pulumi-component

Authoring Pulumi Components

A ComponentResource groups related infrastructure resources into a reusable, logical unit. Components make infrastructure easier to understand, reuse, and maintain. Components appear as a single node with children nested underneath in pulumi preview/pulumi up output and in the Pulumi Cloud console.

This skill covers the full component authoring lifecycle. For general Pulumi coding patterns (Output handling, secrets, aliases, preview workflows), use the pulumi-best-practices skill instead.

When to Use This Skill

Invoke this skill when:

• Creating a new ComponentResource class
• Designing the args interface for a component
• Making a component consumable from multiple Pulumi languages
• Publishing or distributing a component package
• Refactoring inline resources into a reusable component
• Debugging component behavior (missing outputs, stuck creating, children at wrong level)

Component Anatomy

Every component has four required elements:

1. Extend ComponentResource and call super() with a type URN
2. Accept standard parameters: name, args, and ComponentResourceOptions
3. Set parent: this on all child resources
4. Call registerOutputs() at the end of the constructor

TypeScript

import * as pulumi from "@pulumi/pulumi";
import * as aws from "@pulumi/aws";

interface StaticSiteArgs {
    indexDocument?: pulumi.Input<string>;
    errorDocument?: pulumi.Input<string>;
}

class StaticSite extends pulumi.ComponentResource {
    public readonly bucketName: pulumi.Output<string>;
    public readonly websiteUrl: pulumi.Output<string>;

    constructor(name: string, args: StaticSiteArgs, opts?: pulumi.ComponentResourceOptions) {
        // 1. Call super with type URN: <package>:<module>:<type>
        super("myorg:index:StaticSite", name, {}, opts);

        // 2. Create child resources with parent: this
        const bucket = new aws.s3.Bucket(`${name}-bucket`, {}, { parent: this });

        const website = new aws.s3.BucketWebsiteConfigurationV2(`${name}-website`, {
            bucket: bucket.id,
            indexDocument: { suffix: args.indexDocument ?? "index.html" },
            errorDocument: { key: args.errorDocument ?? "error.html" },
        }, { parent: this });

        // 3. Expose outputs as class properties
        this.bucketName = bucket.id;
        this.websiteUrl = website.websiteEndpoint;

        // 4. Register outputs -- always the last line
        this.registerOutputs({
            bucketName: this.bucketName,
            websiteUrl: this.websiteUrl,
        });
    }
}

// Usage
const site = new StaticSite("marketing", {
    indexDocument: "index.html",
});
export const url = site.websiteUrl;

Python

import pulumi
import pulumi_aws as aws

class StaticSiteArgs:
    def __init__(self,
                 index_document: pulumi.Input[str] = "index.html",
                 error_document: pulumi.Input[str] = "error.html"):
        self.index_document = index_document
        self.error_document = error_document

class StaticSite(pulumi.ComponentResource):
    bucket_name: pulumi.Output[str]
    website_url: pulumi.Output[str]

    def __init__(self, name: str, args: StaticSiteArgs,
                 opts: pulumi.ResourceOptions = None):
        super().__init__("myorg:index:StaticSite", name, None, opts)

        bucket = aws.s3.Bucket(f"{name}-bucket",
            opts=pulumi.ResourceOptions(parent=self))

        website = aws.s3.BucketWebsiteConfigurationV2(f"{name}-website",
            bucket=bucket.id,
            index_document=aws.s3.BucketWebsiteConfigurationV2IndexDocumentArgs(
                suffix=args.index_document,
            ),
            error_document=aws.s3.BucketWebsiteConfigurationV2ErrorDocumentArgs(
                key=args.error_document,
            ),
            opts=pulumi.ResourceOptions(parent=self))

        self.bucket_name = bucket.id
        self.website_url = website.website_endpoint

        self.register_outputs({
            "bucket_name": self.bucket_name,
            "website_url": self.website_url,
        })

site = StaticSite("marketing", StaticSiteArgs())
pulumi.export("url", site.website_url)

Type URN Format

The first argument to super() is the type URN: <package>:<module>:<type>.

Segment	Convention	Example
package	Organization or package name	myorg, acme, pkg
module	Usually index	index
type	PascalCase class name	StaticSite, VpcNetwork

Full examples: myorg:index:StaticSite, acme:index:KubernetesCluster

registerOutputs Is Required

Why: Without registerOutputs(), the component appears stuck in a "creating" state in the Pulumi console and outputs are not persisted to state.

Wrong:

class MyComponent extends pulumi.ComponentResource {
    public readonly url: pulumi.Output<string>;

    constructor(name: string, args: MyArgs, opts?: pulumi.ComponentResourceOptions) {
        super("myorg:index:MyComponent", name, {}, opts);
        const bucket = new aws.s3.Bucket(`${name}-bucket`, {}, { parent: this });
        this.url = bucket.bucketRegionalDomainName;
        // Missing registerOutputs -- component stuck "creating"
    }
}

Right:

class MyComponent extends pulumi.ComponentResource {
    public readonly url: pulumi.Output<string>;

    constructor(name: string, args: MyArgs, opts?: pulumi.ComponentResourceOptions) {
        super("myorg:index:MyComponent", name, {}, opts);
        const bucket = new aws.s3.Bucket(`${name}-bucket`, {}, { parent: this });
        this.url = bucket.bucketRegionalDomainName;

        this.registerOutputs({ url: this.url });
    }
}

Derive Child Names from the Component Name

Why: Hardcoded child names cause collisions when the component is instantiated multiple times.

Wrong:

// Collides if two instances of this component exist
const bucket = new aws.s3.Bucket("my-bucket", {}, { parent: this });

Right:

// Unique per component instance
const bucket = new aws.s3.Bucket(`${name}-bucket`, {}, { parent: this });

---

Designing the Args Interface

The args interface is the most impactful design decision. It defines what consumers can configure and how composable the component is.

Wrap Properties in Input

Why: Input<T> accepts both plain values and Output<T> from other resources. Without it, consumers must unwrap outputs manually with .apply().

Wrong:

interface WebServiceArgs {
    port: number;            // Forces consumers to unwrap Outputs
    vpcId: string;           // Cannot accept vpc.id directly
}

Right:

interface WebServiceArgs {
    port: pulumi.Input<number>;     // Accepts 8080 or someOutput
    vpcId: pulumi.Input<string>;    // Accepts "vpc-123" or vpc.id
}

Keep Structures Flat

Avoid deeply nested arg objects. Flat interfaces are easier to use and evolve.

// Prefer flat
interface DatabaseArgs {
    instanceClass: pulumi.Input<string>;
    storageGb: pulumi.Input<number>;
    enableBackups?: pulumi.Input<boolean>;
    backupRetentionDays?: pulumi.Input<number>;
}

// Avoid deep nesting
interface DatabaseArgs {
    instance: {
        compute: { class: pulumi.Input<string> };
        storage: { sizeGb: pulumi.Input<number> };
    };
    backup: {
        config: { enabled: pulumi.Input<boolean>; retention: pulumi.Input<number> };
    };
}

No Union Types

Union types break multi-language SDK generation. Python, Go, and C# cannot represent string | number.

Wrong:

interface MyArgs {
    port: pulumi.Input<string | number>;  // Fails in Python, Go, C#
}

Right:

interface MyArgs {
    port: pulumi.Input<number>;  // Single type, works everywhere
}

If you need to accept multiple forms, use separate optional properties:

interface StorageArgs {
    sizeGb?: pulumi.Input<number>;      // Specify size in GB
    sizeMb?: pulumi.Input<number>;      // Or specify size in MB
}

No Functions or Callbacks

Functions cannot be serialized across language boundaries.

Wrong:

interface MyArgs {
    nameTransform: (name: string) => string;  // Cannot serialize
}

Right:

interface MyArgs {
    namePrefix?: pulumi.Input<string>;   // Configuration instead of callback
    nameSuffix?: pulumi.Input<string>;
}

Use Defaults for Optional Properties

Set sensible defaults inside the constructor so consumers only configure what they need:

interface SecureBucketArgs {
    enableVersioning?: pulumi.Input<boolean>;   // Defaults to true
    enableEncryption?: pulumi.Input<boolean>;   // Defaults to true
    blockPublicAccess?: pulumi.Input<boolean>;  // Defaults to true
}

class SecureBucket extends pulumi.ComponentResource {
    constructor(name: string, args: SecureBucketArgs, opts?: pulumi.ComponentResourceOptions) {
        super("myorg:index:SecureBucket", name, {}, opts);

        const enableVersioning = args.enableVersioning ?? true;
        const enableEncryption = args.enableEncryption ?? true;
        const blockPublicAccess = args.blockPublicAccess ?? true;

        // Apply defaults...
    }
}

// Consumer only overrides what they need
const bucket = new SecureBucket("data", { enableVersioning: false });

---

Exposing Outputs

Expose Only What Consumers Need

Components often create many internal resources. Expose only the values consumers need, not every internal resource.

Wrong:

class Database extends pulumi.ComponentResource {
    // Exposes everything -- consumers see implementation details
    public readonly cluster: aws.rds.Cluster;
    public readonly primaryInstance: aws.rds.ClusterInstance;
    public readonly replicaInstance: aws.rds.ClusterInstance;
    public readonly subnetGroup: aws.rds.SubnetGroup;
    public readonly securityGroup: aws.ec2.SecurityGroup;
    public readonly parameterGroup: aws.rds.ClusterParameterGroup;
    // ...
}

Right:

class Database extends pulumi.ComponentResource {
    // Exposes only what consumers need
    public readonly endpoint: pulumi.Output<string>;
    public readonly port: pulumi.Output<number>;
    public readonly securityGroupId: pulumi.Output<string>;

    constructor(name: string, args: DatabaseArgs, opts?: pulumi.ComponentResourceOptions) {
        super("myorg:index:Database", name, {}, opts);

        const sg = new aws.ec2.SecurityGroup(`${name}-sg`, { /* ... */ }, { parent: this });
        const cluster = new aws.rds.Cluster(`${name}-cluster`, { /* ... */ }, { parent: this });

        this.endpoint = cluster.endpoint;
        this.port = cluster.port;
        this.securityGroupId = sg.id;

        this.registerOutputs({
            endpoint: this.endpoint,
            port: this.port,
            securityGroupId: this.securityGroupId,
        });
    }
}

Derive Composite Outputs

Use pulumi.interpolate or pulumi.concat to build derived values:

this.connectionString = pulumi.interpolate`postgresql://${args.username}:${args.password}@${cluster.endpoint}:${cluster.port}/${args.databaseName}`;

this.registerOutputs({ connectionString: this.connectionString });

---

Component Design Patterns

Sensible Defaults with Override

Encode best practices as defaults. Allow consumers to override when they have specific requirements.

interface SecureBucketArgs {
    enableVersioning?: pulumi.Input<boolean>;
    enableEncryption?: pulumi.Input<boolean>;
    blockPublicAccess?: pulumi.Input<boolean>;
    tags?: pulumi.Input<Record<string, pulumi.Input<string>>>;
}

class SecureBucket extends pulumi.ComponentResource {
    public readonly bucketId: pulumi.Output<string>;
    public readonly arn: pulumi.Output<string>;

    constructor(name: string, args: SecureBucketArgs = {}, opts?: pulumi.ComponentResourceOptions) {
        super("myorg:index:SecureBucket", name, {}, opts);

        const bucket = new aws.s3.Bucket(`${name}-bucket`, {
            tags: args.tags,
        }, { parent: this });

        // Versioning on by default
        if (args.enableVersioning !== false) {
            new aws.s3.BucketVersioningV2(`${name}-versioning`, {
                bucket: bucket.id,
                versioningConfiguration: { status: "Enabled" },
            }, { parent: this });
        }

        // Encryption on by default
        if (args.enableEncryption !== false) {
            new aws.s3.BucketServerSideEncryptionConfigurationV2(`${name}-encryption`, {
                bucket: bucket.id,
                rules: [{ applyServerSideEncryptionByDefault: { sseAlgorithm: "AES256" } }],
            }, { parent: this });
        }

        // Public access blocked by default
        if (args.blockPublicAccess !== false) {
            new aws.s3.BucketPublicAccessBlock(`${name}-public-access`, {
                bucket: bucket.id,
                blockPublicAcls: true,
                blockPublicPolicy: true,
                ignorePublicAcls: true,
                restrictPublicBuckets: true,
            }, { parent: this });
        }

        this.bucketId = bucket.id;
        this.arn = bucket.arn;
        this.registerOutputs({ bucketId: this.bucketId, arn: this.arn });
    }
}

Conditional Resource Creation

Use optional args to gate creation of sub-resources:

interface WebServiceArgs {
    image: pulumi.Input<string>;
    port: pulumi.Input<number>;
    enableMonitoring?: pulumi.Input<boolean>;
    alarmEmail?: pulumi.Input<string>;
}

class WebService extends pulumi.ComponentResource {
    constructor(name: string, args: WebServiceArgs, opts?: pulumi.ComponentResourceOptions) {
        super("myorg:index:WebService", name, {}, opts);

        const service = new aws.ecs.Service(`${name}-service`, {
            // ...service config...
        }, { parent: this });

        // Only create alarm infrastructure when monitoring is enabled
        if (args.enableMonitoring) {
            const topic = new aws.sns.Topic(`${name}-alerts`, {}, { parent: this });

            if (args.alarmEmail) {
                new aws.sns.TopicSubscription(`${name}-alert-email`, {
                    topic: topic.arn,
                    protocol: "email",
                    endpoint: args.alarmEmail,
                }, { parent: this });
            }

            new aws.cloudwatch.MetricAlarm(`${name}-cpu-alarm`, {
                // ...alarm config referencing service...
                alarmActions: [topic.arn],
            }, { parent: this });
        }

        this.registerOutputs({});
    }
}

Composition

Build higher-level components from lower-level ones. Each level manages a single concern.

// Lower-level component
class VpcNetwork extends pulumi.ComponentResource {
    public readonly vpcId: pulumi.Output<string>;
    public readonly publicSubnetIds: pulumi.Output<string>[];
    public readonly privateSubnetIds: pulumi.Output<string>[];

    constructor(name: string, args: VpcNetworkArgs, opts?: pulumi.ComponentResourceOptions) {
        super("myorg:index:VpcNetwork", name, {}, opts);
        // ...create VPC, subnets, route tables...
        this.registerOutputs({ vpcId: this.vpcId });
    }
}

// Higher-level component that uses VpcNetwork
class Platform extends pulumi.ComponentResource {
    public readonly kubeconfig: pulumi.Output<string>;

    constructor(name: string, args: PlatformArgs, opts?: pulumi.ComponentResourceOptions) {
        super("myorg:index:Platform", name, {}, opts);

        // Compose lower-level components
        const network = new VpcNetwork(`${name}-network`, {
            cidrBlock: args.cidrBlock,
        }, { parent: this });

        const cluster = new aws.eks.Cluster(`${name}-cluster`, {
            vpcConfig: {
                subnetIds: network.privateSubnetIds,
            },
        }, { parent: this });

        this.kubeconfig = cluster.kubeconfig;
        this.registerOutputs({ kubeconfig: this.kubeconfig });
    }
}

Provider Passthrough

Accept explicit providers for multi-region or multi-account deployments. ComponentResourceOptions carries provider configuration to children automatically:

// Consumer passes a provider for a different region
const usWest = new aws.Provider("us-west", { region: "us-west-2" });
const site = new StaticSite("west-site", { indexDocument: "index.html" }, {
    providers: [usWest],
});

Children with { parent: this } automatically inherit the provider. No extra code is needed inside the component.

---

Multi-Language Components

If your component will be consumed from multiple Pulumi languages (TypeScript, Python, Go, C#, Java, YAML), package it as a multi-language component.

Do You Need Multi-Language?

Ask: "Will anyone consume this component from a different language than it was authored in?"

Single-language component (no packaging needed):

• Your team uses one language and the component stays within that codebase
• The component is internal to a single project or monorepo
• No PulumiPlugin.yaml needed -- just import the class directly

Multi-language component (packaging required):

• Other teams consume your component in different languages
• Platform teams building abstractions for developers who choose their own language
• YAML consumers need access -- even if you author in TypeScript, YAML programs require multi-language packaging to use your component
• Building a shared component library for your organization
• Publishing to the Pulumi private registry or public registry is a common reason, but not required for multi-language support

Common mistake: A TypeScript platform team builds components only their TypeScript users can consume. If application developers use Python or YAML, those components are invisible to them without multi-language packaging.

Setup

Create a PulumiPlugin.yaml in the component directory to declare the runtime:

runtime: nodejs

Or for Python:

runtime: python

Serialization Constraints

For multi-language compatibility, args must be serializable. These constraints apply regardless of the authoring language:

Allowed	Not Allowed
string, number, boolean	Union types (string | number)
Input<T> wrappers	Functions and callbacks
Arrays and maps of primitives	Complex nested generics
Enums	Platform-specific types

Consuming Multi-Language Components

Consumers install the component with pulumi package add, which automatically downloads the provider plugin, generates a local SDK in the consumer's language, and updates Pulumi.yaml:

# From a Git repository
pulumi package add <git-repo-url>

# From a specific version tag
pulumi package add <git-repo-url>@v1.0.0

For fresh checkouts or CI environments, run pulumi install to ensure all package dependencies are available. The consumer does not need to manually generate SDKs.

Authors who publish SDKs to package managers (npm, PyPI, etc.) can optionally use pulumi package gen-sdk to generate language-specific SDKs for publishing. Most component authors do not need this -- pulumi package add handles SDK generation on the consumer side.

Entry Points

Published multi-language components require an entry point that hosts the component provider process. The entry point pattern differs by language.

TypeScript (runtime: nodejs):

Export component classes from index.ts. No separate entry point file is needed. Pulumi introspects exported classes automatically.

// index.ts -- exports are the entry point
export { StaticSite, StaticSiteArgs } from "./staticSite";
export { SecureBucket, SecureBucketArgs } from "./secureBucket";

Python (runtime: python):

Create a __main__.py that calls component_provider_host with all component classes:

from pulumi.provider.experimental import component_provider_host
from static_site import StaticSite
from secure_bucket import SecureBucket

if __name__ == "__main__":
    component_provider_host(
        name="my-components",
        components=[StaticSite, SecureBucket],
    )

Go (runtime: go):

Create a main.go that builds and runs the provider:

package main

import (
    "context"
    "fmt"
    "os"

    "github.com/pulumi/pulumi-go-provider/infer"
)

func main() {
    p, err := infer.NewProviderBuilder().
        WithComponents(
            infer.ComponentF(NewStaticSite),
            infer.ComponentF(NewSecureBucket),
        ).
        Build()
    if err != nil {
        fmt.Fprintln(os.Stderr, err)
        os.Exit(1)
    }
    if err := p.Run(context.Background(), "my-components", "0.1.0"); err != nil {
        fmt.Fprintln(os.Stderr, err)
        os.Exit(1)
    }
}

C# (runtime: dotnet):

Create a Program.cs that serves the component provider host:

using System.Threading.Tasks;

class Program
{
    public static Task Main(string[] args) =>
        Pulumi.Experimental.Provider.ComponentProviderHost.Serve(args);
}

For a complete working example across all languages, see https://github.com/mikhailshilkov/comp-as-comp.

Reference: https://www.pulumi.com/docs/iac/using-pulumi/pulumi-packages/

---

Distribution

Choose a distribution method based on your audience:

Audience	Method	How
Same project	Direct import	Standard language import
Same organization	Private registry	pulumi package publish to Pulumi Cloud
Same organization	Git repository	pulumi package add <repo> with version tags
Language ecosystem	Package manager	Publish to npm, PyPI, NuGet, or Maven
Public community	Pulumi Registry	Submit via pulumi/registry GitHub repo

Pulumi Private Registry

The private registry is the centralized catalog for your organization's components. It provides automatic API documentation, version management, and discoverability for all teams.

Publish a component to the private registry:

pulumi package publish https://github.com/myorg/my-component --publisher myorg

Version components using git tags with a v prefix:

git tag v1.0.0
git push origin v1.0.0

A README file is required when publishing. Pulumi uses it as the component's documentation page in the registry.

Automate publishing from GitHub Actions using OIDC authentication:

name: Publish Component
on:
  push:
    tags:
      - "v*"

permissions:
  id-token: write
  contents: read

jobs:
  publish:
    runs-on: ubuntu-latest
    env:
      PULUMI_ORG: myorg
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0
      - uses: pulumi/auth-actions@v1
        with:
          organization: ${{ env.PULUMI_ORG }}
          requested-token-type: urn:pulumi:token-type:access_token:organization
      - run: pulumi package publish https://github.com/${{ github.repository }} --publisher ${{ env.PULUMI_ORG }}

Prerequisites: Configure GitHub OIDC integration with Pulumi Cloud before using this workflow.

The registry supports private GitHub and GitLab repositories. For non-OIDC setups, authenticate with GITHUB_TOKEN or GITLAB_TOKEN environment variables.

The private registry automatically generates SDK documentation for each published component. Enrich the generated docs by adding type annotations to your component's inputs and outputs (JSDoc in TypeScript, docstrings in Python, Annotate() methods in Go).

Reference: https://www.pulumi.com/docs/idp/get-started/private-registry/

Git Repository Distribution

Tag releases for consumers to pin versions:

git tag v1.0.0
git push origin v1.0.0

Consumers install with:

pulumi package add https://github.com/myorg/my-component@v1.0.0

Package Manager Distribution

Publish language-specific packages for native dependency management:

• npm: npm publish for TypeScript/JavaScript
• PyPI: twine upload for Python
• NuGet: dotnet nuget push for .NET
• Maven Central: Standard Maven publishing for Java

Reference: https://www.pulumi.com/docs/iac/using-pulumi/pulumi-packages/

---

Anti-Patterns

Anti-Pattern	Problem	Fix
Resources inside apply()	Not visible in pulumi preview	Move resource creation outside apply (see pulumi-best-practices practice 1)
Missing registerOutputs()	Component stuck "creating"	Always call as last line of constructor
Missing parent: this	Children appear at root level	Pass { parent: this } to all child resources
Union types in args	Breaks Python, Go, C# SDKs	Use single types; separate properties for variants
Functions in args	Cannot serialize across languages	Use configuration properties instead
Hardcoded child names	Collisions with multiple instances	Derive names from ${name}-suffix
Over-exposed outputs	Leaks implementation details	Export only what consumers need
Single-use component	Unnecessary abstraction overhead	Use inline resources until a pattern repeats
Deeply nested args	Hard to use and evolve	Keep interfaces flat with optional properties

---

Quick Reference

Topic	Key Point
Type URN	<package>:<module>:<type>, module usually index
Constructor	super(type, name, {}, opts) then children then registerOutputs()
Child resources	Always { parent: this }, derive name from ${name}-suffix
Args interface	Wrap in Input<T>, no unions, no functions, flat structure
Outputs	Public readonly Output<T> properties, expose only essentials
Defaults	Use ?? operator to apply sensible defaults in constructor
Composition	Lower-level components composed into higher-level ones
Multi-language	PulumiPlugin.yaml + entry point; consumers use pulumi package add
Distribution	Private registry, git tags, package managers, or public Pulumi Registry

Related Skills

• pulumi-best-practices: General Pulumi patterns including Output handling, secrets, and aliases
• pulumi-automation-api: Programmatic orchestration for integration testing and multi-stack workflows
• pulumi-esc: Centralized secrets and configuration for component deployments

References

• https://www.pulumi.com/docs/iac/concepts/resources/components/
• https://www.pulumi.com/docs/iac/using-pulumi/pulumi-packages/
• https://www.pulumi.com/docs/idp/get-started/private-registry/
• https://www.pulumi.com/docs/iac/concepts/inputs-outputs/
• https://www.pulumi.com/docs/iac/concepts/resources/options/aliases/