La conversion AWS Lambda fonction à utiliser promesses?

Je suis en train d'écrire un simple HTTP 'ping' fonction qui est d'être régulièrement exécutés à l'aide d'AWS Lambda. Il utilise quatre asynchrone fonctions: http.obtenir, S3.getObject, S3.putObject, et nodemailer.sendMail. Chacun semble avoir un peu différent modèle de rappel.

Après la lecture de promesses, j'ai passé beaucoup trop de temps à essayer de convertir le code suivant pour utiliser Q promesses et a échoué lamentablement.

Pour mon éducation et j'espère que d'autres personnes, j'espérais que quelqu'un pourrait m'aider à convertir ce à l'aide de promesses (n'a pas à être Q):

'use strict';
var http = require('http');
var nodemailer = require('nodemailer');
var AWS = require('aws-sdk');
var s3 = new AWS.S3( { params: { Bucket: 'my-bucket' } } );
exports.handler = (event, context, callback) => {
var lastStatus;
var options = {
host: event.server.host,
port: event.server.port ? event.server.port : 80,
path: event.server.path ? event.server.path : '',
method: event.server.method ? event.server.method : 'HEAD',
timeout: 5000
};
var transporter = nodemailer.createTransport({
host: event.mail.host,
port: event.mail.port ? event.mail.port : 587,
auth: {
user: event.mail.user,
pass: event.mail.pass
}
});
var d = new Date();
var UTCstring = d.toUTCString();
//email templates 
var downMail = {
from: event.mail.from,
to: event.mail.to,
subject: 'Lambda DOWN alert: SITE (' + event.server.host + ') is DOWN',
text: 'LambdaAlert DOWN:\r\nSITE (' + event.server.host + ') is DOWN as at ' + UTCstring + '.'
};
var upMail = {
from: event.mail.from,
to: event.mail.to,
subject: 'Lambda UP alert: SITE (' + event.server.host + ') is UP',
text: 'LambdaAlert UP:\r\nSITE (' + event.server.host + ') is UP as at ' + UTCstring + '.'
};
//Run async chain to ensure that S3 calls execute in proper order
s3.getObject( { Key: 'lastPingStatus' }, (err, data) => {
//get last status from S3
if (err) { lastStatus = "UP"; } else {
lastStatus = data.Body.toString();
console.log("Last observed status: " + lastStatus);
}
http_request(options, lastStatus);
});
function http_request(requestOptions, lastStatus) {
var req = http.request(requestOptions, function(res) {
if (res.statusCode == 200) {
if (lastStatus == "DOWN") {
console.log('Email up notice sending...');
transporter.sendMail(upMail, function(error, info) {
if (error) {
console.log("ERROR: " + error);
callback(null, "ERROR: " + error);
} else {
console.log('No further details available.');
callback(null, 'Up message sent');
}
});
}
s3.putObject({ Key: 'lastPingStatus', Body: 'UP', ContentType: 'text/plain' }, (error, data) => { console.log("Saved last state as UP"); });
callback(null, 'Website is OK.');
}
});
req.on('error', function(e) {
if (lastStatus == "UP") {
console.log('Email down notice sending...');
transporter.sendMail(downMail, function(error, info) {
if (error) {
console.log("ERROR: " + error);
callback(null, "ERROR: " + error);
} else {
console.log('No further details available.');
callback(null, 'Down message sent');
}
});
s3.putObject({ Key: 'lastPingStatus', Body: 'DOWN', ContentType: 'text/plain' }, (error, data) => { console.log("Saved last state as DOWN"); });
callback(null, 'Website is DOWN.');
}
});
req.end();
}
};

EDIT: Première tentative d'écriture à l'aide de promesses:

'use strict';
var http = require('http');
var nodemailer = require('nodemailer');
var AWS = require('aws-sdk');
var s3 = new AWS.S3( { params: { Bucket: 'lambda-key-storage' } } );
exports.handler = (event, context, callback) => {
var lastStatus;
var options = {
host: event.server.host,
port: event.server.port ? event.server.port : 80,
path: event.server.path ? event.server.path : '',
method: event.server.method ? event.server.method : 'HEAD',
timeout: 5000
};
var transporter = nodemailer.createTransport({
host: event.mail.host,
port: event.mail.port ? event.mail.port : 587,
auth: {
user: event.mail.user,
pass: event.mail.pass
}
});
var d = new Date();
var UTCstring = d.toUTCString();
//email templates 
var downMail = {
from: event.mail.from,
to: event.mail.to,
subject: 'Lambda DOWN alert: SITE (' + event.server.host + ') is DOWN',
text: 'LambdaAlert DOWN:\r\nSITE (' + event.server.host + ') is DOWN as at ' + UTCstring + '.'
};
var upMail = {
from: event.mail.from,
to: event.mail.to,
subject: 'Lambda UP alert: SITE (' + event.server.host + ') is UP',
text: 'LambdaAlert UP:\r\nSITE (' + event.server.host + ') is UP as at ' + UTCstring + '.'
};
var myProm = new Promise(function(resolve, reject) {
console.log("called 1");
s3.getObject( { Key: 'lastPingStatus' }, (err, data) => {
//get last status from S3
if (err) { 
resolve("UP"); 
} else {
resolve(data.Body.toString());
}
});
})
.then(function(lastStatus) {
console.log("called 2");
console.log("Last observed status: " + lastStatus);
var req = http.request(options, function(res) {
resolve(res.statusCode);
});
req.on('error', function(e) {
reject(e);
});
req.end();
return "??";
})
.then(function(statusCode) {
console.log("called 3");
if (statusCode == 200) {
if (lastStatus == "DOWN") {
console.log('Email up notice sending...');
resolve("upTrigger");
} else {
resolve("upNoTrigger");
}
s3.putObject({ Key: 'lastPingStatus', Body: 'UP', ContentType: 'text/plain' }, (err, data) => { console.log("Saved last state as UP"); });
callback(null, 'Website is OK.');
}
})
.catch(function(err){
console.log("called 3 - error");
//Send mail notifying of error
if (lastStatus == "UP") {
console.log('Email down notice sending...');
resolve("downTrigger");
s3.putObject({ Key: 'lastPingStatus', Body: 'DOWN', ContentType: 'text/plain' }, (error, data) => { console.log("Saved last state as DOWN"); });
callback(null, 'Website is DOWN.');
return("downTrigger");
} else {
return "downNoTrigger";
}
})
.then(function(trigger) {
console.log("called 4");
if (trigger == "upTrigger") {
transporter.sendMail(upMail, (error, info) => {
if (error) {
console.log("ERROR: " + error);
callback(null, "ERROR: " + error);
} else {
console.log('Up message sent.');
callback(null, 'Up message sent');
}
});
} else if (trigger == "downTrigger") {
transporter.sendMail(downMail, (error, info) => {
if (error) {
console.log("ERROR: " + error);
callback(null, "ERROR: " + error);
} else {
console.log('Down message sent.');
callback(null, 'Down message sent');
}
});
}
console.log("Outcome of ping was: ", trigger);
});
};

Ce n'est pas tout à fait. Le résultat journaux sont:

called 1
called 2
Last observed status: UP
called 3
called 4
Outcome of ping was:  undefined
ReferenceError: resolve is not defined
Gros indice: 2 étapes, (1) promisify au niveau le plus bas - s3.getObject(), s3.putObject(), le transporteur.sendMail() et http.demande (de), (2) construire le flux de l'application à l'aide de la promisified versions de ces quatre méthodes.

OriginalL'auteur GuruJ | 2016-11-06