A Microservices demo based on Istio Service Mesh tool.
This goal of this demo is to demostrate Istio cappabilities observed and managed by Kiali tool.
This demo creates two groups of services to simulate a travel portal scenario.
In a first namespace called travel-portal there will be deployed a set of services that will represent the portals where users access to search and book travels.
One of the characteristics of travel-portal is that there will be different portals depending of which city users are interested on. In this example, there will be three portals for Rome, Paris and London.
Also, every portal will have two versions, one version to handle regular web traffic and a second version that will manage vip users with special offers and discounts.
For our demo, we don't care about the details of the application but the relationships between services as it is shown in the picture:
Portal applications from travel-portal namespace will invoke a travels service from a travel-agency namespace to get travel quotes for their searches.
A second namespace called travel-agency will host a set of services created to provide quotes for travels.
A main travels service will be the business entry point for the travel agency. It receives a city and a user as parameters and it calculates all elements that compose a travel budget: airfares, lodging, car reservation and travel insurances.
There are several services that calculate a separate price and the travels service is responsible to aggregate them in a single response.
Additionally, some users like vip users can have access to special discounts, managed as well by an external service.
The interaction between services can be shown in the following picture:
The travel_agency.go is a tiny program that helps to build the services deployed in the travel-agency namespace.
The travel_agency.yaml descriptor deploys all the services backed by travel_agency.go program as it shows in the following example:
...
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: travels-v1
spec:
replicas: 1
template:
metadata:
annotations:
readiness.status.sidecar.istio.io/applicationPorts: ""
labels:
app: travels
version: v1
spec:
containers:
- name: travels
image: lucasponce/travel_agency:dev
imagePullPolicy: IfNotPresent
ports:
- containerPort: 8000
securityContext:
privileged: false
env:
- name: FLIGHTS_SERVICE
value: "http://flights:8000"
- name: HOTELS_SERVICE
value: "http://hotels:8000"
- name: CARS_SERVICE
value: "http://cars:8000"
- name: INSURANCES_SERVICE
value: "http://insurances:8000"
- name: CURRENT_SERVICE
value: "travels"
- name: CURRENT_VERSION
value: "v1"
---
apiVersion: v1
kind: Service
metadata:
name: travels
labels:
app: travels
spec:
ports:
- name: http
port: 8000
selector:
app: travels
...One of the interesting features, is travel_agency.go allows to introduce conditional delays to emulate different slower services under different versions, like the example defined in travel_agency_v2.yaml descriptor:
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: flights-v2
spec:
replicas: 1
template:
metadata:
annotations:
readiness.status.sidecar.istio.io/applicationPorts: ""
labels:
app: flights
version: v2
spec:
containers:
- name: flights
image: lucasponce/travel_agency:dev
imagePullPolicy: IfNotPresent
ports:
- containerPort: 8000
securityContext:
privileged: false
env:
- name: CURRENT_SERVICE
value: "flights"
- name: CURRENT_VERSION
value: "v2"
- name: DISCOUNTS_SERVICE
value: "http://discounts:8000"
- name: CHAOS_MONKEY
value: "true"
- name: CHAOS_MONKEY_SLEEP
value: "50"Review travel_agency.go code to learn all available options to introduce Chaos in the scenario.