Enable detached exec for remote

The biggest obstacle here was cleanup - we needed a way to remove
detached exec sessions after they exited, but there's no way to
tell if an exec session will be attached or detached when it's
created, and that's when we must add the exit command that would
do the removal. The solution was adding a delay to the exit
command (5 minutes), which gives sufficient time for attached
exec sessions to retrieve the exit code of the session after it
exits, but still guarantees that they will be removed, even for
detached sessions. This requires Conmon 2.0.17, which has the new
`--exit-delay` flag.

As part of the exit command rework, we can drop the hack we were
using to clean up exec sessions (remove them as part of inspect).
This is a lot cleaner, and I'm a lot happier about it.

Otherwise, this is just plumbing - we need a bindings call for
detached exec, and that needed to be added to the tunnel mode
backend for entities.

Signed-off-by: Matthew Heon <matthew.heon@pm.me>

1 files changed, 29 insertions, 0 deletions

diff --git a/pkg/bindings/containers/exec.go b/pkg/bindings/containers/exec.go
index 2aeeae1f8..73cfb5079 100644
--- a/pkg/bindings/containers/exec.go
+++ b/pkg/bindings/containers/exec.go
@@ -1,6 +1,7 @@
 package containers
 
 import (
+	"bytes"
 	"context"
 	"net/http"
 	"strings"
@@ -69,3 +70,31 @@ func ExecInspect(ctx context.Context, sessionID string) (*define.InspectExecSess
 
 	return respStruct, nil
 }
+
+// ExecStart starts (but does not attach to) a given exec session.
+func ExecStart(ctx context.Context, sessionID string) error {
+	conn, err := bindings.GetClient(ctx)
+	if err != nil {
+		return err
+	}
+
+	logrus.Debugf("Starting exec session ID %q", sessionID)
+
+	// We force Detach to true
+	body := struct {
+		Detach bool `json:"Detach"`
+	}{
+		Detach: true,
+	}
+	bodyJSON, err := json.Marshal(body)
+	if err != nil {
+		return err
+	}
+
+	resp, err := conn.DoRequest(bytes.NewReader(bodyJSON), http.MethodPost, "/exec/%s/start", nil, nil, sessionID)
+	if err != nil {
+		return err
+	}
+
+	return resp.Process(nil)
+}