tripleo-image-elements/elements/os-collect-config

Setup os-collect-config to run as a system service. By default it will run os-refresh-config on any changes.

Configuration

Heat Metadata can be used to configure os-collect-config:

os-collect-config:
  command: os-refresh-config
  cachedir: /var/run/os-collect-config
  collectors:
    - heat_local
    - ec2
    - cfn
  polling_interval: 300
  cfn:
    metadata_url: http://foo:8000/v1
    heat_metadata_hint: /var/lib/heat-cfntools/cfn-metadata-server
    stack_name: required-stack-name
    access_key_id: abcdefghijklmnop091234
    secret_access_key: fffeeeeddddccccaaaa99999
    path: ThisResource.Metadata
    ca_certificate: /etc/ssl/ca.crt
  ec2:
    metadata_url: http://169.254.169.254/latest/meta-data
  heat_local:
    path: /var/lib/heat-cfntools/cfn-init-data

Note that metadata_url is optional, as it should be determined by the file heat_metadata_hint refers to. This file is injected by Heat via cloud-init at first boot. Those two parameters are the only optional parameters. All of the others are required for the cfn data source to function. Note that ca_certificate is also optional but required in many cases where the metadata api is behind ssl.

ec2 and heat_local do not require any configuration to work.

Typically the cfn collector is configured via EC2 metadata in a Heat template:

Resources:
  myserver:
    Type: OS::Nova::Server
    Properties:
      ...
    Metadata:
      os-collect-config:
        cfn:
          access_key_id:
            Ref: Key
          path: MyServerConfig.Metadata
          secret_access_key:
            Fn::GetAtt:
            - Key
            - SecretAccessKey
          stack_name:
            Ref: AWS::StackName
          ca_certificate: /etc/ssl/ca.crt

The EC2 collector takes this metadata, passes it to os-apply-config which in turn writes it out to /etc/os-collect-config.conf.

Note that the configuration references some other resources - a key and access key, which are declared using:

Resources:
  Key:
    Properties:
      UserName:
        Ref: User
    Type: AWS::IAM::AccessKey
  User:
    Properties:
      Policies:
      - Ref: AccessPolicy
    Type: AWS::IAM::User

Note also that the IAM::User references an access policy which should look like:

Resources:
  AccessPolicy:
    Properties:
      AllowedResources:
      - MyServerConfig
    Type: OS::Heat::AccessPolicy

and, finally, the crucial bit is the MyServerConfig policy which is referenced in the cfn collector configuration and the access policy:

Resources:
  MyServerConfig:
    Metadata:
      os-collect-config:
        cfn:
          access_key_id:
            Ref: Key
          path: MyServerConfig.Metadata
          secret_access_key:
            Fn::GetAtt:
            - Key
            - SecretAccessKey
          stack_name:
            Ref: AWS::StackName
      nova:
        ...
      keystone:
        ...
    Properties:
      ImageId: '0'
      InstanceType: foo
    Type: AWS::AutoScaling::LaunchConfiguration

Essentially, this AutoScaling::LaunchConfiguration resource is a bunch of boilerplate gunk to provide a metadata container from where the os-collect-config cfn collector can pull configuration which will be applied by os-apply-config. There's a os-collect-config section to ensure the configuration from the EC2 metadata doesn't get overwritten. And the rest is dummy values for the LaunchConfiguration's required properties.