如何允许打包程序在AMI构建期间访问CodeCommit？

Question

I'd like to clone my FreeTier git repos from CodeCommit when using packer to build an AMI. This is incredibly challenging and poorly documented.

Answer 1

This is what finally worked for me. This is Ubuntu 16.04 hvm:ebs as the base image, as it will install a modern and functioning git and awscli. 14.04 had many issues, that in the end weren't worth sorting out.

{                                                                                                         
  "variables": {                                                                                          
    "aws_access_key": "",                                                                                 
    "aws_secret_key": ""                                                                                  
  },                                                                                                      
  "builders": [{                                                                                          
    "type": "amazon-ebs",                                                                                 
    "name": "aws",                                                                                        
    "access_key": "{{user `aws_access_key`}}",                                                            
    "secret_key": "{{user `aws_secret_key`}}",                                                            
    "iam_instance_profile": "packer",                                                                
    "region": "us-east-1",                                                                                
    "source_ami": "ami-840910ee",                                                                         
    "instance_type": "t2.micro",                                                                          
    "ssh_username": "ubuntu",                                                                             
    "ami_name": "myproject {{timestamp}}"                                                                
  }],                                                                                                     
  "provisioners": [{                                                                                      
    "type": "shell",                                                                                      
    "inline": [                                                                                           
      "sleep 30",                                                                                         
      "sudo apt-get update",                                                                              
      "sudo apt-get upgrade -y",                                                                          
      "sudo apt-get install -y git awscli python-virtualenv",                                             
      "sudo install -o ubuntu -g ubuntu -m 755 -d /opt/scratch",                                             
      "virtualenv /opt/scratch/venv",                                                                        
      "git config --global credential.helper '!aws codecommit credential-helper $@'",                     
      "git config --global credential.UseHttpPath true",                                                  
      "git clone https://git-codecommit.us-east-1.amazonaws.com/v1/repos/myproject /opt/scratch/venv/src/myproject", 
      "/opt/scratch/venv/bin/pip install -r /opt/scratch/venv/src/myproject/requirements.txt"                  
    ]                                                                                                     
  }]                                                                                                      
}                                                                                                         

In the IAM console, the user that packer will use needs the iam:PassRole policy to be able to use the iam_instance_profile directive.

Also in the IAM console, you'll need to create a role for EC2, and give it the AWSCodeCommitReadOnly policy.

Note that --profile default is missing from the credential.helper, this is intentional. Using the role there is no ~/.aws/credential file to hold the default profile. Instead aws-cli will use the role assigned to the instance, which allows it to clone from CodeCommit