openstack-manuals/doc/admin-guide-cloud/source/orchestration-stack-domain-users.rst

Stack domain users

Orchestration stack domain users allows Orchestration module to authorize inside VMs booted and execute the following operations:

• Provide metadata to agents inside instances, which poll for changes and apply the configuration expressed in the metadata to the instance.
• Detect signal completion of some action, typically configuration of software on a VM after it is booted (because OpenStack Compute moves the state of a VM to "Active" as soon as it spawns it, not when Orchestration has fully configured it).
• Provide application level status or meters from inside the instance. For example, allow AutoScaling actions to be performed in response to some measure of performance or quality of service.

Orchestration provides APIs which enable all of these things, but all of those APIs require some sort of authentication. For example, credentials to access the instance agent is running on. The heat-cfntools agents use signed requests, which requires an ec2 keypair created via OpenStack Identity, which is then used to sign requests to the Orchestration CloudFormation and CloudWatch compatible APIs, which are authenticated by Orchestration via signature validation (which uses the OpenStack Identity ec2tokens extension). Stack domain users allow to encapsulate all stack-defined users (users created as a result of things contained in an Orchestration template) in a separate domain which is created specifically to contain things related only to the Orchestration stacks. A user is created which is the domain admin, and Orchestration uses that user to manage the lifecycle of the users in the stack user domain.

Stack domain users configuration

To configure stack domain users the following steps shall be executed:

1. A special OpenStack Identity service domain is created. For example, the one called heat and the ID is set in the stack_user_domain option in heat.conf.
2. A user with sufficient permissions to create and delete projects and users in the heat domain is created.
3. The username and password for the domain admin user is set in heat.conf (stack_domain_admin and stack_domain_admin_password). This user administers stack domain users on behalf of stack owners, so they no longer need to be admins themselves, and the risk of this escalation path is limited because the heat_domain_admin is only given administrative permission for the heat domain.

You must complete the following steps to setup stack domain users:

1. Create the domain:

   $OS_TOKEN refers to a token. For example, the service admin token or some other valid token for a user with sufficient roles to create users and domains. $KS_ENDPOINT_V3 refers to the v3 OpenStack Identity endpoint (for example, http://keystone_address:5000/v3 where keystone_address is the IP address or resolvable name for the OpenStack Identity service).

   $ openstack --os-token $OS_TOKEN --os-url=$KS_ENDPOINT_V3 --os-\
     identity-api-version=3 domain create heat --description "Owns \
     users and projects created by heat"

   The domain ID is returned by this command, and is referred to as $HEAT_DOMAIN_ID below.

2. Create the user:

   $ openstack --os-token $OS_TOKEN --os-url=$KS_ENDPOINT_V3 --os-\
     identity-api-version=3 user create --password $PASSWORD --domain \
     $HEAT_DOMAIN_ID heat_domain_admin --description "Manages users \
     and projects created by heat"

   The user ID is returned by this command and is referred to as $DOMAIN_ADMIN_ID below.

3. Make the user a domain admin:

   $ openstack --os-token $OS_TOKEN --os-url=$KS_ENDPOINT_V3 --os-\
     identity-api-version=3 role add --user $DOMAIN_ADMIN_ID --domain \
     $HEAT_DOMAIN_ID admin

   Then you need to add the domain ID, username and password from these steps to heat.conf:

   stack_domain_admin_password = password
   stack_domain_admin = heat_domain_admin
   stack_user_domain = domain id returned from domain create above

Usage workflow

The following steps will be executed during stack creation:

1. Orchestration creates a new stack domain project in the heat domain if the stack contains any resources which require creation of a stack domain user.
2. For any resources which require a user, Orchestration creates the user in the stack domain project, which is associated with the Orchestration stack in the Orchestration database, but is completely separate and unrelated (from an authentication perspective) to the stack owners project (the users created in the stack domain are still assigned the heat_stack_user role, so the API surface they can access is limited via policy.json. See OpenStack Identity documentation <identity_management> for more info).
3. When API requests are processed, Orchestration does an internal lookup and allows stack details for a given stack to be retrieved from the database for both the stack owner's project (the default API path to the stack) and the stack domain project, subject to the policy.json restrictions.

To clarify that last point, that means there are now two paths which can result in retrieval of the same data via the Orchestration API. The example for resource-metadata is below:

GET v1/​{stack_owner_project_id}​/stacks/​{stack_name}​/\
​{stack_id}​/resources/​{resource_name}​/metadata

or:

GET v1/​{stack_domain_project_id}​/stacks/​{stack_name}​/​\
{stack_id}​/resources/​{resource_name}​/metadata

The stack owner uses the former (via heat resource-metadata {stack_name} {resource_name}), and any agents in the instance use the latter.