How can I use environmental variables on AWS Lambda? - amazon-web-services

Question

I'm writing an application which I want to run as an AWS Lambda function but also adhere to the Twelve-Factor app guidelines. In particular Part III. Config which requires the use of environmental variables for configuration.
However, I cannot find a way to set environmental variables for AWS Lambda instances. Can anyone point me in the right direction?
If it isn't possible to use environmental variables can you please recommend a way to use environmental variables for local development and have them transformed to a valid configuration system that can be accessed using the application code in AWS.
Thanks.

Answer 1

As of November 18, 2016, AWS Lambda supports environment variables.
Environment variables can be specified both using AWS console and AWS CLI. This is how you would create a Lambda with an LD_LIBRARY_PATH environment variable using AWS CLI:
aws lambda create-function \
--region us-east-1
--function-name myTestFunction
--zip-file fileb://path/package.zip
--role role-arn
--environment Variables={LD_LIBRARY_PATH=/usr/bin/test/lib64}
--handler index.handler
--runtime nodejs4.3
--profile default

Answer 2

Perhaps the 'custom environment variables' feature of node-lambda would address your concerns:
https://www.npmjs.com/package/node-lambda
https://github.com/motdotla/node-lambda
"AWS Lambda doesn't let you set environment variables for your function, but in many cases you will need to configure your function with secure values that you don't want to check into version control, for example a DB connection string or encryption key. Use the sample deploy.env file in combination with the --configFile flag to set values which will be prepended to your compiled Lambda function as process.env environment variables before it gets uploaded to S3."

Answer 3

There is no way to configure env variables for lambda execution since each invocation is disjoint and no state information is stored. However there are ways to achieve what you want.
AWS credentials - you can avoid storing that in env variables. Instead grant the privileges to your LambdaExec role. In fact, AWS recommends using roles instead of AWS credentials.
Database details: One suggestion is to store it in a well known file in a private bucket. Lambda can download that file when it is invoked, read the contents which can contain database details and other information. Since the bucket is private, others cannot access the file. The LambdaExec role needs IAM privileges to access the private bucket.

Answer 4

AWS just added support for configuration of Lambda functions via environment parameters.
Take a look here

Answer 5

We also had this requirement for our Lambda function and we "solved" this by generating a env file on our CI platform (in our case this is CircleCI). This file gets included in the archive that gets deployed to Lambda.
Now in your code you can include this file and use the variables.
The script that I use to generate a JSON file from CircleCI environment variables is:
cat >dist/env.json <<EOL
{
"CLIENT_ID": "$CLIENT_ID",
"CLIENT_SECRET": "$CLIENT_SECRET",
"SLACK_VERIFICATION_TOKEN": "$SLACK_VERIFICATION_TOKEN",
"BRANCH": "$CIRCLE_BRANCH"
}
EOL
I like this approach because this way you don't have to include environment specific variables in your repository.

Answer 6

I know it has been a while, but I didn't see a solution that works from the AWS Lambda console.
STEPS:
In your AWS Lambda Function Code, look for "Environment variables", and click on "Edit";
For the "Key", type "LD_LIBRARY_PATH";
For the "Value", type "/opt/python/lib".
Look at this screenshot for the details.
The #3 assumes that you are using Python as your runtime environment, and also that your uploaded Layer has its "lib" folder in the following structure:
python/lib
This solution works for the error:
/lib/x86_64-linux-gnu/libz.so.1: version 'ZLIB_1.2.9' not found
assuming the correct libray file is put in the "lib" folder and that the environment variable is set like above.
PS: If you are unsure about the #3 path, just look for the error in your console, and you will be able to see where your "lib" folder for your layer is at runtime.