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− | == Mistral DSL specification == | + | == This Wiki is no longer maintained == |
− | Version 0.1
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− | === Main objects ===
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− | | + | Please see the [https://docs.openstack.org/mistral/latest/user/wf_lang_v2.html Mistral Workflow language documentation]. |
− | * '''Namespace'''
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− | * '''Action'''
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− | * '''Workflow'''
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− | * '''Task'''
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− | * '''Trigger'''
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− | | |
− | === Namespaces ===
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− | | |
− | Contains a list of namespaces grouping custom (ad-hoc) actions. For example, it's possible to create namespace "Nova" that would provide actions "createVM", "deleteVM" and similar for VM management in OpenStack.
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− | | |
− | ==== Attributes ====
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− | | |
− | All attributes are inside main keys of '''Namespaces''' - '''namespaces names'''. Attributes of an individual namespace are:
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− | * '''class''' - currently Mistral supports the following action classes out of the box: std.http, std.mistral_http, std.echo, std.email, std.ssh, this is an optional attribute
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− | * '''base-parameters''' - dictionary depending on type of the namespace, this parameter is optional. Values of these parameters apply to all actions inside the namespace. For example for std.http it can contain url, method, body and headers.
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− | * '''actions''' - list of actions provided by this namespace.
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− | | |
− | ==== YAML example: ====
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− | | |
− | Namespaces:
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− | Nova:
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− | class: std.http
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− | base-parameters:
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− | method: GET
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− | actions:
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− | create-vm:
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− | ......
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− | delete-vm:
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− | .....
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− | | |
− | === Action ===
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− | | |
− | A function provided by specific namespace.
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− | | |
− | ==== Attributes ====
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− | | |
− | * '''name''' - action name (string without space, mandatory attribute).
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− | * '''base-parameters''' - dictionary whose structure is defined by action class (or namespace class if defined). For std.http class it contains url, method, body and headers according to HTTP protocol specification.
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− | * '''parameters''' - list containing parameter names which should or could be specified in task. This attribute is optional and used only for documenting purposes.
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− | * '''output''' - dictionary-transformer for action output to send this output next to task. Keys of this dictionary will be included in task result, values are pure YAQL or inline YAQL expressions per key which define how the specific output should be retrieved from raw output (from action). See more about YAQL at https://pypi.python.org/pypi/yaql/0.3
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− | | |
− | ==== YAML example: ====
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− | | |
− | create-vm:
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− | base-parameters:
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− | url: servers
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− | parameters:
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− | - name
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− | - server_name
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− | output:
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− | vm_id: $.content.server.id
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− | | |
− | === Workflow ===
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− | | |
− | ==== Attributes ====
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− | | |
− | * '''tasks''' - list of tasks in this workflow, each task represents a computational step in the workflow.
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− | | |
− | ==== YAML example: ====
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− | | |
− | Workflow:
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− | tasks:
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− | create-vms:
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− | .....
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− | attache-volumes:
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− | .....
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− | | |
− | === Task ===
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− | | |
− | Represents a step in workflow, for example creating the VM
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− | | |
− | ==== Attributes ====
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− | | |
− | * '''action''' - name of action to perform
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− | * '''requires''' - list of tasks which should be execute before this tasks, or list of task names as a keys and condition as a value, this is optional parameter
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− | * '''parameters''' - actual parameters for the task, each value can be either some number, string etc, or YAQL expression to retrieve value from task context
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− | * '''on-success''' - task which will be scheduled on execution after current task has finished with state 'SUCCESS'
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− | * '''on-error''' - task which will be scheduled on execution after current task has finished with state 'ERROR'
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− | * '''on-finish''' - task which will be scheduled on execution after current task has finished
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− | | |
− | YAML example:
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− | | |
− | create-vm:
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− | action: Nova.create-vm
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− | parameters:
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− | image_id: $.image_id
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− | flavor_id: 42
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− | requires:
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− | task2: '$.value2 = 123'
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− | task4: '$.value4 = 122'
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− | on-success: task3
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− | | |
− | === Triggers ===
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− | | |
− | By trigger it is possible to invoke specific task and put it on schedule.
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− | | |
− | ==== Attributes ====
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− | | |
− | * '''type''' - can be PERIODIC, TIMER, CEILOMETER_ALARM
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− | * '''tasks''' - list of tasks which should be execute on trigger
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− | * '''parameters''' - list of parameters, defined by task
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− | | |
− | ==== YAML example: ====
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− | | |
− | triggers:
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− | backup-vm:
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− | type: periodic
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− | tasks: [create_backup, delete_old_backup]
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− | parameters:
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− | cron-pattern: 1 0 * * *
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− | | |
− | === Full YAML example: ===
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− | | |
− | ====This example requires the following properties provided in execution context:====
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− | # - nova_url ## url to Nova service, e.g. http://0.0.0.0:8774/v3
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− | # - server_name ## Name you want to give to new instance
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− | # - image_id ## image id from Glance service
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− | # - flavor_id ## flavor id - type of instance hardware
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− | # - ssh_username ## username of your VM
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− | # - ssh_password ## password to your VM
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− | # - admin_email ## email address to send notifications to
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− | # - from_email ## email address to send notifications from
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− | # - smtp_server ## SMTP server to use for sending emails (e.g. smtp.gmail.com:587)
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− | # - smtp_password ## password to connect to SMTP server
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− | | |
− | | |
− | Namespaces:
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− | Nova:
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− | # Nova actions for creating VM, retrieving IP and VM deleting.
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− | class: std.http
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− | actions:
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− | createVM:
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− | base-parameters:
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− | url: '{$.nova_url}/{$.project_id}/servers'
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− | method: POST
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− | headers:
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− | X-Auth-Token: $.auth_token
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− | Content-Type: application/json
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− | body:
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− | server:
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− | name: $.server_name
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− | imageRef: $.image_id
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− | flavorRef: $.flavor_id
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− | output:
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− | vm_id: $.content.server.id
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− |
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− | getIP:
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− | base-parameters:
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− | url: '{$.nova_url}/{$.project_id}/servers/{$.vm_id}'
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− | method: GET
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− | headers:
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− | X-Auth-Token: $.auth_token
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− | output:
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− | vm_ip: "$.content.server.addresses.novanetwork.where($.'OS-EXT-IPS:type' = 'floating')[0].addr"
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− |
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− | deleteVM:
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− | base-parameters:
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− | url: '{$.nova_url}/{$.project_id}/servers/{$.vm_id}'
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− | method: DELETE
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− | headers:
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− | X-Auth-Token: $.auth_token
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− | output:
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− | status: $.status
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− |
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− | Server:
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− | actions:
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− | # HTTP request to the server.
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− | calcSumm:
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− | class: std.http
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− | base-parameters:
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− | url: 'http://{$.vm_ip}:5000/summ'
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− | method: POST
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− | body:
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− | arguments: $.arguments
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− | output:
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− | summ_result: $.content.result
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− |
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− | Ssh:
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− | class: std.ssh
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− | base-parameters:
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− | host: $.vm_ip
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− | username: $.username
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− | password: $.password
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− | actions:
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− | # Simple SSH command.
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− | waitSSH:
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− | base-parameters:
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− | cmd: 'ls -l'
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− |
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− | # SSH command to run the server.
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− | runServer:
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− | base-parameters:
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− | cmd: 'nohup python ~/web_app.py > web_app.log &'
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− |
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− | Workflow:
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− | tasks:
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− | # Create a VM (request to Nova).
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− | createVM:
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− | action: Nova.createVM
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− | parameters:
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− | server_name: $.server_name
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− | image_id: $.image_id
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− | flavor_id: $.flavor_id
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− | nova_url: $.nova_url
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− | project_id: $.project_id
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− | auth_token: $.auth_token
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− | publish:
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− | vm_id: vm_id
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− | on-success: waitForIP
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− | on-error: sendCreateVMError
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− |
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− | # Wait till the VM is assigned with IP address (request to Nova).
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− | waitForIP:
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− | action: Nova.getIP
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− | retry:
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− | count: 10
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− | delay: 10
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− | publish:
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− | vm_ip: vm_ip
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− | parameters:
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− | nova_url: $.nova_url
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− | project_id: $.project_id
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− | auth_token: $.auth_token
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− | vm_id: $.vm_id
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− | on-success: waitSSH
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− | on-error: sendCreateVMError
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− |
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− | # Wait till operating system on the VM is up (SSH command).
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− | waitSSH:
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− | action: Ssh.waitSSH
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− | retry:
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− | count: 10
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− | delay: 10
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− | parameters:
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− | username: $.ssh_username
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− | password: $.ssh_password
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− | vm_ip: $.vm_ip
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− | on-success: runServer
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− | on-error: sendCreateVMError
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− |
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− | # When SSH is up, we are able to run the server on VM (SSH command).
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− | runServer:
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− | action: Ssh.runServer
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− | parameters:
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− | vm_ip: $.vm_ip
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− | username: $.ssh_username
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− | password: $.ssh_password
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− | on-success: calcSumm
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− | on-error: sendCreateVMError
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− |
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− | # Send HTTP request on server and calc the result.
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− | calcSumm:
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− | action: Server.calcSumm
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− | retry:
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− | count: 10
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− | delay: 1
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− | parameters:
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− | arguments:
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− | - 32
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− | - 45
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− | - 23
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− | vm_ip: $.vm_ip
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− | publish:
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− | result: summ_result
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− | on-finish: sendResultEmail
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− |
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− | # In case of createVM error send e-mail with error message.
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− | sendResultEmail:
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− | action: std.email
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− | parameters:
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− | params:
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− | to: [$.admin_email]
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− | subject: Workflow result
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− | body: |
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− | Workflow result of execution {$.__execution.id} is {$.result}
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− |
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− | -- Thanks, Mistral Team.
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− | settings:
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− | smtp_server: $.smtp_server
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− | from: $.from_email
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− | password: $.smtp_password
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− | on-finish: deleteVM
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− |
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− | # In case of createVM error send e-mail with error message.
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− | sendCreateVMError:
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− | action: std.email
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− | parameters:
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− | params:
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− | to: [$.admin_email]
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− | subject: Workflow error
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− | body: |
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− | Failed to create a VM in execution {$.__execution.id}
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− |
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− | -- Thanks, Mistral Team.
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− | settings:
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− | smtp_server: $.smtp_server
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− | from: $.from_email
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− | password: $.smtp_password
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− | on-finish: deleteVM
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− |
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− | # Destroy the VM (request to Nova).
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− | deleteVM:
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− | action: Nova.deleteVM
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− | parameters:
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− | nova_url: $.nova_url
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− | project_id: $.project_id
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− | auth_token: $.auth_token
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− | vm_id: $.vm_id
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− | | |
− | ==== Initial execution context ====
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− | {
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− | "nova_url": <nova_url>,
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− | "image_id": <image_id>,
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− | "flavor_id": <flavor_id>,
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− | "server_name": <server_name>,
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− | "ssh_username": <ssh_username>,
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− | "ssh_password": <ssh_password>,
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− | "admin_email": <admin_email>,
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− | "from_email": <from_email>,
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− | "smtp_server": <smtp_server>,
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− | "smtp_password": <smtp_password>,
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− | }
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− | | |
− | '''When a workflow starts Mistral also adds execution information into the context so the context looks like the following:'''
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− | | |
− | {
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− | "nova_url": TBD,
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− | "image_id": TBD,
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− | "image_id": <image_id>,
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− | "flavor_id": <flavor_id>,
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− | "server_name": <server_name>,
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− | "ssh_username": <ssh_username>,
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− | "ssh_password": <ssh_password>,
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− | "admin_email": <admin_email>,
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− | "from_email": <from_email>,
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− | "smtp_server": <smtp_server>,
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− | "smtp_password": <smtp_password>,
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− | "__execution": {
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− | "id": "234234",
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− | "workbook_name" : "my_workbook",
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− | "project_id": "ghfgsdfasdfasdf"
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− | "auth_token": "sdfljsdfsdf-234234234",
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− | "trust_id": "oiretoilkjsdfglkjsdfglkjsdfg"
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− | }
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− | }
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