Contributing Guidelines

Introduction

This document will guide you through the steps to contribute with a new component. You'll add and test an operator that takes a string target as input and returns a "Hello, ${target}!" string as the component output

In order to add a new component, you need to:

Define the component configuration. This will determine the tasks that can be performed by the component and their input and output parameters. The console frontend will use the configuration files to render the component in the pipeline editor page.
Implement the component interfaces so pipeline-backend can execute the component without knowing its implementation details.
Initialize the component, i.e., include the implementation of the component interfaces as a dependency in the pipeline-backend execution.

Prerequisites

This guide builds on top of other documents:

pipeline-backend's README explains the basic concepts in the VDP domain.
component's README digs deeper into the Component entity, its structure and functionalities.
The repository's contribution guidelines document the conventions you'll need to follow when contributing to this repository. They also contain a guide on how to set your development environment, in case you want to see your component in action.
If you find yourself wanting to know more, visit the Instill Docs.

Create the component package

$ cd $MY_WORKSPACE/pipeline-backend/pkg/component
$ mkdir -p operator/hello/v0 && cd $_

Components are isolated in their own packages under their component type (ai, data, application, etc.). The package is versioned so, in case a breaking change needs to be introduced (e.g. supporting a new major version in a vendor API), existing pipelines using the previous version of the component can keep being triggered.

At the end of this guide, this will be the structure of the package:

operator/hello/v0
 ├──.compogen
 │  └──extra-bottom.mdx
 ├──assets
 │  └──hello.svg
 ├──config
 │  ├──definition.json
 │  └──tasks.json
 ├──main.go
 ├──main_test.go
 └──README.mdx

Add the configuration files

Create a config directory and add the files definition.json, tasks.json, and setup.json (optional). Together, these files define the behavior of the component.

`definition.json`

The definition.json file describes the high-level information of the component.

{
  "id": "hello",
  "uid": "e05d3d71-779c-45f8-904d-e90a050ca3b2",
  "title": "Hello",
  "type": "COMPONENT_TYPE_OPERATOR",
  "description": "'Hello, world' operator used as a template for adding components",
  "spec": {},
  "availableTasks": [
    "TASK_GREET"
  ],
  "documentationUrl": "https://www.instill.tech/docs/component/operator/hello",
  "icon": "assets/hello.svg",
  "version": "0.1.0",
  "sourceUrl": "https://github.com/instill-ai/pipeline-backend/pkg/component/blob/main/operator/hello/v0",
  "releaseStage": "RELEASE_STAGE_ALPHA",
  "public": true
}

This file defines the component properties:

id is the ID of the component. It must be unique.
uid is a UUID string that must not be already taken by another component. Once it is set, it must not change.
title: is the display title of the component.
description: is a short sentence describing the purpose of the component. It should be written in imperative tense.
spec contains the parameters required to configure the component and that are independent from its tasks. E.g., the API token of a vendor. In general, only AI, data or application components need such parameters.
availableTasks defines the tasks the component can perform.
- When a component is created in a pipeline, one of the tasks has to be selected, i.e., a configured component can only execute one task.
- Task configurations are defined in tasks.json.
documentationUrl points to the official documentation of the component.
icon is the local path to the icon that will be displayed in the console when creating the component. If left blank, a placeholder icon will be shown.
version must be a SemVer string. It is encouraged to keep a tidy version history.
sourceUrl points to the codebase that implements the component. This will be used by the documentation generation tool and also will be part of the component definition list endpoint.
releaseStage describes the release stage of the component. Unimplemented stages (RELEASE_STAGE_COMING_SOON or RELEASE_STAGE_OPEN_FOR_CONTRIBUTION) will hide the component from the console (i.e. they can't be used in pipelines) but they will appear in the component definition list endpoint.
public indicates whether the component is visible to the public.

`tasks.json`

The tasks.json file describes the task details of the component. The key should be in the format TASK_NAME.

{
  "TASK_GREET": {
    "instillShortDescription": "Greet someone / something",
    "title": "Greet",
    "input": {
      "description": "Input",
      "instillUIOrder": 0,
      "properties": {
        "target": {
          "instillUIOrder": 0,
          "description": "The target of the greeting",
          "instillAcceptFormats": [
            "string"
          ],
          "instillUpstreamTypes": [
            "value",
            "reference",
            "template"
          ],
          "instillUIMultiline": true,
          "title": "Greeting target",
          "type": "string"
        }
      },
      "required": [
        "target"
      ],
      "title": "Input",
      "type": "object"
    },
    "output": {
      "description": "The greeting sentence",
      "instillUIOrder": 0,
      "properties": {
        "greeting": {
          "description": "A greeting sentence addressed to the target",
          "instillUIOrder": 0,
          "required": [],
          "title": "Greeting",
          "type": "string",
          "instillFormat": "string"
        }
      },
      "required": [
        "greeting"
      ],
      "title": "Output",
      "type": "object"
    }
  }
}

This file defines the input and output schema of each task:

Properties within a Task

title is used by the console to provide the title of the task in the component.
description and instillShortDescription are used by the console to provide a description of the task in the component. If instillShortDescription does not exist, it will be the same as description.
input is a JSON Schema that describes the input of the task.
output is a JSON Schema that describes the output of the task.

Properties within input and output Objects

required indicates whether the property is required.
type: describes the JSON type of this field, which could be integer, number, boolean, string, array, or object.
title is used by the console to provide the title of the property in the component.
description is used by the console to provide information about this task in the component.
instillShortDescription: is a concise version of description, used to fit smaller spaces such as a component form field. If this value is empty, the description value will be used.
instillUIOrder defines the order in which the properties will be rendered in the component.
instillUIMultiline indicates whether the text field in the component is multiline.

Properties within input Objects

instillEditOnNodeFields determines whether this field will appear at the forefront of the component. Optional properties can be set in the advanced configuration.
instillAcceptFormats is an array indicating the data types of acceptable input fields. It should be an array of Instill Format.
- Currently, we do not support the time type. When the input is a date or datetime, it should be represented as a string. The date or datetime will be automatically parsed in UTC timezone by the YAML parser. Please ensure this point is noted in the documentation, specifically for the start-to-read-date in the Slack component.
instillUpstreamTypes defines how an input property can be set: as a direct value, a reference to another value in the pipeline, or a combination of both (e.g., ${variable.name} or my dear ${variable.name}).
instillSecret indicates the data must reference the secrets and cannot be used in plaintext.

Properties within output Objects

instillFormat indicates the data type of the output field, which should be one of number, integer, string, object, boolean, or MIME type. Please refer to Instill Format for more details.

See the example recipe to understand how these fields map to the recipe of a pipeline when configured to use this operator.

`setup.json`

For components that need to set up some configuration before execution (typically, components that connect with 3rd party applications or services that need to set up a connection), setup.json can be used to describe these configurations. The format is the same as the input objects in tasks.json.

The setup of a component can be defined within the recipe as key-value fields, or as a reference to a Connection (see the Integrations doc for more information). Certain components support OAuth 2.0 integrations. If you want your component to support this sort of connection:

In setup.json, add the OAuth information under the instillOAuthConfig property.
- authUrl contains the address where the authorization code can be requested.
  - accessUrl contains the address where the authorization code can be exchanged for an access token.
  - scopes contains the permissions that will be associated with the access token. Refer to the vendor you want to integrate with in order to identify the scopes that will be required by the different tasks implemented by the component. Note that, if the component is extended later requiring more scopes, users will need to create a new connection in order to leverage the new functionality.
The OAuth 2.0 exchange for an access token is implemented in the frontend. Make sure to engage with Instill Product in order to prioritise the OAuth support for this component.

Implement the component interfaces

Pipeline communicates with components through the IComponent interface, defined in the base package. This package also defines base implementations for these interfaces, so the hello component will only need to override the following methods:

CreateExecution(ComponentExecution) (IExecution, error) will return an implementation of the IExecution interface. A base execution implementation is passed in order to define only the behaviour of the Execute method.
Execute(context.Context []*structpb.Struct) ([]*structpb.Struct, error) is the most important function in the component. All the data manipulation will take place here.

Paste the following code into a main.go file in operator/hello/v0:

package hello

import (
    "fmt"
    "sync"

    _ "embed"

    "google.golang.org/protobuf/types/known/structpb"

    "github.com/instill-ai/pipeline-backend/pkg/component/base"
)

const (
  taskGreet = "TASK_GREET"
)

var (
  //go:embed config/definition.json
  definitionJSON []byte
  //go:embed config/tasks.json
  tasksJSON []byte

  once   sync.Once
  comp   *component
)

type component struct {
  base.Component
}

// Init returns an implementation of IComponent that implements the greeting
// task.
func Init(bc base.Component) *component {
  once.Do(func() {
    comp = &component{Component: bc}
    err := comp.LoadDefinition(definitionJSON, nil, tasksJSON, nil)
    if err != nil {
      panic(err)
    }
  })
  return comp
}

type execution struct {
    base.ComponentExecution
}

func (c *component) CreateExecution(x base.ComponentExecution) (base.IExecution, error) {
  e := &execution{ ComponentExecution: x }

  if x.Task != taskGreet {
    return nil, fmt.Errorf("unsupported task")
  }

  return e, nil
}

func (e *execution) Execute(ctx context.Context, jobs []*base.Job) error {
  return nil
}

Add the execution logic

The hello operator created in the previous section doesn't implement any logic. This section will add the greeting logic to the Execute method.

Let's modify the following methods:

type execution struct {
  base.ComponentExecution
  execute func(*structpb.Struct) (*structpb.Struct, error)
}

func (c *component) CreateExecution(x base.ComponentExecution) (base.IExecution, error) {
  e := &execution{ ComponentExecution: x }

  // A simple if statement would be enough in a component with a single task.
  // If the number of task grows, here is where the execution task would be
  // selected.
  switch x.Task {
  case taskGreet:
    e.execute = e.greet
  default:
    return nil, fmt.Errorf("unsupported task")
  }

  return e, nil
}

func (e *execution) Execute(ctx context.Context, jobs []*base.Job) error {
  // An execution  might take several inputs. One result will be returned for
  // each one of them, containing the execution output for that set of
  // parameters.
  for _, job := range jobs {
    input, err := job.Input.Read(ctx)
    if err != nil {
      return err
    }
  output, err := e.execute(input)
  if err != nil {
    return err
  }

  err = job.Output.Write(ctx, output)
    if err != nil {
      return err
    }
  }

  return nil
}

func (e *execution) greet(in *structpb.Struct) (*structpb.Struct, error) {
  out := new(structpb.Struct)

  target := in.Fields["target"].GetStringValue()
  greeting := "Hello, " + target + "!"

  out.Fields = map[string]*structpb.Value{
    "greeting": structpb.NewStringValue(greeting),
  }

  return out, nil
}

End-user error messages

The errmsg package allows us to attach messages to our errors.

func (e *execution) greet(in *structpb.Struct) (*structpb.Struct, error) {
  out := new(structpb.Struct)

  greetee := in.Fields["target"].GetStringValue()
  if greetee == "Voldemort" {
    return nil, errmsg.AddMessage(fmt.Errorf("invalid greetee"), "He-Who-Must-Not-Be-Named can't be greeted.")
  }

  greeting := "Hello, " + greetee + "!"

  out.Fields = map[string]*structpb.Value{
    "greeting": structpb.NewStringValue(greeting),
  }

  return out, nil
}

The middleware in pipeline-backend will capture error messages in order to to return a human-friendly errors to the API clients and console users.

Unit tests

Before initializing testing your component in 💧 Instill VDP, we can unit test its behaviour. The following code covers the newly added logic by replicating how the pipeline-backend workers execute the component logic. Create a main_test.go file containing the following code:

package hello

import (
  "context"
  "testing"

  "go.uber.org/zap"
  "google.golang.org/protobuf/types/known/structpb"

  qt "github.com/frankban/quicktest"

  "github.com/instill-ai/pipeline-backend/pkg/component/base"
  "github.com/instill-ai/pipeline-backend/pkg/component/internal/mock"
  "github.com/instill-ai/x/errmsg"
)

func TestOperator_Execute(t *testing.T) {
  c := qt.New(t)
  ctx := context.Background()

  bc := base.Component{Logger: zap.NewNop()}
  component := Init(bc)

  c.Run("ok - greet", func(c *qt.C) {
    exec, err := component.CreateExecution(base.ComponentExecution{
      Component: component,
      Task:      taskGreet,
    })
    c.Assert(err, qt.IsNil)

    pbIn, err := structpb.NewStruct(map[string]any{"target": "bolero-wombat"})
    c.Assert(err, qt.IsNil)

    ir, ow, eh, job := mock.GenerateMockJob(c)
    ir.ReadMock.Return(&pbIn, nil)
    ow.WriteMock.Optional().Set(func(ctx context.Context, output *structpb.Struct) (err error) {
      // Check JSON in the output string.
      greeting := output.Fields["greeting"].GetStringValue()
      // When we use minimock, we can't use the `c.Assert` function.
      // Instead, we use the `mock.Equal` function built in the mock package.
      mock.Equal(greeting, "Hello, bolero-wombat!")
      return nil
    })
    eh.ErrorMock.Optional()

    err = execution.Execute(ctx, []*base.Job{job})
    c.Assert(err, qt.IsNil)
  })

  c.Run("nok - invalid greetee", func(c *qt.C) {
    x, err := comp.CreateExecution(base.ComponentExecution{
      Component: comp,
      Task:      taskGreet,
    })
    c.Assert(err, qt.IsNil)

    pbIn, err := structpb.NewStruct(map[string]any{"target": "Voldemort"})
    c.Assert(err, qt.IsNil)

    ir, ow, eh, job := mock.GenerateMockJob(c)
    ir.ReadMock.Return(pbIn, nil)
    ow.WriteMock.Optional().Set(func(ctx context.Context, output *structpb.Struct) (err error) {
      // Check JSON in the output string.
      greeting := output.Fields["greeting"].GetStringValue()
      mock.Equal(greeting, "Hello, Voldemort!")
      return nil
    })
    eh.ErrorMock.Optional()

    err = x.Execute(ctx, []*base.Job{job})
    c.Assert(err, qt.ErrorMatches, "invalid greetee")
    c.Assert(errmsg.Message(err), qt.Matches, "He-Who-Must-Not-Be-Named can't be greeted.")
  })
}

func TestOperator_CreateExecution(t *testing.T) {
  c := qt.New(t)

  bc := base.Component{Logger: zap.NewNop()}
  operator := Init(bc)

  c.Run("nok - unsupported task", func(c *qt.C) {
    task := "FOOBAR"

    _, err := operator.CreateExecution(base.ComponentExecution{
      Component: component,
      Task: task,
    })
    c.Check(err, qt.ErrorMatches, "unsupported task")
  })
}

In our testing methodology, we use two main approaches for mocking external services:

In some components, we mock only the interface and skip testing the actual client, as with services like Slack and HubSpot.
In other components, we create a fake server for test purposes, as with OpenAI integrations.

Moving forward, we plan to standardize on the second approach, integrating all components to use a fake server setup for testing.

Initialize the component

The last step before being able to use the component in 💧 Instill VDP is loading the hello operator. This is done in the Init function in store.go:

package store

import (
  // ...
  "github.com/instill-ai/pipeline-backend/pkg/component/operator/hello/v0"
)

// ...

func Init(logger *zap.Logger) *Store {
  baseComp := base.component{Logger: logger}

  once.Do(func() {
    compStore = &Store{
      componentUIDMap: map[uuid.UUID]*component{},
      componentIDMap:  map[string]*component{},
    }
    // ...
    compStore.Import(hello.Init(baseComp))
  })

  return compStore
}

Use the component in 💧 Instill VDP

Re-run your local pipeline-backend build:

$ make rm && make dev
$ docker exec pipeline-backend go run ./cmd/init # this will load the new component into the database
$ docker exec -d pipeline-backend go run ./cmd/worker # run without -d in a separate terminal if you want to access the logs
$ docker exec pipeline-backend go run ./cmd/main

Head to the console at http://localhost:3000/ (default password is password) and create a pipeline.

In the variable component, add a who text field.
Create a hello operator and reference the variable input field by adding ${variable.who} to the target field.
In the output component, add a greeting output value that references the hello output by introducing ${hello-0.output.greeting}.

You can copy the recipe from the example.

If you introduce a Wombat string value in the Input form and Run the pipeline, you should see Hello, Wombat! in the response.

Example recipe

variable:
  who:
    title: Who
    description: Who should be greeted?
    instill-format: string
component:
  hello-0:
    type: hello
    task: TASK_GREET
    input:
      target: ${variable.who}
output:
  greeting:
    title: Greeting
    description: The output greeting
    value: ${hello-0.output.greeting}

Document the component

Documentation helps user to integrate the component in their pipelines. A good component definition will have clear names for their fields, which will also contain useful descriptions. The information described in definition.json and tasks.json is enough to understand how a component should be used. compogen is a tool that parses the component configuration and builds a README.mdx file document displaying its information in a human-readable way. To generate the document, just add the following line on top of operator/hello/v0/main.go:

//go:generate compogen readme ./config ./README.mdx

Then, go to the base of the pipeline-backend repository and run:

$ make gen-component-doc

Adding extra sections

The documentation of the component can be extended with the --extraContents flag:

$ mkdir -p operator/hello/.compogen
$ echo '### Final words

Thank you for reading!' > operator/hello/.compogen/extra-bottom.mdx

//go:generate compogen readme ./config ./README.mdx --extraContents bottom=.compogen/extra-bottom.mdx

Check compogen's README for more information.

Sane version control

The version of a component is useful to track its evolution and to set expectations about its stability. When the interface of a component (defined by its configuration files) changes, its version should change following the Semantic Versioning guidelines.

Patch versions are intended for bug fixes.
Minor versions are intended for backwards-compatible changes, e.g., a new task or a new input field with a default value.
Major versions are intended for backwards-incompatible changes.
- At this point, since there might be pipelines using the previous version, a new package MUST be created. E.g., operator/json/v0 -> operator/json/v1.
Build and pre-release labels are discouraged, as components are shipped as part of 💧 Instill VDP and they aren't likely to need such fine-grained version control.

It is recommended to start a component at v0.1.0. A major version 0 is intended for rapid development.

The releaseStage property in definition.json indicates the stability of a component.

A component skeleton (with only the minimal configuration files and a dummy implementation of the interfaces) may use the Coming Soon or Open For Contribution stages in order to communicate publicly about upcoming components. The major and minor versions in this case MUST be 0.
Alpha pre-releases are used in initial implementations, intended to gather feedback and issues from early adopters. Breaking changes are acceptable at this stage.
Beta pre-releases are intended for stable components that don't expect breaking changes.
General availability indicates production readiness. A broad adoption of the beta version in production indicates the transition to GA is ready.

The typical version and release stage evolution of a component might look like this:

Version	Release Stage
0.1.0	`RELEASE_STAGE_ALPHA`
0.1.1	`RELEASE_STAGE_ALPHA`
0.1.2	`RELEASE_STAGE_ALPHA`
0.2.0	`RELEASE_STAGE_ALPHA`
0.2.1	`RELEASE_STAGE_ALPHA`
0.3.0	`RELEASE_STAGE_BETA`
0.3.1	`RELEASE_STAGE_BETA`
0.4.0	`RELEASE_STAGE_BETA`
1.0.0	`RELEASE_STAGE_GA`

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CONTRIBUTING.md

CONTRIBUTING.md

Contributing Guidelines

Introduction

Prerequisites

Create the component package

Add the configuration files

`definition.json`

`tasks.json`

`setup.json`

Implement the component interfaces

Add the execution logic

End-user error messages

Unit tests

Initialize the component

Use the component in 💧 Instill VDP

Example recipe

Document the component

Adding extra sections

Sane version control

Files

CONTRIBUTING.md

Latest commit

History

CONTRIBUTING.md

File metadata and controls

Contributing Guidelines

Introduction

Prerequisites

Create the component package

Add the configuration files

definition.json

tasks.json

setup.json

Implement the component interfaces

Add the execution logic

End-user error messages

Unit tests

Initialize the component

Use the component in 💧 Instill VDP

Example recipe

Document the component

Adding extra sections

Sane version control

`definition.json`

`tasks.json`

`setup.json`