ArgoCD實踐之基於設定清單建立Application
2023-03-26 15:01:25
1. 什麼是Application
1.0 什麼是基礎不可變設施
GitOps當中是這樣定義的。應用都需要執行在多臺機器上，它們被組織成不同的環境，例如開發環境、測試環境和生產環境等等。需要將相同的應用部署到不同的機器上。通常需要系統管理員確保所有的機器都處於相同的狀態。接著所有的修改、修補程式、升級需要在所有的機器中進行。隨著時間的推移，很難再確保所有的機器處於相同的狀態，同時越來越容易出錯。這就是傳統的可變架構中經常出現的問題。這時我們有了不可變架構，它將整個機器環境打包成一個單一的不可變單元，而不是傳統方式僅僅打包應用。這個單元包含了之前所說的整個環境棧和應用所有的修改、修補程式和升級，這就解決了前面的問題。 —— 摘自 InfoQ 的《關於不可變架構以及為什麼需要不可變架構》作者 百佔輝
1.1 Application核心元件
Synced：一致
OutOfSync：不一致
Healthy：健康
Degraded：降級
Missing：缺失，即在GitRepo中存在資源定義，但並未完成部署
2. ArgoCD Application的建立
ArgoCD可以基於WEB-UI的方式來進行應用的釋出，也可以基於Configuration List的方式去部署應用。
2.1 檢視ArgoCD支援的API-Resources
kubectl api-resources --api-group=argoproj.io
NAME SHORTNAMES APIVERSION NAMESPACED KIND
applications app,apps argoproj.io/v1alpha1 true Application
applicationsets appset,appsets argoproj.io/v1alpha1 true ApplicationSet
appprojects appproj,appprojs argoproj.io/v1alpha1 true AppProject
2.2 檢視ArgoCD的欄位屬性
explain可以分級檢視欄位屬性
[root@c-k-m1-10 argocd]# kubectl explain application
KIND: Application
VERSION: argoproj.io/v1alpha1
DESCRIPTION:
Application is a definition of Application resource.
FIELDS:
apiVersion <string>
APIVersion defines the versioned schema of this representation of an
object. Servers should convert recognized schemas to the latest internal
value, and may reject unrecognized values. More info:
https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#resources
kind <string>
Kind is a string value representing the REST resource this object
represents. Servers may infer this from the endpoint the client submits
requests to. Cannot be updated. In CamelCase. More info:
https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#types-kinds
metadata <Object> -required-
Standard object's metadata. More info:
https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#metadata
operation <Object>
Operation contains information about a requested or running operation
spec <Object> -required-
ApplicationSpec represents desired application state. Contains link to
repository with application definition and additional parameters link
definition revision.
status <Object>
ApplicationStatus contains status information for the application
2.3 準Git源
GitOps中定義以特定Repository(設定倉庫)為應用程式部署和管理的唯一可信源，該Repository負責定義Application的期望狀態。本次測試使用gitee作為唯一的可信源。支援更多的設定管理工具例如helm、kustomize、jsonnet等；本次使用kubernetes原生的設定清單包含如下一個namespace一個裸Pod以及一個Service。
kind: Namespace
apiVersion: v1
metadata:
name: hello
apiVersion: v1
kind: Service
metadata:
name: hello-svc
namespace: hello
spec:
type: NodePort
selector:
app: hello
ports:
- name: http # 埠名稱
protocol: TCP # 協定型別，目前支援TCP、UDP、SCTP預設為TCP
port: 80 # Service的埠號
targetPort: 8080 # 後端目標程序的埠號
nodePort:
apiVersion: v1
kind: Pod
metadata:
name: hello
namespace: hello
labels:
app: hello
spec:
containers:
- name: hello
image: lihuahaitang/helloworld:v1
imagePullPolicy: IfNotPresent
2.4 編輯資源設定清單；
[root@c-k-m1-10 argocd]# cat application-hello.yaml
apiVersion: argoproj.io/v1alpha1 # 定義的API版本，可通過API-Resources檢視
kind: Application # 定義的資源型別
metadata:
name: hello # 名稱
namespace: argocd # argocd所在的名稱空間
spec:
project: default # 指明所屬的專案是default
source: # 設定倉庫及相關的設定存取的方法
repoURL: https://gitee.com/good-news/apps.git # 資源設定清單的Git的倉庫源地址
targetRevision: HEAD # 期望基於哪個修訂版本來部署
path: kubernetes # Git倉庫的子目錄路徑
destination: # 應用程式要部署到的目標位置
server: https://kubernetes.default.svc # 目標kubernetes叢集的API-Server存取入口，這裡為本地叢集
namespace: hello # 目標應用要部署的名稱空間
syncPolicy: # 同步策略，如果不寫預設就是Manual為手動同步
automated: null # 為自動同步策略
2.5 檢視應用狀態
這裡的應用狀態為未同步，因為我們未指定同步策略為自動。預設為手動同步；
[root@c-k-m1-10 argocd]# argocd app list
WARN[0000] Failed to invoke grpc call. Use flag --grpc-web in grpc calls. To avoid this warning message, use flag --grpc-web.
NAME CLUSTER NAMESPACE PROJECT STATUS HEALTH SYNCPOLICY CONDITIONS REPO PATH TARGET
argocd/hello https://kubernetes.default.svc hello default <none> <none> https://gitee.com/good-news/apps.git kubernetes HEAD
2.6 手動執行同步策略
[root@c-k-m1-10 argocd]# argocd app sync hello
WARN[0000] Failed to invoke grpc call. Use flag --grpc-web in grpc calls. To avoid this warning message, use flag --grpc-web.
TIMESTAMP GROUP KIND NAMESPACE NAME STATUS HEALTH HOOK MESSAGE
2023-03-25T22:00:35+08:00 Service default hello Unknown Healthy
2023-03-25T22:00:37+08:00 Service default hello Unknown Healthy ignored (requires pruning)
2023-03-25T22:00:37+08:00 Namespace hello hello Running Synced namespace/hello created
2023-03-25T22:00:37+08:00 Service hello hello-svc Running Synced service/hello-svc created
2023-03-25T22:00:37+08:00 Pod hello hello Running Synced pod/hello created
2023-03-25T22:00:37+08:00 Service default hello OutOfSync Healthy ignored (requires pruning)
2023-03-25T22:00:37+08:00 Service hello hello-svc OutOfSync Healthy service/hello-svc created
2023-03-25T22:00:37+08:00 Pod hello hello Synced Progressing pod/hello created
2023-03-25T22:00:37+08:00 Namespace hello Synced
Name: argocd/hello
Project: default
Server: https://kubernetes.default.svc
Namespace: hello
URL: https://argocd.k8s.local/applications/hello
Repo: https://gitee.com/good-news/apps.git
Target: HEAD
Path: kubernetes
SyncWindow: Sync Allowed
Sync Policy: <none>
Sync Status: OutOfSync from HEAD (c916463)
Health Status: Healthy
Operation: Sync
Sync Revision: c916463463c2244ae78ba442a0de764b743a493b
Phase: Succeeded
Start: 2023-03-25 22:00:34 +0800 CST
Finished: 2023-03-25 22:00:37 +0800 CST
Duration: 3s
Message: successfully synced (all tasks run)
GROUP KIND NAMESPACE NAME STATUS HEALTH HOOK MESSAGE
Service default hello OutOfSync Healthy ignored (requires pruning)
Namespace hello hello Running Synced namespace/hello created
Service hello hello-svc OutOfSync Healthy service/hello-svc created
Pod hello hello Synced Healthy pod/hello created
2.7 檢視名稱空間的Pod以及Service
[root@c-k-m1-10 argocd]# kubectl get po,svc -n hello
NAME READY STATUS RESTARTS AGE
pod/hello 1/1 Running 0 5m22s
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/hello-svc NodePort xx.xx.xx.xx <none> 80:32618/TCP 5m22s
2.8 WEBUI檢視應用狀態
2.9 嘗試存取應用
sh-3.2# curl -I http://xx.xx.xx.xx32618/
HTTP/1.1 200 OK
Date: Sat, 25 Mar 2023 14:07:57 GMT
Connection: keep-alive
我們一直奔跑在進步的旅途