Merge pull request #1 from WeltN24/addsnsrouting

add sns as routing provider

Author: chgohlke

README.md

@@ -5,7 +5,7 @@
 
 ## aws-lambda-router
 
-A small library providing routing for AWS ApiGateway ```any``` method
+A small library providing routing for AWS ApiGateway Proxy Integrations and SNS...
 
 ## Install
 
@@ -16,40 +16,57 @@ $ npm install aws-lambda-router
 ## Usage
 
 ```js
-const httpRouteHandler = require('aws-lambda-router');
-
-exports.handler = httpRouteHandler.handler({
-    cors: true,
-    routes: [
-        {
-            path: '/graphql',
-            method: 'POST',
-            action: request=>doAnything(request.body)
-        },
-        {
-            path: '/article/{id}',
-            method: 'GET',
-            action: request=>getArticleInfo(request.body)
-        },
-        {
-            path: '/:sourcepath',
-            method: 'DELETE',
-            action: request=>deleteSourcepath(request.paths.sourcepath)
+const router = require('aws-lambda-router');
+
+exports.handler = router.handler(
+    // the router-config contains configs for every type of 'processor'
+{
+    // for handling an http-call from an AWS Apigateway proxyIntegration we provide the following config:
+    proxyIntegration: {
+        // activate CORS on all http-methods:
+        cors: true,
+        routes: [
+            {
+                // the request-path-pattern to match:
+                path: '/graphql',
+                // http method to match
+                method: 'POST',
+                // provide a function to be called with the propriate data
+                action: request=>doAnything(request.body)
+            },
+            {
+                // request-path-pattern with a path variable:
+                path: '/article/:id',
+                method: 'GET',
+                // we can use the path param 'id' in the action call:
+                action: request=>getSomething(request.paths.id)
+            },
+            {
+                path: '/:id',
+                method: 'DELETE',
+                action: request=>deleteSomething(request.paths.id)
+            }
+        ],
+        debug: true,
+        errorMapping: {
+            'NotFound': 404,
+            'RequestError': 500
         }
-    ],
-    debug: true,
-    errorMapping: {
-        'NotFound': 404,
-        'RequestError': 500
+    },
+    // for handling calls initiated from AWS-SNS:
+    sns: {
+        routes: [
+            {
+                // a regex to match the content of the SNS-Subject:
+                subject: /.*/,
+                // Attention: the message is JSON-stringified 
+                action: sns => service.doSomething(JSON.parse(sns.Message))
+            }
+        ]
     }
 });
 ```
 
-## Publish a new version to npmjs.org
-
-
-
-
 ## local developement
 
 The best is to work with ```npm link```
@@ -59,5 +76,6 @@ See here: http://vansande.org/2015/03/20/npm-link/
 
 ## Release History
 
+* 0.2.0 Attention: breaking changes for configuration; add SNS event process
 * 0.1.0 make it work now 
 * 0.0.1 initial release

index.js

@@ -0,0 +1,50 @@
+"use strict";
+
+function handler(routeConfig) {
+    const eventProcessorMapping = extractEventProcessorMapping(routeConfig);
+    return (event, context, callback) => {
+        for (const eventProcessorName of eventProcessorMapping.keys()) {
+
+            try {
+                // the contract of 'processors' is as follows:
+                // - their method 'process' is called with (config, event)
+                // - the method...
+                //   - returns null: the processor does not feel responsible for the event
+                //   - throws Error: the 'error.toString()' is taken as the error message of processing the event
+                //   - returns object: this is taken as the result of processing the event
+                //   - returns promise: when the promise is resolved, this is taken as the result of processing the event
+                const result = eventProcessorMapping.get(eventProcessorName)(routeConfig[eventProcessorName], event);
+                if (result) {
+                    // be resilient against a processor returning a value instead of a promise:
+                    return Promise.resolve(result)
+                        .then(result => callback(null, result))
+                        .catch(error => {
+                            console.log(error.stack);
+                            callback(error.toString());
+                        });
+                }
+            } catch (error) {
+                if (error.stack) {
+                    console.log(error.stack);
+                }
+                callback(error.toString());
+                return;
+            }
+        }
+        callback('No event processor found to handle this kind of event!');
+    }
+}
+
+function extractEventProcessorMapping(routeConfig) {
+    const processorMap = new Map();
+    for (let key of Object.keys(routeConfig)) {
+        try {
+            processorMap.set(key, require(`./lib/${key}`));
+        } catch (error) {
+            throw new Error(`The event processor '${key}', that is mentioned in the routerConfig, cannot be instantiated (${error.toString()})`);
+        }
+    }
+    return processorMap;
+}
+
+module.exports = {handler: handler};

httpRouteHandler.js renamed to lib/proxyIntegration.js

@@ -1,62 +1,63 @@
 "use strict";
 
-// TODO: req id in log sync u async
-
-const NO_MATCHING_ACTION = request=> {
-    throw {reason: 'NO_MATCHING_ACTION', message: `Could not find matching action for ${request.path} and method ${request.httpMethod}`}
+const NO_MATCHING_ACTION = request => {
+    throw {
+        reason: 'NO_MATCHING_ACTION',
+        message: `Could not find matching action for ${request.path} and method ${request.httpMethod}`
+    }
 };
 
-function handler(routeConfig) {
-    return (event, context, callback) => process(event, routeConfig, callback)
-}
-
-function process(event, routeConfig, callback) {
-    if (routeConfig.debug) {
-        console.log('Event', event);
+function process(proxyIntegrationConfig, event) {
+    //validate config
+    if (!Array.isArray(proxyIntegrationConfig.routes) || proxyIntegrationConfig.routes.length < 1) {
+        throw new Error('proxyIntegration.routes must not be empty');
     }
 
-    const headers = {
+    // detect if it's an http-call at all:
+    if (!event.httpMethod || !event.path) {
+        return null;
+    }
+    const headers = Object.assign({
         'Content-Type': 'application/json'
-    };
-    // assure necessary values have sane defaults:
-    event.path = event.path || '';
-    const errorMapping = routeConfig.errorMapping || {};
-    errorMapping['NO_MATCHING_ACTION'] = 404;
-    routeConfig.routes = routeConfig.routes || [];
-    if (routeConfig.cors) {
+    }, proxyIntegrationConfig.defaultHeaders);
+    if (proxyIntegrationConfig.cors) {
         headers["Access-Control-Allow-Origin"] = "*";
     }
-    // ugly hack: if host is from 'Custom Domain Name Mapping', then event.path has the value '/basepath/resource-path/';
-    // if host is from amazonaws.com, then event.path is just '/resource-path':
-    const apiId = event.requestContext ? event.requestContext.apiId : null; // the apiId that is the first part of the amazonaws.com-host
-    if ((apiId && event.headers && event.headers.Host && event.headers.Host.substring(0, apiId.length) != apiId)) {
-        // remove first path element:
-        const groups = /\/[^\/]+(.*)/.exec(event.path) || [null, null];
-        event.path = groups[1] || '/';
-    }
+
+    // assure necessary values have sane defaults:
+    const errorMapping = proxyIntegrationConfig.errorMapping || {};
+    errorMapping['NO_MATCHING_ACTION'] = 404;
+
+    event.path = normalizeRequestPath(event);
 
     try {
-        const actionConfig = findMatchingActionConfig(event.httpMethod, event.path, routeConfig) || {action: NO_MATCHING_ACTION};
+        const actionConfig = findMatchingActionConfig(event.httpMethod, event.path, proxyIntegrationConfig) || {action: NO_MATCHING_ACTION};
         event.paths = actionConfig.paths;
         if (event.body) {
             event.body = JSON.parse(event.body);
         }
-        const result = actionConfig.action(event);
-        if (result && result.then) {
-            return result
-                .then(res=> {
-                    callback(null, {statusCode: 200, headers: headers, body: JSON.stringify(res)});
-                })
-                .catch(err=> {
-                    callback(null, convertError(err, errorMapping, headers))
-                });
-        } else {
-            callback(null, {statusCode: 200, headers: headers, body: JSON.stringify(result)});
-        }
+        return Promise.resolve(actionConfig.action(event)).then(res => {
+            return {statusCode: 200, headers: headers, body: JSON.stringify(res)};
+        }).catch(err => {
+            return convertError(err, errorMapping, headers);
+        });
     } catch (error) {
         console.log('Error while evaluating matching action handler', error);
-        callback(null, convertError(error, errorMapping, headers));
+        return Promise.resolve(convertError(error, errorMapping, headers));
+    }
+}
+
+function normalizeRequestPath(event) {
+    // ugly hack: if host is from API-Gateway 'Custom Domain Name Mapping', then event.path has the value '/basepath/resource-path/';
+    // if host is from amazonaws.com, then event.path is just '/resource-path':
+    const apiId = event.requestContext ? event.requestContext.apiId : null; // the apiId that is the first part of the amazonaws.com-host
+    if ((apiId && event.headers && event.headers.Host && event.headers.Host.substring(0, apiId.length) != apiId)) {
+        // remove first path element:
+        const groups = /\/[^\/]+(.*)/.exec(event.path) || [null, null];
+        return groups[1] || '/';
     }
+
+    return event.path;
 }
 
 function convertError(error, errorMapping, headers) {
@@ -68,7 +69,7 @@ function convertError(error, errorMapping, headers) {
 
 function findMatchingActionConfig(httpMethod, httpPath, routeConfig) {
     const paths = {};
-    var matchingMethodRoutes = routeConfig.routes.filter(route=>route.method == httpMethod);
+    const matchingMethodRoutes = routeConfig.routes.filter(route => route.method == httpMethod);
     for (let route of matchingMethodRoutes) {
         if (routeConfig.debug) {
             console.log(`Examining route ${route.path} to match ${httpPath}`);
@@ -104,5 +105,4 @@ function extractPathNames(pathExpression) {
     return pathNames && pathNames.length > 0 ? pathNames.slice(1) : null;
 }
 
-
-module.exports = {handler: handler};
+module.exports = process;

lib/sns.js

@@ -0,0 +1,72 @@
+"use strict";
+
+function process(snsConfig, event) {
+    // detect if it's an sns-event at all:
+    if(snsConfig.debug){
+        console.log('sns:Event', JSON.stringify(event));
+    }
+
+    if (!Array.isArray(event.Records) || event.Records.length<1 || !event.Records[0].Sns) {
+        console.log('Event does not look like SNS');
+        return null;
+    }
+
+    const sns = event.Records[0].Sns;
+    for(let routeConfig of snsConfig.routes){
+        if(routeConfig.subject instanceof RegExp){
+            if(routeConfig.subject.test(sns.Subject)){
+                const result = routeConfig.action(sns);
+                return result || {};
+            }
+        }else{
+            console.log(`SNS-Route with subject-regex '${routeConfig.subject}' is not a Regex; it is ignored!`);
+        }
+    }
+
+    if (snsConfig.debug) {
+        console.log(`No subject-match for ${sns.Subject}`);
+    }
+
+    return null;
+}
+
+module.exports = process;
+
+/*
+const cfgExample = {
+    routes:[
+        {
+            subject: /.*\/,
+            action: sns => articleService.invalidate(JSON.parse(sns.Message).escenicId)
+        }
+    ]
+};
+*/
+
+
+/* this is an example for a standard SNS notification message:
+
+{
+    "Records": [
+        {
+            "EventSource": "aws:sns",
+            "EventVersion": "1.0",
+            "EventSubscriptionArn": "arn:aws:sns:eu-west-1:933782373565:production-escenic-updates:2fdd994c-f2b7-4c2f-a2f9-da83b590e0fc",
+            "Sns": {
+                "Type": "Notification",
+                "MessageId": "0629603b-448e-5366-88b4-309d651495c5",
+                "TopicArn": "arn:aws:sns:eu-west-1:933782373565:production-escenic-updates",
+                "Subject": null,
+                "Message": "{\"escenicId\":\"159526803\",\"model\":\"news\",\"status\":\"draft\"}",
+                "Timestamp": "2016-11-16T08:56:58.227Z",
+                "SignatureVersion": "1",
+                "Signature": "dtXM9BlAJJhYkVObnKmzY012kjgl4uYHEPQ1DLUalBHnPNzkDf12YeVcvHmq0SF6QbdgGwSYw0SgtsOkBiW3WSxVosqEb5xKUWIbQhlXwKdZnzekUigsgl3d231RP+9U2Cvd4QUc6klH5P+CuQM/F70LBIIv74UmR2YNMaxWxrv7Q+ETmz/TF6Y5v8Ip3+GLikbu6wQ/F5g3IHO2Lm7cLpV/74odm48SQxoolh94TdgvtYaUnxNjFVlF8Js8trbRkr7DYTogh73cTwuR77Mo+K9GlYn53txiMW5rMl3KhVdw4U3L190gtBJVwgHbqcB60pmNdEAE9f4bEOohizfPhg==",
+                "SigningCertUrl": "https://sns.eu-west-1.amazonaws.com/SimpleNotificationService-b95095beb82e8f6a046b3aafc7f4149a.pem",
+                "UnsubscribeUrl": "https://sns.eu-west-1.amazonaws.com/?Action=Unsubscribe&SubscriptionArn=arn:aws:sns:eu-west-1:933782373565:production-escenic-updates:2fdd994c-f2b7-4c2f-a2f9-da83b590e0fc",
+                "MessageAttributes": {}
+            }
+        }
+    ]
+}
+
+*/

package.json

@@ -2,7 +2,7 @@
   "name": "aws-lambda-router",
   "version": "0.1.1",
   "description": "AWS lambda router",
-  "main": "httpRouteHandler.js",
+  "main": "index.js",
   "scripts": {
     "test": "gulp test"
   },
@@ -15,6 +15,7 @@
     "lambda",
     "apigateway",
     "any",
+    "sns",
     "router",
     "routing"
   ],
@@ -25,10 +26,11 @@
   },
   "homepage": "https://github.com/WeltN24/aws-lambda-router#readme",
   "devDependencies": {
-    "del": "2.2.2",
-    "gulp": "3.9.1",
-    "gulp-install": "0.6.0",
-    "gulp-jasmine": "2.4.2",
-    "gulp-zip": "3.2.0"
+    "del": "^2.2.2",
+    "gulp": "^3.9.1",
+    "gulp-install": "^0.6.0",
+    "gulp-jasmine": "^2.4.2",
+    "gulp-zip": "^3.2.0",
+    "proxyquire": "^1.7.10"
   }
 }