Packer's assume role functionality should not error out if the build itself is invoked with the role credentials

[paololazzari]

Packer version

> packer --version
1.8.4

Description

I created an IAM role (packer-role) with the following trust relationship:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Principal": {
                "AWS": "arn:aws:iam::275019390123:root"
            },
            "Action": "sts:AssumeRole",
        }
    ]
}

I then assumed the role and set the credentials:

$creds=(aws sts assume-role --role-arn arn:aws:iam::275019390123:role/packer-role --role-session-name packer-session | ConvertFrom-Json)

$env:AWS_ACCESS_KEY_ID=$creds.Credentials.AccessKeyId
$env:AWS_SECRET_ACCESS_KEY=$creds.Credentials.SecretAccessKey
$env:AWS_SESSION_TOKEN=$creds.Credentials.SessionToken

and confirmed that the new credentials were correctly set:

(aws sts get-caller-identity | ConvertFrom-Json).Arn
arn:aws:sts::275019390123:assumed-role/packer-role/packer-session

I then tried to run the following Packer build:

source "amazon-ebs" "basic-example" {
  assume_role {
    role_arn     = "arn:aws:sts::275019390123:assumed-role/packer-role"
  }

  region        = "us-east-1"
  source_ami    = "ami-fce3c696"
  instance_type = "t2.micro"
  ssh_username  = "ubuntu"
  ami_name      = "packer_AWS {{timestamp}}"
}

build {
  sources = [
    "source.amazon-ebs.basic-example"
  ]
}

this errors out:

Build 'amazon-ebs.basic-example' errored after 688 milliseconds 339 microseconds: IAM Role (arn:aws:sts::275019390123:assumed-role/packer-role) cannot be assumed.

There are a number of possible causes of this - the most common are:

• The credentials used in order to assume the role are invalid
• The credentials do not have appropriate permission to assume the role
• The role ARN is not valid

Error: NoCredentialProviders: no valid providers in chain. Deprecated. For verbose messaging see aws.Config.CredentialsChainVerboseErrors

---

Use Case(s)

My actual use case is a bit more complex.

I have a time consuming Packer build (>1 hour) which is being executed from a Gitlab CI pipeline. The job in the pipeline runs in another account (account B) and has a role associated to it. To run the Packer build in my account, I configured the job to assume the role in my account (account A). This would work fine if it wasn't for the fact that the build is longer than an hour. The sts assume role session chaining is in fact limited to one hour, which means that I can't use this workflow for my build.

I then tried to use the assume_role functionality, because my understanding is that by using it Packer would be able to refresh the credentials during the build, which would resolve my problem. The issue however, as illustrated above, is that Packer tries to assume the role even though the role is already assumed.

Should Packer be smart enough to understand that it is running under the assumed role that I specified in the assume_role config, and avoid trying to assume it when the build starts?

[RootMePLS]

Same here

[github-actions[bot]]

This issue has been synced to JIRA for planning.

JIRA ID: HPR-983

[Hellseher]

Hi,

packer --version                                                                                                                                                                                            
1.9.1   

What is the status of this issue, there is no way to check linked Jira ticket.

aws-vault exec <profile>
packer init <src>
packer build <src>

sources.pkr.hcl

source "amazon-ebs" "arm_al2023_no_swap" {
  ami_name               = "${local.prefix}-{{timestamp}}"
  iam_instance_profile   = "packer-instance-role"
  instance_type          = var.build_instance_type
  region                 = var.region
  skip_region_validation = true
  ssh_username           = "ec2-user"

  source_ami_filter {
    filters = {
      name                = var.source_ami_pattern
      architecture        = "arm64"
      root-device-type    = "ebs"
      virtualization-type = "hvm"
    }
    most_recent = true
    owners      = ["amazon"]
  }

  assume_role {
    role_arn     = local.assume_role_arn
    session_name = "packer-build-session"
  }

  tags = {
    Name   = "${local.prefix}-{{timestamp}}"
    commit = var.source_commit
  }
}

Error output:

There are a number of possible causes of this - the most common are:
  * The credentials used in order to assume the role are invalid
  * The credentials do not have appropriate permission to assume the role
  * The role ARN is not valid

Error: NoCredentialProviders: no valid providers in chain. Deprecated.
        For verbose messaging see aws.Config.CredentialsChainVerboseErrors

==> Builds finished but no artifacts were created.

Thanks, Oleg

[DNedkov-hedgeserv]

Any workaround or fix for this in 2024? We are facing the exact same issue