Minikube 上的 Flask 应用程序使用入口拒绝连接答案

【问题标题】：Flask application on Minikube refuse connection using ingressMinikube 上的 Flask 应用程序使用入口拒绝连接
【发布时间】：2021-08-12 13:31:29
【问题描述】：

我有一个在 5000 端口上运行 python 烧瓶应用程序的单副本 pod。下面是我的配置和详细信息。

[ec2-user@ip-172-31-1-120 ~]$ cat tree_management/application/*.yml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: tree-deployment
spec:
  selector:
    matchLabels:
      app: tree-management
  replicas: 1
  template:
    metadata:
      labels:
        app: tree-management
    spec:
      containers:
      - name: tree-management
        image: tree-management
        imagePullPolicy: Never
        ports:
        - containerPort: 5000

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: tree-ingress
  #  annotations:
  #    nginx.ingress.kubernetes.io/rewrite-target: /
spec:
  rules:
  - host: local.ec.org
    http:
      paths:
      - path: /tree
        pathType: Prefix
        backend:
          service:
            name: tree-service
            port:
              number: 5000

apiVersion: v1
kind: Service
metadata:
  name: tree-service
spec:
        #  type: NodePort
  selector:
    app: tree-management
  ports:
    - protocol: TCP
      port: 5000
      targetPort: 5000

应用程序在 pod 内运行良好，因为当我在 pod 中执行 kubectl exec 以点击 api url 时，它会给我输出。下面是一些 kubectl 输出。

[ec2-user@ip-172-31-1-120 ~]$ minikube service list
|----------------------|------------------------------------|--------------|---------------------------|
|      NAMESPACE       |                NAME                | TARGET PORT  |            URL            |
|----------------------|------------------------------------|--------------|---------------------------|
| default              | kubernetes                         | No node port |
| default              | tree-service                       | No node port |
| ingress-nginx        | ingress-nginx-controller           | http/80      | http://192.168.49.2:31893 |
|                      |                                    | https/443    | http://192.168.49.2:30453 |
| ingress-nginx        | ingress-nginx-controller-admission | No node port |
| kube-system          | kube-dns                           | No node port |
| kubernetes-dashboard | dashboard-metrics-scraper          | No node port |
| kubernetes-dashboard | kubernetes-dashboard               | No node port |
|----------------------|------------------------------------|--------------|---------------------------|
[ec2-user@ip-172-31-1-120 ~]$ kubectl get svc --all-namespaces
NAMESPACE              NAME                                 TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)                      AGE
default                kubernetes                           ClusterIP   10.96.0.1        <none>        443/TCP                      39h
default                tree-service                         ClusterIP   10.99.136.46     <none>        5000/TCP                     14m
ingress-nginx          ingress-nginx-controller             NodePort    10.96.58.167     <none>        80:31893/TCP,443:30453/TCP   21h
ingress-nginx          ingress-nginx-controller-admission   ClusterIP   10.103.107.214   <none>        443/TCP                      21h
kube-system            kube-dns                             ClusterIP   10.96.0.10       <none>        53/UDP,53/TCP,9153/TCP       39h
kubernetes-dashboard   dashboard-metrics-scraper            ClusterIP   10.98.246.45     <none>        8000/TCP                     39h
kubernetes-dashboard   kubernetes-dashboard                 ClusterIP   10.98.103.55     <none>        80/TCP                       39h
[ec2-user@ip-172-31-1-120 ~]$ minikube ip
192.168.49.2

我在本地以及 minikube IP 中添加了主机条目。当我尝试使用 nodeIp 访问我的烧瓶应用程序时，它不起作用。这是我点击 URL 时得到的结果

[ec2-user@ip-172-31-1-120 ~]$ curl http://192.168.49.2/tree
<html>
<head><title>404 Not Found</title></head>
<body>
<center><h1>404 Not Found</h1></center>
<hr><center>nginx</center>
</body>
</html>

下面是来自 nginx 入口的日志

2021/05/24 07:59:44 [error] 298#298: *20007 connect() failed (111: Connection refused) while connecting to upstream, client: 192.168.49.1, server: local.ec.org, request: "GET /tree HTTP/1.1", upstream: "http://172.17.0.5:5000/tree", host: "local.ec.org"
2021/05/24 07:59:44 [error] 298#298: *20007 connect() failed (111: Connection refused) while connecting to upstream, client: 192.168.49.1, server: local.ec.org, request: "GET /tree HTTP/1.1", upstream: "http://172.17.0.5:5000/tree", host: "local.ec.org"
2021/05/24 07:59:44 [error] 298#298: *20007 connect() failed (111: Connection refused) while connecting to upstream, client: 192.168.49.1, server: local.ec.org, request: "GET /tree HTTP/1.1", upstream: "http://172.17.0.5:5000/tree", host: "local.ec.org"
192.168.49.1 - - [24/May/2021:07:59:44 +0000] "GET /tree HTTP/1.1" 502 150 "-" "curl/7.61.1" 84 0.000 [default-tree-service-5000] [] 172.17.0.5:5000, 172.17.0.5:5000, 172.17.0.5:5000 0, 0, 0 0.000, 0.000, 0.000 502, 502, 502 bd34da31533e0f3393ff490efe37a90d

也尝试使用以下 CURL 组合，但都失败了。

  curl http://local.ec.org:5000
  curl http://local.ec.org
  curl http://local.ec.org/tree
  curl http://local.ec.org/tree -H local.ec.org
  curl http://local.ec.org -H local.ec.org
  curl http://local.ec.org/ -H local.ec.org
  curl http://local.ec.org/tree -H local.ec.org
  curl http://192.168.49.2:5000/tree -H Host:local.ec.org

你能帮忙看看这里出了什么问题吗？

更新 1 在进行了一些配置更改后，我可以看到我是否点击了以下 URL，然后请求将发送到 nginx，但不确定为什么它返回 502 bad gateway。

curl http://local.ec.org/tree

Nginx 错误。不知道为什么nginx连接不上上游？

2021/05/24 13:01:58 [error] 447#447: *168693 connect() failed (111: Connection refused) while connecting to upstream, client: 192.168.49.1, server: local.ec.org, request: "GET /tree HTTP/1.1", upstream: "http://172.17.0.5:5000/tree", host: "local.ec.org"
192.168.49.1 - - [24/May/2021:13:01:58 +0000] "GET /tree HTTP/1.1" 502 150 "-" "curl/7.61.1" 84 0.001 [default-tree-service-5000] [] 172.17.0.5:5000, 172.17.0.5:5000, 172.17.0.5:5000 0, 0, 0 0.000, 0.000, 0.000 502, 502, 502 dff2ca8a83f9d2237300b6d46f978e43
2021/05/24 13:01:58 [error] 447#447: *168693 connect() failed (111: Connection refused) while connecting to upstream, client: 192.168.49.1, server: local.ec.org, request: "GET /tree HTTP/1.1", upstream: "http://172.17.0.5:5000/tree", host: "local.ec.org"
2021/05/24 13:01:58 [error] 447#447: *168693 connect() failed (111: Connection refused) while connecting to upstream, client: 192.168.49.1, server: local.ec.org, request: "GET /tree HTTP/1.1", upstream: "http://172.17.0.5:5000/tree", host: "local.ec.org"

【问题讨论】：

你试过http://192.168.49.2:31893/tree吗？那是 minikube 实际给你的 URL。
@coderanger 是的，刚刚尝试过，但 nginx 给出了 404 ..
嗨@AshifNataliya，我可以看到你的ingress nginx-controller。你用minikube tunnel了吗？如果你想在 Minikube 中有入口控制器，你可以通过命令添加minikube ingress：minikube addons enable ingress。启用入口插件后，特别说明：After the addon is enabled, please run "minikube tunnel" and your ingress resources would be available at "127.0.0.1"。看类似的问题here。
@MikołajGłodziak 是的，我已经启用了入口插件。我以前没有运行过 minikube 隧道。我刚试过，但没有帮助。也尝试使用 127.0.0.1 卷曲，但仍然失败
502 表示没有准备好的 pod。检查您的 pod 是否在启动时崩溃。

标签： python nginx flask kubernetes minikube

【解决方案1】：

我能够解决这个问题，罪魁祸首是 Flask 应用程序。为了解决问题，我已经登录到 Flask Pod 并执行以下命令。

netstat -tupln

这向我解释了应用程序正在侦听端口 5000，但默认情况下它只允许来自 127.0.0.1 的连接。（即来自自己）。这是因为我使用 app.run() 命令启动了应用程序。我必须按如下方式更改此命令。

# Run flask app.
app.run(
host="0.0.0.0",
port=5000
    )

这允许从任何主机（即 0.0.0.0）进行连接。

注意：这是一个演示应用程序，因此我允许从 0.0.0.0 开始，但不建议在生产环境中进行。

【讨论】：