Please see the following
// labmdaBridge.js
// ------------------------------------------------------------------
//
// connect to Lambda functions...
//
var AWS = require('aws-sdk'),
express = require('express'),
app = express();
AWS.config.loadFromPath('./config.json');
var lambda = new AWS.Lambda();
// Generic Send Error Function
function sendError(res, code, msg) {
res.status(code);
res.json({ error: msg });
}
var knownEntityTypes = [ 'Cart' ];
var entityToIdPropertyName = {
'Cart' : 'cartId'
};
function entityTypeIsKnown(entity) {
return (knownEntityTypes.indexOf(entity) > -1);
}
// GET /Cart/aaaa-bbbb-cccd
app.get('/:entityType/:entityId', function(req, res) {
try {
// validate
if (entityTypeIsKnown(req.params.entityType)) {
var payload = {};
payload[entityToIdPropertyName[req.params.entityType]] = req.params.entityId;
if (req.query.filter) {
payload.descriptionFilter = req.query.filter;
}
if (req.query.sortPrice) {
payload.orderByPrice = true;
}
var params = {
FunctionName: req.params.entityType,
Payload: JSON.stringify( payload )
};
// invoke the first Lambda function
lambda.invoke(params, function(e, data) {
if (e) {
console.log("Error: for lambda", e);
sendError(res, 500, "Lambda Error - " + e.message);
return ;
}
console.log("%s(%s): %s",
req.params.entityType, req.params.entityId, data.Payload);
if (data.Payload == "null") {
res.status(404).end();
return;
}
if (data.Payload == "null") {
res.status(404).end();
return;
}
var payload = JSON.parse(data.Payload);
if (payload.errorMessage || payload.errorType) {
console.log("Error in lambda fn: ", data.Payload);
payload.additionalNote = "the attached error was emitted by AWS lambda";
sendError(res, 500, payload);
return ;
}
// the first request has succeeded. Can now make a second ...
var params2 = {
FunctionName: 'AdditionalFunctionNameHere',
Payload: data.Payload // or whatever you like
};
// invoke the second Lambda function
lambda.invoke(params2, function(e, data2) {
if (e) {
console.log("Error: for lambda", e);
sendError(res, 500, "Lambda Error - " + e.message);
return ;
}
console.log("Respinse: %s", JSON.stringify(data2.Payload));
res.status(200);
payload.secondPayload = data2.Payload;
res.json(payload);
});
});
}
else {
sendError(res, 404, "Unknown entity type");
}
}
catch(e) {
sendError(res, 500, "internal server error\n" + e.message);
}
});
// catch and return 404
app.use(function(req, res, next) {
res.status(404);
res.json({ error: { code: 404.01, message: "Not found" }});
});
// start the server
var listener = app.listen(process.env.PORT || 7000, function() {
console.log('lambda bridge up');
console.log('endpoint: ' + JSON.stringify(lambda.endpoint));
});
You need a config file that looks like:
{
"accessKeyId": "YOUR_KEY_HERE",
"secretAccessKey": "YOUR_SECRET_HERE",
"region": "us-east-1"
}
and I used this in my package.json
"dependencies": {
"aws-sdk": "^2.2.30",
"express": "^4.13.3"
}
...
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