OpenShift 4.2 Service Mesh

1.和社区版Istio的区别

OpenShift 4.2的Service Mesh和upstream的Istio项目的增强，除了产品化之外，借用官方文档，区别在于：

Red Hat OpenShift Service Mesh differs from Istio in ways that help resolve issues, provide additional features, and ease deployment on OpenShift Container Platform. An installation of Red Hat OpenShift Service Mesh differs from upstream Istio community installations in multiple ways:

OpenShift Service Mesh installs a multi-tenant control plane by default
OpenShift Service Mesh extends Role Based Access Control (RBAC) features
OpenShift Service Mesh replaces BoringSSL with OpenSSL
Kiali and Jaeger are enabled by default in OpenShift Service Mesh

2.架构

各个模块功能不再熬述。

3.安装和部署

基于OperatorHub部署service mesh,部署顺序为:elasticsearch Operator->Jaeger Opeartor->Kiali Operator->OpenShift Service Mesh Operator->OpenShift Service Mesh Controller Plane

详细可以参考

https://docs.openshift.com/container-platform/4.2/service_mesh/service_mesh_install/installing-ossm.html

部署完control plane后，会在istio-system下生成如下Pod

[root@clientvm 0 ~]# oc get pods -n istio-system
NAME                                      READY   STATUS    RESTARTS   AGE
grafana-b67df64b6-2kp7h                   2/2     Running   0          2d23h
istio-citadel-79979464d-kxpxw             1/1     Running   0          2d23h
istio-egressgateway-7d897695c4-c868b      1/1     Running   0          2d23h
istio-galley-6bb46858c5-pf476             1/1     Running   0          2d23h
istio-ingressgateway-8465bbf788-j9jgk     1/1     Running   0          2d23h
istio-pilot-54b65495c4-4tg6m              2/2     Running   0          2d23h
istio-policy-5fc74b8697-mk85l             2/2     Running   0          2d23h
istio-sidecar-injector-65cd4c8c6f-cnp5t   1/1     Running   0          2d23h
istio-telemetry-69cb778b9-qlpqj           2/2     Running   0          2d23h
jaeger-57776787bc-ljls5                   2/2     Running   0          2d23h
kiali-6d6f9cf658-kzdwf                    1/1     Running   0          2d1h
prometheus-b8bdc6b77-rbxzs                2/2     Running   0          2d23h

和下面的服务

[root@clientvm 0 ~]# oc get svc -n istio-system
NAME                        TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)                                  AGE
grafana                     ClusterIP   172.30.124.97    <none>        3000/TCP                                 2d23h
istio-citadel               ClusterIP   172.30.122.114   <none>        8060/TCP,15014/TCP                       2d23h
istio-egressgateway         ClusterIP   172.30.60.175    <none>        80/TCP,443/TCP,15443/TCP                 2d23h
istio-galley                ClusterIP   172.30.167.213   <none>        443/TCP,15014/TCP,9901/TCP               2d23h
istio-ingressgateway        ClusterIP   172.30.221.247   <none>        15020/TCP,80/TCP,443/TCP,15443/TCP       2d23h
istio-pilot                 ClusterIP   172.30.19.129    <none>        15010/TCP,15011/TCP,8080/TCP,15014/TCP   2d23h
istio-policy                ClusterIP   172.30.99.48     <none>        9091/TCP,15004/TCP,15014/TCP             2d23h
istio-sidecar-injector      ClusterIP   172.30.102.34    <none>        443/TCP                                  2d23h
istio-telemetry             ClusterIP   172.30.229.205   <none>        9091/TCP,15004/TCP,15014/TCP,42422/TCP   2d23h
jaeger-agent                ClusterIP   None             <none>        5775/TCP,5778/TCP,6831/TCP,6832/TCP      2d23h
jaeger-collector            ClusterIP   172.30.66.202    <none>        9411/TCP,14250/TCP,14267/TCP,14268/TCP   2d23h
jaeger-collector-headless   ClusterIP   None             <none>        9411/TCP,14250/TCP,14267/TCP,14268/TCP   2d23h
jaeger-query                ClusterIP   172.30.84.61     <none>        443/TCP                                  2d23h
kiali                       NodePort    172.30.55.80     <none>        20001:31380/TCP                          2d23h
prometheus                  ClusterIP   172.30.122.232   <none>        9090/TCP                                 2d23h
zipkin                      ClusterIP   172.30.189.90    <none>        9411/TCP                                 2d23h

查看对外暴露的路由

[root@clientvm 0 ~]# oc get route -n istio-system
NAME                   HOST/PORT                                                                    PATH   SERVICES               PORT    TERMINATION   WILDCARD
grafana                grafana-istio-system.apps.cluster-4674.sandbox580.opentlc.com                       grafana                <all>   reencrypt     None
istio-ingressgateway   istio-ingressgateway-istio-system.apps.cluster-4674.sandbox580.opentlc.com          istio-ingressgateway   8080                  None
jaeger                 jaeger-istio-system.apps.cluster-4674.sandbox580.opentlc.com                        jaeger-query           <all>   reencrypt     None
kiali                  kiali-istio-system.apps.cluster-4674.sandbox580.opentlc.com                         kiali                  <all>   reencrypt     None
prometheus             prometheus-istio-system.apps.cluster-4674.sandbox580.opentlc.com                    prometheus             <all>   reencrypt     None

值得注意的是instio-ingressgateway这个路由是OpenShift Service Mesh暴露给外端访问的路由。也就是通过这个唯一的链接，调用接入到Service Mesh服务网格。

基于Operator的安装和部署确实使得整个过程方便不少，但也封装了很多的架构的细节了，所以我们所需要做的就是对架构更加了解。

4.使用

部署完成sample的bookinfo项目以后，再部署一个自己的简单的tomcat服务。然后访问发现访问不通。经过排查发现是virtualservice的路径问题。

kind: VirtualService
apiVersion: networking.istio.io/v1alpha3
metadata:
  name: mytomcat
  namespace: myproject
  selfLink: >-
    /apis/networking.istio.io/v1alpha3/namespaces/myproject/virtualservices/mytomcat
  uid: 834c4724-0812-11ea-b3a1-0a1bba0ac472
  resourceVersion: '1631674'
  generation: 8
  creationTimestamp: '2019-11-16T01:43:39Z'
spec:
  hosts:
    - '*'
  gateways:
    - mytomcat-gateway
  http:
    - match:
        - uri:
            exact: /
      route:
        - destination:
            host: mytomcat
            port:
              number: 8080

gateway会拼接uri,也就是/到你的service的路径，如果你填入mytomcat,其实真实访问路径是http://mytomcat:8080/mytomcat,就会出现找不到应用的状况。