Question

我有一个带有asp.net核心的docker容器和一个带有mysql的容器。现在我需要等待asp.net核心容器，以便mysql容器启动并准备就绪（两个容器都通过docker-compose.yml启动）。

像https://github.com/jwilder/dockerize之类的东西，wait-for-it.sh或wait-for似乎不适用于asp.net核心容器。

有人知道如何解决该问题？

UPDATE

这是我的dockerfile：

FROM microsoft/aspnetcore-build:2.0 AS build-env
WORKDIR /app

# Copy csproj and restore as distinct layers
COPY *.csproj ./
RUN dotnet restore test.csproj

# Copy everything else and build
COPY . ./
RUN dotnet publish -c Release -o out test.csproj



# Build runtime image
FROM microsoft/aspnetcore:2.0
WORKDIR /app
COPY ./entrypoint.sh ./app/
RUN chmod +x ./app/entrypoint.sh
CMD /bin/bash ./app/entrypoint.sh

COPY --from=build-env /app/out .
ENTRYPOINT ["dotnet", "test.dll"]

这是我的入口点。

#!/bin/bash

set -e
run_cmd="dotnet run --server.urls http://*:80"

until dotnet ef database update; do
>&2 echo "SQL Server is starting up"
sleep 1
done

>&2 echo "SQL Server is up - executing command"
exec $run_cmd

如果我使用docker-compose启动容器，则会收到错误消息：

Unhandled Exception: System.FormatException: Value for switch '/app/entrypoint.sh' is missing.
test          |    at Microsoft.Extensions.Configuration.CommandLine.CommandLineConfigurationProvider.Load()
test          |    at Microsoft.Extensions.Configuration.ConfigurationRoot..ctor(IList`1 providers)
test          |    at Microsoft.Extensions.Configuration.ConfigurationBuilder.Build()
test          |    at Microsoft.AspNetCore.Hosting.WebHostBuilder.BuildCommonServices(AggregateException& hostingStartupErrors)
test          |    at Microsoft.AspNetCore.Hosting.WebHostBuilder.Build()
test          |    at test.Program.Main(String[] args) in /app/Program.cs:line 19

如何将ENTRYPOINT和CMD / bin / bash ./app/entrypoint.sh命令合并到一个文件中。我认为我需要ENTRYPOINT才能运行dotnet应用程序，而cmd则需要entrypoint.sh来等待数据库容器。有没有解决方案可以同时运行？

Answer 1

https://docs.docker.com/compose/aspnet-mssql-compose/

泊坞窗文档列出了如何通过让entrypoint.sh轮询数据库连接来获取ASP.net容器以等待其数据库。

#!/bin/bash

set -e
run_cmd="dotnet run --server.urls http://*:80"

until dotnet ef database update; do
>&2 echo "SQL Server is starting up"
sleep 1
done

>&2 echo "SQL Server is up - executing command"
exec $run_cmd

Answer 2

除了具有从外部推迟推迟启动dotnet应用程序的脚本之外，您还可以从在内部检查并等待数据库连接。

在下面，您可以了解如何将host.Run()推迟到waitForDb()返回之前。

在下面的示例中，我将逻辑检查SQL DB（在docker容器中运行）是否已经在名为DbHealthChecker的服务（实际上是整个方法waitForDb）内启动。可以提供专用服务）。此运行状况检查程序使用this stackoverflow thread中描述的一种技术来检查数据库是否正在运行。

public class Program
{
  public static void Main(string[] args)
  {
    var host = CreateWebHostBuilder(args).Build();

    Task.Run(async () => {
      using (var scope = host.Services.CreateScope())
      {
        var services = scope.ServiceProvider;

        await waitForDb(services);

        // ... other initializations, e.g. seeding db ...
      }
    }).Wait();

    host.Run();
  }

  private static async Task waitForDb(IServiceProvider services)
  {
    // create your own connection checker here
    // see https://stackoverflow.com/questions/19211082/testing-an-entity-framework-database-connection

    var healthChecker = services.GetRequiredService<DbHealthChecker>();
    var maxAttemps = 12;
    var delay = 5000;

    for (int i = 0; i < maxAttemps; i++) {
      if (healthChecker.isConnected()) {
        return;
      }
      await Task.Delay(delay);
    }

    // after a few attemps we give up
    throw new HttpException(503);
  }
}

docker asp.net核心容器在mysql容器之后启动

2 个答案: