Dapr Store

Dapr Store is a sample/reference application showcasing the use of Dapr to build microservices based applications. It is a simple online store with all the core components that make up such system, e.g. a frontend for users, authentication, product catalog, and order processing etc.

Dapr is an “event-driven, portable runtime for building microservices on cloud and edge”. The intention of this project was to show off many of the capabilities and features of Dapr, but in the context of a real working application. This has influenced the architecture and design decisions, balancing between realism and a simple “demo-ware” showcase.

The backend microservices are written in Go (however it’s worth nothing that Dapr is language independent), and the frontend is a single-page application (SPA) written in Vue.js. All APIs are REST & HTTP based

This repo is a monorepo, containing the source for several discreet but closely linked codebases, one for each component of the project, as described below.
The “Go Standard Project Layout” has been used.

Architecture

The following diagram shows all the components of the application and main interactions. It also highlights which Dapr API/feature (aka Dapr building block) is used and where. architecture diagram

Dapr Interfaces & Building Blocks

The application uses the following Dapr Building Blocks and APIs

Project Status

Deployed instance: https://daprstore.kube.benco.io/

Application Elements & Services

The main elements and microservices that make up the Dapr Store system are described here

Each service uses the Go REST API Starter Kit & Library as a starting basis, lots of the boilerplate and repeated code is located there.

Service Code

Each Go microservice (in cmd/) follows a very similar layout (the exception being frontend-host which has no business logic)

Primary runtime code:

For testing:

💰 Orders service

This service provides order processing to the Dapr Store.
It is written in Go, source is in cmd/orders and it exposes the following API routes:

/get/{id}                GET a single order by orderID
/getForUser/{userId}   GET all orders for a given user

See cmd/orders/spec for details of the Order entity.

The service provides some fake order processing activity so that orders are moved through a number of statuses, simulating some back-office systems or inventory management. Orders are initially set to OrderReceived status, then after 30 seconds moved to OrderProcessing, then after 2 minutes moved to OrderComplete

Orders - Dapr Interaction

👦 Users service

This provides a simple user profile service to the Dapr Store. Only registered users can use the store to place orders etc.
It is written in Go, source is in cmd/users and it exposes the following API routes:

/register               POST a new user to register them
/get/{userId}           GET the user profile for given user
/private/get/{userId}   GET the user profile for given user. Private endpoints are NOT exposed through the gateway
/isregistered/{userId}  GET the registration status for a given user

See cmd/users/spec for details of the User entity.

The service is notable as it consists of a mix of both secured API routes, and two that are anonymous/open /isregistered and /private/get

Users - Dapr Interaction

📑 Products service

This is the product catalog service for Dapr Store.
It is written in Go, source is in cmd/products and it exposes the following API routes:

/get/{id}        GET a single product with given id
/catalog         GET all products in the catalog, returns an array of products
/offers          GET all products that are on offer, returns an array of products
/search/{query}  GET search the product database, returns an array of products

See cmd/products/spec for details of the Product entity.

The products data is held in a SQLite database, this decision was taken due to the lack of support for queries and filtering with the Dapr state API. The source data to populate the DB is in etc/products.csv and the database can be created with the scripts/create-products-db.sh. The database file (sqlite.db) is currently stored inside the products container, effectively making catalogue baked in at build time. This could be changed/improved at a later date

Products - Dapr Interaction

None directly, but is called via service invocation from other services, the API gateway & the cart service.

🛒 Cart service

This provides a cart service to the Dapr Store. The currently implementation is a MVP.
It is written in Go, source is in cmd/cart and it exposes the following API routes:

/setProduct/{userId}/{productId}/{count}    PUT a number of products in the cart of given user
/get/{userId}                               GET cart for user
/submit                                       POST submit a cart, and turn it into an 'Order'
/clear/{userId}                             PUT clear a user's cart

The service is responsible for maintaining shopping carts for each user and persisting them. Submitting a cart will validate the contents and turn it into a order, which is sent to the Orders service for processing

Cart - Dapr Interaction

💻 Frontend

This is the frontend accessed by users of store and visitors to the site. It is a single-page application (SPA) as such it runs entirely client side in the browser. It was created using the Vue CLI and written in Vue.js

It follows the standard SPA pattern of being served via static hosting (the ‘frontend host’ described below) and all data is fetched via a REST API endpoint. Note. Vue Router is used to provide client side routing, as such it needs to be served from a host that is configured to support it.

The default API endpoint is / and it makes calls to the Dapr invoke API, namely /v1.0/invoke/{service} this is routed via the API gateway to the various services.

📡 Frontend host

A very standard static content server using gorilla/mux. See https://github.com/gorilla/mux#static-files. It simply serves up the static bundled files output from the build process of the frontend, it expects to find these files in ./dist directory but this is configurable

In addition it exposes a simple /config endpoint, this is to allow dynamic configuration of the frontend. It passes two env vars AUTH_CLIENT_ID and API_ENDPOINT from the frontend host to the frontend Vue SPA as a JSON response, which are fetched & read as the app is loaded in the browser.

🌍 API gateway

This component is critical but consists of no code. It’s a NGINX reverse proxy configured to do two things:

Note. This is not to be confused with Azure API Management, Azure App Gateway or AWS API Gateway 😀

This is done with path based routing, it aggregates the various APIs and frontend SPA into a single endpoint or host, making configuration much easier (and the reason the API endpoint for the SPA can simply be /)

NGINX is run with the Dapr sidecar alongside it, so that it can proxy requests to the /v1.0/invoke Dapr API, via this the downstream services are invoked, through Dapr.

Routing logic (in order of priority):

  1. Routes that match /v1.0/invoke/.*/method/private/.* are blocked with 403
  2. Routes that match /v1.0/invoke/ are proxied to the Dapr sidecar
  3. Routes that match / are proxied to the frontend host

Within Kubernetes

Inspired by this blog post it is deployed in Kubernetes as a “Daprized NGINX ingress controller”. See deploy/ingress for details on how this is done.

Locally

To provide a like for like experience with Kubernetes, and the single aggregated endpoint - the same model is used locally. NGINX is run as a Docker container exposed to the host network, and NGINX configuration applied allow to route traffic. This is then run via the dapr CLI (i.e dapr run) so that the daprd sidecar process is available to it.

See scripts/local-gateway for details on how this is done, the scripts/local-gateway/run.sh script starts the gateway which will run on port 9000

Running in Kubernetes - Quick guide

📃 SUB-SECTION: Deployment guide for Kubernetes

Running Locally - Quick guide

This is a (very) basic guide to running Dapr Store locally. Only instructions for WSL 2/Linux/MacOS are provided. It’s advised to only do this if you wish to develop or debug the project.

Prereqs

Setup

Install and initialize Dapr

wget -q https://raw.githubusercontent.com/dapr/cli/master/install/install.sh -O - | /bin/bash
dapr init

Clone repo

git clone https://github.com/benc-uk/dapr-store/

Run all services

Run everything. Run from the project root (e.g. dapr-store directory), this will run all the services, the API gateway and the Vue frontend

make run

Access the store from http://localhost:9000/

💣 Gotcha! The Vue frontend will start and display a message “App running at” saying it is running on port 8000, do not access the frontend directly on this port, it will not function!, always go via the gateway running on port 9000

Working Locally

A makefile is provided to assist working with the project and building/running it, the list of targets is:

help                 💬 This help message :)
lint                 🔎 Lint & format, check to be run in CI, sets exit code on error
lint-fix             📝 Lint & format, fixes errors and modifies code
test                 🎯 Unit tests for services and snapshot tests for SPA frontend 
test-reports         📜 Unit tests with coverage and test reports (deprecated)
bundle               💻 Build and bundle the frontend Vue SPA
clean                🧹 Clean the project, remove modules, binaries and outputs
run                  🚀 Start & run everything locally as processes
docker-run           🐋 Run locally using containers and Docker compose
docker-build         🔨 Build all containers using Docker compose
docker-push          📤 Push all containers using Docker compose
docker-stop          🚫 Stop and remove local containers
stop                 ⛔ Stop & kill everything started locally from `make run`

CI / CD

A set of CI and CD release GitHub Actions workflows are included in .github/workflows/, automated builds are run in GitHub hosted runners

GitHub Actions

Security, Identity & Authentication

The default mode of operation for the Dapr Store is in “demo mode” where there is no identity provided configured, and no security on the APIs. This makes it simple to run and allows us to focus on the Dapr aspects of the project. In this mode a demo/dummy user account can be used to sign-in and place orders in the store.

Optionally Dapr store can be configured utilise the Microsoft identity platform (aka Azure Active Directory v2) as an identity provider, to enable real user sign-in, and securing of the APIs.

📃 SUB-SECTION: Full details on security, identity & authentication

Configuration

Environmental Variables

The services support the following environmental variables. All settings are optional with default values.

The following vars are used only by the Cart and Orders services:

The following vars are only used by the Orders service:

Frontend host config:

Default ports

Dapr Components

📃 SUB-SECTION: Details of the Dapr components used by the application and how to configure them.

Roadmap & known issues

See project plan on GitHub

Concepts and Terms

Clarity of terminology is sometimes important, here’s a small glossary