store a large key use in EB

Hi,

I'm developping a node js site in EB and inside i use Google API. For this i have a large private key

-----BEGIN PRIVATE KEY-----\nihriohioerhfierjfirejfi=\n-----END PRIVATE KEY-----\n

I tried to store it inside environment variable but it's limited with 256 characters. EC2 key pair value has the same size limit So my question is: Where do i have to store this key and how can i use it inside my node js app? I found this link but i'm not sure if it's the right way and it's not enough explain (https://docs.aws.amazon.com/elasticbeanstalk/latest/dg/https-storingprivatekeys.html)

Thanks for your help