Add logging binary support when terminal is true

Currently the shims only support starting the logging binary process if the
io.Creator Config does not specify Terminal: true. This means that the program
using containerd will only be able to specify FIFO io when Terminal: true,
rather than allowing the shim to fork the logging binary process. Hence,
containerd consumers face an inconsistent behavior regarding logging binary
management depending on the Terminal option.

Allowing the shim to fork the logging binary process will introduce consistency
between the running container and the logging process. Otherwise, the logging
process may die if its parent process dies whereas the container will keep
running, resulting in the loss of container logs.

Signed-off-by: Akshat Kumar <kshtku@amazon.com>

cio/io.go

@@ -260,6 +260,26 @@ func BinaryIO(binary string, args map[string]string) Creator {
 	}
 }
 
+// TerminalBinaryIO forwards container STDOUT|STDERR directly to a logging binary
+// It also sets the terminal option to true
+func TerminalBinaryIO(binary string, args map[string]string) Creator {
+	return func(_ string) (IO, error) {
+		uri, err := LogURIGenerator("binary", binary, args)
+		if err != nil {
+			return nil, err
+		}
+
+		res := uri.String()
+		return &logURI{
+			config: Config{
+				Stdout:   res,
+				Stderr:   res,
+				Terminal: true,
+			},
+		}, nil
+	}
+}
+
 // LogFile creates a file on disk that logs the task's STDOUT,STDERR.
 // If the log file already exists, the logs will be appended to the file.
 func LogFile(path string) Creator {