packer-cn/website/source/docs/builders/amazon.html.markdown

---
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](/docs/builders/amazon-ebs.html) - 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](/docs/builders/amazon-instance.html) - Create
  instance-store AMIs by launching and provisioning a source instance, then
  rebundling it and uploading it to S3.

* [amazon-chroot](/docs/builders/amazon-chroot.html) - Create EBS-backed AMIs
  from an existing EC2 instance by mounting the root device and using a
  [Chroot](http://en.wikipedia.org/wiki/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](/docs/builders/amazon-ebs.html). It is
much easier to use and Amazon generally recommends EBS-backed images nowadays.

<div id="specifying-amazon-credentials">## Specifying Amazon Credentials</div>

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](https://packer.io/docs/templates/user-variables.html) 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](http://docs.aws.amazon.com/cli/latest/userguide/cli-chap-getting-started.html#cli-config-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](http://docs.aws.amazon.com/cli/latest/userguide/cli-chap-getting-started.html#cli-config-files)
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:

``` {.javascript}
{
  "Statement": [{
      "Effect": "Allow",
      "Action" : [
        "ec2:AttachVolume",
        "ec2:CreateVolume",
        "ec2:DeleteVolume",
        "ec2:CreateKeypair",
        "ec2:DeleteKeypair",
        "ec2:CreateSecurityGroup",
        "ec2:DeleteSecurityGroup",
        "ec2:AuthorizeSecurityGroupIngress",
        "ec2:CreateImage",
        "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](http://blogs.aws.amazon.com/security/post/Tx3M0IFB5XBOCQX/Granting-Permission-to-Launch-EC2-Instances-with-IAM-Roles-PassRole-Permission). 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.

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