Sample code contribution

.gitignore

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+/client/client
+/server/server
+
+
+# Created by https://www.toptal.com/developers/gitignore/api/go,terraform,intellij+all,visualstudiocode,macos
+# Edit at https://www.toptal.com/developers/gitignore?templates=go,terraform,intellij+all,visualstudiocode,macos
+
+### Go ###
+# If you prefer the allow list template instead of the deny list, see community template:
+# https://github.com/github/gitignore/blob/main/community/Golang/Go.AllowList.gitignore
+#
+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+# Test binary, built with `go test -c`
+*.test
+
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out
+
+# Dependency directories (remove the comment below to include it)
+# vendor/
+
+# Go workspace file
+go.work
+
+### Go Patch ###
+/vendor/
+/Godeps/
+
+### Intellij+all ###
+# Covers JetBrains IDEs: IntelliJ, RubyMine, PhpStorm, AppCode, PyCharm, CLion, Android Studio, WebStorm and Rider
+# Reference: https://intellij-support.jetbrains.com/hc/en-us/articles/206544839
+
+# User-specific stuff
+.idea/**/workspace.xml
+.idea/**/tasks.xml
+.idea/**/usage.statistics.xml
+.idea/**/dictionaries
+.idea/**/shelf
+
+# AWS User-specific
+.idea/**/aws.xml
+
+# Generated files
+.idea/**/contentModel.xml
+
+# Sensitive or high-churn files
+.idea/**/dataSources/
+.idea/**/dataSources.ids
+.idea/**/dataSources.local.xml
+.idea/**/sqlDataSources.xml
+.idea/**/dynamic.xml
+.idea/**/uiDesigner.xml
+.idea/**/dbnavigator.xml
+
+# Gradle
+.idea/**/gradle.xml
+.idea/**/libraries
+
+# Gradle and Maven with auto-import
+# When using Gradle or Maven with auto-import, you should exclude module files,
+# since they will be recreated, and may cause churn.  Uncomment if using
+# auto-import.
+# .idea/artifacts
+# .idea/compiler.xml
+# .idea/jarRepositories.xml
+# .idea/modules.xml
+# .idea/*.iml
+# .idea/modules
+# *.iml
+# *.ipr
+
+# CMake
+cmake-build-*/
+
+# Mongo Explorer plugin
+.idea/**/mongoSettings.xml
+
+# File-based project format
+*.iws
+
+# IntelliJ
+out/
+
+# mpeltonen/sbt-idea plugin
+.idea_modules/
+
+# JIRA plugin
+atlassian-ide-plugin.xml
+
+# Cursive Clojure plugin
+.idea/replstate.xml
+
+# SonarLint plugin
+.idea/sonarlint/
+
+# Crashlytics plugin (for Android Studio and IntelliJ)
+com_crashlytics_export_strings.xml
+crashlytics.properties
+crashlytics-build.properties
+fabric.properties
+
+# Editor-based Rest Client
+.idea/httpRequests
+
+# Android studio 3.1+ serialized cache file
+.idea/caches/build_file_checksums.ser
+
+### Intellij+all Patch ###
+# Ignores the whole .idea folder and all .iml files
+# See https://github.com/joeblau/gitignore.io/issues/186 and https://github.com/joeblau/gitignore.io/issues/360
+
+.idea/*
+
+# Reason: https://github.com/joeblau/gitignore.io/issues/186#issuecomment-249601023
+
+*.iml
+modules.xml
+.idea/misc.xml
+*.ipr
+
+# Sonarlint plugin
+.idea/sonarlint
+
+### macOS ###
+# General
+.DS_Store
+.AppleDouble
+.LSOverride
+
+# Icon must end with two \r
+Icon
+
+
+# Thumbnails
+._*
+
+# Files that might appear in the root of a volume
+.DocumentRevisions-V100
+.fseventsd
+.Spotlight-V100
+.TemporaryItems
+.Trashes
+.VolumeIcon.icns
+.com.apple.timemachine.donotpresent
+
+# Directories potentially created on remote AFP share
+.AppleDB
+.AppleDesktop
+Network Trash Folder
+Temporary Items
+.apdisk
+
+### Terraform ###
+# Local .terraform directories
+**/.terraform/*
+
+# .tfstate files
+*.tfstate
+*.tfstate.*
+
+# Crash log files
+crash.log
+crash.*.log
+
+# Exclude all .tfvars files, which are likely to contain sensitive data, such as
+# password, private keys, and other secrets. These should not be part of version
+# control as they are data points which are potentially sensitive and subject
+# to change depending on the environment.
+*.tfvars
+
+# Ignore override files as they are usually used to override resources locally and so
+# are not checked in
+override.tf
+override.tf.json
+*_override.tf
+*_override.tf.json
+
+# Include override files you do wish to add to version control using negated pattern
+# !example_override.tf
+
+# Include tfplan files to ignore the plan output of command: terraform plan -out=tfplan
+# example: *tfplan*
+
+# Ignore CLI configuration files
+.terraformrc
+terraform.rc
+
+### VisualStudioCode ###
+.vscode/*
+!.vscode/settings.json
+!.vscode/tasks.json
+!.vscode/launch.json
+!.vscode/extensions.json
+!.vscode/*.code-snippets
+
+# Local History for Visual Studio Code
+.history/
+
+# Built Visual Studio Code Extensions
+*.vsix
+
+### VisualStudioCode Patch ###
+# Ignore all local history of files
+.history
+.ionide
+
+# Support for Project snippet scope
+
+# End of https://www.toptal.com/developers/gitignore/api/go,terraform,intellij+all,visualstudiocode,macos

README.md

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-## My Project
+# Using AWS Cloud Map as gRPC name resolver
 
-TODO: Fill this README out!
+This repository show how AWS Cloud Map can be used as a name resolver in gRPC clients. Using the AWS Cloud Map HTTP API instead of DNS based resolution allows to create custom client-side loadbalancing policies leveraging the metadata associated with registered instances of AWS Cloud Map services. 
 
-Be sure to:
+Potential benefits of this approach are:
+* Cutting out one or more loadbalancers which would be fronting Fargate services. This reduces cost, removes a network hop and may reduce efforts to maintain the loadbalancer. 
+* Options for advanced loadbalancing scenarios. This sample shows, as an example, how AWS Cloud Map metadata can be used to prefer calling service instances which reside in the same az as the client.  
 
-* Change the title in this README
-* Edit your repository description on GitHub
+## Running the sample 
 
-## Security
+Build the client and server:
 
-See [CONTRIBUTING](CONTRIBUTING.md#security-issue-notifications) for more information.
+```bash
+#---
+cd client
+# generate gRPC code 
+mkdir pb
+go generate 
+# build executable
+GOOS=linux GOARCH=amd64 go build -o client .
 
-## License
+#---
+cd server
+# generate gRPC code 
+mkdir pb
+go generate 
+# build executable
+GOOS=linux GOARCH=amd64 go build -o server .
+```
 
-This library is licensed under the MIT-0 License. See the LICENSE file.
+Provision the CDK app. Make sure docker is running as the Docker images are built as CDK assets during CDK app execution.
 
+Account and Region will be picked up during CDK app execution.
+
+**Important**: Region **must** be eu-central-1 currently, as this region is used in the coding.
+
+```bash
+cd cdk
+cdk deploy
+```
+
+## Create sample data
+
+After the CDK app is deployed, test drive with a couple of calls. It is best to use tools like `hey` or `ab` to provide a large enough number of calls to see the loadbalancing preference show up.
+
+Obtain the Public IP of the single task of the client service from the ECS console
+
+```bash
+# with curl
+curl http://<pubip>:8080/describe
+
+# with hey, runs a total of 200 requests by default over 10s
+hey -c 2 -q 10 -m GET http://<pubip>:8080/describe
+# this will take a couple of seconds to run without giving an output 
+```
+
+## Observe custom loadbalancing policy 
+
+We route approx 50% of requests to the same availability zone (see balancer.go:53).
+
+Use CloudWatch Insights for the log group and run the following query on log group `grpcdemo`:
+
+```
+fields @timestamp, @message
+| limit 1000
+| filter @message like 'server response from az'
+| parse 'server response from az: *' as az
+| stats count(az) as az_calls by az
+```
+
+**Be sure to allow a couple of minutes for all logsto arrive, otherwise the count will not be correct.**
+
+You should see approx. 50% of calls going to the AZ in which the single task of service `client` is located in.

cdk/.gitignore

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+*.js
+!jest.config.js
+*.d.ts
+node_modules
+
+# CDK asset staging directory
+.cdk.staging
+cdk.out
+
+cdk.context.json

cdk/.npmignore

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+*.ts
+!*.d.ts
+
+# CDK asset staging directory
+.cdk.staging
+cdk.out

cdk/README.md

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+# Welcome to your CDK TypeScript project!
+
+This is a blank project for TypeScript development with CDK.
+
+The `cdk.json` file tells the CDK Toolkit how to execute your app.
+
+## Useful commands
+
+ * `npm run build`   compile typescript to js
+ * `npm run watch`   watch for changes and compile
+ * `npm run test`    perform the jest unit tests
+ * `cdk deploy`      deploy this stack to your default AWS account/region
+ * `cdk diff`        compare deployed stack with current state
+ * `cdk synth`       emits the synthesized CloudFormation template

cdk/bin/cdk.ts

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+#!/usr/bin/env node
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: MIT-0
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this
+ * software and associated documentation files (the "Software"), to deal in the Software
+ * without restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+ * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+ * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+import 'source-map-support/register';
+import * as cdk from 'aws-cdk-lib';
+import { DemoStack } from '../lib/demo-stack';
+
+const app = new cdk.App();
+new DemoStack(app, 'DemoStack', {
+  /* If you don't specify 'env', this stack will be environment-agnostic.
+   * Account/Region-dependent features and context lookups will not work,
+   * but a single synthesized template can be deployed anywhere. */
+
+  /* Uncomment the next line to specialize this stack for the AWS Account
+   * and Region that are implied by the current CLI configuration. */
+  env: { account: process.env.CDK_DEFAULT_ACCOUNT, region: process.env.CDK_DEFAULT_REGION },
+
+  /* Uncomment the next line if you know exactly what Account and Region you
+   * want to deploy the stack to. */
+  // env: { account: '123456789012', region: 'us-east-1' },
+
+  /* For more information, see https://docs.aws.amazon.com/cdk/latest/guide/environments.html */
+});