Trying to update posgres database in docker resulting in machine refusing connection - docker

Question

While doing first database update i get an error
System.Net.Sockets.SocketException (10061): No connection could be made because the target machine actively refused it.
at Npgsql.NpgsqlConnector.Connect(NpgsqlTimeout timeout)
at Npgsql.NpgsqlConnector.RawOpen(NpgsqlTimeout timeout, Boolean async, CancellationToken cancellationToken)
at Npgsql.NpgsqlConnector.Open(NpgsqlTimeout timeout, Boolean async, CancellationToken cancellationToken)
at Npgsql.NpgsqlConnection.<>c__DisplayClass32_0.<g__OpenLong|0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at Npgsql.NpgsqlConnection.Open()
at Npgsql.EntityFrameworkCore.PostgreSQL.Storage.Internal.NpgsqlDatabaseCreator.Exists()
at Microsoft.EntityFrameworkCore.Migrations.HistoryRepository.Exists()
at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.Migrate(String targetMigration)
at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.UpdateDatabase(String targetMigration, String contextType)
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
No connection could be made because the target machine actively refused it.
I'm using Docker Toolbox for low end pc. And I ran postgres container with command:
docker run --name pg -e POSTGRES_PASSWORD=password -p 5432:5432 -d postgres;
For connecting EF Core to pgsql I used Npgsql nuget package and connectionString
"Server=127.0.0.1;Port=5432;Database=postgres;Username=postgres;Password=password"
Next, I created in MyDbContext file
public class MyDbContext : DbContext
{
public MyDbContext(DbContextOptions<MyDbContext> options) : base(options) { }
}
public class MyDbContextFactory : IDesignTimeDbContextFactory<MyDbContext>
{
public MyDbContext CreateDbContext(string[] args)
{
var optionsBuilder = new DbContextOptionsBuilder<MyDbContext>();
optionsBuilder.UseNpgsql("Server=127.0.0.1;Port=5432;Database=postgres;Username=postgres;Password=password");
return new MyDbContext(optionsBuilder.Options);
}
}
After which i added dbContext in Startup class
public void ConfigureServices(IServiceCollection services, IConfiguration config)
{
services.AddDbContext<Models.MyDbContext>();
Can anyone help me, or suggest what could I have missed?

Answer 1

For your scenario, Server=127.0.0.1 will work when you start your .net core project from host.
I assume you start your .net core project from docker, if so, you need to follow steps belwo which connect the two container.
Change your connectionstring with postgres container name pg like
"Server=pg;Port=5432;Database=postgres;Username=postgres;Password=password"
Specify the --link=pg while running the .net core like
docker run -it -p 8585:80 --link=pg dockerpostgres