diff --git a/.github/workflows/environment-outputs.yaml b/.github/workflows/environment-outputs.yaml
new file mode 100644
index 000000000..2089c3789
--- /dev/null
+++ b/.github/workflows/environment-outputs.yaml
@@ -0,0 +1,65 @@
+name: environment-outputs
+
+on:
+  pull_request:
+    paths:
+      - environment-outputs/**
+      - '*.json'
+      - '*.yaml'
+      - .github/workflows/environment-outputs.yaml
+  push:
+    branches:
+      - main
+    paths:
+      - environment-outputs/**
+      - '*.json'
+      - '*.yaml'
+      - .github/workflows/environment-outputs.yaml
+
+defaults:
+  run:
+    working-directory: environment-outputs
+  
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+      - uses: actions/setup-node@60edb5dd545a775178f52524783378180af0d1f8 # v4.0.2
+        with:
+          node-version: 20
+      - run: corepack enable pnpm
+      - run: pnpm i
+      - run: pnpm test
+
+  e2e-test:
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+      - uses: actions/setup-node@60edb5dd545a775178f52524783378180af0d1f8 # v4.0.2
+        with:
+          node-version: 20
+      - run: corepack enable pnpm
+      - run: pnpm i
+      - run: pnpm build
+      - uses: ./environment-outputs
+        id: environment
+        with:
+          service: example
+          rules: |
+            - pull_request:
+                base: '**'
+                head: '**'
+              outputs:
+                overlay: pr
+                namespace: pr-${{ github.event.pull_request.number }}
+            - push:
+                ref: refs/heads/main
+              outputs:
+                overlay: development
+                namespace: development
+      - run: echo 'overlay=${{ steps.environment.outputs.overlay }}'
+      - run: echo 'namespace=${{ steps.environment.outputs.namespace }}'
+      - run: echo 'github-deployment-url=${{ steps.environment.outputs.github-deployment-url }}'
diff --git a/environment-outputs/README.md b/environment-outputs/README.md
new file mode 100644
index 000000000..3bdb15c47
--- /dev/null
+++ b/environment-outputs/README.md
@@ -0,0 +1,146 @@
+# environment-outputs [![environment-outputs](https://github.com/quipper/monorepo-deploy-actions/actions/workflows/environment-outputs.yaml/badge.svg)](https://github.com/quipper/monorepo-deploy-actions/actions/workflows/environment-outputs.yaml)
+
+This action generates outputs to deploy a service to the corresponding environment.
+
+## Getting Started
+
+Let's think about the following example:
+
+- When a pull request is created, deploy it to `pr-NUMBER` namespace
+- When `main` branch is pushed, deploy it to `development` namespace
+
+It can be descibed as the following rules:
+
+```yaml
+- pull_request:
+    base: '**'
+    head: '**'
+  outputs:
+    overlay: pr
+    namespace: pr-${{ github.event.pull_request.number }}
+- push:
+    ref: refs/heads/main
+  outputs:
+    overlay: development
+    namespace: development
+```
+
+This action finds a rule matched to the current context.
+If any rule is matched, this action returns the outputs corresponding to the rule.
+For example, when `main` branch is pushed, this action returns the following outputs:
+
+```yaml
+overlay: development
+namespace: development
+```
+
+This action finds a rule in order.
+If no rule is matched, this action fails.
+
+## GitHub Deployment
+
+This action supports [GitHub Deployment](https://docs.github.com/en/rest/deployments/deployments) to receive the deployment status from an external system, such as Argo CD.
+
+It creates a GitHub Deployment for each environment in the form of `{overlay}/{namespace}/{service}`,
+if the following fields are given:
+
+- `overlay` (in `environments`)
+- `namespace` (in `environments`)
+- `service` (in the inputs)
+
+If an old deployment exists, this action deletes it and recreates new one.
+
+This action sets `github-deployment-url` field to the output.
+For example, the below inputs are given,
+
+```yaml
+- uses: quipper/monorepo-deploy-actions/environment-outputs@v1
+  with:
+    service: backend
+    rules: |
+      - pull_request:
+          base: '**'
+          head: '**'
+        outputs:
+          overlay: pr
+          namespace: pr-${{ github.event.pull_request.number }}
+```
+
+this action creates a GitHub Deployment of `pr/pr-1/backend` and returns the following outputs:
+
+```yaml
+overlay: pr
+namespace: pr-1
+github-deployment-url: https://api.github.com/repos/octocat/example/deployments/1
+```
+
+## Example
+
+Here is the example workflow.
+
+```yaml
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    timeout-minutes: 3
+    steps:
+      - uses: quipper/monorepo-deploy-actions/environment-outputs@v1
+        id: environment
+        with:
+          service: example
+          rules: |
+            - pull_request:
+                base: '**'
+                head: '**'
+              outputs:
+                overlay: pr
+                namespace: pr-${{ github.event.pull_request.number }}
+            - push:
+                ref: refs/heads/main
+              outputs:
+                overlay: development
+                namespace: development
+      - uses: quipper/monorepo-deploy-actions/git-push-service@v1
+        with:
+          manifests: # (omit in this example)
+          overlay: ${{ steps.environment.outputs.overlay }}
+          namespace: ${{ steps.environment.outputs.namespace }}
+          service: example
+          application-annotations: |
+            argocd-commenter.int128.github.io/deployment-url=${{ steps.environment.outputs.github-deployment-url }}
+```
+
+## Spec
+
+### Inputs
+
+| Name      | Default        | Description                                                 |
+| --------- | -------------- | ----------------------------------------------------------- |
+| `rules`   | (required)     | YAML string of rules                                        |
+| `service` | (optional)     | Name of service to deploy. If set, create GitHub Deployment |
+| `token`   | `github.token` | GitHub token, required if `service` is set                  |
+
+The following fields are available in the rules YAML.
+
+```yaml
+- pull_request: # on pull_request event
+    base: # base branch name (wildcard available)
+    head: # head branch name (wildcard available)
+  outputs: # map<string, string>
+- push: # on push event
+    ref: refs/heads/main # ref name (wildcard available)
+  outputs: # map<string, string>
+```
+
+It supports the wildcard pattern.
+See https://github.com/isaacs/minimatch for details.
+
+### Outputs
+
+This actions returns the outputs corresponding to the rule.
+
+It also returns the below outputs.
+
+| Name                    | Description                                                           |
+| ----------------------- | --------------------------------------------------------------------- |
+| `github-deployment-url` | URL of GitHub Deployment. Available if `service` is set in the inputs |
diff --git a/environment-outputs/action.yaml b/environment-outputs/action.yaml
new file mode 100644
index 000000000..272202015
--- /dev/null
+++ b/environment-outputs/action.yaml
@@ -0,0 +1,19 @@
+name: environment-matrix
+description: generate a JSON for matrix deploy
+inputs:
+  rules:
+    description: YAML string of rules
+    required: true
+  service:
+    description: Name of service. If set, create GitHub Deployment
+    required: false
+  token:
+    description: GitHub token, required if service is set
+    required: false
+    default: ${{ github.token }}
+outputs:
+  github-deployment-url:
+    description: URL of the GitHub Deployment, e.g. https://api.github.com/repos/octocat/example/deployments/1
+runs:
+  using: 'node20'
+  main: 'dist/index.js'
diff --git a/environment-outputs/jest.config.js b/environment-outputs/jest.config.js
new file mode 100644
index 000000000..4f97e5f78
--- /dev/null
+++ b/environment-outputs/jest.config.js
@@ -0,0 +1,7 @@
+module.exports = {
+  preset: 'ts-jest',
+  clearMocks: true,
+  testEnvironment: 'node',
+  testMatch: ['**/*.test.ts'],
+  verbose: true,
+}
diff --git a/environment-outputs/package.json b/environment-outputs/package.json
new file mode 100644
index 000000000..9185ca4be
--- /dev/null
+++ b/environment-outputs/package.json
@@ -0,0 +1,22 @@
+{
+  "name": "environment-outputs",
+  "version": "0.0.0",
+  "private": true,
+  "scripts": {
+    "build": "ncc build --source-map --license licenses.txt src/main.ts",
+    "test": "jest"
+  },
+  "dependencies": {
+    "@actions/core": "1.10.1",
+    "@actions/github": "6.0.0",
+    "@octokit/plugin-retry": "6.0.1",
+    "@octokit/request-error": "5.0.1",
+    "ajv": "8.12.0",
+    "js-yaml": "4.1.0",
+    "minimatch": "9.0.3"
+  },
+  "devDependencies": {
+    "@types/js-yaml": "4.0.9",
+    "@types/minimatch": "5.1.2"
+  }
+}
diff --git a/environment-outputs/src/deployment.ts b/environment-outputs/src/deployment.ts
new file mode 100644
index 000000000..49fd0239e
--- /dev/null
+++ b/environment-outputs/src/deployment.ts
@@ -0,0 +1,82 @@
+import * as core from '@actions/core'
+import * as github from '@actions/github'
+import { RequestError } from '@octokit/request-error'
+import { Octokit, assertPullRequestPayload } from './github'
+import assert from 'assert'
+
+type Context = Pick<typeof github.context, 'eventName' | 'repo' | 'ref' | 'payload'>
+
+export const createDeployment = async (
+  octokit: Octokit,
+  context: Context,
+  overlay: string,
+  namespace: string,
+  service: string,
+) => {
+  const environment = `${overlay}/${namespace}/${service}`
+
+  core.info(`Finding the old deployments for environment ${environment}`)
+  const oldDeployments = await octokit.rest.repos.listDeployments({
+    owner: context.repo.owner,
+    repo: context.repo.repo,
+    environment,
+  })
+
+  core.info(`Deleting ${oldDeployments.data.length} deployment(s)`)
+  for (const deployment of oldDeployments.data) {
+    try {
+      await octokit.rest.repos.deleteDeployment({
+        owner: context.repo.owner,
+        repo: context.repo.repo,
+        deployment_id: deployment.id,
+      })
+    } catch (error) {
+      if (error instanceof RequestError) {
+        core.warning(`Could not delete the old deployment ${deployment.url}: ${error.status} ${error.message}`)
+        continue
+      }
+      throw error
+    }
+    core.info(`Deleted the old deployment ${deployment.url}`)
+  }
+  core.info(`Deleted ${oldDeployments.data.length} deployment(s)`)
+
+  const ref = getDeploymentRef(context)
+  core.info(`Creating a deployment for environment=${environment}, ref=${ref}`)
+  const created = await octokit.rest.repos.createDeployment({
+    owner: context.repo.owner,
+    repo: context.repo.repo,
+    ref,
+    environment,
+    auto_merge: false,
+    required_contexts: [],
+    transient_environment: context.eventName === 'pull_request',
+    payload: { overlay, namespace, service },
+  })
+  assert.strictEqual(created.status, 201)
+  core.info(`Created a deployment ${created.data.url}`)
+
+  // If the deployment is not deployed for a while, it will cause the following error:
+  //   This branch had an error being deployed
+  //   1 abandoned deployment
+  //
+  // To avoid this, we set the deployment status to inactive immediately.
+  core.info(`Setting the deployment status to inactive`)
+  await octokit.rest.repos.createDeploymentStatus({
+    owner: context.repo.owner,
+    repo: context.repo.repo,
+    deployment_id: created.data.id,
+    state: 'inactive',
+  })
+  core.info(`Set the deployment status to inactive`)
+  return created.data.url
+}
+
+const getDeploymentRef = (context: Context): string => {
+  if (context.eventName === 'pull_request') {
+    // Set the head ref to associate a deployment with the pull request
+    assertPullRequestPayload(context.payload.pull_request)
+    return context.payload.pull_request.head.ref
+  }
+  return context.ref
+}
diff --git a/environment-outputs/src/github.ts b/environment-outputs/src/github.ts
new file mode 100644
index 000000000..54dc1cac3
--- /dev/null
+++ b/environment-outputs/src/github.ts
@@ -0,0 +1,36 @@
+import assert from 'assert'
+import * as github from '@actions/github'
+import * as pluginRetry from '@octokit/plugin-retry'
+
+export type Octokit = ReturnType<typeof github.getOctokit>
+
+export const getOctokit = (token: string): Octokit => {
+  return github.getOctokit(token, { previews: ['ant-man', 'flash'] }, pluginRetry.retry)
+}
+
+// picked from https://docs.github.com/en/rest/pulls/pulls#get-a-pull-request
+export type PullRequestPayload = {
+  head: {
+    ref: string
+  }
+  base: {
+    ref: string
+  }
+}
+
+export function assertPullRequestPayload(x: unknown): asserts x is PullRequestPayload {
+  assert(typeof x === 'object')
+  assert(x != null)
+
+  assert('base' in x)
+  assert(typeof x.base === 'object')
+  assert(x.base != null)
+  assert('ref' in x.base)
+  assert(typeof x.base.ref === 'string')
+
+  assert('head' in x)
+  assert(typeof x.head === 'object')
+  assert(x.head != null)
+  assert('ref' in x.head)
+  assert(typeof x.head.ref === 'string')
+}
diff --git a/environment-outputs/src/main.ts b/environment-outputs/src/main.ts
new file mode 100644
index 000000000..34f3f2792
--- /dev/null
+++ b/environment-outputs/src/main.ts
@@ -0,0 +1,24 @@
+import * as core from '@actions/core'
+import { run } from './run'
+
+const main = async (): Promise<void> => {
+  const outputs = await run({
+    rules: core.getInput('rules', { required: true }),
+    service: core.getInput('service'),
+    token: core.getInput('token'),
+  })
+  core.info('Setting outputs:')
+  for (const [k, v] of Object.entries(outputs.outputs)) {
+    core.info(`${k}=${v}`)
+    core.setOutput(k, v)
+  }
+  if (outputs.githubDeploymentURL) {
+    core.info(`github-deployment-url=${outputs.githubDeploymentURL}`)
+    core.setOutput('github-deployment-url', outputs.githubDeploymentURL)
+  }
+}
+
+main().catch((e: Error) => {
+  core.setFailed(e)
+  console.error(e)
+})
diff --git a/environment-outputs/src/matcher.ts b/environment-outputs/src/matcher.ts
new file mode 100644
index 000000000..4df00ce82
--- /dev/null
+++ b/environment-outputs/src/matcher.ts
@@ -0,0 +1,28 @@
+import * as github from '@actions/github'
+import { minimatch } from 'minimatch'
+import { Rule, Rules } from './rule'
+import { assertPullRequestPayload } from './github'
+
+type Context = Pick<typeof github.context, 'eventName' | 'ref' | 'payload'>
+
+export const find = (context: Context, rules: Rules): Record<string, string> | undefined => {
+  for (const rule of rules) {
+    if (match(context, rule)) {
+      return rule.outputs
+    }
+  }
+}
+
+const match = (context: Context, rule: Rule): boolean => {
+  if (context.eventName === 'pull_request' && rule.pull_request !== undefined) {
+    assertPullRequestPayload(context.payload.pull_request)
+    return (
+      minimatch(context.payload.pull_request.base.ref, rule.pull_request.base) &&
+      minimatch(context.payload.pull_request.head.ref, rule.pull_request.head)
+    )
+  }
+  if (context.eventName === 'push' && rule.push !== undefined) {
+    return minimatch(context.ref, rule.push.ref)
+  }
+  return false
+}
diff --git a/environment-outputs/src/rule.ts b/environment-outputs/src/rule.ts
new file mode 100644
index 000000000..b4fcd6c95
--- /dev/null
+++ b/environment-outputs/src/rule.ts
@@ -0,0 +1,64 @@
+import * as yaml from 'js-yaml'
+import Ajv, { JTDSchemaType } from 'ajv/dist/jtd'
+
+export type Rule = {
+  pull_request?: {
+    base: string
+    head: string
+  }
+  push?: {
+    ref: string
+  }
+  outputs: Record<string, string>
+}
+
+const RuleSchema: JTDSchemaType<Rule> = {
+  properties: {
+    outputs: {
+      values: {
+        type: 'string',
+      },
+    },
+  },
+  optionalProperties: {
+    pull_request: {
+      properties: {
+        base: {
+          type: 'string',
+        },
+        head: {
+          type: 'string',
+        },
+      },
+    },
+    push: {
+      properties: {
+        ref: {
+          type: 'string',
+        },
+      },
+    },
+  },
+}
+
+export type Rules = Rule[]
+
+const rulesSchema: JTDSchemaType<Rules> = {
+  elements: RuleSchema,
+}
+
+const ajv = new Ajv()
+export const validateRules = ajv.compile(rulesSchema)
+
+export const parseRulesYAML = (s: string): Rules => {
+  const rules = yaml.load(s)
+  if (!validateRules(rules)) {
+    if (validateRules.errors) {
+      throw new Error(
+        `invalid rules YAML: ${validateRules.errors.map((e) => `${e.instancePath} ${e.message || ''}`).join(', ')}`,
+      )
+    }
+    throw new Error('invalid rules YAML')
+  }
+  return rules
+}
diff --git a/environment-outputs/src/run.ts b/environment-outputs/src/run.ts
new file mode 100644
index 000000000..fa36f38a5
--- /dev/null
+++ b/environment-outputs/src/run.ts
@@ -0,0 +1,40 @@
+import assert from 'assert'
+import * as core from '@actions/core'
+import * as github from '@actions/github'
+import { parseRulesYAML } from './rule'
+import { find } from './matcher'
+import { createDeployment } from './deployment'
+import { getOctokit } from './github'
+
+type Inputs = {
+  rules: string
+  service: string
+  token: string
+}
+
+type Outputs = {
+  outputs: Record<string, string>
+  githubDeploymentURL?: string
+}
+
+export const run = async (inputs: Inputs): Promise<Outputs> => {
+  const rules = parseRulesYAML(inputs.rules)
+  core.info(`rules: ${JSON.stringify(rules, undefined, 2)}`)
+  const outputs = find(github.context, rules)
+  if (outputs === undefined) {
+    throw new Error(`no environment to deploy`)
+  }
+
+  if (!inputs.service) {
+    return { outputs }
+  }
+
+  core.info(`Creating a GitHub Deployment for the environment`)
+  const { overlay, namespace } = outputs
+  assert(overlay, `overlay is required in the rule outputs`)
+  assert(namespace, `namespace is required in the rule outputs`)
+  assert(inputs.token, `inputs.token is required`)
+  const octokit = getOctokit(inputs.token)
+  const githubDeploymentURL = await createDeployment(octokit, github.context, overlay, namespace, inputs.service)
+  return { outputs, githubDeploymentURL }
+}
diff --git a/environment-outputs/tests/matcher.test.ts b/environment-outputs/tests/matcher.test.ts
new file mode 100644
index 000000000..4d50ffe3f
--- /dev/null
+++ b/environment-outputs/tests/matcher.test.ts
@@ -0,0 +1,91 @@
+import { find } from '../src/matcher'
+import { Rules } from '../src/rule'
+
+const rules: Rules = [
+  {
+    pull_request: {
+      head: '*/qa',
+      base: '*/production',
+    },
+    outputs: {
+      overlay: 'pr',
+      namespace: 'pr-2',
+    },
+  },
+  {
+    pull_request: {
+      head: '**',
+      base: '**',
+    },
+    outputs: {
+      overlay: 'pr',
+      namespace: 'pr-1',
+    },
+  },
+  {
+    push: {
+      ref: 'refs/heads/main',
+    },
+    outputs: {
+      overlay: 'development',
+      namespace: 'development',
+    },
+  },
+]
+
+test('pull_request with any branches', () => {
+  const context = {
+    eventName: 'pull_request',
+    payload: {
+      pull_request: {
+        number: 1,
+        head: { ref: 'topic' },
+        base: { ref: 'main' },
+      },
+    },
+    ref: 'refs/pull/1/merge',
+  }
+  expect(find(context, rules)).toStrictEqual({
+    overlay: 'pr',
+    namespace: 'pr-1',
+  })
+})
+
+test('pull_request with patterns', () => {
+  const context = {
+    eventName: 'pull_request',
+    payload: {
+      pull_request: {
+        number: 2,
+        head: { ref: 'microservice/qa' },
+        base: { ref: 'microservice/production' },
+      },
+    },
+    ref: 'refs/pull/2/merge',
+  }
+  expect(find(context, rules)).toStrictEqual({
+    overlay: 'pr',
+    namespace: 'pr-2',
+  })
+})
+
+test('push', () => {
+  const context = {
+    eventName: 'push',
+    payload: {},
+    ref: 'refs/heads/main',
+  }
+  expect(find(context, rules)).toStrictEqual({
+    overlay: 'development',
+    namespace: 'development',
+  })
+})
+
+test('push with no match', () => {
+  const context = {
+    eventName: 'push',
+    payload: {},
+    ref: 'refs/tags/v1.0.0',
+  }
+  expect(find(context, rules)).toBeUndefined()
+})
diff --git a/environment-outputs/tests/rule.test.ts b/environment-outputs/tests/rule.test.ts
new file mode 100644
index 000000000..99eee8f33
--- /dev/null
+++ b/environment-outputs/tests/rule.test.ts
@@ -0,0 +1,53 @@
+import { Rules, parseRulesYAML } from '../src/rule'
+
+test('parse a valid YAML', () => {
+  const yaml = `
+- pull_request:
+    base: '**'
+    head: '**'
+  outputs:
+    overlay: pr
+    namespace: pr-1
+- push:
+    ref: refs/heads/main
+  outputs:
+    overlay: development
+    namespace: development
+`
+  expect(parseRulesYAML(yaml)).toStrictEqual<Rules>([
+    {
+      pull_request: {
+        base: '**',
+        head: '**',
+      },
+      outputs: {
+        overlay: 'pr',
+        namespace: 'pr-1',
+      },
+    },
+    {
+      push: {
+        ref: 'refs/heads/main',
+      },
+      outputs: {
+        overlay: 'development',
+        namespace: 'development',
+      },
+    },
+  ])
+})
+
+test('parse an empty string', () => {
+  expect(() => parseRulesYAML('')).toThrow(`invalid rules YAML:  must be array`)
+})
+
+test('parse an invalid string', () => {
+  const yaml = `
+- pull_request:
+    base: '**'
+  outputs:
+    overlay: pr
+    namespace: pr-1
+`
+  expect(() => parseRulesYAML(yaml)).toThrow(`invalid rules YAML: /0/pull_request must have property 'head'`)
+})
diff --git a/environment-outputs/tsconfig.json b/environment-outputs/tsconfig.json
new file mode 100644
index 000000000..a854be8f7
--- /dev/null
+++ b/environment-outputs/tsconfig.json
@@ -0,0 +1,6 @@
+{
+  "extends": "../tsconfig.json",
+  "compilerOptions": {
+    "outDir": "./lib"
+  }
+}
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 879dfeca8..3a3dcea6b 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -112,6 +112,8 @@ importers:
         specifier: 5.0.1
         version: 5.0.1
 
+  delete-pull-request-namespaces/dist: {}
+
   environment-matrix:
     dependencies:
       '@actions/core':
@@ -143,6 +145,37 @@ importers:
         specifier: 5.1.2
         version: 5.1.2
 
+  environment-outputs:
+    dependencies:
+      '@actions/core':
+        specifier: 1.10.1
+        version: 1.10.1
+      '@actions/github':
+        specifier: 6.0.0
+        version: 6.0.0
+      '@octokit/plugin-retry':
+        specifier: 6.0.1
+        version: 6.0.1(@octokit/core@5.1.0)
+      '@octokit/request-error':
+        specifier: 5.0.1
+        version: 5.0.1
+      ajv:
+        specifier: 8.12.0
+        version: 8.12.0
+      js-yaml:
+        specifier: 4.1.0
+        version: 4.1.0
+      minimatch:
+        specifier: 9.0.3
+        version: 9.0.3
+    devDependencies:
+      '@types/js-yaml':
+        specifier: 4.0.9
+        version: 4.0.9
+      '@types/minimatch':
+        specifier: 5.1.2
+        version: 5.1.2
+
   git-push-namespace:
     dependencies:
       '@actions/core':