Hello, I’m one of the engineer working on Murano project. Recently we started a discussion about Murano and Heat Software orchestration and I want to continue this discussion with more technical details.
In our project we do deployment of complex multi-instance Windows services. Those services usually require specific multi-VM orchestration that is currently impossible or at least not that easy to achieve with Heat. As you are currently doing HOT software orchestration design we would like to participate in HOT Software orchestration design and contribute into it, so that the Heat could address use-cases which we believe are very common. For example here is how deployment of a SQL Server cluster goes: 1. Allocate Windows VMs for SQL Server cluster 2. Enable secondary IP address from user input on all SQL Windows instances 3. Install SQL Server prerequisites on each node 4. Choose a master node and install Failover Cluster on it 5. Configure all nodes so that they know which one of them is the master 6. Install SQL Server on all nodes 7. Initialize AlwaysOn on all nodes except for the master 8. Initialize Primary replica 9. Initialize secondary replicas All of the steps must take place in appropriate order depending on the state of other nodes. Some steps require an output from previous steps and all of them require some input parameters. SQL Server requires an Active Directory service in order to use Failover mechanism and installation of Active Directory with primary and secondary controllers is a complex workflow of its own. That is why it is necessary to have some central coordination service which would handle deployment workflow and perform specific actions (create VMs and other OpenStack resources, do something on that VM) on each stage according to that workflow. We think that Heat is the best place for such service. Our idea is to extend HOT DSL by adding workflow definition capabilities as an explicit list of resources, components’ states and actions. States may depend on each other so that you can reach state X only after you’ve reached states Y and Z that the X depends on. The goal is from initial state to reach some final state “Deployed”. There is such state graph for each of our deployment entities (service, VMs, other things). There is also an action that must be performed on each state. For example states graph from example above would look like this: The goal is to reach Service_Done state which depends on VM1_Done and VM2_Done states and so on from initial Service_Start state. We propose to extend HOT DSL with workflow definition capabilities where you can describe step by step instruction to install service and properly handle errors on each step. We already have an experience in implementation of the DSL, workflow description and processing mechanism for complex deployments and believe we’ll all benefit by re-using this experience and existing code, having properly discussed and agreed on abstraction layers and distribution of responsibilities between OS components. There is an idea of implementing part of workflow processing mechanism as a part of Convection proposal, which would allow other OS projects to benefit by using this. We would like to discuss if such design could become a part of future Heat version as well as other possible contributions from Murano team. Regards, Stan Lagun -- Senior Developer Mirantis 35b/3, Vorontsovskaya St. Moscow, Russia Skype: stanlagun www.mirantis.com sla...@mirantis.com
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