Execute powershell command in running container via Docker API - powershell

Question

I want to execute a powershell command in a docker container running on a windows host.
The specific command I want to execute is "powershell Get-PSDrive C | Select-Object Used,Free"
I have implemented this using the Docker API for python and it is simple like calling:
cmd = "powershell Get-PSDrive C | Select-Object Used,Free"
output = container.exec_run(cmd)
This works as intended, but I need to implement this in golang.
But somehow, it is not clear for me how to interact with the Docker API for golang. I looked into the API and was confused by the hijackedSession. How do I have to setup the calls for ContainerExecCreate, ContainerExecAttach and ContainerExecStart ?
I expect the golang script to deliver the same results like the python code does:
Used Free
---- ----
199181606912 307151622144
Which then can be parsed by me.

Answer 1

The HijackedResponse struct:
type HijackedResponse struct {
Conn net.Conn
Reader *bufio.Reader
}
You need to copy the response from the resp.Reader,here is my code:
package main
import (
"bytes"
"context"
"fmt"
"github.com/docker/docker/api/types"
"github.com/docker/docker/client"
"github.com/docker/docker/pkg/stdcopy"
"strings"
)
func readFromCommand() (string, error) {
cli, err := client.NewEnvClient()
if err != nil {
return "", err
}
ctx := context.Background()
config := types.ExecConfig{
Cmd: strings.Split("powershell Get-PSDrive C | Select-Object Used,Free", " "),
AttachStdout: true,
AttachStderr: true,
}
response, err := cli.ContainerExecCreate(ctx,
// container id
"cf59d65ab1", config)
if err != nil {
return "", err
}
execID := response.ID
resp, err := cli.ContainerExecAttach(ctx, execID, config)
if err != nil {
return "", err
}
defer resp.Close()
stdout := new(bytes.Buffer)
stderr := new(bytes.Buffer)
_, err = stdcopy.StdCopy(stdout, stderr, resp.Reader)
if err != nil {
return "", err
}
s := stdout.String()
fmt.Println(s)
i := stderr.String()
fmt.Println(i)
return s, nil
}
Do remember to change the container id.