在 docker 文件中添加 Nginx 的健康检查

如何解决在 docker 文件中添加 Nginx 的健康检查

我有一个在本地运行的 WebAssmebly Blazor 应用，我使用 Helm 将其部署到 Azure K8s 集群，

当我检查日志时应用程序 pod 不断重启，它抱怨缺少健康检查

[21/Apr/2021:11:23:55 +0000] "GET /health/liveness HTTP/1.1" 404 153 "-" "kube-probe/1.17" "-"
2021/04/21 11:23:55 [error] 31#31: *3 open() "/usr/share/nginx/html/health/liveness" failed (2: No such file or directory),client: 10.244.0.1,server: localhost,request: "GET /health/liveness HTTP/1.1",host: "10.244.0.230:80"

由于 WebAssmebly Blazor 在客户端运行，因此不需要运行状况。

所以，我尝试在 Nginx 级别编写一些静态健康检查。

这是 docker 文件：

FROM mcr.microsoft.com/dotnet/core/sdk:3.1 AS build
WORKDIR /source

FROM build AS publish
WORKDIR /source/app.CustomerApplication/
RUN dotnet publish -c release

FROM nginx AS runtime

COPY --from=publish /source/app.CustomerApplication/bin/release/netstandard2.1/publish/wwwroot/. /usr/share/nginx/html/.
COPY ./app.CustomerApplication/nginx.conf /etc/nginx/nginx.conf
RUN rm /etc/nginx/conf.d/default.conf

和 Nginx 配置文件：

server {
    location / {
        root /usr/share/nginx/html;
    }

    location //health/liveness {
        return 200 'alive';
        add_header Content-Type text/plain;
    }
}

我一直收到这个错误

cust-app       /docker-entrypoint.sh: Configuration complete; ready for start up
cust-app       | 2021/04/20 23:56:16 [emerg] 1#1: unknown directive "server" in /etc/nginx/nginx.conf:1
cust-app       | nginx: [emerg] unknown directive "server" in /etc/nginx/nginx.conf:1

解决方法

首先 WebAssmebly Blazor 在客户端运行，因此为了破解 K8s 健康检查，我通过修改 Nginx 配置文件在 Nginx 中的特定路由上创建了静态回复。 对于有效的健康检查，我建议使用 Server Blazor 类型，因为它在服务器端运行，因此可以在 startup 类中添加实际的健康检查。

关于 Nginx config 文件的发布者模板我错了，更新到这个

server {
  #listen                80;
  #root                 /usr/share/nginx;

  location / {
      root /usr/share/nginx/html; #sepecify Blazor app route
  }

  location /health/liveness {
    #access_log off;
    error_log   off;
    return 200 'ok';
  }

  location /health/readiness {
    #access_log off;
    error_log   off;
    return 200 'ok';
  }
}

在 Dockerfile 中还需要更新：

FROM mcr.microsoft.com/dotnet/core/sdk:3.1 AS build
WORKDIR /source

FROM build AS publish
WORKDIR /source/app.CustomerApplication/
RUN dotnet publish -c release

FROM nginx AS runtime

COPY --from=publish /source/app.CustomerApplication/bin/release/netstandard2.1/publish/wwwroot/. /usr/share/nginx/html/.
ADD ./app.CustomerApplication/default.conf /etc/nginx/conf.d/default.conf

更新 Nginx 后的 K8s 健康检查日志：

10.244.0.1 - - [22/Apr/2021:07:15:43 +0000] "GET /health/liveness HTTP/1.1" 200 2 "-" "kube-probe/1.17" "-"
10.244.0.1 - - [22/Apr/2021:07:15:58 +0000] "GET /health/liveness HTTP/1.1" 200 2 "-" "kube-probe/1.17" "-"