/register').default
+
+register({ extensions: ['.ts', '.tsx', '.js', '.jsx'] })

packages/following-handler/test/stub.test.ts

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+import { expect } from 'chai'
+import 'mocha'
+
+describe('stub test', () => {
+  it('should pass', () => {
+    expect(true).to.be.true
+  })
+})

packages/following-handler/tsconfig.json

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+{
+  "extends": "./../../tsconfig.json",
+  "compilerOptions": {
+    "outDir": "build",
+    "rootDir": "."
+  },
+  "include": ["src"]
+}