This document provides an overview of Mistral, an OpenStack workflow service. It describes Mistral's architecture and capabilities for defining, executing, and monitoring workflows. Workflows in Mistral are graphs of tasks with control and data flow. The current version supports basic task types like SSH and REST calls. Future plans include improving the workflow definition syntax, adding standard OpenStack actions, and developing the Horizon dashboard interface.

1. 1
Mistral
Workflow Service for OpenStack
Renat Akhmerov
Senior Software Engineer @ Mirantis
Dmitri Zimine
Chief Stormer @ StackStorm

2. 2
Agenda
• Overview
• Workflow Service: what and why
• Architecture
• Roadmap
• Discussion

3. 3
What is Mistral?
Mistral = Workflow Service for OpenStack

4. 4
Workflow Service
!
• Service to define, execute, and monitor workflows
• Keeps state
• Carries data
• Provides goodies: HA, tracking, history, etc.
• Best for cross-service integration “orchestration”

5. 5
Mistral Workflow
• Workflow: a graph of tasks
• Task Actions: call REST, run
command, create VM, send
email…
• Control flow:
• transitions
• conditions
• Data Flow: passing data
between tasks
• Triggers: cron, events, API
T1
T5
T3
T4
T2
Start
T6
T7
T8
T9

6. 6
Workflow Definition Snippet
Workflow:!
tasks:!
...!
runJob:!
action: Demo.runJob!
on-error: deleteVM!
on-success: sendJobError!
publish:!
job_results: job_results!
!
deleteVM:!
action: Nova:deleteVM!
on-finish: end!
!
sendJobError:!
action: std.email!
parameters:!
to: admin@mycompany.com!
subject: Workflow completed!
body: | !
! ! Workflow {$.execution.id} completed !
with results {$.job_results}!
on-finish: deleteVM!
...

7. 7
Data Flow Concept
RunVM
input:
image_id
SendMsg
input:
person.email
IsApprover
input:
person.name
GoOn
“image_id”: “123”,
“person”: {
“name”: “John”,
“email”: “john@me.com"
}
“image_id”: “123”,
“person”: {
“name”: “John”,
“email”: “john@me.com”
},
“vm_ip”: “10.0.0.3”
“image_id”: “123”,
“person”: {
“name”: “John”,
“email”: “john@me.com”
},
“vm_ip”: “10.0.0.3”
“image_id”: “123”,
“person”: {
“name”: “John”,
“email”: “john@me.com”
},
“vm_ip”: “10.0.0.3”,
“approver”: “true”
“image_id”: “123”,
“person”: {
“name”: “John”,
“email”: “john@me.com”
},
“vm_ip”: “10.0.0.3”,
“sent_msg”: “true”
“image_id”: “123”,
“person”: {
“name”: “John”,
“email”: “john@me.com”
},
“vm_ip”: “10.0.0.3”,
“approver”: “true”,
“sent_msg”: “true”
- task input - task result (added into context)

8. 8
Architecture
Scheduler
Executor
API ServerEngine
Executor
!
...
workflows
executions
tasks
events
Workflow Queue
Task Queue

9. 9
Dashboard

10. © MIRANTIS 2014
10
ROADMAP
NOW -> NEXT-> FUTURE

11. 11
What Works Now (ver 0.0.2)
• API, Engine, Executor, Scheduler, scale up/down
• Workflow DSL *
• Workflow engine:
• Control flow - transitions, conditions *
• Data Flow
• Basic tasks: ssh, HTTP/REST, email, echo
• ‘Ad-hoc’ actions
• Keystone integration
• CLI and Python client
• Horizon dashboard *

12. 12
Next
• Apply POC learnings
• Finalize workflow capabilities
• Simplify definition syntax
• Create content
• openstack action pack: nova, heat
• more standard actions
• Provide extensibility for writing custom actions
• Work on maturity, stability, performance
• Horizon Dashboard improvements

13. 13
Future
• Ceilometer Triggers
• Event Listeners
• Rollback
• Horizon Dashboard - Graphical Workflow
Presentation
• “Dry-run” mode
• TaskFlow integration, when ready

14. 14
More Info
Discussion etherpad: !
https://etherpad.openstack.org/p/juno-summit-mistral
!
More info:
• Mistral POC Demo: Expo E-26 booth
• Launchpad: https://launchpad.net/mistral
• Wiki: https://wiki.openstack.org/wiki/Mistral
• Screencast: https://www.youtube.com/watch?v=x-
zqz1CRVkI (search for “OpenStack Mistral POC Demo”)