Packer-Cn/website/source/docs/builders/amazon.html.markdown

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description: | Packer is able to create Amazon AMIs. To achieve this, Packer comes with multiple builders depending on the strategy you want to use to build the AMI. layout: docs page_title: Amazon AMI Builder ...

Amazon AMI Builder

Packer is able to create Amazon AMIs. To achieve this, Packer comes with multiple builders depending on the strategy you want to use to build the AMI. Packer supports the following builders at the moment:

• amazon-ebs - Create EBS-backed AMIs by launching a source AMI and re-packaging it into a new AMI after provisioning. If in doubt, use this builder, which is the easiest to get started with.

• amazon-instance - Create instance-store AMIs by launching and provisioning a source instance, then rebundling it and uploading it to S3.

• amazon-chroot - Create EBS-backed AMIs from an existing EC2 instance by mounting the root device and using a Chroot environment to provision that device. This is an advanced builder and should not be used by newcomers. However, it is also the fastest way to build an EBS-backed AMI since no new EC2 instance needs to be launched.

-> Don't know which builder to use? If in doubt, use the amazon-ebs builder. It is much easier to use and Amazon generally recommends EBS-backed images nowadays.

Specifying Amazon Credentials

When you use any of the amazon builders, you must provide credentials to the API in the form of an access key id and secret. These look like:

access key id:     AKIAIOSFODNN7EXAMPLE
secret access key: wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY

If you use other AWS tools you may already have these configured. If so, packer will try to use them, unless they are specified in your packer template. Credentials are resolved in the following order:

1. Values hard-coded in the packer template are always authoritative.
2. Variables in the packer template may be resolved from command-line flags or from environment variables. Please read about User Variables for details.
3. If no credentials are found, packer falls back to automatic lookup.

Automatic Lookup

If no AWS credentials are found in a packer template, we proceed on to the following steps:

1. Lookup via environment variables.

   • First AWS_ACCESS_KEY_ID, then AWS_ACCESS_KEY
   • First AWS_SECRET_ACCESS_KEY, then AWS_SECRET_KEY

2. Look for local AWS configuration files

   • First ~/.aws/credentials
   • Next based on AWS_PROFILE

3. Lookup an IAM role for the current EC2 instance (if you're running in EC2)

~> Subtle details of automatic lookup may change over time. The most reliable way to specify your configuration is by setting them in template variables (directly or indirectly), or by using the AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY environment variables.

Environment variables provide the best portability, allowing you to run your packer build on your workstation, in Atlas, or on another build server.

Using an IAM Instance Profile

If AWS keys are not specified in the template, a credentials file or through environment variables Packer will use credentials provided by the instance's IAM profile, if it has one.

The following policy document provides the minimal set permissions necessary for Packer to work:

{
  "Statement": [{
      "Effect": "Allow",
      "Action" : [
        "ec2:AttachVolume",
        "ec2:CreateVolume",
        "ec2:DeleteVolume",
        "ec2:CreateKeypair",
        "ec2:DeleteKeypair",
        "ec2:DescribeSubnets",
        "ec2:CreateSecurityGroup",
        "ec2:DeleteSecurityGroup",
        "ec2:AuthorizeSecurityGroupIngress",
        "ec2:CreateImage",
        "ec2:CopyImage",
        "ec2:RunInstances",
        "ec2:TerminateInstances",
        "ec2:StopInstances",
        "ec2:DescribeVolumes",
        "ec2:DetachVolume",
        "ec2:DescribeInstances",
        "ec2:CreateSnapshot",
        "ec2:DeleteSnapshot",
        "ec2:DescribeSnapshots",
        "ec2:DescribeImages",
        "ec2:RegisterImage",
        "ec2:CreateTags",
        "ec2:ModifyImageAttribute"
      ],
      "Resource" : "*"
  }]
}

Troubleshooting

Attaching IAM Policies to Roles

IAM policies can be associated with user or roles. If you use packer with IAM roles, you may encounter an error like this one:

==> amazon-ebs: Error launching source instance: You are not authorized to perform this operation.

You can read more about why this happens on the Amazon Security Blog. The example policy below may help packer work with IAM roles. Note that this example provides more than the minimal set of permissions needed for packer to work, but specifics will depend on your use-case.

{
    "Sid": "PackerIAMPassRole",
    "Effect": "Allow",
    "Action": "iam:PassRole",
    "Resource": [
        "*"
    ]
}