问题
I've created a lambda and cloud formation template which grants a lambda access to the parameter store and secrets manager. When I test the lambda I have the following functions outside of the export.handler function:
function getParameterFromStore(param){
let promise = new Promise(function(resolve, reject){
console.log('++ ' + param.Path);
servmgr.getParametersByPath(param, function(err, data){
if(err){
reject(console.log('Error getting parameter: ' + err, err.stack));
} else {
resolve(data);
}
});
});
let parameterResult = promise.then(function(result){
console.log('---- result: '+ JSON.stringify(result));
return result;
});
return parameterResult;
};
servmgr is instantiated as var servmgr = new AWS.SSM();
When I call this function from the export.handler function I do so as:
myFirstParam = { Path : '/myPath/Service/servicesEndpoint'};
let endpointResult = getParameterFromStore(myFirstParam);
In the lambda I have the function retrieve the parameter defined outside of the export.handler function bt wrapped in a promise.
When I run/test this lambda the object returned is always undefined... I get Parameters[] back but no values.
2019-02-20T21:42:41.340Z 2684fe88-d552-4560-a477-6761f2de6717 ++ /myPath/Service/serviceEndpoint
2019-02-20T21:42:41.452Z 2684fe88-d552-4560-a477-6761f2de6717 ---- result: {"Parameters":[]}
How do you get parameter values returned back to a lambda at run time?
update
based upon the suggestion/answer from Thales I've simplified the lambda to just this:
const getParameterFromStoreAsync = (param) => {
return new Promise((resolve, reject) => {
servmgr.getParametersByPath(param, (err, data) => {
if(err){
reject(console.log('Error getting parameter: ' + err, err.stack));
}
return resolve(data);
});
});
};
exports.handler = async(event, ctx, callback) => {
console.log('INFO[lambda]: Event: [' + JSON.stringify(event, null, 2) + ']');
console.log('this is the event' + JSON.stringify(event));
sfdcEndPointParam = { Path : '/PartnerBanking/Service/SfdcEndpoint'};
let myendpoint = await getParameterFromStoreAsync(sfdcEndPointParam);
console.log('### endpoint path: ' + JSON.stringify(myendpoint));
done = ()=>{}
callback(null, done());
};
I am still seeing an empty array being returned in my tests:
### endpoint path: {"Parameters":[]}
I've also moved the function into the callback as
exports.handler = (event,ctx, callback){
done = async()=>{
console.log('this is the event' + JSON.stringify(event));
sfdcEndPointParam = { Path : '/PartnerBanking/Service/SfdcEndpoint'};
let myendpoint = await getParameterFromStoreAsync(sfdcEndPointParam);
console.log('### endpoint path: ' + JSON.stringify(myendpoint));}
}
callback(null, done());
Same result ... empty array. Any additional things to try?
回答1:
This is because your getParameterFromStore returns before your then() code is executed, thus parameterResult is undefined. If you don't want to change your code too much, I would return the Promise you create, like this:
function getParameterFromStore(param){
return new Promise(function(resolve, reject){
console.log('++ ' + param.Path);
servmgr.getParametersByPath(param, function(err, data){
if(err){
reject(console.log('Error getting parameter: ' + err, err.stack));
} else {
resolve(data);
}
});
});
};
And finally, on your function's client, you can get the result like this:
const myFirstParam = { Path : '/myPath/Service/servicesEndpoint'}
getParameterFromStore(myFirstParam).then(console.log)
When coding in NodeJS, however, I highly recommend you use async/await instead, so you'll be able to escape the Promise Hell (chaninig Promise after Promise in order to achieve something "synchronously")
When using async/await, you can design your code as though it was synchronous. Here's a refactored version of your example, using async/await as well as arrow functions:
const getParameterFromStore = param => {
return new Promise((resolve, reject) => {
console.log('++ ' + param.Path);
servmgr.getParametersByPath(param, (err, data) => {
if (err) {
console.log('Error getting parameter: ' + err, err.stack)
return reject(err);
}
return resolve(data);
});
})
}
exports.handler = async (event) => {
const endpointResult = await getParameterFromStore(event.someAttributeFromTheEventThatYouWantToUse)
console.log(endpointResult)
};
EDIT: After the OP fixed the first issue, I created a working example on my own. It turned out that the way the OP was invoking the API was incorrect.
Here's the full working example:
'use strict';
const AWS = require('aws-sdk')
AWS.config.update({
region: 'us-east-1'
})
const parameterStore = new AWS.SSM()
const getParam = param => {
return new Promise((res, rej) => {
parameterStore.getParameter({
Name: param
}, (err, data) => {
if (err) {
return rej(err)
}
return res(data)
})
})
}
module.exports.get = async (event, context) => {
const param = await getParam('MyTestParameter')
console.log(param);
return {
statusCode: 200,
body: JSON.stringify(param)
};
};
Mind the Name attribute which must be provided as part of the API call to the ServiceManager.getAttribute method.
This attribute is stated in the official docs
I have run this myself and here's the output in CloudWatch Logs:
As you can see, the value was returned successfully.
Hope this helps!
回答2:
If your lambda is deployed on VPC, make sure that Security Group is attached to it and outbound traffic is allowed. It will be able to access parameter store automatically.
https://aws.amazon.com/premiumsupport/knowledge-center/lambda-vpc-parameter-store/
回答3:
A simpler solution would be:
const getParameterFromStore = (params) => servmgr.getParametersByPath(params).promise();
const myFirstParam = { Path : '/myPath/Service'};
getParameterFromStore(myFirstParam).then(console.log);
As you can see, the SDK itself provides utility functinality that you can use depending on your needs to use in an async or syncronious fashion.
Hope it helps.
- m
来源：https://stackoverflow.com/questions/54798083/how-to-access-the-aws-parameter-store-from-a-lambda-using-node-js-and-aws-sdk