Pulumi Best Practices

When to Use This Skill

Invoke this skill when:

• Writing new Pulumi programs or components

• Reviewing Pulumi code for correctness

• Refactoring existing Pulumi infrastructure

• Debugging resource dependency issues

• Setting up configuration and secrets

Practices

1. Never Create Resources Inside apply()

Why: Resources created inside apply() don't appear in pulumi preview, making changes unpredictable. Pulumi cannot properly track dependencies, leading to race conditions and deployment failures.

Detection signals:

• new aws. or other resource constructors inside .apply() callbacks

• Resource creation inside pulumi.all([...]).apply()

• Dynamic resource counts determined at runtime inside apply

Wrong:

const bucket = new aws.s3.Bucket("bucket");

bucket.id.apply(bucketId => {

    // WRONG: This resource won't appear in preview

    new aws.s3.BucketObject("object", {

        bucket: bucketId,

        content: "hello",

    });

});

Right:

const bucket = new aws.s3.Bucket("bucket");

// Pass the output directly - Pulumi handles the dependency

const object = new aws.s3.BucketObject("object", {

    bucket: bucket.id,  // Output<string> works here

    content: "hello",

});

When apply is appropriate:

• Transforming output values for use in tags, names, or computed strings

• Logging or debugging (not resource creation)

• Conditional logic that affects resource properties, not resource existence

Reference: https://www.pulumi.com/docs/concepts/inputs-outputs/

2. Pass Outputs Directly as Inputs

Why: Pulumi builds a directed acyclic graph (DAG) based on input/output relationships. Passing outputs directly ensures correct creation order. Unwrapping values manually breaks the dependency chain, causing resources to deploy in wrong order or reference values that don't exist yet.

Detection signals:

• Variables extracted from .apply() used later as resource inputs

• await on output values outside of apply

• String concatenation with outputs instead of pulumi.interpolate

Wrong:

const vpc = new aws.ec2.Vpc("vpc", { cidrBlock: "10.0.0.0/16" });

// WRONG: Extracting the value breaks the dependency chain

let vpcId: string;

vpc.id.apply(id => { vpcId = id; });

const subnet = new aws.ec2.Subnet("subnet", {

    vpcId: vpcId,  // May be undefined, no tracked dependency

    cidrBlock: "10.0.1.0/24",

});

Right:

const vpc = new aws.ec2.Vpc("vpc", { cidrBlock: "10.0.0.0/16" });

const subnet = new aws.ec2.Subnet("subnet", {

    vpcId: vpc.id,  // Pass the Output directly

    cidrBlock: "10.0.1.0/24",

});

For string interpolation:

// WRONG

const name = bucket.id.apply(id => `prefix-${id}-suffix`);

// RIGHT - use pulumi.interpolate for template literals

const name = pulumi.interpolate`prefix-${bucket.id}-suffix`;

// RIGHT - use pulumi.concat for simple concatenation

const name = pulumi.concat("prefix-", bucket.id, "-suffix");

Reference: https://www.pulumi.com/docs/concepts/inputs-outputs/

3. Use Components for Related Resources

Why: ComponentResource classes group related resources into reusable, logical units. Without components, your resource graph is flat, making it hard to understand which resources belong together, reuse patterns across stacks, or reason about your infrastructure at a higher level.

Detection signals:

• Multiple related resources created at top level without grouping

• Repeated resource patterns across stacks that should be abstracted

• Hard to understand resource relationships from the Pulumi console

Wrong:

// Flat structure - no logical grouping, hard to reuse

const bucket = new aws.s3.Bucket("app-bucket");

const bucketPolicy = new aws.s3.BucketPolicy("app-bucket-policy", {

    bucket: bucket.id,

    policy: policyDoc,

});

const originAccessIdentity = new aws.cloudfront.OriginAccessIdentity("app-oai");

const distribution = new aws.cloudfront.Distribution("app-cdn", { /* ... */ });

Right:

interface StaticSiteArgs {

    domain: string;

    content: pulumi.asset.AssetArchive;

}

class StaticSite extends pulumi.ComponentResource {

    public readonly url: pulumi.Output<string>;

    constructor(name: string, args: StaticSiteArgs, opts?: pulumi.ComponentResourceOptions) {

        super("myorg:components:StaticSite", name, args, opts);

        // Resources created here - see practice 4 for parent setup

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

        // ...

        this.url = distribution.domainName;

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

    }

}

// Reusable across stacks

const site = new StaticSite("marketing", {

    domain: "marketing.example.com",

    content: new pulumi.asset.FileArchive("./dist"),

});

Component best practices:

• Use a consistent type URN pattern: organization:module:ComponentName

• Call registerOutputs() at the end of the constructor

• Expose outputs as class properties for consumers

• Accept ComponentResourceOptions to allow callers to set providers, aliases, etc.

For in-depth component authoring guidance (args design, multi-language support, testing, distribution), use skill pulumi-component.

Reference: https://www.pulumi.com/docs/concepts/resources/components/

4. Always Set parent: this in Components

Why: When you create resources inside a ComponentResource without setting parent: this, those resources appear at the root level of your stack's state. This breaks the logical hierarchy, makes the Pulumi console hard to navigate, and can cause issues with aliases and refactoring. The parent relationship is what makes the component actually group its children.

Detection signals:

• ComponentResource classes that don't pass { parent: this } to child resources

• Resources inside a component appearing at root level in the console

• Unexpected behavior when adding aliases to components

Wrong:

class MyComponent extends pulumi.ComponentResource {

    constructor(name: string, opts?: pulumi.ComponentResourceOptions) {

        super("myorg:components:MyComponent", name, {}, opts);

        // WRONG: No parent set - this bucket appears at root level

        const bucket = new aws.s3.Bucket(`${name}-bucket`);

    }

}

Right:

class MyComponent extends pulumi.ComponentResource {

    constructor(name: string, opts?: pulumi.ComponentResourceOptions) {

        super("myorg:components:MyComponent", name, {}, opts);

        // RIGHT: Parent establishes hierarchy

        const bucket = new aws.s3.Bucket(`${name}-bucket`, {}, {

            parent: this

        });

        const policy = new aws.s3.BucketPolicy(`${name}-policy`, {

            bucket: bucket.id,

            policy: policyDoc,

        }, {

            parent: this

        });

    }

}

What parent: this provides:

• Resources appear nested under the component in Pulumi console

• Deleting the component deletes all children

• Aliases on the component automatically apply to children

• Clear ownership in state files

Reference: https://www.pulumi.com/docs/concepts/resources/components/

5. Encrypt Secrets from Day One

Why: Secrets marked with --secret are encrypted in state files, masked in CLI output, and tracked through transformations. Starting with plaintext config and converting later requires credential rotation, reference updates, and audit of leaked values in logs and state history.

Detection signals:

• Passwords, API keys, tokens stored as plain config

• Connection strings with embedded credentials

• Private keys or certificates in plaintext

Wrong:

# Plaintext - will be visible in state and logs

pulumi config set databasePassword hunter2

pulumi config set apiKey sk-1234567890

Right:

# Encrypted from the start

pulumi config set --secret databasePassword hunter2

pulumi config set --secret apiKey sk-1234567890

In code:

const config = new pulumi.Config();

// This retrieves a secret - the value stays encrypted

const dbPassword = config.requireSecret("databasePassword");

// Creating outputs from secrets preserves secrecy

const connectionString = pulumi.interpolate`postgres://user:${dbPassword}@host/db`;

// connectionString is also a secret Output

// Explicitly mark values as secret

const computed = pulumi.secret(someValue);

Use Pulumi ESC for centralized secrets:

# Pulumi.yaml

environment:

  - production-secrets  # Pull from ESC environment

# ESC manages secrets centrally across stacks

esc env set production-secrets db.password --secret "hunter2"

What qualifies as a secret:

• Passwords and passphrases

• API keys and tokens

• Private keys and certificates

• Connection strings with credentials

• OAuth client secrets

• Encryption keys

References:

• https://www.pulumi.com/docs/concepts/secrets/

• https://www.pulumi.com/docs/esc/

6. Use Aliases When Refactoring

Why: Renaming resources, moving them into components, or changing parents causes Pulumi to see them as new resources. Without aliases, refactoring destroys and recreates resources, potentially causing downtime or data loss. Aliases preserve resource identity through refactors.

Detection signals:

• Resource rename without alias

• Moving resource into or out of a ComponentResource

• Changing the parent of a resource

• Preview shows delete+create when update was intended

Wrong:

// Before: resource named "my-bucket"

const bucket = new aws.s3.Bucket("my-bucket");

// After: renamed without alias - DESTROYS THE BUCKET

const bucket = new aws.s3.Bucket("application-bucket");

Right:

// After: renamed with alias - preserves the existing bucket

const bucket = new aws.s3.Bucket("application-bucket", {}, {

    aliases: [{ name: "my-bucket" }],

});

Moving into a component:

// Before: top-level resource

const bucket = new aws.s3.Bucket("my-bucket");

// After: inside a component - needs alias with old parent

class MyComponent extends pulumi.ComponentResource {

    constructor(name: string, opts?: pulumi.ComponentResourceOptions) {

        super("myorg:components:MyComponent", name, {}, opts);

        const bucket = new aws.s3.Bucket("bucket", {}, {

            parent: this,

            aliases: [{

                name: "my-bucket",

                parent: pulumi.rootStackResource,  // Was at root

            }],

        });

    }

}

Alias types:

// Simple name change

aliases: [{ name: "old-name" }]

// Parent change

aliases: [{ name: "resource-name", parent: oldParent }]

// Full URN (when you know the exact previous URN)

aliases: ["urn:pulumi:stack::project::aws:s3/bucket:Bucket::old-name"]

Lifecycle:

• Add alias during refactor

• Run pulumi up on all stacks

• Remove alias after all stacks updated (optional, but keeps code clean)

Reference: https://www.pulumi.com/docs/iac/concepts/resources/options/aliases/

7. Preview Before Every Deployment

Why: pulumi preview shows exactly what will be created, updated, or destroyed. Surprises in production come from skipping preview. A resource showing "replace" when you expected "update" means imminent destruction and recreation.

Detection signals:

• Running pulumi up --yes interactively without reviewing changes

• No preview step anywhere in the CI/CD workflow for a given change

• Preview output not reviewed before merge or deployment approval

Wrong:

# Deploying blind

pulumi up --yes

Right:

# Always preview first

pulumi preview

# Review the output, then deploy

pulumi up

What to look for in preview:

• + create - New resource will be created

• ~ update - Existing resource will be modified in place

• - delete - Resource will be destroyed

• +-replace - Resource will be destroyed and recreated (potential downtime)

• ~+-replace - Resource will be updated, then replaced

Warning signs:

• Unexpected replace operations (check for immutable property changes)

• Resources being deleted that shouldn't be

• More changes than expected from your code diff

CI/CD integration:

# GitHub Actions example

jobs:

  preview:

    runs-on: ubuntu-latest

    steps:

      - uses: actions/checkout@v4

      - name: Pulumi Preview

        uses: pulumi/actions@v5

        with:

          command: preview

          stack-name: production

        env:

          PULUMI_ACCESS_TOKEN: ${{ secrets.PULUMI_ACCESS_TOKEN }}

  deploy:

    needs: preview

    runs-on: ubuntu-latest

    if: github.ref == 'refs/heads/main'

    steps:

      - name: Pulumi Up

        uses: pulumi/actions@v5

        with:

          command: up

          stack-name: production

PR workflow:

• Run preview on every PR

• Post preview output as PR comment

• Require preview review before merge

• Deploy only on merge to main

References:

• https://www.pulumi.com/docs/cli/commands/pulumi_preview/

• https://www.pulumi.com/docs/iac/packages-and-automation/continuous-delivery/github-actions/

Quick Reference

Practice

Key Signal

Fix

No resources in apply

new Resource() inside .apply()

Move resource outside, pass Output directly

Pass outputs directly

Extracted values used as inputs

Use Output objects, pulumi.interpolate

Use components

Flat structure, repeated patterns

Create ComponentResource classes

Set parent: this

Component children at root level

Pass { parent: this } to all child resources

Secrets from day one

Plaintext passwords/keys in config

Use --secret flag, ESC

Aliases when refactoring

Delete+create in preview

Add alias with old name/parent

Preview before deploy

pulumi up --yes

Always run pulumi preview first

Validation Checklist

When reviewing Pulumi code, verify:

• No resource constructors inside apply() callbacks

• Outputs passed directly to dependent resources

• Related resources grouped in ComponentResource classes

• Child resources have { parent: this }

• Sensitive values use config.requireSecret() or --secret

• Refactored resources have aliases preserving identity

• Deployment process includes preview step

Related Skills

• pulumi-component: Deep guide to authoring ComponentResource classes, designing args interfaces, multi-language support, testing, and distribution. Use skill pulumi-component.

• pulumi-automation-api: Programmatic orchestration of multiple stacks. Use skill pulumi-automation-api.

• pulumi-esc: Centralized secrets and configuration management. Use skill pulumi-esc.