Kubernetes持續集成：Jenkins關於java.nio.file.NoSuchFileException錯誤的緣由

時間 2019-11-16

標籤 kubernetes 持續集成 jenkins 關於 java.nio.file.nosuchfileexception java nio file nosuchfileexception 錯誤緣由欄目自動化構建简体版

原文原文鏈接

背景

爲了使用Kubernetes管理並自動化部署應用程序，領導"糾結"了幾個同事搭了一個Kubernetes集羣環境。
不過，爲了減小複雜度，採用了非官方推薦的方式：java

API Server使用http方式
不使用Admission Controllers，即API Server啓動參數admission-control設爲空

關於Admission Controllers的解釋，能夠參照官方文檔node

搭好k8s環境後，參考文檔初試 Jenkins 使用 Kubernetes Plugin 完成持續構建與發佈部署了Jenkins Server。git

嘗試運行pipeline腳本：github

def label = "mypod-${UUID.randomUUID().toString()}"

podTemplate(label: label, cloud: 'kubernetes', containers: [
    containerTemplate(name: 'maven', image: 'maven:3.3.9-jdk-8-alpine', ttyEnabled: true, command: 'cat'),
  ]) {

    node(label) {
        stage('Get a Maven Project') {
            git 'https://github.com/jenkins-docs/simple-java-maven-app.git'
            container('maven') {
                stage('Build a Maven project') {
                    sh 'mvn -B clean install'
                }
            }
        }
    }
}

發生了java.nio.file.NoSuchFileException: /var/run/secrets/kubernetes.io/serviceaccount/namespace的錯誤。錯誤信息：api

...
 > git checkout -f 0d85b7e1fd39bc6978511f92381aa10534ca4c1b
 > git branch -a -v --no-abbrev # timeout=10
 > git checkout -b master 0d85b7e1fd39bc6978511f92381aa10534ca4c1b
Commit message: "Amend README.md"
First time build. Skipping changelog.
[Pipeline] container
[Pipeline] // container
[Pipeline] }
[Pipeline] // stage
[Pipeline] }
[Pipeline] // node
[Pipeline] }
[Pipeline] // podTemplate
[Pipeline] End of Pipeline
java.nio.file.NoSuchFileException: /var/run/secrets/kubernetes.io/serviceaccount/namespace
    at sun.nio.fs.UnixException.translateToIOException(UnixException.java:86)
    at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:102)
    at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:107)
...

接下來就是2，3天的調查，關於這個錯誤的能查到的資料幾乎沒有，也嘗試了不少方法，無果... 很是煎熬。安全

緣由

關於這個錯誤，有幾個疑問app

文件/var/run/secrets/kubernetes.io/serviceaccount/namespace有什麼用
爲何Jenkins(Kubernetes Plugin)要去找這個文件
爲何這個文件不存在

帶着這些問題找到了官方文檔 Accessing Clusters,文檔中出現了這個文件的身姿。dom

Accessing the API from a Pod
When accessing the API from a pod, locating and authenticating to the apiserver are somewhat different.
The recommended way to locate the apiserver within the pod is with the kubernetes.default.svc DNS name, which resolves to a Service IP which in turn will be routed to an apiserver.maven

The recommended way to authenticate to the apiserver is with a service account credential. By kube-system, a pod is associated with a service account, and a credential (token) for that service account is placed into the filesystem tree of each container in that pod, at /var/run/secrets/kubernetes.io/serviceaccount/token.ui

If available, a certificate bundle is placed into the filesystem tree of each container at/var/run/secrets/kubernetes.io/serviceaccount/ca.crt , and should be used to verify the serving certificate of the apiserver.

Finally, the default namespace to be used for namespaced API operations is placed in a file at /var/run/secrets/kubernetes.io/serviceaccount/namespace in each container.

那爲何咱們搭建環境的container裏沒有這個文件呢？就連目錄 /var/run/secrets 都沒有...

調查過程當中，漸漸地把疑點定位到API Server的啓動參數 admission-control （1.10版本後被替換成 enable-admission-plugins）。官方推薦的設值有 ServiceAccount 可是搭環境的時候沒有設置，即設置爲空。

因而，把API Server的啓動admission-control參數改爲了 --admission-control=ServiceAccount。
而後，重啓API Server，修改Jenkins的Deployment（爲了讓k8s從新部署Jenkins Pod）。
接着，進入新部署的Jenkins Pod(container)確認，上帝保佑，生成了目錄/var/run/secrets以及相關文件！

因爲從新部署了Jenkins，須要從新設置Jenkins（安裝Plugin、設置k8s雲、建立上述腳本的pipeline job）

運行job(item)，腳本運行成功。問題解決了！