Trying to send off a webhook to Slack whenever onWrite() is triggered directed toward my Firebase DB. Going off a few other posts/guides I was able to deploy the below code, but get the ReferenceError: Request is not defined error on execution. I can't figure out how to fix the Request is not defined.
const functions = require('firebase-functions');
const webhookURL = "https://hooks.slack.com/services/string/string";
exports.firstTest = functions.database.ref('first').onWrite( event => {
return request.post(
webhookURL,
{json: {text: "Hello"}}
);
});
Calling your Cloud Function via an URL and sending back a response
By doing exports.firstTest = functions.database.ref('first').onWrite() you trigger your firstTest Cloud Function when data is created, updated, or deleted in the Realtime Database. It is called a background trigger, see https://firebase.google.com/docs/functions/database-events?authuser=0
With this trigger, everything happens in the back-end and you do not have access to a Request (or a Response) object. The Cloud Function doesn't have any notion of a front-end: for example it can be triggered by another back-end process that writes to the database. If you want to detect, in your front-end, the result of the Cloud Function (for example the creation of a new node) you would have to set a listener to listen to this new node location.
If you want to call your function through an HTTP request (possibly from your front-end, or from another "API consumer") and receive a response to the HTTP Request, you need to use another type of Cloud Function, the HTTP Cloud Function, see https://firebase.google.com/docs/functions/http-events. See also the other type of Cloud Function that you can call directly: the Callable Cloud Functions.
Finally, note that:
With .onWrite( event => {}), you are using the old syntax, see https://firebase.google.com/docs/functions/beta-v1-diff?authuser=0
The Firebase video series on Cloud Function is a good point to start to learn more on all these concepts, see https://firebase.google.com/docs/functions/video-series?authuser=0
Calling, from your Cloud Function, an external URL
If you want, from a Cloud Function, to call an external URL (the Slack webhook mentioned in your question, for example) you need to use a library like request-promise (https://github.com/request/request-promise).
See How to fetch a URL with Google Cloud functions? request? or Google Cloud functions call URL hosted on Google App Engine for some examples
Important: Note that you need to be on the "Flame" or "Blaze" pricing plan.
As a matter of fact, the free "Spark" plan "allows outbound network requests only to Google-owned services". See https://firebase.google.com/pricing/ (hover your mouse on the question mark situated after the "Cloud Functions" title)
Related
I have a firebase cloud function that is an endpoint for an external API, and it handles a POST request.
This external API POSTS data to my cloud function endpoint at random intervals (this cloud function gets pinged with a POST request based on when a result is returned from this external API, and there can be multiple at once and its unpredictable)
exports.handleResults = functions.https.onRequest((req, res) => {
if (req.method === 'POST') {
// run code here that handles the POST payload
}
})
What happens when there is more than one POST request that come in at the same time?
Is there a queue? Does it finish the first request before moving on to the next?
Or if another request comes in while the function is running, does it block/ignore the request until the function is done?
Cloud Functions will automatically scale up the server instances running your functions when it determines that more capacity is needed. Those instances will run your function concurrently. The instances will be scaled down when they are no longer needed. The exact behavior is not documented - it should be considered an implementation detail that may change over time.
To learn more about this, watch my video about Cloud Functions scaling and isolation.
Beginner here, I'm using Firebase real time database and I need my API to constantly return that value when something has been added see my code below.
apiCalls.get('/api/getallusers',function(req,res){
userFunc.getAllUsers(function(err,result){
if (err) return res.status(500).send('internal server error!');
res.status(200).write(JSON.stringify(result));
res.end();
return res;
})
})
this will return the error
Error [ERR_STREAM_WRITE_AFTER_END]: write after end
but if i remove res.end it will show 1 record and constantly load until the page times out..
is what I'm doing possible or are there different ways to do it.
also I'm using firebase cloud functions for this api.
UPDATE:
Uploaded the API but it does not return anything...
here is the link https://us-central1-testproject-e6819.cloudfunctions.net/api1/api/getUser
tried axios and Event Source
Firebase functions logs the values but it does not return it..
If you're viewing the API response like a web page, your browser is buffering the data it's received until there's enough of it to form a more full page. Your browser is expecting content that ends, not some endless stream of data.
You should remove .end() if you expect to be able to continue to write to the output stream.
Also, I recommend using the Server-Sent Events (SSE) protocol for this. https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events It provides a nice standards-based abstraction that makes it very easy to handle event streams client-side.
const eventSource = new EventSource('https://api.example.com/someApi');
eventSource.addEventListener('userupdate', (e) => {
console.log(e.data);
});
Server-side, there are a couple Express-based middlewares to make this even easier than it already is.
Operations in Cloud Functions must be relatively short-lived and end deterministically. There is no way to keep a connection open from Cloud Functions to the client.
Typically consider what triggers the need to send new data. For example, if it is triggered by the fact that a new user is registered, you can use trigger your Cloud Functions from Firebase Authentication. Then the function could for example write to the Realtime Database (or Cloud Firestore), and your client/app listens to the database for realtime updates. That way you're using all the pieces of Firebase in the way they're designed: Cloud Functions for short-lived updates triggered from events in the system, and the Realtime Database or Cloud Firestore for sending realtime updates.
If that doesn't work for your use-case, you'll need a runtime environment that allows you to keep processes alive. Something like App Engine flex, Kubernetes, or many other options come to mind for that.
I have a self-hosted parse-server in AWS EC2. I want to update my database when I receive POSTnotifications from Apple. For that, I created a cloud function, but since Apple asks for a urlto send notifications, I'm not sure how to make my cloud function directly accessible via url or if I need to create an endpoint somewhere (AWS) to receive the notification from Apple and then make a new httpRequest or curl to my cloud function.
I'm looking for any directions or services (AWS) on how to perform this.
I don't think you need to do anything in AWS. You just need to add the cloudFunction to your main.js
As an example, here is an endPoint called add3NumbersTogether . I put this in my main.js file and then I can call this code from iOs (or another client). In iOs I use the Parse iOs SDK to make calls
Parse.Cloud.define("add3NumbersTogether", function(request, response) {
response.success( {request.params.num1 + request.params.num2 + request.params.num3});
});
I want to make a Google Cloud Function with HTTP trigger that call another function (example: changeString). I know that I can include the function changeString in index.js. However, I want to reuse changeString so others Google Cloud Functions can call it.
exports.helloWorld = function helloWorld(req, res) {
var result = changeString(req.body.string);
res.send(result);
};
I know that there is a similar question, but it did not solve my problem.
I was wondering about this myself and I think the answer is that you don’t call the function. Instead, you should send a payload to the PubSub service from your HTTP Cloud Function. A secondary Cloud Function subscribes to the PubSub topic and consumes the payload (which is Base64 encoded).
As #user3158158 brings out, you would publish a message to a Pub/Sub service. This is highlighted here: https://cloud.google.com/functions/docs/calling/pubsub#publishing_a_message_from_within_a_function
I shows the sample syntax at the above link, I needed to do the same thing today.
The Alexa skill docs will eventually allow you to send webhooks to https endpoints. However the SDK only documents lambda style alexa-sdk usage. How would one go about running Alexa applications on one's own server without anything abstracting Lambda? Is it possible to wrap the event and context objects?
You can already use your own endpoint. When you create a new skill, in the configuration tab, just choose HTTPS and provide your https endpoint. ASK will call your endpoint where you can run anything you want (tip, check ngrok.com to tunnel to your own dev machine). Regarding the event and context objects; your endpoint will receive the event object information. You don't need the context object for anything, that just lets you interact with Lambda-specific stuff (http://docs.aws.amazon.com/lambda/latest/dg/python-context-object.html). Just make sure that you comply with the (undocumented) timeouts by ASK and you are good to go.
Here's a way to do this that requires only a small change to your Skill code:
In your main index.js entry point, instead of:
exports.handler = function (event, context) {
use something like:
exports.myAppName = function (funcEvent, res) {
Below that, add the following workaround:
var event = funcEvent.body
// since not using Lambda, create dummy context with fail and succeed functions
const context = {
fail: () => {
res.sendStatus(500);
},
succeed: data => {
res.send(data);
}
};
Install and use Google Cloud Functions Local Emulator on your laptop. When you start and deploy your function to the emulator, you will get back a Resource URL something like http://localhost:8010/my-project-id/us-central1/myAppName.
Create a tunnel with ngrok. Then take the ngrok endpoint and put it in place of localhost:8010 in the Resource URL above. Your resulting fulfillment URL will be something like: https://b0xyz04e.ngrok.io/my-project-id/us-central1/myAppName
Use the fulfillment URL (like above) under Configuration in the Alexa dev console, selecting https as the Service Endpoint Type.