how to mask aws key in git and code

Question

Currently I'm interacting with AWS by using AWS_ACCESS_KEY and SECRETE_KEY to deploy services in aws ec2. However, I have following 2 problems when writing keys in plain text in code:

1. I put the key a config file, but everyone(developer) in this repo can see the keys in plain text which is not appropriate.
2. Code would be uploaded to aws ec2 instance to do deployment. In this way, each one who can access to the instance can access to the plain text keys directly without any mask.

Could anyone help me to figure out how I can mask aws keys both in git and terminal? Thanks in advance!