added nodejs8 aws lambda boilerplate (#790)

community/boilerplates/event-triggers/aws-lambda/nodejs8/echo/README.md

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+# Setup tables
+1. Create table:
+
+```
+notes:
+  id: int
+  note: text
+```
+
+# Setup AWS Lambda
+Create a lambda function in AWS. This will be our webhook.
+
+1. Create a function.
+2. Select Node.js 8.10 as the runtime.
+3. Select "start from scratch".
+4. Add API gateway as a trigger.
+5. Add an API to API gateway.
+6. Add the code in `index.js`. The handler function of your lambda will be the `index.handler`.
+
+# Add the trigger in Hasura GraphQL
+1. In events tab, add a trigger
+2. Select all insert, update, delete operations for the trigger.
+3. Paste the API endpoint of your AWS lambda as the webhook.

community/boilerplates/event-triggers/aws-lambda/nodejs8/echo/index.js

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+exports.handler = async (event) => {
+  let response = {}
+  try {
+    let { table: { name }, event: { op, data } } = event.body;
+    response.statusCode = 200;
+    if (name === "notes" && op === "INSERT") {
+      response.body = `New note ${data.new.id} inserted, with data: ${data.new.note}`;
+    }
+    else if (name === "notes" && op === "UPDATE") {
+      response.body = `Note ${data.new.id} updated, with data: ${data.new.note}`;
+    }
+    else if (name === "notes" && op === "DELETE") {
+      response.body = `Note ${data.old.id} deleted, with data: ${data.old.note}`;
+    }
+    return response
+  } catch (e) {
+    response.statusCode = 400;
+    response.body = "cannot parse hasura event";
+    return response
+  }
+};

community/boilerplates/event-triggers/aws-lambda/nodejs8/mutation/.gitignore

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+node_modules
+*.zip

community/boilerplates/event-triggers/aws-lambda/nodejs8/mutation/README.md

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+# Setup tables
+
+1. Create the table using the console:
+
+```
+Table name: notes
+
+Columns:
+id: Integer auto-increment
+note: Text
+
+Table name: note_revision
+
+Columns:
+id: Integer auto-increment
+note: Text
+note_id: Integer (foreign key to notes.id)
+update_at: Timestamp, default `now()`
+
+```
+
+# Setup AWS Lambda
+Create a lambda function in AWS. This will be our webhook.
+
+1. In this folder, run `npm install`
+2. Then create a zip: `zip -r hge-mutation.zip .`
+3. Create a Lambda function.
+4. Select Node.js 8.10 as the runtime.
+5. Select "start from scratch".
+6. Add API gateway as a trigger.
+7. Add an API to API gateway.
+8. Upload the zip from previous step. The handler function of your lambda will be `index.handler`.
+9. Add the following enviroment variables in your lambda config:
+   1. `ACCESS_KEY`: this is the access key you configured when you setup HGE.
+   2. `HGE_ENDPOINT`: the URL on which you HGE instance is running.
+
+# Add the trigger in Hasura GraphQL
+1. In events tab, add a trigger
+2. Select all insert, update, delete operations for the trigger.
+3. Paste the API endpoint of your AWS lambda as the webhook.

community/boilerplates/event-triggers/aws-lambda/nodejs8/mutation/index.js

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+// Lambda which gets triggered on insert, and in turns performs a mutation
+
+const fetch = require('node-fetch');
+
+const accessKey = process.env.ACCESS_KEY;
+const hgeEndpoint = process.env.HGE_ENDPOINT;
+
+const query = `
+mutation updateNoteRevision ($noteId: Int!, $data: String!) {
+  insert_note_revision (objects: [
+    {
+      note_id: $noteId,
+      note: $data
+    }
+  ]) {
+    affected_rows
+  }
+}
+`;
+
+exports.handler = async (event) => {
+  try {
+    const qv = { noteId: event.body.event.data.old.id, data: event.body.event.data.old.note };
+    const result = await fetch(hgeEndpoint + '/v1alpha1/graphql', {
+      method: 'POST',
+      body: JSON.stringify({ query: query, variables: qv }),
+      headers: { 'Content-Type': 'application/json', 'x-hasura-access-key': accessKey },
+    });
+    
+    const { errors, data } = await result.json();
+
+    if (errors) {
+      throw new Error(errors);
+    } else {
+      return {
+        statusCode: 200,
+        body: "success"
+      };
+    }
+  } catch (e) {
+    return {
+      statusCode: 400,
+      body: "cannot parse hasura event"
+    };
+  }
+};

community/boilerplates/event-triggers/aws-lambda/nodejs8/mutation/package.json

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+{
+  "name": "mutation-trigger",
+  "version": "1.0.0",
+  "description": "sample lambda to react to database updates",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "license": "ISC",
+  "dependencies": {
+    "node-fetch": "^2.2.0"
+  }
+}