docs: example of using this module in multi-cluster mode with Istio s…

…ervice mesh

Signed-off-by: Ali Mukadam <ali.mukadam@oracle.com>

examples/istio-mc/README.md

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+# Multi-region service mesh with Istio and OKE
+
+## Assumptions
+
+1. A pair of OKE clusters in 2 different OCI regions will be used.
+2. The OKE clusters will use private control planes.
+3. The topology model used is [Multi-Primary on different networks](https://istio.io/latest/docs/setup/install/multicluster/multi-primary_multi-network/).
+
+![Multi-primary on multiple networks](docs/assets/multi-primary%20multi-networks.png)
+4. This example uses self-signed certificates.
+
+## Create the OKE Clusters
+
+1. Copy the terraform.tfvars.example to terraform.tfvars and provide the necessary values as detailed in steps 2-6.
+
+2. Configure the provider parameters:
+
+```
+# provider
+api_fingerprint = ""
+
+api_private_key_path = "~/.oci/oci_rsa.pem"
+
+home_region = "ashburn"
+
+tenancy_id = "ocid1.tenancy.oc1.."
+
+user_id = "ocid1.user.oc1.."
+
+compartment_id = "ocid1.compartment.oc1.."
+```
+
+3. Configure an ssh key pair:
+
+```
+# ssh
+ssh_private_key_path = "~/.ssh/id_rsa"
+ssh_public_key_path  = "~/.ssh/id_rsa.pub"
+```
+
+4. Configure your clusters' regions.
+
+```
+# clusters
+clusters = {
+  c1 = { region = "sydney", vcn = "10.1.0.0/16", pods = "10.201.0.0/16", services = "10.101.0.0/16", enabled = true }
+  c2 = { region = "melbourne", vcn = "10.2.0.0/16", pods = "10.202.0.0/16", services = "10.102.0.0/16", enabled = true }
+}
+```
+
+5. Configure additional parameters if necessary:
+
+```
+kubernetes_version = "v1.28.2"
+
+cluster_type = "basic"
+
+oke_control_plane = "private"
+```
+
+6. Configure your node pools:
+
+```
+nodepools = {
+  np1 = {
+    shape            = "VM.Standard.E4.Flex",
+    ocpus            = 2,
+    memory           = 64,
+    size             = 2,
+    boot_volume_size = 150,
+  }
+}
+```
+
+7. Run terraform to create your clusters:
+
+```
+terraform apply --auto-approve
+```
+
+8. Once the Dynamic Routing Gateways (DRGs) and Remote Peering Connections (RPCs) have been created, use the OCI console to establish a connection between them.
+
+## Install Istio
+
+1. Terraform will output an ssh convenience command. Use it to ssh to the operator host:
+
+```
+ssh_to_operator = "ssh -o ProxyCommand='ssh -W %h:%p -i ~/.ssh/id_rsa opc@<bastion_ip>' -i ~/.ssh/id_rsa opc@<operator_ip>"
+```
+
+2. Verify connectivity to both clusters:
+
+```
+for cluster in c1 c2; do
+  ktx $cluster
+  k get nodes
+done
+```
+
+3. Generate certs for each cluster:
+
+```
+export ISTIO_HOME=/home/opc/istio-1.20.2
+cd $ISTIO_HOME/tools/certs 
+make -f Makefile.selfsigned.mk c1-cacerts
+make -f Makefile.selfsigned.mk c2-cacerts
+```
+
+4. Create and label istio-system namespace in each cluster:
+
+```
+for cluster in c1 c2; do
+  ktx $cluster
+  k create ns istio-system
+  k label namespace istio-system topology.istio.io/network=$cluster
+done
+```
+
+5. Create a secret containing the certificates in istio-system namespace for both clusters:
+
+```
+for cluster in c1 c2; do
+  ktx $cluster
+  kubectl create secret generic cacerts -n istio-system \
+      --from-file=$cluster/ca-cert.pem \
+      --from-file=$cluster/ca-key.pem \
+      --from-file=$cluster/root-cert.pem \
+      --from-file=$cluster/cert-chain.pem
+done
+```
+
+6. Install Istio in both clusters:
+
+```
+for cluster in c1 c2; do
+  ktx $cluster
+  istioctl install --set profile=default -f $HOME/$cluster.yaml
+done
+```
+
+7. Verify the Istio installation in both clusters:
+
+```
+for cluster in c1 c2; do
+  ktx $cluster
+  istioctl verify-install
+done
+```
+
+8. Check if the load balancers have been properly provisioned:
+
+```
+for cluster in c1 c2; do
+  ktx $cluster
+  k -n istio-system get svc
+done
+```
+
+9. Check if Istio pods are running:
+
+```
+for cluster in c1 c2; do
+  ktx $cluster
+  k -n istio-system get pods
+done
+```
+
+10. Create an Gateway to expose all services through the eastwest ingress gateway:
+
+```
+cd $ISTIO_HOME
+for cluster in c1 c2; do
+  ktx $cluster
+  k apply -f samples/multicluster/expose-services.yaml
+done
+```
+
+11. Set the environment variables to verify multi-cluster connectivity:
+```
+export CTX_CLUSTER1=c1
+export CTX_CLUSTER2=c2
+```
+
+12. Enable endpoint discovery in each cluster by creating a remote secret:
+
+```
+istioctl create-remote-secret \
+  --context="${CTX_CLUSTER1}" \
+  --name="${CTX_CLUSTER1}" | \
+  kubectl apply -f - --context="${CTX_CLUSTER2}"
+
+
+ istioctl create-remote-secret \
+  --context="${CTX_CLUSTER2}" \
+  --name="${CTX_CLUSTER2}" | \
+  kubectl apply -f - --context="${CTX_CLUSTER1}"
+```
+
+## Verify cross-cluster connectivity
+
+1. Deploy the HelloWorld Service in both clusters:
+
+```
+for cluster in c1 c2; do
+  kubectl create --context="${cluster}" namespace sample
+  kubectl label --context="${cluster}" namespace sample istio-injection=enabled
+  kubectl apply --context="${cluster}" -f samples/helloworld/helloworld.yaml -l service=helloworld -n sample
+done
+```
+
+2. Deploy v1 to cluster c1:
+
+```
+kubectl apply --context="${CTX_CLUSTER1}" \
+    -f samples/helloworld/helloworld.yaml \
+    -l version=v1 -n sample
+
+kubectl get pod --context="${CTX_CLUSTER1}" -n sample -l app=helloworld
+```
+
+3. Deploy v2 to cluster c2:
+
+```
+kubectl apply --context="${CTX_CLUSTER2}" \
+    -f samples/helloworld/helloworld.yaml \
+    -l version=v2 -n sample
+
+kubectl get pod --context="${CTX_CLUSTER2}" -n sample -l app=helloworld
+```
+
+4. Deploy Sleep client pod in both clusters:
+
+```
+kubectl apply --context="${CTX_CLUSTER1}" \
+    -f samples/sleep/sleep.yaml -n sample
+kubectl apply --context="${CTX_CLUSTER2}" \
+    -f samples/sleep/sleep.yaml -n sample
+```
+
+5. Generate traffic from c1. The response should alternate between c1 (v1) and c2 (v2) regions:
+
+```
+for i in $(seq 1 100); do
+kubectl exec --context="${CTX_CLUSTER1}" -n sample -c sleep \
+    "$(kubectl get pod --context="${CTX_CLUSTER1}" -n sample -l \
+    app=sleep -o jsonpath='{.items[0].metadata.name}')" \
+    -- curl -sS helloworld.sample:5000/hello
+done
+```
+
+6. Generate traffic from c2. The response should alternate between c1 (v1) and c2 (v2) regions:
+
+```
+for i in $(seq 1 100); do
+kubectl exec --context="${CTX_CLUSTER2}" -n sample -c sleep \
+    "$(kubectl get pod --context="${CTX_CLUSTER2}" -n sample -l \
+    app=sleep -o jsonpath='{.items[0].metadata.name}')" \
+    -- curl -sS helloworld.sample:5000/hello
+done
+```
+
+7. Cross-cluster connectivity has been verified.
+

examples/istio-mc/c1.tf

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+# Copyright (c) 2024 Oracle Corporation and/or its affiliates.
+# Licensed under the Universal Permissive License v 1.0 as shown at https://oss.oracle.com/licenses/upl
+
+module "c1" {
+
+  source  = "oracle-terraform-modules/oke/oci"
+  version = "5.1.1"
+
+  count = lookup(lookup(var.clusters, "c1"), "enabled") ? 1 : 0
+
+  home_region = lookup(local.regions, var.home_region)
+
+  region      = lookup(local.regions, lookup(lookup(var.clusters, "c1"), "region"))
+
+  tenancy_id = var.tenancy_id
+
+  # general oci parameters
+  compartment_id = var.compartment_id
+
+  # ssh keys
+  ssh_private_key_path = var.ssh_private_key_path
+  ssh_public_key_path  = var.ssh_public_key_path
+
+  # networking
+  create_drg       = var.oke_control_plane == "private" ? true : false
+  drg_display_name = "c1"
+
+  remote_peering_connections = var.oke_control_plane == "private" ? {
+    for k, v in var.clusters : "rpc-to-${k}" => {} if k != "c1"
+  } : {}
+
+  nat_gateway_route_rules = var.oke_control_plane == "private" ? [
+    for k, v in var.clusters :
+    {
+      destination       = lookup(v, "vcn")
+      destination_type  = "CIDR_BLOCK"
+      network_entity_id = "drg"
+      description       = "Routing to allow connectivity to ${title(k)} cluster"
+    } if k != "c1"
+  ] : []
+
+  vcn_cidrs     = [lookup(lookup(var.clusters, "c1"), "vcn")]
+  vcn_dns_label = "c1"
+  vcn_name      = "c1"
+
+  #subnets
+  subnets = {
+    bastion  = { newbits = 13, netnum = 0, dns_label = "bastion" }
+    operator = { newbits = 13, netnum = 1, dns_label = "operator" }
+    cp       = { newbits = 13, netnum = 2, dns_label = "cp" }
+    int_lb   = { newbits = 11, netnum = 16, dns_label = "ilb" }
+    pub_lb   = { newbits = 11, netnum = 17, dns_label = "plb" }
+    workers  = { newbits = 2, netnum = 1, dns_label = "workers" }
+    pods     = { newbits = 2, netnum = 2, dns_label = "pods" }
+  }
+
+  # bastion host
+  create_bastion        = true
+  bastion_allowed_cidrs = ["0.0.0.0/0"]
+  bastion_upgrade       = false
+
+  # operator host
+  create_operator            = true
+  operator_upgrade           = false
+  create_iam_resources       = true
+  create_iam_operator_policy = "always"
+  operator_install_k9s       = true
+
+  # oke cluster options
+  cluster_name                = "c1"
+  cluster_type                = var.cluster_type
+  cni_type                    = var.preferred_cni
+  control_plane_is_public     = var.oke_control_plane == "public"
+  control_plane_allowed_cidrs = [local.anywhere]
+  kubernetes_version          = var.kubernetes_version
+  pods_cidr                   = lookup(lookup(var.clusters, "c1"), "pods")
+  services_cidr               = lookup(lookup(var.clusters, "c1"), "services")
+
+
+  # node pools
+  allow_worker_ssh_access           = true
+  kubeproxy_mode                    = "iptables"
+  worker_pool_mode                  = "node-pool"
+  worker_pools                      = var.nodepools
+  worker_cloud_init                 = local.worker_cloud_init
+  worker_image_type                 = "oke"
+
+  # oke load balancers
+  load_balancers          = "both"
+  preferred_load_balancer = "public"
+
+  allow_rules_internal_lb = {
+    for p in local.service_mesh_ports :
+
+    format("Allow ingress to port %v", p) => {
+      protocol = local.tcp_protocol, port = p, source = lookup(lookup(var.clusters, "c2"), "vcn"), source_type = local.rule_type_cidr,
+    }
+  }
+
+  allow_rules_public_lb = {
+    for p in local.public_lb_allowed_ports :
+
+    format("Allow ingress to port %v", p) => {
+      protocol = local.tcp_protocol, port = p, source = "0.0.0.0/0", source_type = local.rule_type_cidr,
+    }
+  }
+
+  user_id = var.user_id
+
+  providers = {
+    oci      = oci.c1
+    oci.home = oci.home
+  }
+}