.net core api doesn't work in a local docker container, but works in my visual studio

Question

I have a dot net core API + SQL Server which are working fine when I run them on my Mac Visual Studio. However, when I try to deploy the API to a docker container and run a SQL server in a separate docker container, it doesn't work. Here are the details:

API Docker file:

FROM mcr.microsoft.com/dotnet/core/sdk:3.1-buster AS build-env
WORKDIR /TechTalksAPI
COPY NuGet.config ./
COPY TechTalksAPI.csproj ./
RUN dotnet restore
COPY . ./
RUN dotnet publish --configuration Release --output releaseOutput --no-restore

#build runtime image
FROM mcr.microsoft.com/dotnet/core/sdk:3.1-buster

ENV ASPNETCORE_URLS=http://+:58508  
EXPOSE 58508
WORKDIR /TechTalksAPI
COPY --from=build-env /TechTalksAPI/releaseOutput ./
ENTRYPOINT ["dotnet", "TechTalksAPI.dll"]

The appsettings.Development.json file:

{
  "ConnectionStrings": {
    "DefaultConnection": "Server=192.168.1.6,1433;Database=TechTalksDB;User Id=sa;Password=Miles1984$$!;"
  },
  "Logging": {
    "LogLevel": {
      "Default": "Debug",
      "System": "Information",
      "Microsoft": "Information"
    }
  }
}

Here is the project file:

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <!-- <TargetFramework>netcoreapp2.1</TargetFramework> -->
    <TargetFramework>netcoreapp3.0</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <Folder Include="wwwroot\" />
  </ItemGroup>

  <ItemGroup>
    <!-- <PackageReference Include="Microsoft.AspNetCore.App" /> -->
    <PackageReference Include="Microsoft.ENtityFrameworkCore.SqlServer" Version="3.1.0" />
  </ItemGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.App" />
  </ItemGroup>

  <ItemGroup>
    <None Include="TechTalksAPI.csproj" />
  </ItemGroup>
</Project>

Regarding the connection string above - I can definitely connect to the local db using either the connection string from above, or with this one: Server=localhost,1433\\Catalog=TechTalksDB;Database=TechTalksDB;User Id=sa;Password=Miles1984$$!;

Regarding the SQL Server:

I run it like this:

docker run -e 'ACCEPT_EULA=Y' -e 'SA_PASSWORD=Miles1984$$!' -p 1433:1433 --name sql1 -d mcr.microsoft.com/mssql/server:2019-latest

Regarding the API: I run it like this:

docker run --name backend -p 58508:58508 application/backend:v1.0

As you may notice, both containers are running in the default bridge network. I tried with the custom network and it didn't work.

Any idea what is causing the issue?

Here is what I got on my terminal:

Hosting environment: Production
Content root path: /TechTalksAPI
Now listening on: http://[::]:58508
Application started. Press Ctrl+C to shut down.
fail: Microsoft.EntityFrameworkCore.Database.Connection[20004]
      An error occurred using the connection to database 'TechTalksDB' on server 'localhost'.
fail: Microsoft.EntityFrameworkCore.Query[10100]
      An exception occurred while iterating over the results of a query for context type 'TechTalksAPI.Model.TechTalksDBContext'.
      Microsoft.Data.SqlClient.SqlException (0x80131904): A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: TCP Provider, error: 40 - Could not open a connection to SQL Server)
         at Microsoft.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, SqlCredential credential, Object providerInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString userConnectionOptions, SessionData reconnectSessionData, Boolean applyTransientFaultHandling, String accessToken, DbConnectionPool pool, SqlAuthenticationProviderManager sqlAuthProviderManager)
         at Microsoft.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection, DbConnectionOptions userOptions)
         at Microsoft.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnectionPool pool, DbConnection owningObject, DbConnectionOptions options, DbConnectionPoolKey poolKey, DbConnectionOptions userOptions)
         at Microsoft.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
         at Microsoft.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
         at Microsoft.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection)
         at Microsoft.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection)
         at Microsoft.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection)
         at Microsoft.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
         at Microsoft.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
         at Microsoft.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
         at Microsoft.Data.SqlClient.SqlConnection.Open()
         at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenDbConnection(Boolean errorsExpected)
         at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.Open(Boolean errorsExpected)
         at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReader(RelationalCommandParameterObject parameterObject)
         at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.Enumerator.InitializeReader(DbContext _, Boolean result)
         at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerExecutionStrategy.Execute[TState,TResult](TState state, Func`3 operation, Func`3 verifySucceeded)
         at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.Enumerator.MoveNext()
      ClientConnectionId:00000000-0000-0000-0000-000000000000
Microsoft.Data.SqlClient.SqlException (0x80131904): A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: TCP Provider, error: 40 - Could not open a connection to SQL Server)
   at Microsoft.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, SqlCredential credential, Object providerInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString userConnectionOptions, SessionData reconnectSessionData, Boolean applyTransientFaultHandling, String accessToken, DbConnectionPool pool, SqlAuthenticationProviderManager sqlAuthProviderManager)
   at Microsoft.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection, DbConnectionOptions userOptions)
   at Microsoft.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnectionPool pool, DbConnection owningObject, DbConnectionOptions options, DbConnectionPoolKey poolKey, DbConnectionOptions userOptions)
   at Microsoft.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
   at Microsoft.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
   at Microsoft.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   at Microsoft.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   at Microsoft.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection)
   at Microsoft.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at Microsoft.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at Microsoft.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
   at Microsoft.Data.SqlClient.SqlConnection.Open()
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenDbConnection(Boolean errorsExpected)
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.Open(Boolean errorsExpected)
   at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReader(RelationalCommandParameterObject parameterObject)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.Enumerator.InitializeReader(DbContext _, Boolean result)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerExecutionStrategy.Execute[TState,TResult](TState state, Func`3 operation, Func`3 verifySucceeded)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.Enumerator.MoveNext()
ClientConnectionId:00000000-0000-0000-0000-000000000000

If you are getting an error, use the [edit] feature, don't put it in the comments. — Thom A, Jul 25 '22 at 10:45
Bearing in mind that Docker containers are essentially their own little Linux VMs... from a networking perspective each container's `localhost` points to itself. If you're publishing container ports on the host then you could, I suppose, use `host.docker.internal` and the appropriate port but, really, you should be using `docker-compose.yml` files to orchestrate the containers in your application. Each composition runs up its own Docker network with DNS services which then allows the containers to connect between each other using the names you assign them in the `docker-compose.yml` file. — AlwaysLearning, Jul 25 '22 at 11:04
@AlwaysLearning did answer your question, you have to change connection string, Check this link for details https://www.twilio.com/blog/containerize-your-aspdotnet-core-application-and-sql-server-with-docker — Matija Gluhak, Jan 28 '23 at 11:12

Saheed Lawanson · Answer 1 · 2022-08-23T20:04:04.293

0

The solution from here works!!!, spent the whole day on this issue. In a single sentence, replace "localhost" with "172.17.0.1" in your connection string in the appsettings.json file

edited Aug 23 '22 at 20:04

answered Aug 23 '22 at 20:01

Saheed Lawanson

1
1

Can you please extract the solution from the embedded link and put it in your answer in case that link breaks one day? – Otter Aug 29 '22 at 17:28

.net core api doesn't work in a local docker container, but works in my visual studio

1 Answers1