goTemp

goTemp is a full stack Golang microservices sample application built using go-micro. The application is built as a series of services that provide:

• Authentication using JWT
• Creation and maintenance of :
  • Users
  • Customers
  • Products
  • Promotions
• Auditing of all changes to the application data

In it current incarnation (this is wip), this mono-repo uses the following stack as backend:

• Golang as its main implementation technology
• go-Micro as the micro service framework
• gRPC for inter-service real time communication
• NATS for Pub/Sub event driven communication
• multicast DNS for service registration and discovery
• PostgreSql for transactional data storage
• TimescaleDB time series DB used for historical audit data storage
• ArangoDBis a multi-model database used for master data storage
• Redis is used to cache data and reduce number of data requests to other services
• Docker for creating application images
• Docker-compose to run the application
• Minikube to run the application in Kubernetes

In terms of the web front end, the stack is as follows:

• Javascript as its main implementation technology
• Svelte is used as the compilation engine (via rollup)
• Sapper is the javascript framework
• Sveltestrap provides the css framework and is based on bootstrap
• Font Awesome to display icons in the application

Below is a diagram that displays the overall setup of the application:

In a nutshell. the application functionality is as follows in the backend:

• The frontend connects to the different services through the API gateway
• For each service the frontend provides:
  • Search page
  • Detail page
• Additionally, the frontend provides:
  • Landing page
  • Login page
  • Register page
• Each service performs the basic CRUD operations to their underlying databases
• All services authenticate via the user service
• All completed CUD operations are forwarded to the NATS broker which in turn forwards the message to the auditing service. This service saves the data into TimescaleDB.
• Each service has a client which can be used to test all basic CRUD functionality

Starting the application

Before running the application the first time:

• Clone the repository
• cd into gotemp/web/sapper
• Run the following command to generate the javascript dependencies.

    npm install

To start the application:

• Ensure that Docker is installed and running. Then, run the following command from a terminal in the goTemp root folder:

   make start

Depending on whether you have run the application before, docker may have to download all the dependent images (PostgreSql, TimescaleDB, Nodejs, etc). This may take a while depending on your internet connection speed. Once everything has been downloaded and started, you should see a message in the terminal indicating that the application is listening at localhost:3000. At that point, yo can open your browser and navigate to:

    http://localhost:3000

Running the application on Kubernetes (Minikube)

Prerequisites

Minikube

Ensure that Minikube is installed and running.

Ingress

The application front end connects with the API gateway using via a K8s ingress resource. As such, the ingress addon must be enabled in Minikube. To enabled it, run:

    minikube addons enable ingress

Check the ingress is working using the command below. The command's results should include an entry for the ingress.

    kubectl get pods -n kube-system

Building and pushing images (optional)

Out of the box, the Kubernetes manifest will pull existing Bolbeck goTemp images from Docker Hub. You are welcome to change the Kubernetes manifests in the ./cicd/K8s folder to pull your own images. To build your own images of each service and push them to docker hub run the command below for each of the services:

    make hubpush SERVICE=<serivceName> FOLDER=<folderName>

where serviceName is the name of the service for which the image should be built folderName is the folder that contains the docker file used to build the service image

Example:

     make hubpush SERVICE=usersrv FOLDER=./user

Note that for the web front end and for Timescale DB the command to be used is slightly different:

     make hubpushcontext SERVICE=<serivceName> FOLDER=<folderName

Running

Once the ingress has been enabled, deploy the application to Minikube:

    make startkub

Once the application is deployed, check the address and host assigned to the ingress:

    kubectl get ingress

Note that it takes a couple of minutes for K8s to assign the IP to the ingress. As such wait for that happens before moving ahead.

If this is the first time running the app in Minikube: Grab the address & the host from the result of the command above, and add it to your /etc/hosts file.

Finally, access app:

    minikube service web

Repo organization

The project is organized in a way that each folder represents either a service, a database or a shared library package. Currently, we have the following:

• arangodb: Volumes mounted to the ArangoDB container as well as data initialization scripts
• audit: Audit service to collect and store historical audit information
• cicd : Holds files related to CI/CD and orchestration
• customer: Customer master data service
• diagramforDocs: Diagrams used in the readme documents
• globalErrors: Generic errors shared package
• globalProtos: Generic protobuf message definitions shared across packages
• globalUtils: Generic utilities shared package
• nats: NATS dockerfile and configuration
• postgres: Volumes mounted to the PostgreSQL DB container as well as data initialization scripts
• product: Product master data service
• promotion: Promotion service to track product discounts (this was the first service built)
• redis: Volumes mounted on the redis container as well as config files (if any)
• timescaleDB: Volumes mounted to the Timescale DB container as well as data initialization scripts
• user: User and authentication service
• web: application web frontend

Additionally, we have the following files in the root directory as well:

• .dockerignore: Files to be ignored when building service images
• .gitignore: Files to be ignored by git
• docker-compose: File controls the building of the different services and their dependencies
• docker-compose-test: Override compose file that can be used to test different services with their dependencies
• go.mod and go.sum: Go modules control
• main.go: Not used for services yet
• Makefile: shortcuts to common actions
• Readme.md: Well... this file...

Services

We use go-micro as the main GO microservices framework. Using go-micro simplifies many of the tasks associated with building micro services including (but not limited to):

• Service discovery
• gRPC for inter service communication
• Pluggable interfaces to popular software applications like NATS and Redis
• Built in async messaging (in our case used to set up pub/sub messages to NATS )
• Built-in data storage interface (in our case used to interact with Redis)
• API gateway:
  • Request routing
  • Load balancing
  • Automatic conversion of frontend JSON payloads to backend gRPC messages

Organization

Each one of the services has a similar structure:

• client: Contains a client service that calls the server service to perform multiple operations
• proto: Proto buffer messages and services definitions. Empty if service does not handle real time inter-service communication.
• server: Service that performs a number of actions like interacting with the DB
• Dockerfile: Build the image for the server service
• DockerfileCLI: Build the image of the client service
• docker-compose.env: Environment variable required to run the service when running the service with docker-compose
• docker-compose-cli.env: Environment variable required to run the client when running the client with docker-compose

Building

The different service's images can be built from the root of the repo using the docker build command. For example the user service can be built using:

docker build -t usersrv -f user/Dockerfile .

Note that there is no need to run this if you are using docker-compose as that will build the image automatically

Running individual services

The services are designed to run in containers, and the easiest way to run them is to bring them up using docker-compose: As an example we will run the user service with the commands below in a terminal:

docker-compose up usersrv

This will bring up the user service, the postgreSQL DB and NATS Then to run some data through the service, we can start the user client in a new terminal:

docker-compose up usercli

This will bring up run the client service which will attempt to create,update and delete a user. The results will be printed in the console. The server user service will update the DB as necessary and send the updated information to the broker (NATS) so that the audit service may eventually store it in the time series DB. The audit service can be started using:

docker-compose up auditsrv

Databases Initialization

The project initializes each of the DBs and seeds them with tables and data. Data changes made at run time are automatically persisted using mounted volumes when running via docker-compose. See the folders for each DB for details as well as the docker-compose file.

Web front end

Our web front end is built with Svelte and Sapper which have some interesting benefits:

• Server-side initial rendering of our pages
• File based routing
• Smaller code base than other Javascript frameworks. Does more with less.
• Svelte translates the code to vanilla javascript. Thus, smaller application footprint than most frameworks
• Emphasis on component re-usability

Organization

The web application lives in the ./web folder. Since Sapper and Svelte generate multiple files and folders, we will just discuss the relevant folders below:

• sapper: The main folder containing the web app
  • src: This is where the bulk of the application resides
    • components: Contains re-usable Svelte components
    • globalUtils: Shared javascript utilities
    • routes: application routes to the different pages
    • client.js: This is a required file. It is used to start Sapper.
    • server.js: Used to configure the app with items like middleware and compression
    • template.html: Main page that contains our application. We added Bootstrap and Font Awesome CDN references in this page.
  • static: Holds static items
• Dockerfile: Used to build the docker image for the web app

Routes

All of our main routes are pretty standard in terms of organization. We will use the customer route (./web/sapper/src/routes/customer) as an example:

• index.svelte: Main customers search page that serves at localhost:3000/customer
• _searchGridSlot: Component holds the template for the search grid to be display in hte search page (index.svelte)
• new.svelte: Page to be displayed when user want to create a new customer. Displayed at localhost:3000/customer/new .
• [slug].svelte: Page to view and modify existing customers. Displayed at localhost:3000/customer/[customerid]
• _detail.svelte: Holds the gui and bulk of the logic for adding or editing customers. It is called by new.svelte and [slug].svelte .

There are three routes that do not share the structure above as they have very little functionality and thus are server by a single index.svelte component: root, register and login.

Kubernetes

The application configuration in K8s can be seen in the diagram below. Note that the diagram shows just one of the different microservices and its associated database. The configuration for all other microservices, beyond the shared ingress and API Gateway, is similar to the one depicted in the diagram.

Organization

The K8s files live in the ./cicd/K8s folder and it is organized as follows:

• Clients : These are the test clients for each of the services.
• Ingress: Manifest to create the ingress resource that allows the front end and the back end to communicate
• Services : Contains all the services and related entities manifest (deployment, service, etc...). It also contains the manifests for the related databases.
• web: Manifest for the web front end and the API gateway

Note that within each of the folders, most related manifests are organized using a prefix. For example, all the front end related services start with the 'web' prefix.

Additional information:

Additional information can be found in the individual folders either in a readme.md or a doc.go file. Additionally, the Makefile contains many command samples that can be used for development.