service.py

from flask import Flask
from flask import request
import socket
import os
import sys
import requests

app = Flask(__name__)

TRACE_HEADERS_TO_PROPAGATE = [
	'X-Ot-Span-Context',
	'X-Request-Id',

	# Zipkin headers
	'X-B3-TraceId',
	'X-B3-SpanId',
	'X-B3-ParentSpanId',
	'X-B3-Sampled',
	'X-B3-Flags',

	# Jaeger header (for native client)
	"uber-trace-id"
]

@app.route('/service/<service_number>')
def hello(service_number):
	return ('Hello from behind Envoy (service {})! hostname: {} resolved'
			'hostname: {}\n'.format(os.environ['SERVICE_NUMBER'],
									socket.gethostname(),
									socket.gethostbyname(socket.gethostname())))

# this is first, second
@app.route('/trace/<service_number>')
def trace(service_number):
	headers = {}
	ret_body = ''
	# call service 2 from service 1
	if int(os.environ['SERVICE_NUMBER']) == 1 :
		for header in TRACE_HEADERS_TO_PROPAGATE:
			if header in request.headers:
				headers[header] = request.headers[header]
		ret = requests.get("http://second:9080/trace/2", headers=headers)
		ret_body = ret.content
	return ('Hello from behind Envoy (service {})! hostname: {} resolved'
			'hostname: {}\n'
			'ret: {}\n'.format(os.environ['SERVICE_NUMBER'],
									socket.gethostname(),
									socket.gethostbyname(socket.gethostname()),
									ret_body))

if __name__ == "__main__":
	app.run(host='0.0.0.0', port=9080, debug=True)

servicepy.yaml

apiVersion: v1
kind: Service
metadata:
  name: first
  labels:
    app: first
spec:
  ports:
  - port: 9080
    name: http
  selector:
    app: first

---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: first-v1
spec:
  replicas: 1
  template:
    metadata:
      labels:
        app: first
        version: v1
    spec:
      containers:
      - name: first
        image: docker.io/chanwit/service
        ports:
        - containerPort: 9080
        env:
        - name: SERVICE_NUMBER
          value: "1"

---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: first-v2
spec:
  replicas: 1
  template:
    metadata:
      labels:
        app: first
        version: v2
    spec:
      containers:
      - name: first
        image: docker.io/chanwit/service
        ports:
        - containerPort: 9080
        env:
        - name: SERVICE_NUMBER
          value: "1"

---
apiVersion: v1
kind: Service
metadata:
  name: second
  labels:
    app: second
spec:
  ports:
  - port: 9080
    name: http
  selector:
    app: second

---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: second-v1
spec:
  replicas: 1
  template:
    metadata:
      labels:
        app: second
        version: v1
    spec:
      containers:
      - name: second
        image: docker.io/chanwit/service
        ports:
        - containerPort: 9080
        env:
        - name: SERVICE_NUMBER
          value: "21"

---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: second-v2
spec:
  replicas: 1
  template:
    metadata:
      labels:
        app: second
        version: v2
    spec:
      containers:
      - name: second
        image: docker.io/chanwit/service
        ports:
        - containerPort: 9080
        env:
        - name: SERVICE_NUMBER
          value: "22"

---
apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
  name: first-gateway
spec:
  selector:
    istio: ingressgateway # use Istio default gateway implementation
  servers:
  - port:
      number: 80
      name: http
      protocol: HTTP
    hosts:
    - "*"

---
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: first
spec:
  hosts:
  - "*"
  gateways:
  - first-gateway
  http:
  - match:
    - uri:
        prefix: /service
    - uri:
        prefix: /trace
    route:
    - destination:
        host: first
        port:
          number: 9080
        subset: v2

---
apiVersion: networking.istio.io/v1alpha3
kind: DestinationRule
metadata:
  name: first-default
spec:
  host: first
  subsets:
  - name: v1
    labels:
      version: v1
  - name: v2
    labels:
      version: v2

---
apiVersion: networking.istio.io/v1alpha3
kind: DestinationRule
metadata:
  name: second-default
spec:
  host: second
  subsets:
  - name: v1
    labels:
      version: v1

---
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: second
spec:
  hosts:
  - second
  gateways:
  - mesh
  http:
  - route:
    - destination:
        host: second
        port:
          number: 9080
        subset: v1