Access Cloudformation Parameters From Java Lambda

Question

I have a lambda function with environment variables defined like the following in the cloud formation template.

Parameters:
  Parameter1: { Type: String }
Resources:
 LambdaFunction:
   Type: AWS::Serverless::Function
   Properties:
     FunctionName: "Function"
     CodeUri: // relevant parameters
     Handler: handler::handlerequest 
    Role: //Role
    Runtime: java8
    Timeout: 300
  Environment:
    Variables:
      refParamter1:
        Ref: Parameter1

My code for the handle request is as follows:

String referenceParameter = System.getenv("refParamter1");
System.out.println("Referenced Paramter "+ referenceParameter );

When I deploy this and trigger my lambda it gives me the null for the printed referenceParameter.

Is using System.getenv incorrect when referencing environment variables in lambda?

There is a similar question : CloudFormation - Access Parameter from Lambda Code for python but doesn't give any answer for Java

This is the question with the answer which suggests to use System.getenv : Accessing AWS Lambda environment variables in Java code

System.getenv is the right way...do you see the variable in the lambda console of AWS after deploying? — Nune Isabekyan
– Nune Isabekyan, Commented Aug 27, 2018 at 12:17
No. It was not there in the console. I figured out that the problem was with the indenting of the yml where Environment is defined. Once the indentation is fixed the issue is resolved. — SanD
– SanD, Commented Aug 27, 2018 at 17:30

jtafurth · Accepted Answer · 2018-08-27 12:56:10Z

1

If I am correct you are trying to reference a parameter from the resource, then your syntax is wrong, try this:

  Environment:
    Variables:
      refParamter1: !Ref Parameter1

The environment variables definition is an array of key:value, you can see the documentation here https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-lambda-function-environment.html

When deploying make sure to go to the lambda console and check that it correctly appears under environments variables in your function UI, and then you can use:

String referenceParameter = System.getenv("refParamter1");

To access your variable.

Cheers

answered Aug 27, 2018 at 12:56

jtafurth

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SanD · Accepted Answer · 2018-08-27 17:34:04Z

1

The indentation was wrong in the Lambda function and the yml depends on the indentation it has not taken the environment variables into account.

Parameters:
  Parameter1: { Type: String }
Resources:
  LambdaFunction:
    Type: AWS::Serverless::Function
    Properties:
      FunctionName: "Function"
      CodeUri: // relevant parameters
      Handler: handler::handlerequest 
      Role: //Role
      Runtime: java8
      Timeout: 300
      Environment:
        Variables:
          refParamter1:
            Ref: Parameter1

answered Aug 27, 2018 at 17:34

SanD

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