從docker到istio之四 - istio分流應用
前言
容器化，雲原生越演越烈，新概念很是之多。信息爆炸的同時，帶來層層迷霧。我嘗試從擴容出發理解其脈路，通過實踐探索，整理造成一個入門教程，包括下面四篇文章。linux
- 從docker到istio之一 - 使用Docker將應用容器化
- 從docker到istio之二 - 使用compose部署應用
- 從docker到istio之三 - kubernetes編排應用
- 從docker到istio之四 - istio分流應用
這是第四篇，istio分流應用。nginx
istio
服務網格（Service Mesh）這個術語一般用於描述構成這些應用程序的微服務網絡以及應用之間的交互。隨着規模和複雜性的增加，服務網格愈來愈難以理解和管理。它的需求包括服務發現、負載均衡、故障恢復、指標收集和監控以及一般更加複雜的運維需求，例如 A/B 測試、金絲雀發佈、限流、訪問控制和端到端認證等。git
Istio 提供了一個完整的解決方案，經過爲整個服務網格提供行爲洞察和操做控制來知足微服務應用程序的多樣化需求。github
安裝istio
istio1.1支持kubernetes1.11,1.12,1.13,Docker for mac的stable版本過低，須要切換Docker for mac 到 edge版本，kubernetes會升級到1.13。使用 kubectl version 確認kubernetes版本:redis
Client Version: version.Info{Major:"1", Minor:"13", GitVersion:"v1.13.0", GitCommit:"ddf47ac13c1a9483ea035a79cd7c10005ff21a6d", GitTreeState:"clean", BuildDate:"2018-12-03T21:04:45Z", GoVersion:"go1.11.2", Compiler:"gc", Platform:"darwin/amd64"}
Server Version: version.Info{Major:"1", Minor:"13", GitVersion:"v1.13.0", GitCommit:"ddf47ac13c1a9483ea035a79cd7c10005ff21a6d", GitTreeState:"clean", BuildDate:"2018-12-03T20:56:12Z", GoVersion:"go1.11.2", Compiler:"gc", Platform:"linux/amd64"}
複製代碼
按照安裝指南安裝istio到k8s。 kubectl get svc -n istio-system 查看isto服務(svc是service的速記別名)docker
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
grafana ClusterIP 10.96.238.84 <none> 3000/TCP 19s
istio-citadel ClusterIP 10.110.233.235 <none> 8060/TCP,15014/TCP 19s
istio-egressgateway ClusterIP 10.107.81.184 <none> 80/TCP,443/TCP,15443/TCP 20s
istio-galley ClusterIP 10.108.48.185 <none> 443/TCP,15014/TCP,9901/TCP 20s
istio-ingressgateway LoadBalancer 10.99.64.197 localhost 15020:31681/TCP,80:31380/TCP,443:31390/TCP,31400:31400/TCP,15029:32145/TCP,15030:31376/TCP,15031:30092/TCP,15032:31491/TCP,15443:32689/TCP 19s
istio-pilot ClusterIP 10.101.105.130 <none> 15010/TCP,15011/TCP,8080/TCP,15014/TCP 19s
istio-policy ClusterIP 10.107.208.244 <none> 9091/TCP,15004/TCP,15014/TCP 19s
istio-sidecar-injector ClusterIP 10.104.152.19 <none> 443/TCP 19s
istio-telemetry ClusterIP 10.102.233.77 <none> 9091/TCP,15004/TCP,15014/TCP,42422/TCP 19s
jaeger-agent ClusterIP None <none> 5775/UDP,6831/UDP,6832/UDP 18s
jaeger-collector ClusterIP 10.100.208.250 <none> 14267/TCP,14268/TCP 18s
jaeger-query ClusterIP 10.104.246.180 <none> 16686/TCP 18s
kiali ClusterIP 10.100.34.9 <none> 20001/TCP 19s
prometheus ClusterIP 10.103.238.247 <none> 9090/TCP 19s
tracing ClusterIP 10.103.49.38 <none> 80/TCP 18s
zipkin ClusterIP 10.105.126.70 <none> 9411/TCP
複製代碼
查看isto的pod是否所有正常啓動:flask
➜ kubectl get pods -n istio-system
NAME READY STATUS RESTARTS AGE
grafana-749c78bcc5-jczt2 1/1 Running 1 20m
istio-citadel-899dfb67c-r6cmx 1/1 Running 0 20m
istio-cleanup-secrets-1.1.3-d42jx 0/1 Completed 0 20m
istio-egressgateway-748d5fd794-zkcjs 1/1 Running 1 20m
istio-galley-555dd7c7d7-t9fhz 1/1 Running 0 20m
istio-grafana-post-install-1.1.3-2qzg5 0/1 Completed 0 20m
istio-ingressgateway-55dd86767f-n5v7m 1/1 Running 1 20m
istio-pilot-7979d58649-lg6vq 2/2 Running 0 20m
istio-policy-f89c945dc-8d6mn 2/2 Running 0 55s
istio-security-post-install-1.1.3-4ggpf 0/1 Completed 0 20m
istio-sidecar-injector-998dd6cbb-fbdgw 1/1 Running 0 20m
istio-telemetry-7d9d866c65-2pngr 2/2 Running 0 16s
istio-tracing-595796cf54-mp6tp 1/1 Running 1 20m
kiali-5df77dc9b6-jq26m 1/1 Running 0 20m
prometheus-7f87866f5f-p2568 1/1 Running 0 20m
複製代碼
部署應用
調整pods符合istio規範
部署引用前，須要按照Istio對Pod和服務的要求，進行微調。api
微調後的istio\flaskapp.yaml以下:bash
apiVersion: v1
kind: Service
metadata:
name: flaskapp
spec:
ports:
- port: 5000
name: http
selector:
app: business
---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: flaskapp
spec:
replicas: 1
template:
metadata:
labels:
app: business
version: v1
spec:
containers:
- image: flaskapp:0.0.2
name: flaskapp
ports:
- containerPort: 5000
複製代碼
微調後的istio\redis.yaml以下:網絡
apiVersion: v1
kind: Service
metadata:
name: redis
spec:
ports:
- port: 6379
name: redis
selector:
app: redis
---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: redis
spec:
replicas: 1
template:
metadata:
labels:
app: redis
version: v1
spec:
containers:
- image: redis:4-alpine3.8
name: redisdb
ports:
- containerPort: 6379
複製代碼
由於istio附帶ingress，因此咱們取消了前置的nginx負載，直接使用ingress。
啓動istio的sidecar自動注入
istio經過在pod中輸入sidecar，用來管理流量，設置default名稱空間下默認注入:
➜ docker2istio kubectl label namespace default istio-injection=enabled
namespace/default labeled
複製代碼
啓動服務
啓動服務方式和k8s沒有區別
➜ docker2istio kubectl apply -f k8s/redis.yaml -f k8s/flaskapp.yaml
service/redis created
deployment.extensions/redis created
service/flaskapp created
deployment.extensions/flaskapp created
複製代碼
使用kubectl describe pod/flaskapp-757cd47df4-zkzv2 確認istio正常管理app:
Name: flaskapp-757cd47df4-zkzv2
Namespace: default
Priority: 0
PriorityClassName: <none>
Node: docker-desktop/192.168.65.3
Start Time: Wed, 24 Apr 2019 18:43:16 +0800
Labels: app=business
pod-template-hash=757cd47df4
version=v1
Annotations: sidecar.istio.io/status:
{"version":"3420543c87a5049f8ec099530c3992a5c1f06bf54fa56d7a3877e7ffc658ea8d","initContainers":["istio-init"],"containers":["istio-proxy"]...
Status: Running
IP: 10.1.0.45
Controlled By: ReplicaSet/flaskapp-757cd47df4
Init Containers:
istio-init:
Container ID: docker://0bac5e70832c287a1c446d38034c75ebe5b8e66b9e2fb6d5a1fc3bcb8a9f644c
Image: docker.io/istio/proxy_init:1.1.3
Image ID: docker-pullable://istio/proxy_init@sha256:000d022d27c198faa6cc9b03d806482d08071e146423d6e9f81aa135499c4ed3
Port: <none>
Host Port: <none>
Args:
...
Containers:
flaskapp:
Container ID: docker://9cdf76e12c710f1d50c2b3a2ac349909f481975f220af5b31e1b76717bcabd95
Image: flaskapp:0.0.2
Image ID: docker://sha256:d52877069956696bb9009c0af43a0d339d2d253e67f5fb09c9f1f052a35528de
Port: 5000/TCP
Host Port: 0/TCP
State: Running
Started: Wed, 24 Apr 2019 18:43:19 +0800
Ready: True
Restart Count: 0
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-ndv6q (ro)
istio-proxy:
Container ID: docker://84eecd89d7c203b7b97749d2a02c63cb8b4c57cfda96f0c7585547a8918344c1
Image: docker.io/istio/proxyv2:1.1.3
Image ID: docker-pullable://istio/proxyv2@sha256:b682918f2f8fcca14b3a61bbd58f4118311eebc20799f24b72ceddc5cd749306
Port: 15090/TCP
Host Port: 0/TCP
Args:
...
State: Running
Started: Wed, 24 Apr 2019 18:43:19 +0800
Ready: True
Restart Count: 0
Limits:
cpu: 2
memory: 128Mi
Requests:
cpu: 10m
memory: 40Mi
Readiness: http-get http://:15020/healthz/ready delay=1s timeout=1s period=2s #success=1 #failure=30
Environment:
POD_NAME: flaskapp-757cd47df4-zkzv2 (v1:metadata.name)
POD_NAMESPACE: default (v1:metadata.namespace)
INSTANCE_IP: (v1:status.podIP)
ISTIO_META_POD_NAME: flaskapp-757cd47df4-zkzv2 (v1:metadata.name)
ISTIO_META_CONFIG_NAMESPACE: default (v1:metadata.namespace)
ISTIO_META_INTERCEPTION_MODE: REDIRECT
ISTIO_METAJSON_LABELS: {"app":"business","pod-template-hash":"757cd47df4","version":"v1"}
Mounts:
/etc/certs/ from istio-certs (ro)
/etc/istio/proxy from istio-envoy (rw)
/var/run/secrets/kubernetes.io/serviceaccount from default-token-ndv6q (ro)
...
複製代碼
!!!注意 這裏的pod，會被自動注入名爲istio-init的initContainer和名爲**istio-proxy的container。具備這2個container，標誌pod接受istio流量管理。
確認服務正常啓動
➜ docker2istio kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
flaskapp ClusterIP 10.107.67.44 <none> 5000/TCP 4m31s
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 36m
redis ClusterIP 10.100.210.72 <none> 6379/TCP 4m31s
複製代碼
確認pod正常啓動
➜ docker2istio kubectl get pods
NAME READY STATUS RESTARTS AGE
flaskapp-77ddb9698c-xb2gm 1/1 Running 0 4m2s
redis-c5dd6fcfc-8tqwm 1/1 Running 0 4m2s
複製代碼
部署istio的gateway
由於取消了前置的nginx負載，須要設置gateway，集羣外部纔可以訪問服務。istio\gateway.yaml:
apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
name: flaskapp-gateway
spec:
selector:
istio: ingressgateway # use istio default controller
servers:
- port:
number: 80
name: http
protocol: HTTP
hosts:
- "*"
---
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
name: flaskapp
spec:
hosts:
- "*"
gateways:
- flaskapp-gateway
http:
- match:
- uri:
exact: /
route:
- destination:
host: flaskapp
port:
number: 5000
複製代碼
kubectl apply -f istio/gateway.yaml提交後，查看gameway的端口:
➜ docker2istio kubectl get svc istio-ingressgateway -n istio-system
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
istio-ingressgateway LoadBalancer 10.99.64.197 localhost 15020:31681/TCP,80:31380/TCP,443:31390/TCP,31400:31400/TCP,15029:32145/TCP,15030:31376/TCP,15031:30092/TCP,15032:31491/TCP,15443:32689/TCP 179m
複製代碼
這裏的服務類型爲LoadBalancer，能夠直接使用80端口訪問服務:
➜ docker2istio curl http://localhost
Hello World by 10.1.0.40 from 10.1.0.30 ! 該頁面已被訪問 1 次。
複製代碼
金絲雀發佈
istio的流量管理提供了很是便捷的金絲雀發佈功能。
首先，咱們調整app/flaskapp.py,將域名獲取調整成爲主機名稱:
#-*- coding:utf-8 -*-
import socket
from flask import Flask
from redis import Redis
app = Flask(__name__)
redis = Redis(host='redis', port=6379)
def get_host_ip():
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
try:
s.connect(('8.8.8.8', 80))
ip = s.getsockname()[0]
except:
ip = '127.0.0.1'
finally:
s.close()
return ip
def get_hostname():
return socket.gethostname()
@app.route('/')
def hello():
app.logger.debug('hello in')
from flask import request
count = redis.incr('hits')
# host_ip = get_host_ip()
host_id = get_hostname()
client_ip= request.headers['X-Real-Ip'] if 'X-Real-Ip' in request.headers else request.remote_addr
app.logger.debug("Hello out {} {} {}:".format(host_id,client_ip,count))
return 'Hello World by {} from {} ! 該頁面已被訪問 {} 次。\n'.format(host_id,client_ip,count)
if __name__ == "__main__":
app.run(host="0.0.0.0", debug=True)
複製代碼
使用 docker build -f app/Dockerfile -t flaskapp:0.0.3 app 編譯新的鏡像。
製做新的deployment，使其使用新的鏡像:
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: flaskapp-v2
spec:
replicas: 1
template:
metadata:
labels:
app: business
version: v2
spec:
containers:
- image: flaskapp:0.0.3
name: flaskapp
ports:
- containerPort: 5000
複製代碼
建立並確認新的部署生效:
➜ docker2istio kubectl apply -f istio/flaskappv2.yaml
deployment.extensions/flaskapp-v2 created
➜ docker2istio kubectl get deployment
NAME READY UP-TO-DATE AVAILABLE AGE
flaskapp 3/3 3 3 72m
flaskapp-v2 1/1 1 1 7s
redis 1/1 1 1 129m
複製代碼
調整VirtualService，控制流量分發策略:
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
name: flaskapp
spec:
hosts:
- "*"
gateways:
- flaskapp-gateway
http:
- match:
- uri:
exact: /
route:
- destination:
host: flaskapp
port:
number: 5000
- route:
- destination:
host: flaskapp
subset: v1
weight: 80
- destination:
host: flaskapp
subset: v2
weight: 20
複製代碼
這裏重點是指定規則，按照8:2，將flaskapp的訪問分配到deployment v1 和 deployment v2 上。
kubectl apply -f istio/gateway2.yaml 應用新的流量分配策略:
訪問觀察服務:
➜ docker2istio curl http://localhost
Hello World by 10.1.0.45 from 127.0.0.1 ! 該頁面已被訪問 7 次。
➜ docker2istio curl http://localhost
Hello World by 10.1.0.45 from 127.0.0.1 ! 該頁面已被訪問 8 次。
➜ docker2istio curl http://localhost
Hello World by flaskapp-v2-ff9f8cfdb-vh788 from 127.0.0.1 ! 該頁面已被訪問 9 次。
➜ docker2istio curl http://localhost
Hello World by 10.1.0.45 from 127.0.0.1 ! 該頁面已被訪問 10 次。
➜ docker2istio curl http://localhost
Hello World by 10.1.0.45 from 127.0.0.1 ! 該頁面已被訪問 11 次。
➜ docker2istio curl http://localhost
Hello World by 10.1.0.45 from 127.0.0.1 ! 該頁面已被訪問 12 次。
➜ docker2istio curl http://localhost
Hello World by 10.1.0.45 from 127.0.0.1 ! 該頁面已被訪問 13 次。
➜ docker2istio curl http://localhost
Hello World by flaskapp-v2-ff9f8cfdb-vh788 from 127.0.0.1 ! 該頁面已被訪問 14 次。
複製代碼
能夠看到，訪問被按比例分配到v1和v2兩個版本上。
總結
從上面實踐過程空可見，istio完善了k8s提供的編排功能，在縱向擴容的基礎上能夠實現橫向擴展。
相關文章
- 1. 從docker到istio之一 - 使用Docker將應用容器化
- 2. 從docker到istio之二 - 使用compose部署應用
- 3. Kubernetes-1.16部署之四 Istio
- 4. istio應用示例-控制ingress流量
- 5. 從docker到istio之三 - kubernetes集羣編排
- 6. Istio流量管理實踐之(3): 基於Istio實現流量對比分析
- 7. 【從小白到專家】Istio技術實踐專題（四）：應用接入Istio的正確姿式
- 8. 【從小白到專家】Istio技術實踐專題（四）：應用接入Istio的正確姿勢
- 9. istio部署-istio prometheus
- 10. Istio 流量劫持
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相關文章
- 1. 從docker到istio之一 - 使用Docker將應用容器化
- 2. 從docker到istio之二 - 使用compose部署應用
- 3. Kubernetes-1.16部署之四 Istio
- 4. istio應用示例-控制ingress流量
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