TOSCA workflows

TOSCA workflows Default workflow is declarative (generated from nodes and relationships) install at the beginning of install workflow all instances are in initial state. at the end of install workflow all planned instances must be in started state uninstall at the end of uninstall workflow all instances must be in deleted state Multiple solutions to allow users customize workflows Imperative Full override Partial override Declarative improvements Various solutions are not exclusive

Full workflow override Upsides Simple from orchestrator perspective User has a full-vision and understanding of the workflow No doubt on TOSCA default workflow weaving (dependencies and sequencing between related nodes). Downsides Can be fastidious to write without tools Workflow is specific to a given topology template

Full workflow override Inspired by mistral http://docs.openstack.org/developer/mistral/dsl/dsl_v2.html Adapted for TOSCA Simplified declaration Simplification, no need for inputs and outputs that are already defined on operations and using get_operation_output

Full workflow override Single activity per step Or allow multiple sequential activities per step ? topology_template: workflows: <workflow_identifier> description: <workflow_description> inputs: <parameter_definition_list> # (can be used from operations using get_input as in standard topology template) steps: # map of steps <step_name>: node: <node_name> requirement: <relationship_name> # name of the requirement/relationship of the node activity: # sequence of activities to be executed in a sequential way <activity_type>: <activity_configuration> on-success: - <list of step names> topology_template: workflows: <workflow_identifier> description: <workflow_description> inputs: <parameter_definition_list> # (can be used from operations using get_input as in standard topology template) steps: # map of steps <step_name>: node: <node_name> requirement: <relationship_name> # name of the requirement/relationship of the node activities: # sequence of activities to be executed in a sequential way - <activity_type>: <activity_configuration> on-success: - <list of step names>

Full workflow override Activity type description delegate Activity to be used when a node is not provided by a user but should be provided by the orchestrator engine (Compute, BlockStorage etc.). For such node weaving operations of relationships that are not also provided by the orchestrator should be prohibited. set_state Change the state of a node to a given state. call_operation Call the operation of the specified node (or one of it’s relationship). Inputs of the operation are defined on the operation element. Delegate activity is important for portability in some use-cases Orchestrator to provide nodes (Compute, BlockStorage etc.) where implementation can be specific Reusability of existing services (an existing Oracle DB on the cloud to be matched against an abstract DB node in the topology one one cloud vs. creating one on the fly on another cloud)

Full workflow override The on-success values are used to build the workflow graph. All steps that have a on-success defined to a given step should be executed before it (join). All steps that doesn’t have a predecessor are considered as initial step and can run in parallel. All steps that doesn’t have a successor are considered as final. The TOSCA parser/validator SHOULD ensure that all nodes MUST reach the started state at the end of the install workflow all nodes MUST reach the deleted state at the end of the uninstall workflow

Full workflow override steps: A: on-success: - B - C B: - D C: D: E: - F F: A E B C F D

Sample: The workflow that creates the compute node until started state is delegated to the orchestrator compute started tomcat Tomcat Requirements Host mysql creating tomcat creating mysql create tomcat create mysql created tomcat created HostedOn mysql MySQL Requirements Host mysql starting mysql start mysql started HostedOn compute tosca.nodes.Compute Capabilities Container This scenario aims to allow to perform tomcat’s creation in parallel of mysql creation and start (bypass the single concurrent operation per compute constraint) Start tomcat after mysql even if no relation is specified between the two nodes Tomcat starting tomcat start Tomcat started

Sample Delegating can be a mapping. topology_template: workflows: install: description: Workflow to deploy the application steps: Compute_install: target: Compute activities: - delegate: install on-success: - Mysql_initial - Tomcat_initial Tomcat_initial: target: Tomcat - set_state: creating - call_operation: tosca.interfaces.node.lifecycle.Standard.create - set_state: created - Tomcat_starting Mysql_initial: node: Mysql - set_state: starting - call_operation: tosca.interfaces.node.lifecycle.Standard.start - set_state: started Sample Tomcat_starting: target: Tomcat activities: - set_state: starting - call_operation: tosca.interfaces.node.lifecycle.Standard.start - set_state: started on-success: - Tomcat_starting Delegating can be a mapping. Think about convention for sure naming

Partial workflow override Work in progress Upsides Easier to write if a user has no tool Downsides May be prone to errors as it may be harder to understand what will be added or not by the TOSCA orchestrator (no automatic weaving should be done between steps that are defined in an implicit workflow). Only for install and uninstall workflows ? Custom workflows and other scenarios will anyway probably require a full-workflow describtion Workflow is specific to a given topology template

Partial workflow override Work in progress Similar to full workflow override but you can have more than one partial workflow. Partial workflow let the orchestrator generate the workflow of nodes before the topology_template: workflows: <workflow_identifier> description: <workflow_description> inputs: <parameter_definition_list> # (can be used from operations using get_input as in standard topology template) partials: steps: # map of steps for the partial workflow <step_name>: node: <node_name> requirement: <relationship_name> # name of the requirement/relationship of the node activities: # sequence of activities to be executed in a sequential way - <activity_type>: <activity_configuration> on-success: - <list of step names>

Declarative workflows improvements (TOSCA-219) Upsides Can onboard ‘workflow updates’ on types and make them reusable (not specific to a topology template) Downsides Less focused on reusability on a specific existing workflow for a specific topology (need to get into TOSCA declarative workflow logic)

Declarative workflows improvements Add elements to instruct the declarative workflows for types Node Types Relationships Types Allow to override them on templates (like interfaces)

Declarative workflows improvements Work in progress node_types: <node_type>: workflows: # Defines the workflow for the given node. <workflow_identifier>: steps: # map of steps (you can even do some things in parallel for a single node if that make sense) <step_name>: activities: # sequence of activities to be executed in a sequential way - <activity_type>: <activity_configuration> on-success: - <list of step names>

Declarative workflows improvements Work in progress node_types: tosca.nodes.Root: workflows: install: steps: install_sequence: activities: - set_state: creating - call_operation: tosca.interfaces.node.lifecycle.Standard.create - set_state: created - set_state: configuring - call_operation: tosca.interfaces.node.lifecycle.Standard.configure - set_state: configured - set_state: starting - call_operation: tosca.interfaces.node.lifecycle.Standard.start - set_state: started uninstall: uninstall_sequence: - set_state: stopping - call_operation: tosca.interfaces.node.lifecycle.Standard.stop - set_state: stopped - set_state: deleting - call_operation: tosca.interfaces.node.lifecycle.Standard.delete - set_state: deleted Group and clusters - Mongo Scalable single nodes - Zookeeper

Declarative workflows improvements Work in progress relationship_types: tosca.relationships.ConnectsTo: workflow: install: # name of the workflow for wich the weaving has to be taken in account source_weaving: # Instruct how to weave some tasks on the source workflow (executed on SOURCE instance) - after: configuring # instruct that this operation should be weaved after the target reach configuring state wait_target: created # add a join from a state of the target activity: tosca.interfaces.relationships.Configure.pre_configure_source - before: configured # instruct that this operation should be weaved before the target reach configured state activity: tosca.interfaces.relationships.Configure.post_configure_source - before: starting wait_target: started # add a join from a state of the target - after: started activity: tosca.interfaces.relationships.Configure.add_target target_weaving: # Instruct how to weave some tasks on the target workflow (executed on TARGET instance) after_source: created # add a join from a state of the source activity: tosca.interfaces.relationships.Configure.pre_configure_target activity: tosca.interfaces.relationships.Configure.post_configure_target activity: tosca.interfaces.relationships.Configure.add_source

Declarative workflows improvements TODO: Provide elements relative to instance model Scaled Apache node: each node has independent workflow Scaled Zookeeper node: Ideally I would like to wait that all zookeeper instances are created before I do the configure operations Manage impacts and weaving of Groups interfaces for some clusters scenarios