1.总得扯点啥
目前对kubernetes上无服务器架构(Faas/Serverless)都是热门话题，各大公司也都相继进行投入。本文主要是想通过实际例子，了解无服务器架构。
2.什么是无服务器架构(Faas/Serverless)
自己的认识:care code, don`t care server。开发人员将通用的功能以函数的形式提交注册到kubernetes作为其中的CRD，使用这根据输入规范使用CRD。当然函数提供方和基础设施（kubernetes）提供方会按照相应的规则计量计费。
3.Serverless的开发框架
Serverless的开发框架由很多，比如：
- Kubeless：Kubernetes原生的无服务器框架
- Fission：Kubernetes的快速无服务器框架，专注于开发人员的生产力和高性能。支持ython，NodeJS，Go，C＃或PHP编写函数。
- Funktion：专为Kubernetes设计的开源事件驱动的Lambda风格编程模型。Funktion与fabric8平台紧密相连。
- IronFunctions：一个开源的无服务器平台或FaaS平台，可以在任何地方运行。IronFunction是用Golang编写的，实际上支持任何语言的功能。
还有OpenWhisk，OpenFaaS，Nuclio，Virtual Kubelet，Fnproject等其他的开源框架。
4.以Kubeless为例，开发Serverless。
环境准备
# 下载kubeless
[root@node4 kubeless]# ll
total 9792
-rw-r--r-- 1 root root 10004863 Oct 14 14:47 kubeless_linux-amd64.zip
-rw-r--r-- 1 root root 17544 Oct 14 14:47 kubeless-v1.0.4.yaml
#解压将kubeless拷贝到/usr/local/bin
#如果不能俩连外网，预先加载以下镜像
#这里只下载go-init和go的镜像，因为这里的函数式基于golang写的，不同的开发语言可以下载对应的镜像
[root@node4 soft]# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
kubeless/function-controller v1.0.4 b65aa9b834b7 3 months ago 85.3MB
kubeless/go-init latest e07ff96bf0a5 3 months ago 954MB
kubeless/go latest 493ee8f547df 3 months ago 58.4MB
kubeless/http-trigger-controller v1.0.1 d6f09f3299d9 3 months ago 83.4MB
kubeless/cronjob-trigger-controller v1.0.1 aec1dd30bb57 3 months ago 77.1MB
kubeless/unzip latest abb7a6ac3e05 3 months ago 75.4MB
bitnami/kubeless-ui latest 43d3109c8a74 9 months ago 231MB
lachlanevenson/k8s-kubectl v1.13.1 d2525e8609a3 10 months ago 44.2MB
k8s.gcr.io/pause 3.1 da86e6ba6ca1 22 months ago 742kB
注册kubeless到kubernetes集群中
[root@node4 kubeless]# kubectl create ns kubeless
namespace/kubeless created
#下载地址：https://github.com/kubeless/kubeless/releases
[root@node4 kubeless]# kubectl apply -f kubeless-v1.0.4.yaml
clusterrole.rbac.authorization.k8s.io/kubeless-controller-deployer created
clusterrolebinding.rbac.authorization.k8s.io/kubeless-controller-deployer created
customresourcedefinition.apiextensions.k8s.io/functions.kubeless.io created
customresourcedefinition.apiextensions.k8s.io/httptriggers.kubeless.io created
customresourcedefinition.apiextensions.k8s.io/cronjobtriggers.kubeless.io created
configmap/kubeless-config created
deployment.apps/kubeless-controller-manager created
serviceaccount/controller-acct created
#查看部署情况
[root@node4 kubeless]# kubectl get all -n kubeless
NAME READY STATUS RESTARTS AGE
pod/kubeless-controller-manager-5bcb6757d9-wb6hr 3/3 Running 0 28s
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/kubeless-controller-manager 1/1 1 1 29s
NAME DESIRED CURRENT READY AGE
replicaset.apps/kubeless-controller-manager-5bcb6757d9 1 1 1 29s
#查看CRD
[root@node4 kubeless]# kubectl get crd |grep kubeless
cronjobtriggers.kubeless.io 2019-10-14T08:18:28Z
functions.kubeless.io 2019-10-14T08:18:28Z
httptriggers.kubeless.io 2019-10-14T08:18:28Z
开发函数，主要通过golang实现数组求和
package main
import (
"github.com/kubeless/kubeless/pkg/functions"
"strconv"
"strings"
)
func Sum(event functions.Event, context functions.Context) (string, error) {
strs := strings.Split(event.Data,",")
var result = 0;
for _,str := range strs {
value,_ := strconv.Atoi(str)
result += value
}
return strconv.Itoa(result), nil
}
发布function
- 通过kubeless发布
### flink： 表示function名称
### runtime： 表示运行时,实际对应镜像，支持的类型可通过kubeless get-server-config查看
###image-pull-policy：镜像拉去策略，默认Always，这里无法连接外网设置为IfNotPresent
### from-file： 表示function源文件
### handler： 表示function具体函数名称，模块.函数名称
如果需要有依赖包通过dependencies指定，
--dependencies Gopkg.toml
[root@node4 kubeless]# kubeless function deploy flink \
> --runtime go1.12 \
> --image-pull-policy IfNotPresent \
> --from-file flink.go \
> --handler flink.Sum
INFO[0000] Deploying function...
INFO[0000] Function flink submitted for deployment
INFO[0000] Check the deployment status executing 'kubeless function ls flink'
#查看发布的functions和对应的pod
[root@node4 kubeless]# kubeless function ls flink
NAME NAMESPACE HANDLER RUNTIME DEPENDENCIES STATUS
flink default flink.Sum go1.12 1/1 READY
[root@node4 kubeless]# kubectl get pod
NAME READY STATUS RESTARTS AGE
flink-69c84f8fd7-hrf2w 1/1 Running 0 16s
#错误排查
[root@node4 kubeless]# kubectl get pod -l function=flink -o yaml
- 通过apiserver发布
apiVersion: kubeless.io/v1beta1
kind: Function
metadata:
name: testfunc
spec:
deployment: ### Definition as per v1beta2.Deployment
metadata:
annotations:
"annotation-to-deploy": "final-value-in-deployment"
spec:
replicas: 2 ### Final deployment gets Replicas as 2
template:
metadata:
annotations:
"annotation-to-pod": "value"
deps: ""
function: |
module.exports = {
foo: function (req, res) {
res.end('hello world updated!!!')
}
}
function-content-type: text
handler: hello.foo
runtime: nodejs8
service:
ports:
- name: http-function-port
port: 8080
protocol: TCP
targetPort: 8080
type: ClusterIP
函数调用 <除了主动请求，还支持事件和数据流的输入方式>
#kubeless客户端方式
[root@node4 kubeless]# kubeless function call flink --data '1,3,5'
9
#API接口方式，通常是Ingress->Service，为外部提供接口
[root@node4 kubeless]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
flink ClusterIP 172.20.49.159 8080/TCP 6m18s
kubernetes ClusterIP 172.20.0.1 443/TCP 5d
[root@node4 kubeless]# curl -L --data '1,3,5,7,8' \
> --header "Content-Type:application/json" \
> 172.20.49.159:8080/api/v1/namespaces/default/services/flink:http-function-port/proxy/
24
调用参数模板
event:
data: # Event data
foo: "bar" # The data is parsed as JSON when required
event-id: "2ebb072eb24264f55b3fff" # Event ID
event-type: "application/json" # Event content type
event-time: "2009-11-10 23:00:00 +0000 UTC" # Timestamp of the event source
event-namespace: "kafkatriggers.kubeless.io" # Event emitter
extensions: # Optional parameters
request: ... # Reference to the request received
response: ... # Reference to the response to send
# (specific properties will depend on the function language)
context:
function-name: "pubsub-nodejs"
timeout: "180"
runtime: "nodejs6"
memory-limit: "128M"
5.kubeless-UI
#下载地址：https://github.com/kubeless/kubeless-ui/releases
#修改内部的imagePullPolicy策略
[root@node4 kubeless]# kubectl apply -f kubeless-ui.yaml
[root@node4 kubeless]# kubectl get svc -n kubeless
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
ui NodePort 172.20.207.2 3000:30498/TCP 3h23m
访问测试
image.png