metrics: Add fio exec

This PR adds fio exec for the FIO benchmark.

Signed-off-by: Gabriela Cervantes <gabriela.cervantes.tellez@intel.com>

tests/metrics/storage/fio-k8s/pkg/exec/Exec.go

@@ -0,0 +1,68 @@
+// Copyright (c) 2021 Intel Corporation
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+package exec
+
+import (
+	"bytes"
+	"io"
+	"os"
+	"os/exec"
+
+	"github.com/pkg/errors"
+)
+
+//logger interface for pkg
+var log logger
+
+type logger interface {
+	Infof(string, ...interface{})
+	Debugf(string, ...interface{})
+	Errorf(string, ...interface{})
+}
+
+func SetLogger(l logger) {
+	log = l
+}
+
+// Exec a command
+// err != nil if command fails to execute
+// output is a string with a combined stdout and stderr
+func ExecCmd(c string, showInStdout bool) (stdout string, err error) {
+	if c == "" {
+		return "", errors.New("command is empty")
+	}
+
+	log.Debugf("Exec: %s", c)
+	cmd := exec.Command("bash", "-o", "pipefail", "-c", c)
+	var stdBuffer bytes.Buffer
+	var writers []io.Writer
+	writers = append(writers, &stdBuffer)
+	if showInStdout {
+		writers = append(writers, os.Stdout)
+	}
+	mw := io.MultiWriter(writers...)
+
+	cmd.Stdout = mw
+	cmd.Stderr = mw
+
+	err = cmd.Run()
+	output := stdBuffer.String()
+
+	return stdBuffer.String(), errors.Wrap(err, output)
+}
+
+// Exec a command
+// Send output to Stdout and Stderr
+func ExecStdout(c string) error {
+	if c == "" {
+		return errors.New("command is empty")
+	}
+
+	log.Debugf("Exec: %s", c)
+	cmd := exec.Command("bash", "-o", "pipefail", "-c", c)
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	return cmd.Run()
+}