SendGrid with Firebase Cloud Functions error: "socket hang up" - firebase

Question

I have a Cloud Function triggered by a pub/sub event. I use sendgrid nodejs api. The main idea is sending my clients a weekly stats email. sendEmail() function run for each client (80 times). But when I check function logs I see that 25-30 of client emails are sent with success but the remaining it gives that error: "socket hang up"
I shortened the whole code to show the main part related sending email. Here is the last part.
// I shortened the whole function as it is a very long function.
// The main and the last part is as below
// I have nearly 80 clients and sendEmail function run for each client.
function calcData(i, data) {
return admin.database().ref('clientUrlClicks/' + data.key)
.orderByChild('date')
.startAt(dateStartEpox)
.endAt(dateEndEpox)
.once('value', urlClickSnap => {
clients[i].clickTotalWeek = urlClickSnap.numChildren();
clients[i].listTotalWeek = 0;
admin.database().ref('clientImpressions/' + data.key)
.orderByKey()
.startAt(dateStart)
.endAt(dateEnd)
.once('value', snap => {
snap.forEach(function(impressionSnap) {
clients[i].listTotalWeek += impressionSnap.val();
})
}).then(resp => {
return sendEmail(i, clients[i]);
}).catch(err => {
console.log(err);
});
}).catch(err => {
clients[i].clickTotalWeek = 0;
console.log(err);
});
}
function sendEmail(i, data) {
var options = {
method: 'POST',
url: 'https://api.sendgrid.com/v3/mail/send',
headers:
{
'content-type': 'application/json',
authorization: 'Bearer ' + sgApiKey
},
body:
{
personalizations:
[{
to: [{ email: data.email, name: data.name }],
dynamic_template_data:
{
dateStart: xxx,
dateEnd: xxx,
}
}],
from: { email: 'info#xxx.com', name: 'xxx' },
reply_to: { email: 'info#xxx.com', name: 'xxx' },
template_id: 'd-f44eeexxxxxxxxxxxxx'
},
json: true
};
request(options, function (error, response, body) {
if (error) {
console.log("err: " + error);
return;
}
return;
});
}
Edit:
In addition to answers below related to "chaining the promises correctly", I also added all emails and personalizations to "personalizations" array as an object on "sendEmail" function. So, instead making a request for each email I make one request. No problem now.

Answer 1

You are not chaining the promises correctly and therefore not returning a final promise at the end of the chaining, which is mandatory for a Cloud Function.
The following set of modifications is a first attempt to solve this problem.
Also, it is not crystal clear how do you call Sendgrid and return the Promise returned by the Sendgrid call. I would suggest that you use the send() method, which returns a Promise, as explained in the doc of the Sendgrid v3 Web API for Node.js, see https://github.com/sendgrid/sendgrid-nodejs/tree/master/packages/mail.
function calcData(i, data) {
//Declare clients aray here
return admin.database().ref('clientUrlClicks/' + data.key)
.orderByChild('date')
.startAt(dateStartEpox)
.endAt(dateEndEpox)
.once('value')
.then(urlClickSnap => {
clients[i].clickTotalWeek = urlClickSnap.numChildren();
clients[i].listTotalWeek = 0;
return admin.database().ref('clientImpressions/' + data.key) //Here you didn't return the promise
.orderByKey()
.startAt(dateStart)
.endAt(dateEnd)
.once('value');
.then(snap => {
snap.forEach(function(impressionSnap) {
clients[i].listTotalWeek += impressionSnap.val();
})
return sendEmail(i, clients[i]);
}).catch(err => {
clients[i].clickTotalWeek = 0;
console.log(err);
return null;
});
}

Answer 2

I see two issues with your code related to promise chaining, which may be causing this problem.
First is that you are using request with callback in your sendEmail function. This will simply not wait for your network call to finish and returns the function. Now this will build up the calls in parallel and before you hit your 80 clients counts the execution of your cloud function will finish. The solution would be to use request-promise-native (https://github.com/request/request-promise-native) library with your request library. So your sendEmail Function will now become
sendEmail (i, data) {
.
.
.
return rpn(options).then((d)=>{return d}).catch((e)=>{return console.log(e)})
}
Other solution is to use sendgrid client for nodejs which will simply return the promise and you don't need to use request. https://github.com/sendgrid/sendgrid-nodejs/tree/master/packages/mail
Second issue is in you call for data read from firebase where you are also using callbacks instead of promises. Correct solution will be:
function calcData(i, data) {
return admin.database().ref('clientUrlClicks/' + data.key)
.orderByChild('date')
.startAt(dateStartEpox)
.endAt(dateEndEpox)
.once('value').then( urlClickSnap => {
clients[i].clickTotalWeek = urlClickSnap.numChildren();
clients[i].listTotalWeek = 0;
return admin.database().ref('clientImpressions/' + data.key)
.orderByKey()
.startAt(dateStart)
.endAt(dateEnd)
.once('value').then( snap => {
snap.forEach(function(impressionSnap) {
clients[i].listTotalWeek += impressionSnap.val();
})
return sendEmail(i, clients[i]);
})
.catch(err => {
console.log(err);
});
}).catch(err => {
clients[i].clickTotalWeek = 0;
console.log(err);
});
}
This will make sure that you function calcData returns after finishing the execution of all the promises chained.
One more thing if you are calling calcData in a loop, then make sure that you store all the promises in an array and after loop call Promise.all(promisesArray), so that you function waits for all the executions to finish.