Additions/comments inline below. Thanks, Unmesh G. From: Murugan, Visnusaran Sent: Thursday, September 18, 2014 1:46 PM To: openstack-dev@lists.openstack.org Subject: [openstack-dev] [heat] Persist graph for convergence
Hi All, Below is the model proposal for persisting ResourceGraph. Column name Type Constraint resource_id varchar(36) NOT NULL ForeignKey resource.id needed_by varchar(36) NULL ForeignKey resource.id stack_id varchar(36) NOT NULL ForeignKey stack.id retry_count Integer Default (0) observed_ready Boolean Default False Create cycle: 1. Persist graph [Unmesh] - So, it is a pre-requisite to persist all the resources of a stack (in the resource table) to be able to persist a graph (i.e step #0). 2. Mark desired states for all resources in the stack. (table: resources) [Unmesh] - This I believe should be done as a part of persisting a stack's resources (in step #0). 3. Initiate stack create by calculating leaf nodes (All observed_ready=False nodes in resource_id column but not in needed_by column) 4. Post create resource jobs to engine worker 5. Engine worker upon task initiation posts observe task to convergence-observer and complete tack execution (return true) 6. Mark observed_ready upon receiving resource completion notification from observer. Repeat step 3 through 6 till all nodes (resources) are marked observed_ready. [Unmesh] - In case resource creation fails, the worker will increment retry_count and try creating the resource for a maximum of 'action_retry_limit' configured value. 7. If not more nodes, then mark stack create complete and return happy Update cycle: 1. Persist new graph for new stack created 2. Mark desired state for all resources in both old and new stacks. 3. Perform steps 3 to 6 4. Delete old stack, garbage collect unwanted resources 5. Mark stack update complete and return happy. Clint had in fact proposed to have a "version Integer default(0)". To achieve this I feel Table:Stack should also have versioning instead of creating a backup_stack. Currently backup and nested stack relation is achieved using owner_id. In case if update, versioning makes more sense instead on creating a backup stack and setting owner_id as current stack. -Vishnu
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