Add context propagation sample (traditional and go-style)

Author: mjameswh

.scripts/list-of-samples.json

@@ -4,6 +4,7 @@
     "activities-dependency-injection",
     "activities-examples",
     "child-workflows",
+    "context-propagation",
     "continue-as-new",
     "cron-workflows",
     "custom-logger",

README.md

@@ -151,6 +151,10 @@ and you'll be given the list of sample options.
 
 - **Interceptors**:
   - [**OpenTelemetry**](./interceptors-opentelemetry): Use the Interceptors feature to add OpenTelemetry metrics reporting to your workflows.
+  - [**Context Propagation**](./context-propagation): Uses SDK interceptors to propagate contextual data from the client, to workflows, child workflows and activities, and automatically include these as metadata emitted log messages.
+    Two variants are presented:
+    - [**Traditional**](./context-propagation/traditional): Uses the `AsyncLocalStorage` API to implicitly propagate context. This is the recommended approach.
+    - [**Go-Style**](./context-propagation/go-style): Propagate context using an explicit `ctx` argument on workflow and activity functions, following the Go style. This is a less common approach, but demonstrated for the benefit of teams that have strong reasons to prefer it.
   - [**Query Subscriptions**](./query-subscriptions): Use Redis Streams, Immer, and SDK Interceptors to subscribe to Workflow state.
 - [**gRPC calls**](./grpc-calls): Make raw gRPC calls for advanced queries not covered by the WorkflowClient API.
 

context-propagation/go-style-context/.eslintignore

@@ -0,0 +1,3 @@
+node_modules
+lib
+.eslintrc.js

context-propagation/go-style-context/.eslintrc.js

@@ -0,0 +1,48 @@
+const { builtinModules } = require('module');
+
+const ALLOWED_NODE_BUILTINS = new Set(['assert']);
+
+module.exports = {
+  root: true,
+  parser: '@typescript-eslint/parser',
+  parserOptions: {
+    project: './tsconfig.json',
+    tsconfigRootDir: __dirname,
+  },
+  plugins: ['@typescript-eslint', 'deprecation'],
+  extends: [
+    'eslint:recommended',
+    'plugin:@typescript-eslint/eslint-recommended',
+    'plugin:@typescript-eslint/recommended',
+    'prettier',
+  ],
+  rules: {
+    // recommended for safety
+    '@typescript-eslint/no-floating-promises': 'error', // forgetting to await Activities and Workflow APIs is bad
+    'deprecation/deprecation': 'warn',
+
+    // code style preference
+    'object-shorthand': ['error', 'always'],
+
+    // relaxed rules, for convenience
+    '@typescript-eslint/no-unused-vars': [
+      'warn',
+      {
+        argsIgnorePattern: '^_',
+        varsIgnorePattern: '^_',
+      },
+    ],
+    '@typescript-eslint/no-explicit-any': 'off',
+  },
+  overrides: [
+    {
+      files: ['src/workflows.ts', 'src/workflows-*.ts', 'src/workflows/*.ts'],
+      rules: {
+        'no-restricted-imports': [
+          'error',
+          ...builtinModules.filter((m) => !ALLOWED_NODE_BUILTINS.has(m)).flatMap((m) => [m, `node:${m}`]),
+        ],
+      },
+    },
+  ],
+};

context-propagation/go-style-context/.gitignore

@@ -0,0 +1,2 @@
+lib
+node_modules

context-propagation/go-style-context/.npmrc

@@ -0,0 +1 @@
+package-lock=false

context-propagation/go-style-context/.nvmrc

@@ -0,0 +1 @@
+16

context-propagation/go-style-context/.post-create

@@ -0,0 +1,18 @@
+To begin development, install the Temporal CLI:
+
+  Mac: {cyan brew install temporal}
+  Other: Download and extract the latest release from https://github.com/temporalio/cli/releases/latest
+
+Start Temporal Server:
+
+  {cyan temporal server start-dev}
+
+Use Node version 16+:
+
+  Mac: {cyan brew install node@16}
+  Other: https://nodejs.org/en/download/
+
+Then, in the project directory, using two other shells, run these commands:
+
+  {cyan npm run start.watch}
+  {cyan npm run workflow}

context-propagation/go-style-context/.prettierignore

@@ -0,0 +1 @@
+lib

context-propagation/go-style-context/.prettierrc

@@ -0,0 +1,2 @@
+printWidth: 120
+singleQuote: true