eb extension for pulling ssh config from s3

01_setupssh.config

--- 
Resources: 
  AWSEBAutoScalingGroup: 
    Metadata: 
      ? "AWS::CloudFormation::Authentication"
      : 
        S3Auth: 
          buckets: 
            - bucket-name
          roleName: 
            ? "Fn::GetOptionSetting"
            : 
              DefaultValue: aws-elasticbeanstalk-ec2-role
              Namespace: "aws:asg:launchconfiguration"
              OptionName: IamInstanceProfile
          type: s3
files: 
  /tmp/.ssh/deploy_key: 
    authentication: S3Auth
    mode: "000600"
    owner: ec2-user
    source: "S3-file-URL"
  /tmp/.ssh/config: 
    authentication: S3Auth
    mode: "000600"
    owner: ec2-user
    source: "S3-file-URL"

Elastic beanstalk runs npm install as the user 'nodejs' with home directory /tmp.
The ssh config needs to be in the /tmp/.ssh folder

This will overwrite /tmp/.ssh/config - you shouldn't really be depending on a config file in /tmp anyway, but a workaround would be getting the file and concatenating in the existing file using ebextensions 'commands'

I ran into this issue and found the following solution: https://stackoverflow.com/questions/43497663/setting-up-ssh-keys-for-github-private-repo-access-on-elastic-beanstalk

That thread suggests that /tmp/.ssh/ should be /root/.ssh/. Have you run into this?