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Description: - Connect two microservices belonging to stateless applications

In this scenario, Unlike HTTP, instead of the service URL, ports are exposed.

The services hosted behind Istio service mesh has the sidecar proxy installed with each pod of the service. The communication between these is possible only when the TLS option is set to the "ISTIO_MUTUAL"

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SERVER - httpbin (If TLS Mode is "SIIMPLESIMPLE", it will accept both traffic for tls and plain text. TLS Mode must be ISTIO_MUTUAL for talking to other istio clients and MUTUAL (with ca) when talking to other external services)

CLIENTS - sleep (TLS Mode can be "SIMPLE" (for services with no sidecars) or ISTIO_MUTUAL(services with sidecars))

Diagram

Drawio

border	true

diagramName	us-to-us intent
simpleViewer	false
width
links	auto
tbstyle	top
lbox	true
diagramWidth	1136
revision	12

NOTE - For this scenario, the default mesh wide policy must be set to "PERMISSIVE" on both the clusters. It will not work if the default Mesh Policy is "STRICT"

Important Info - cert-chain.pem is Envoy’s cert that needs to be presented to the other side. key.pem is Envoy’s private key paired with Envoy’s cert in cert-chain.pem. root-cert.pem is the root cert to verify the peer’s cert. In this example, we only have one Citadel in a cluster, so all Envoys have the same root-cert.pem.

Add Inbound service

The intent for this scenario

...

Code Block

language	js
theme	Midnight
title	POST
linenumbers	true

URL: /v2/projects/{project-name}/composite-apps/{composite-app-name}/{version}/traffic-intent-set/us-to-us-intents/

POST BODY:
{
	"metadata": {
	"name": "<name>" // unique name for each intent
    "description": "connectivity intent for stateless micro-service to stateless micro-service communication"
	"userdata1": <>,
	"userdata2": <>
	}

	"spec": { // update the memory allocation for each field as per OpenAPI standards
	"application": "<app1>",
	"servicename": "httpbintcp-echo" //actual name of the client service
	"protocol": "HTTPTCP",
	"headless": "false", // default is false. Option "True" will make sure all the instances of the headless service will have access to the client service
	"mutualTLS": "DISABLESIMPLE", // Support 2 modes. SIMPLE and ISTIO_MUTUAL, For external Client, it is SIMPLE and MUTUAL (caCertificate required)
	"port" : "8031400", // port on which service is exposed as through servicemesh, not the port it is actually running on
	"serviceMesh": "istio", // get it from cluster record
	"istio-proxy": "yes", // The features (mTLS, LB, Circuit breaking) are no avaialble to services without istio-proxy. Only inbound routing is possible.

	// Traffic configuration - Loadbalancing is applicable per service. The traffic to this service is distrbuted amongst the pods under it.
	"loadbalancingType": "ConsistenHash", // "Simple" and "consistentHash" are the two modes
	"loadBalancerMode": "httpCookie" // Modes for consistentHash - "httpHeaderName", "httpCookie", "useSourceIP", "minimumRingSize", Modes for simple - "LEAST_CONN", "ROUND_ROBIN", "RANDOM", "PASSTHROUGH" // choices of the mode must be explicit
	"httpCookie": "user1" // Name of the cookie to maitain stick sessions

	// Circuit Breaking
	"maxConnections": 10 //connection pool for tcp and http traffic
	"concurrenthttp2Requests": 1000 // concurentCircuit http2 requests which can be allowed
Breaking
	"httpRequestPerConnectionmaxConnections": 10010 //numberconnection ofpool httpfor requests per connection. Valid only fortcp and http traffic
	"consecutiveErrors": 8 // Default is 5.  Number of consecutive error before the host is removed from load balancing pool
	"baseEjectionTime" : 15 // Default is 5, time for which the host will be removed from load balancing pool when it returns error for no of times more than "consecutiveErrors" limit
	"intervalSweep": 5m, //time limit before the removed hosts are added back to the load balancing pool.
	"connectTimeout": 10s

	// credentials for mTLS. Not required in this scenario since the services are in one logical cloud with common rootCA. ISTIO_MUTUAL is enabled by default.
	"Servicecertificate" : "" // Present actual certificate here.
	"ServicePrivateKey" : "" // Present actual private key here.

	// Access Control
	namespaces: [] // Workloads from this namespaces can access the inbound service
	
	}
}

RETURN STATUS: 201
RETURN BODY: 
{ 
  "name": "servicehttpbin"
  "Message": "inbound service created"
}

Add Clients

POST - traffic intent to add clients for accessing a specific inbound service

Code Block

language	js
theme	Midnight
title	POST
linenumbers	true

URL: /v2/projects/{project-name}/composite-apps/{composite-app-name}/{version}/traffic-group-intent/uservice-to-uservice-intent/clients
POST BODY:
{
	"metadata": {
	"name": "<name>" // unique name for each intent
    "description": "connectivity intent add client communication"
	"application": "<app1>",
	"userdata1": <>,
	"userdata2": <>
	}

	spec: {
		"clientServiceName": "sleep", // Name of the client service
		"headless": "false", // default is false. Option "True" will generate the required configs for all the instances of headless service
		"mTLS": "DISABLESIMPLE", // will be the same as that of inbound service, if both are part of same logical cloud
	}
}

RETURN STATUS: 201
RETURN BODY:
{ 
  "name": "sleep"
  "Message": "Client created"
}

Add Security details for clients

WARNING - This task requires mutual TLS enabled because the following examples use principal and namespace in the policies

Code Block

language	js
theme	Midnight
title	GET
linenumbers	true

URL: /v2/projects/{project-name}/composite-apps/{composite-app-name}/{version}/traffic-group-intent/uservice-to-uservice-intent/clients/sleep/security/security-intent
{
	"metadata": {
	"name": "<name>" // unique name for each intent
    "description": "Security intent"
	"application": "<app1>",
	"userdata1": <>,
	"userdata2": <>
	}

	spec:{
	serviceAccountAccess : {[ "cluster.local/ns/default/sa/sleep": ["GET": "/status"],
							  "cluster.local/ns/default/sa/sleep" : ["GET": "/headers"]}
	}
}

RETURN STATUS: 201
RETURN BODY:
{ 
  "name": "<name>"
  "Message": "Security Rules created"
}

...

Name of the Cluster

Microservice

Istio Configuration

Comments

Cluster01

sleep

Microservice	Resource
common	serviceEntry (httpbin)
sleep	destinationRule for simple TLS

Cluster02

httpbin

Microservice

Resource

httpbin

destinationRule for simple TLS, Loadbalancing and circuit breaking

AuthorizationPolicy for Access Control

Cluster01 Resources

1. ServiceEntry - To enable sleep to access httpbin

Code Block

language	yml
theme	Eclipse
title	ServiceEntry
linenumbers	true

apiVersion: networking.istio.io/v1alpha3
kind: ServiceEntry
metadata:
  name: servicename-httpbin
spec:
  hosts:
  - httpbin.default.global
  # template for the remote service name - <servicename.namespace.global>
  # Treat remote cluster services as part of the service mesh
  # as all clusters in the service mesh share the same root of trust.
  location: MESH_INTERNAL
  ports:
  - name: http1
    number: 8000
    protocol: http
  resolution: DNS
  addresses:
  # the IP address to which httpbin.<namespace>.<logicalcloudname> will resolve to
  # must be unique for each remote service, within a given cluster.
  # This address need not be routable. Traffic for this IP will be captured
  # by the sidecar and routed appropriately.
  - 240.0.0.2
  endpoints:
  # This is the routable address of the istio ingress gateway in cluster02
  # routed to this address.
  - address: 172.25.55.50
    ports:
      http1: 15443 //Sni. Do not change this

2. DestinationRule for TLS - sleep

Code Block

language	yml
theme	Eclipse
title	DestinationRule
linenumbers	true

apiVersion: networking.istio.io/v1alpha3
kind: DestinationRule
metadata:
  name: sleep-dr
  namespace: default
spec:
  host: "sleep.default.svc.cluster.local"
  trafficPolicy:
    tls:
      mode: DISABLE

Cluster 02 Resources

1. DestinationRule for simple TLS, Loadbalancing and circuit breaking - httpbin

Code Block

language	yml
theme	Eclipse
title	DestinationRule
linenumbers	true

apiVersion: networking.istio.io/v1alpha3
kind: DestinationRule
metadata:
  name: httpbin-dr
  namespace: default
spec:
  host: "httpbin.default.svc.cluster.local"
  trafficPolicy:
    tls:
      mode: DISABLE
    loadbalancer:
      consistentHash:
        httpCookie: "user1"
    connectionPool:
      tcp:
        maxConnections: 10
      http:
        http2MaxRequests: 1000
        maxRequestsPerConnection: 100
    outlierDetection:
      consecutiveErrors: 7
      interval: 5m
      baseEjectionTime: 15m

2. AuthorizationPolicy

Code Block

language	yml
theme	Eclipse
title	AuthorizationPolicy
linenumbers	true

apiVersion: security.istio.io/v1beta1
kind: AuthorizationPolicy
metadata:
 name: deny-all
 namespace: default
spec:
  selector:
   matchLabels:
     app: httpbin
  rules:
  - from:
    - source:
        principals: ["cluster.local/ns/default/sa/sleep"]
    to:
    - operation:
        methods: ["GET"]
        paths: ["/status*"]
    - operation:
        methods: ["POST"]
        paths: ["/headers"]

...

Versions Compared

Old Version 1

New Version 2

Key

Diagram

Add Inbound service

Add Clients

Add Security details for clients

Cluster01 Resources

1. ServiceEntry - To enable sleep to access httpbin

2. DestinationRule for TLS - sleep

Cluster 02 Resources

1. DestinationRule for simple TLS, Loadbalancing and circuit breaking - httpbin

2. AuthorizationPolicy