如何使用 Docker.DotNet (NET CORE) 连接到工作容器

Question

I try to use https://github.com/dotnet/Docker.DotNet for control docker container. One of important future to working with running container is attaching to running container with one command. Or with /bin/bash if we can attach interactively. So, this is command:

# sudo docker exec -it 7dde487b4424 bash
# sudo docker exec -it 7dde487b4424 pwd

Unfortunately, I can not found this command Docker.DotNet, some functions has similar name, but has no parameters like "bash command"

Public Interface IContainerOperations
    Function ListContainersAsync(parameters As ContainersListParameters, Optional cancellationToken As CancellationToken = Nothing) As Task(Of IList(Of ContainerListResponse))
    Function ExtractArchiveToContainerAsync(id As String, parameters As ContainerPathStatParameters, stream As Stream, Optional cancellationToken As CancellationToken = Nothing) As Task
    Function GetArchiveFromContainerAsync(id As String, parameters As GetArchiveFromContainerParameters, statOnly As Boolean, Optional cancellationToken As CancellationToken = Nothing) As Task(Of GetArchiveFromContainerResponse)
    Function RemoveContainerAsync(id As String, parameters As ContainerRemoveParameters, Optional cancellationToken As CancellationToken = Nothing) As Task
    Function WaitContainerAsync(id As String, Optional cancellationToken As CancellationToken = Nothing) As Task(Of ContainerWaitResponse)
    Function AttachContainerAsync(id As String, tty As Boolean, parameters As ContainerAttachParameters, Optional cancellationToken As CancellationToken = Nothing) As Task(Of MultiplexedStream)
    Function UnpauseContainerAsync(id As String, Optional cancellationToken As CancellationToken = Nothing) As Task
    Function PauseContainerAsync(id As String, Optional cancellationToken As CancellationToken = Nothing) As Task
    Function RenameContainerAsync(id As String, parameters As ContainerRenameParameters, cancellationToken As CancellationToken) As Task
    Function KillContainerAsync(id As String, parameters As ContainerKillParameters, Optional cancellationToken As CancellationToken = Nothing) As Task
    Function RestartContainerAsync(id As String, parameters As ContainerRestartParameters, Optional cancellationToken As CancellationToken = Nothing) As Task
    Function StopContainerAsync(id As String, parameters As ContainerStopParameters, Optional cancellationToken As CancellationToken = Nothing) As Task(Of Boolean)
    Function StartContainerAsync(id As String, parameters As ContainerStartParameters, Optional cancellationToken As CancellationToken = Nothing) As Task(Of Boolean)
    Function ResizeContainerTtyAsync(id As String, parameters As ContainerResizeParameters, Optional cancellationToken As CancellationToken = Nothing) As Task
    Function GetContainerStatsAsync(id As String, parameters As ContainerStatsParameters, progress As IProgress(Of ContainerStatsResponse), Optional cancellationToken As CancellationToken = Nothing) As Task
    <Obsolete("Use 'Task GetContainerStatsAsync(string id, ContainerStatsParameters parameters, CancellationToken cancellationToken, IProgress<JSONMessage> progress)'")>
    Function GetContainerStatsAsync(id As String, parameters As ContainerStatsParameters, cancellationToken As CancellationToken) As Task(Of Stream)
    Function ExportContainerAsync(id As String, Optional cancellationToken As CancellationToken = Nothing) As Task(Of Stream)
    Function InspectChangesAsync(id As String, Optional cancellationToken As CancellationToken = Nothing) As Task(Of IList(Of ContainerFileSystemChangeResponse))
    Function GetContainerLogsAsync(id As String, tty As Boolean, parameters As ContainerLogsParameters, Optional cancellationToken As CancellationToken = Nothing) As Task(Of MultiplexedStream)
    Function GetContainerLogsAsync(id As String, parameters As ContainerLogsParameters, cancellationToken As CancellationToken, progress As IProgress(Of String)) As Task
    <Obsolete("The stream returned by this method won't be demultiplexed properly if the container was created without a TTY. Use GetContainerLogsAsync(string, bool, ContainerLogsParameters, CancellationToken) instead")>
    Function GetContainerLogsAsync(id As String, parameters As ContainerLogsParameters, Optional cancellationToken As CancellationToken = Nothing) As Task(Of Stream)
    Function ListProcessesAsync(id As String, parameters As ContainerListProcessesParameters, Optional cancellationToken As CancellationToken = Nothing) As Task(Of ContainerProcessesResponse)
    Function InspectContainerAsync(id As String, Optional cancellationToken As CancellationToken = Nothing) As Task(Of ContainerInspectResponse)
    Function CreateContainerAsync(parameters As CreateContainerParameters, Optional cancellationToken As CancellationToken = Nothing) As Task(Of CreateContainerResponse)
    Function PruneContainersAsync(Optional parameters As ContainersPruneParameters = Nothing, Optional cancellationToken As CancellationToken = Nothing) As Task(Of ContainersPruneResponse)
    Function UpdateContainerAsync(id As String, parameters As ContainerUpdateParameters, Optional cancellationToken As CancellationToken = Nothing) As Task(Of ContainerUpdateResponse)
End Interface

UPD: According to notes @kthompso

If we can see to exec interface

Public Interface IExecOperations
    Function ExecCreateContainerAsync(id As String, parameters As ContainerExecCreateParameters, Optional cancellationToken As CancellationToken = Nothing) As Task(Of ContainerExecCreateResponse)
    Function StartContainerExecAsync(id As String, Optional cancellationToken As CancellationToken = Nothing) As Task
    Function StartAndAttachContainerExecAsync(id As String, tty As Boolean, Optional cancellationToken As CancellationToken = Nothing) As Task(Of MultiplexedStream)
    Function StartWithConfigContainerExecAsync(id As String, eConfig As ContainerExecStartParameters, Optional cancellationToken As CancellationToken = Nothing) As Task(Of MultiplexedStream)
    Function ResizeContainerExecTtyAsync(id As String, parameters As ContainerResizeParameters, Optional cancellationToken As CancellationToken = Nothing) As Task
    Function InspectContainerExecAsync(id As String, Optional cancellationToken As CancellationToken = Nothing) As Task(Of ContainerExecInspectResponse)
End Interface

We can see only two methods with CMD parameters - ExecCreateContainerAsync and StartWithConfigContainerExecAsync.

I try to use it

            AttachToContainer(DockerHub, ContainerId, CMD, LogCtsSrc.Token)
            ReadContainerLog(DockerHub, ContainerId, Sub(X) Console.WriteLine(X), LogCtsSrc.Token)

            Function AttachToContainer(DockerHub As DockerClient, ContainerID As String, Cmd As IList(Of String), ExecCts As CancellationToken) As Task(Of ContainerExecCreateResponse)
                Dim ExecTask As Task(Of ContainerExecCreateResponse) = DockerHub.Exec.ExecCreateContainerAsync(ContainerID, New ContainerExecCreateParameters With {
                                 .AttachStdin = False,
                                 .AttachStderr = True,
                                 .AttachStdout = True,
                                 .Tty = False,
                                 .Cmd = Cmd
                                },
                                ExecCts)
                 Return ExecTask
             End Function

And receive nothing, only old part of container log instead response of my commands in CMD.

It's not looks as result of standard docker operation as

 # sudo docker exec -it 7dde487b4424 pwd

Answer 1

You are only creating the exec instance but you are not starting it. From the documentation :

Exec

Run new commands inside running containers. Refer to the command-line reference for more information.

To exec a command in a container, you first need to create an exec instance, then start it . These two API endpoints are wrapped up in a single command-line command, docker exec .

Example Program

using Docker.DotNet;
using Docker.DotNet.Models;

namespace App
{
    public class Program
    {
        private static void Usage()
        {
            Console.WriteLine("Usage: dotnet run <container-id-or-name> <commands...>");
        }

        public async static Task Main(string[] args)
        {
            if (args.Length < 2)
            {
                Usage();
                return;
            }

            await ExecAsync(args[0], args[1..^0]);
        }

        private static async Task ExecAsync(string imageIdOrName, string[] command)
        {
            DockerClient client = new DockerClientConfiguration(
                new Uri("unix:///var/run/docker.sock"))
                    .CreateClient();

            var execParams = new ContainerExecCreateParameters()
            {
                AttachStderr = true,
                AttachStdout = true,
                Cmd = command,
            };

            # Create the exec instance, it is not started yet.
            var exec = await client.Exec.ExecCreateContainerAsync(imageIdOrName, execParams);
            # Start the exec instance and capture the output stream.
            var stream = await client.Exec.StartAndAttachContainerExecAsync(exec.ID, false);
            await stream.CopyOutputToAsync(
                null,
                Console.OpenStandardOutput(),
                Console.OpenStandardError(),
                CancellationToken.None);
        }
    }
}

Example Program Output

# Create a running container
$ docker run --name docker-dotnet-test -d alpine tail -f
38a4dac4c5a2d42d57defbaa17778bb071a94e5a69c6427078ad278334fe5598
# Call our program with the container name and a command
$ dotnet run docker-dotnet-test echo hello world
hello world

Notes

• I'm using the StartAndAttachContainerExecAsync method to capture stdout/stderr. You can use StartContainerExecAsync if you don't care about the streams.