Fail to create ElasticBeanstalk custom platform with "Unmatched region" - amazon-elastic-beanstalk

Question

I'm trying to create a custom platform for region ap-northeast-1 following aws documentation.
ebp create ends with failure, and ebp events shows an error indicating that the created AMI is in different region from the service region.
2018-04-28 00:49:18 INFO Initiated platform version creation for 'NodePlatform_Ubuntu/1.0.0'.
2018-04-28 00:49:22 INFO Creating Packer builder environment 'eb-custom-platform-builder-packer'.
2018-04-28 00:52:39 INFO Starting Packer building task.
2018-04-28 00:52:44 INFO Creating CloudWatch log group '/aws/elasticbeanstalk/platform/NodePlatform_Ubuntu'.
2018-04-28 01:03:48 INFO Successfully built AMI(s): 'ami-5f2f4527' for 'arn:aws:elasticbeanstalk:ap-northeast-1:392559473945:platform/NodePlatform_Ubuntu/1.0.0'
2018-04-28 01:04:03 ERROR Unmatched region for created AMI 'ami-5f2f4527': 'us-west-2' (service region: 'ap-northeast-1').
2018-04-28 01:04:03 INFO Failed to create platform version 'NodePlatform_Ubuntu/1.0.0'.
I used this sample custom platform provided in aws document and modified only custom_platform.json for builders.region and builders.source_ami to match with the region of my Custom Platform Builder.
.elasticbeanstalk/config.yml
global:
application_name: Custom Platform Builder
branch: null
default_ec2_keyname: null
default_platform: null
default_region: ap-northeast-1
instance_profile: null
platform_name: NodePlatform_Ubuntu
platform_version: null
profile: eb-cli
repository: null
sc: git
workspace_type: Platform
custom_platform.json
{
"variables": {
"platform_name": "{{env `AWS_EB_PLATFORM_NAME`}}",
"platform_version": "{{env `AWS_EB_PLATFORM_VERSION`}}",
"platform_arn": "{{env `AWS_EB_PLATFORM_ARN`}}"
},
"builders": [
{
"type": "amazon-ebs",
"name": "HVM AMI builder",
"region": "ap-northeast-1",
"source_ami": "ami-60a4b21c",
"instance_type": "m3.medium",
"ssh_username": "ubuntu",
"ssh_pty": "true",
"ami_name": "NodeJs running on Ubuntu Server 16.04 LTS (built on {{isotime \"20060102150405\"}})",
"tags": {
"eb_platform_name": "{{user `platform_name`}}",
"eb_platform_version": "{{user `platform_version`}}",
"eb_platform_arn": "{{user `platform_arn`}}"
}
}
],
"provisioners": [
{
"type": "file",
"source": "builder",
"destination": "/tmp/"
},
{
"type": "shell",
"execute_command": "chmod +x {{ .Path }}; {{ .Vars }} sudo {{ .Path }}",
"scripts": [
"builder/builder.sh"
]
}
]
}
It seems my modification to custom_platform.json does not take effect.

Answer 1

What I missed was committing the changes...
Though EB and Packer documentation do not refer to anything about vcs or git, it seems packer uses git to create an archive of the custom platform files and thus the changes I made was not included in it because I did not commit them.
I noticed that ebp create was giving me this warning...
mac.local:NodePlatform_Ubuntu% ebp create
WARNING: You have uncommitted changes.