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Operator

Operator is a DataOS Resource that provides a standardized interface for orchestrating resources situated outside the DataOS cluster, empowering data developers with the capability to invoke actions programmatically upon these external resources directly from interfaces of DataOS.

Operator Architecture
High-level view of the Operator Resource within DataOS Architecture

At its core, an Operator empowers the DataOS orchestrator, referred to as Poros, to manage these external resources using custom-built Operators.

Key Features of Operator

Extensibility

The Operator augments DataOS capabilities by facilitating integration with external tools and data developer platforms such as Azure Data Factory, Databricks, Snowflake, and more. The external platform could be any platform, application, or service. It doesn't have to be Kubernetes-based, it could be anything that the Operator Pattern supports.

Common Management Plane

The Operator establishes a common management plane to orchestrate external resources. This not only enables CRUD operations but also provides comprehensive monitoring and logging, streamlining Root Cause Analyses (RCAs) and enhancing operational efficiency.

Scalability and Speed

In collaboration with the Bundle Resource within the DataOS, the Operator automates processes, thus accelerating both the scale and speed of data product creation.

Collaboration

The Operator alleviates collaboration hurdles arising from the diversity of technologies, each with its own frameworks, protocols, and languages. It achieves this by enabling cross-functional collaboration through a unified interface.

Integration Burden

The Operator enhances the developer experience and enhances productivity by offering a unified and consistent interface across all external resources. While it does not simplify the underlying architecture, it significantly streamlines interaction with the infrastructure.

How to create an Operator?

Let’s take a scenario in which a data developer wants to trigger a pipeline run in Azure Data Factory (external platform) and synchronize the metadata from ADF back into DataOS for observability. But before proceeding ahead, make sure you have the following prerequisites.

Prerequisites

Azure Connection Fields

To set up your Azure Data Factory Operator, ensure you have the following four fields readily available:

  • AZURE_SUBSCRIPTION_ID
  • AZURE_CLIENT_ID
  • AZURE_CLIENT_SECRET
  • AZURE_TENANT_ID

Pipeline Run-specific Fields

For programmatic triggering, gather information regarding the various fields required for initiating a pipeline run. Refer to the official Azure Data Factory Pipeline Run API documentation for details.

Steps

Creating your operator involves a series of logical steps, as outlined below:

  1. Implementing the Operator Interfaces
    a. Reconciler Interface
    b. OController Interface
    c. Message Handler Interface
  2. Dockerize the Code
  3. Create manifest file for an Operator
  4. Apply the Operator manifest
  5. Verify Operator creation
  6. Manifest for Resource (external Resource)
  7. Apply the Resource manifest
  8. Get Status of Resource
  9. Check Status on Azure Data Factory UI
  10. Metadata Synchronization in DataOS

Implementing the Operator Interfaces

The first step in creating an Operator is implementing three key interfaces: Reconciler, OController, and Message Handler Interface using the the DataOS SDK-Go.

Reconciler Interface

The Reconciler Interface is responsible for reconciling resources based on state changes.

type Reconciler interface {
    Id() string
    Init(OController)
    Reconcile(ReconcileRequest, context.Context) (ReconcileResult, error)
}

OController Interface

OController, the Operator Controller Interface, manages the entity status. The SDK incorporates an entity store, extendable to Redis or a database if required.

type OController interface {
    GetEntity(key string, typ EntityOfInterestType) (*Entity, error)
    GetEntityStatus(key string, typ EntityOfInterestType) (*EntityStatus, error)
    UpdateEntityStatus(es *EntityStatus) error
}

The SDK's controller object implements the OController interface, and the reconciler implementation is integrated into this controller.

Message Handler Interface

The Message Handler Interface deals with communication from the DataOS Orchestrator, Poros.

type MessageHandler interface {
    // HandleCommand is the way that upstream controllers can request this
    // operator to create, update and delete entities of interest.
    HandleCommand(
        me *models.MessageEnvelope,
        es state.EntityStore,
        ess state.EntityStatusStore,
        node *snowflake.Node,
    ) error
    // HandleQuery is the way that upstream controllers
    // can request information about entities of interest and their status.
    HandleQuery(
        me *models.MessageEnvelope,
        es state.EntityStore,
        ess state.EntityStatusStore,
        node *snowflake.Node,
    ) (*models.MessageEnvelope, error)
}

The message handler implementation is employed to create an instance of Messaging API, which manages the communication interface with the NATS Cluster. The state is subsequently captured within the Poros orchestrator using the query interface.

Sample Implementation for the interfaces can be found here.

Dockerize the Code

After implementing the required interfaces, dockerize your code and move the image to a docker container registry.

Create a Manifest for Operator

Once you have done that proceed to create a YAML manifest for your Operator. An Operator Resource YAML manifest can be structurally broken down into following sections:

Resource Meta section

An Operator is classified as a Resource-type within DataOS. The YAML configuration file of an Operator Resource includes a Resource Meta section that encompasses metadata attributes shared among all Resource-types. For in-depth information about the attributes of Resource Meta section, please consult the Attributes of Resource Meta section.

Operator-specific section

The Operator-specific section is further divided into four distinct sections: Computational components, Resource definition, NATS Cluster configuration, Enabled Workspaces. Each of these sections should be appropriately configured when crafting an Operator YAML.

  • Computational Components: Computational Components encapsulate the logic for managing the interactions with resources within the external platform/application/service (external resource), handling the entire lifecycle of associated resources. These components are responsible for reconciling resource states and translating them back to the DataOS orchestrator, Poros. The components section in the Operator-specific section is a list of mappings allowing you to define multiple computational components. Each component is either a Worker or a Service Resource. These components can be customized with unique Docker images, secret configuration, and environment variables to facilitate their execution.
  • Resource Definition: The Resource definition encompasses specifications for external resources to be orchestrated through DataOS. This definition acts as a comprehensive blueprint, providing all necessary information about the resource and the schema it must adhere to. The resource definition is flexible and can be tailored to suit the specific requirements of the external resource you intend to orchestrate. Multiple resources can be defined to interact with different external platforms as needed.
  • NATS Cluster Configuration: NATS is a lightweight pub-sub system. It is used to implement a Command Query Responsibility Segregation (CQRS)-based communication channel between the Operator Runtime, which lives in Poros, and the computational components mentioned above. It's a 2-way communication channel. The operator components have the specific knowledge regarding the management of the resources. They listen for commands and queries on the NATS Cluster. The Operator runtime communicates with the operator components using the specific commands for a Resource-type. Poros Operator takes care of manifesting the NATS Cluster.
  • Enabled Workspaces: The enabledWorkspaces attribute is a list of strings for selectively specifying the Operator within specific workspaces.

The following YAML manifest illustrates the attributes specified within the Operator YAML:

# Resource meta section
name: ${{azure-data-factory}}
version: v1alpha
type: operator
layer: user
description: ${{provides management of azure data factory resources lifecycle}}
tags:
    - ${{operator}}
    - ${{adf}}
    - ${{azure-data-factory}}

# Operator-specific section
operator:

  # NATS Cluster configuration
    natsClusterConfig:
        name: ${{adf-nats}}
        compute: ${{runnable-default}}
        runAsUser: ${{minerva-cluster}} 

  # Computational Components
    components:
        - name: ${{adf-controller}}
            type: ${{worker}}
            compute: ${{runnable-default}}
            runAsUser: ${{minerva-cluster}}
            image: ${{docker.io/rubiklabs/azure-operator:0.1.5-dev}}
            imagePullSecret: ${{dataos-container-registry}}
            command: 
                - ${{/opt/tmdc-io/azure-operator}}
            arguments:
                - ${{operator}}
                - adf
                - --electionStateFile
                - /opt/tmdc-io/leader-election.log
            replicas: 2
            environmentVars: 
                LOG_LEVEL: info
                METRIC_PORT: 30001
                ELECTION_CLUSTER_NAME: azure-operators
                ELECTION_CLUSTER_SIZE: 1
                OPERATOR_MAX_WORKERS: 1
                OPERATOR_RECONCILE_WORKERS_INTERVAL: 10s
                OPERATOR_MAINTENANCE_INTERVAL: 1m
                OPERATOR_PURGE_STATE_STORE_BEFORE: 5m
                OPERATOR_STATE_STORE_TYPE: jetstream_kv
                MESSAGE_DURABILITY: true
                # NATS Cluster specific environment variables
                ENTITY_OF_INTEREST_MESSAGE_QUEUE: azure-entities-adf-52323
                ENTITY_OF_INTEREST_MESSAGE_STREAM: dataos-azure-entities
                ENTITY_OF_INTEREST_MESSAGE_COMMAND_SUBJECT: adf.pipeline.run
                ENTITY_OF_INTEREST_MESSAGE_QUERY_SUBJECT: adf.pipeline.run.query
                ENTITY_OF_INTEREST_MESSAGE_QUERY_REPLY_SUBJECT: dataos.operator.adf.reply
                # Azure Data Factory specific environment variables
                AZURE_TENANT_ID: 191b8015-c70b-4cc7-afb0-818de32c05df
                AZURE_CLIENT_ID: 769f7469-eaed-4210-8ab7-obc4549d85a1
                AZURE_CLIENT_SECRET: LGz8Q-NcuMf~GcPwjAjpJINM6n(iLFiuBsrPubAz
                AZURE_SUBSCRIPTION_ID: 79d26b17-3fbf-4c85-a88b-10a4480fac77
            ports:
                - name: metrics
                    servicePort: 30001
                    targetPort: 30001
    # Resource Definition
    resources: 
        - name: pipeline-run
            isRunnable: true
            specSchema:
                jsonSchema: |
                        {
                        "$schema": "https://json-schema.org/draft/2020-12/schema",
                        "$id": "https://dataos.io/v1.0/azure-data-factory/pipeline-run",
                        "title": "pipeline-run",
                        "type": "object",
                        "properties": {
                          "factoryName": {
                            "type": "string"
                          },
                          "pipelineName": {
                            "type": "string"
                          },
                          "resourceGroupName": {
                            "type": "string"
                          },
                          "parameters": {
                            "type": "object",
                            "additionalProperties": true
                          },
                          "referencePipelineRunID": {
                            "type": "string",
                            "nullable": true
                          },
                          "startActivityName": {
                            "type": "string",
                            "nullable": true
                          },
                          "startFromFailure": {
                            "type": "boolean",
                            "nullable": true
                          }
                        },
                        "required": [
                          "factoryName",
                          "pipelineName",
                          "resourceGroupName"
                            ],"additionalProperties": false
                        }
        natsApi:
            command:
                stream: dataos-zure-entities
                subject: adf.pipeline.run
            query:
                subject: adf.pipeline.run.query
                replySubject: dataos.operator.adf.reply

    # Enabled Workspaces
    enabledWorkspaces: 
        - public
        - sandbox

You can also pass the Azure-specific Secrets seperately.

How to pass Secrets as a Resource and refer them in a separate Resource? Create a Secret Resource manifest 
name: ${{adf-operator}}
version: v1
description: ${{the secrets for adf operator}}
secret: 
    type: key-value-properties
    acl: rw
    data: 
        AZURE_TENANT_ID: ${{azure tenant id}}
        AZURE_CLIENT_ID: ${{azure client id}}
        AZURE_CLIENT_SECRET: ${{azure client secret}}
        AZURE_SUBSCRIPTION_ID: ${{azure subscription id}}
Apply the Secret YAML 
dataos-ctl apply -f ${{secret-yaml-file-path}} -w ${{workspace}}
Reference the Secrets in the Operator YAML 
# Resource meta section
name: ${{azure-data-factory}}
version: v1alpha
type: operator
layer: user
description: ${{provides management of azure data factory resources lifecycle}}
tags:
    - ${{operator}}
    - ${{adf}}
    - ${{azure-data-factory}}

# Operator-specific section
operator:

    # NATS Cluster configuration
    natsClusterConfig:
        name: ${{adf-nats}}
        compute: ${{runnable-default}}
        runAsUser: ${{minerva-cluster}} 

    # Computational Components
    components:
        - name: ${{adf-controller}}
            type: ${{worker}}
            compute: ${{runnable-default}}
            runAsUser: ${{minerva-cluster}}
            image: ${{docker.io/rubiklabs/azure-operator:0.1.5-dev}}
            imagePullSecret: ${{dataos-container-registry}}
            command: 
                - ${{/opt/tmdc-io/azure-operator}}
            arguments:
                - ${{operator}}
                - adf
                - --electionStateFile
                - /opt/tmdc-io/leader-election.log
            replicas: 2
            environmentVars: 
                LOG_LEVEL: info
                METRIC_PORT: 30001
                ELECTION_CLUSTER_NAME: azure-operators
                ELECTION_CLUSTER_SIZE: 1
                OPERATOR_MAX_WORKERS: 1
                OPERATOR_RECONCILE_WORKERS_INTERVAL: 10s
                OPERATOR_MAINTENANCE_INTERVAL: 1m
                OPERATOR_PURGE_STATE_STORE_BEFORE: 5m
                OPERATOR_STATE_STORE_TYPE: jetstream_kv
                MESSAGE_DURABILITY: true
# NATS specific stuff (not exposing to the user)
                ENTITY_OF_INTEREST_MESSAGE_QUEUE: azure-entities-adf-52323
                ENTITY_OF_INTEREST_MESSAGE_STREAM: dataos-azure-entities
                ENTITY_OF_INTEREST_MESSAGE_COMMAND_SUBJECT: adf.pipeline.run
                ENTITY_OF_INTEREST_MESSAGE_QUERY_SUBJECT: adf.pipeline.run.query
                ENTITY_OF_INTEREST_MESSAGE_QUERY_REPLY_SUBJECT: dataos.operator.adf.reply
# Passed as Secret Resource
            dataosSecrets:
                - name: adf-operator
                    workspace: user-system
                    allKeys: true
                    consumptionType: envVars
            ports:
                - name: metrics
                    servicePort: 30001
                    targetPort: 30001
    resources: # Resources is a list of Resources that we want to manage
        - name: pipeline-run
            isRunnable: true
            specSchema:
                jsonSchema: |
                        {
                        "$schema": "https://json-schema.org/draft/2020-12/schema",
                        "$id": "https://dataos.io/v1.0/azure-data-factory/pipeline-run",
                        "title": "pipeline-run",
                        "type": "object",
                        "properties": {
                            "factoryName": {
                            "type": "string"
                            },
                            "pipelineName": {
                            "type": "string"
                            },
                            "resourceGroupName": {
                            "type": "string"
                            },
                            "parameters": {
                            "type": "object",
                            "additionalProperties": true
                            },
                            "referencePipelineRunID": {
                            "type": "string",
                            "nullable": true
                            },
                            "startActivityName": {
                            "type": "string",
                            "nullable": true
                            },
                            "startFromFailure": {
                            "type": "boolean",
                            "nullable": true
                            }
                        },
                        "required": [
                            "factoryName",
                            "pipelineName",
                            "resourceGroupName"
                            ],"additionalProperties": false
                        }
        natsApi:
            command:
                stream: dataos-zure-entities
                subject: adf.pipeline.run
            query:
                subject: adf.pipeline.run.query
                replySubject: dataos.operator.adf.reply

    enabledWorkspaces: 
        - public
        - sandbox

The table below summarizes the attributes of the Operator-specific section:

Attribute Data Type Default Value Possible Value Requirement
operator mapping none none mandatory
components list of mappings none none mandatory
name string none none mandatory
type string none service/worker mandatory
compute string none runnable-default or any other custom Compute Resource name mandatory
runAsApiKey string Apikey of user valid DataOS Apikey mandatory
runAsUser string none user-id of Use Case Assignee optional
image string none valid image name mandatory
imagePullSecret string none valid Secret Resource for pulling images from the Private Container Registry optional
command list of strings none valid command optional
arguments list of strings none valid arguments optional
replicas integer none any integer mandatory
environmentVars mapping none list of available environment variables given here optional
secrets mapping none none optional
name string none valid Secret Resource name mandatory
workspace string none valid Workspace name mandatory
ports list of mappings none none optional
name string none valid string mandatory
servicePort integer none valid port mandatory
targetPort integer none valid port mandatory
resources mapping none none mandatory
name string none valid resources name mandatory
nameJqFilter string none valid string optional
isRunnable boolean false true/false mandatory
specSchema mapping none none optional
jsonSchema string none none mandatory
natsApi mapping none none optional
command mapping none none mandatory
stream string none valid stream mandatory
subject string none valid subject mandatory
query mapping none none mandatory
subject string none valid subject mandatory
replySubject string none valid replySubject mandatory
natsClusterConfig mapping none none mandatory
name string none valid name mandatory
compute string none runnable-default or any other custom Compute Resource name mandatory
runAsUser string none user-id of Use Case Assignee optional
runAsApiKey string Apikey of user valid DataOS Apikey (if not provided it takes the user’s default apikey) mandatory
enabledWorkspaces list of strings none valid DataOS Workspace mandatory

For in-depth information about the attributes of the Operator-specific section, please consult the Attributes of Operator-specific section.

Apply the Operator manifest

After creating the YAML configuration file for the Operator Resource, it's time to apply it to instantiate the Resource-instance in the DataOS environment. To apply the Operator YAML file, utilize the apply command.

dataos-ctl apply -f ${{operator yaml manifest file path}}

Verify Operator Creation

To ensure that your Operator has been successfully created, you can verify it in two ways:

Check the name of the newly created Operator in the list of Operators where you are named as the owner:

dataos-ctl get -t operator

# Expected Output
INFO[0000] 🔍 get...                                     
INFO[0000] 🔍 get...complete                             

      NAME     | VERSION |   TYPE   | WORKSPACE | STATUS | RUNTIME |  OWNER        
---------------|---------|----------|-----------|--------|---------|-------------------
  adf-operator | v1alpha | operator |           | active |         | iamgroot

Alternatively, retrieve the list of all Operators created in your organization:

dataos-ctl get -t operator -a

You can also access the details of any created Operator through the DataOS GUI in the Operations App.

Manifestation of Operator
Manifestation of Operator in DataOS

Manifestation of Operator

Manifestation of Operator in DataOS

Manifest for a Resource

Now once we have created an Operator, we would need to create a Resource (external Resource) which is an Azure Data Factory pipeline that would be managed by this Operator. In DataOS, the process of creating external Resources involves utilizing a specific type of Resource called, aptly, "Resource." These Resources are categorized as second-class Resources, distinct from the first-class Resources like Workflow, Service, and Policy.

Resource as a Resource, in essence, serves as a means to interact with Operators. While Workflow, Service, and Policy Resources are first-class and can be independently managed, Resources created through the Resource are specifically designed for use with Operators. Below is the Resource YAML for the external ADF pipeline Resource:

# Resource meta section
name: ${{pipeline-run-1}}
version: v1alpha
type: resource
tags:
    - ${{adf-pipeline}}
    - ${{adf-operator}}
description: ${{adf pipeline run}}
owner: iamgroot

# Resource-specific section
resource: 
    operator: ${{adf-operator}}
    type: ${{pipeline-run}}
    spec: 
        factoryName: ${{datafactoryoz3un3trdpaa}}
        pipelineName: ${{ArmtemplateSampleCopyPipeline}}
        resourceGroupName: ${{Engineering}}

When creating Resources with this approach, the Operator's JSON Schema plays a vital role in validation. The spec provided in the Resource YAML is validated against this schema, ensuring that the Resource conforms to the predefined structure.

Apply the Resource manifest

To trigger a pipeline run, you can apply the Resource YAML using the following command:

dataos-ctl apply -f ${{resource-yaml-file-path}} -w ${{workspace}}

# Sample
dataos-ctl apply -f ./resources/adf-operator/resource.yaml -w public

Get Status of Pipeline Run

dataos-ctl get -t resource -w ${{workspace}}

# Sample
dataos-ctl get -t resource -w public

# Expected Output
INFO[0000] 🔍 get...                                     
INFO[0000] 🔍 get...complete                             

      NAME       | VERSION |   TYPE   | WORKSPACE | STATUS |  RUNTIME   |   OWNER        
-----------------|---------|----------|-----------|--------|------------|-------------------
  pipeline-run-1 | v1alpha | resource | public    | active | inprogress |  iamgroot

Check the Status on Azure Data Factory UI

Once we apply we can go over on the Azure Data Factory UI.

Before Pipeline run

ADF Before Pipeline Run
Azure Data Factory UI before pipeline run

After Pipeline run

ADF After Pipeline Run
Azure Data Factory UI after pipeline run
ADF Pipeline Runs
Azure Data Factory UI various pipeline runs

Metadata Synchronization in DataOS

While the pipeline is in progress, you have the capability to capture metadata from Azure Data Factory back into DataOS Metis. The process of metadata capture is orchestrated through the Operator Component and NATS Cluster. While coding the Operator, you have the complete complete control over determining which specific state information from the external cluster, in this case, Azure Cluster, should be retrieved and synchronized with DataOS. To get information about which information is being synchronized, utilize the following command:

dataos-ctl get -t resource -w public -n ${{external-resource-name}} -d

Here, ${{external-resource-name}} should be replaced with the relevant identifier, such as the name of the specific external resource (Resource) run:

dataos-ctl get -t resource -w public -n pipeline-run-1 -d

Delete Operator

If you need to delete an operator, you first need to delete all the workloads or Resources that are dependent on it. Once it's done, use the delete command to remove the specific operator from the DataOS instance:

dataos-ctl delete -t operator -n ${{name of operator}}

How does the Operator Work?

Working of Operator
Working of an Operator

The diagram illustrates the workings of the DataOS Kubernetes Cluster and the process that unfolds when applying an Operator YAML via the DataOS Command Line Interface (CLI).

  1. Applying YAML Manifest: When a user applies an Operator YAML through the CLI, the Resource API takes this information to the DataOS Orchestrator, known as Poros.
  2. Poros Orchestrator: Poros serves as an Operator Manager, housing multiple Operators within it. One of these Operators is the Poros Operator, responsible for managing DataOS-specific Resources within the Kubernetes cluster.
  3. Custom Operator Runtime: The Operator YAML creates a custom Operator runtime within Poros. This runtime is responsible for overseeing the operation of an external Resource.
  4. NATS Cluster Creation: The Operator YAML also includes NATS Cluster configuration. The Operator Runtime establishes a pub-sub communication with the NATS Cluster.
  5. Operator Component: This is the Worker or Service Resource that contains the docker image, and secret configurations for interfacing with external third-party services, platforms, or ecosystems. It could involve services like Databricks Workspace, Azure Data Factory, or others. The Operator Component interacts with these external resources via their REST APIs, enabling CRUD (Create, Read, Update, Delete) operations and other specific functionalities.
  6. NATS Cluster Communication: The Operator Component communicates with the NATS Cluster, which acts as the communication channel between the Operator Component and the Operator Runtime.
  7. JSON Schema and Resource Definition: The creation of the Operator YAML also involves providing a JSON schema for the external Resource.
  8. Resource YAML Application: Additionally, a secondary YAML is created, defining a new Resource-type called "Resource." Within this Resource, a reference to the specific Operator responsible for managing it is specified. The Resource spec is validated against the Operator's JSON schema. When the Resource YAML is applied, it informs the DataOS Orchestrator that this Resource will be managed by the custom Operator runtime created earlier.
  9. Command Query Responsibility Segregation (CQRS) Pattern: The Operator adheres to the Command Query Responsibility Segregation (CQRS) Pattern, ensuring a clear separation of commands and queries.
    1. Command: When executing commands such as creating, updating, or deleting, the system forwards these actions to the NATS Cluster. The NATS Cluster then communicates with the compute component associated with the Operator, which subsequently dispatches the pertinent information to the external platform or service.
    2. Query: Simultaneously, the system offers a querying mechanism for retrieving information about the status and details of the service. Executing the dataos-ctl get command initiates a query operation, which traverses through the NATS Cluster. The query is then directed to the entity store within the computational component, which maintains the desired state information.
Working of Operator
Operator behind the scenes

Case Scenarios