如何使用 pyrax 将云块存储卷附加到 OnMetal 服务器？

Question

我想自动附加 Cloud Block Storage volume to an OnMetal server running CentOS 7 by writing a Python script that make uses of the pyrax Python 模块。你知道怎么做吗？

Answer 1

将云块存储卷附加到 OnMetal 服务器比将其附加到普通 Rackspace 虚拟服务器要复杂一些。当您尝试在 Rackspace Web 界面 Cloud Control Panel 中将 Cloud Block Storage 卷附加到 OnMetal 服务器时，您会注意到这一点，正如您将看到的文本：

注意：将卷附加到 OnMetal 服务器时，您必须登录到 OnMetal 服务器以设置启动器名称、发现目标然后连接到目标。

因此您可以在 Web 界面中附加卷，但您还需要登录 OnMetal 服务器和运行一些命令。实际命令可以从 Web 界面复制并粘贴到 OnMetal 服务器的终端。

此外，在分离之前，您需要运行命令。

但是网页界面其实是不需要的。可以用 Python 模块 pyrax.

来完成

首先在OnMetal服务器上安装RPM包iscsi-initiator-utils

[root@server-01 ~]# yum -y install iscsi-initiator-utils

假设 volume_id 和 server_id 已知，此 Python 代码首先附加卷，然后分离卷。不幸的是，mount_point 参数 attach_to_instance() 不适用于 OnMetal 服务器，因此我们需要在附加卷之前和之后使用命令 lsblk -n -d。通过比较输出，我们可以推断出用于附加卷的设备名称。（推断设备名称的部分未由以下 Python 代码处理）。

#/usr/bin/python
# Disclaimer: Use the script at your own Risk!                                                                                                                                    
import json
import os
import paramiko
import pyrax

# Replace server_id and volume_id                                                                                                                                                                       
# to your settings                                                                                                                                                                                      
server_id = "cbdcb7e3-5231-40ad-bba6-45aaeabf0a8d"
volume_id = "35abb4ba-caee-4cae-ada3-a16f6fa2ab50"
# Just to demonstrate that the mount_point argument for                                                                                                                                                 
# attach_to_instance() is not working for OnMetal servers                                                                                                                                               
disk_device = "/dev/xvdd"

def run_ssh_commands(ssh_client, remote_commands):
    for remote_command in remote_commands:
        stdin, stdout, stderr = ssh_client.exec_command(remote_command)
        print("")
        print("command: " + remote_command)
        for line in stdout.read().splitlines():
            print(" stdout: " + line)
        exit_status = stdout.channel.recv_exit_status()
        if exit_status != 0:
            raise RuntimeError("The command :\n{}\n"
                               "exited with exit status: {}\n"
                               "stderr: {}".format(remote_command,
                                                   exit_status,
                                                   stderr.read()))

pyrax.set_setting("identity_type", "rackspace")
pyrax.set_default_region('IAD')
creds_file = os.path.expanduser("~/.rackspace_cloud_credentials")
pyrax.set_credential_file(creds_file)
server = pyrax.cloudservers.servers.get(server_id)
vol = pyrax.cloud_blockstorage.find(id = volume_id)
vol.attach_to_instance(server, mountpoint=disk_device)
pyrax.utils.wait_until(vol, "status", "in-use", interval=3, attempts=0,
                       verbose=True)

ssh_client = paramiko.SSHClient()
ssh_client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
ssh_client.connect(server.accessIPv4, username='root', allow_agent=True)

# The new metadata is only available if we get() the server once more                                                                                                                                   
server = pyrax.cloudservers.servers.get(server_id)

metadata = server.metadata["volumes_" + volume_id]
parsed_json = json.loads(metadata)
target_iqn = parsed_json["target_iqn"]
target_portal = parsed_json["target_portal"]
initiator_name = parsed_json["initiator_name"]

run_ssh_commands(ssh_client, [
    "lsblk -n -d",
    "echo InitiatorName={} > /etc/iscsi/initiatorname.iscsi".format(initiator_name),
    "iscsiadm -m discovery --type sendtargets --portal {}".format(target_portal),
    "iscsiadm -m node --targetname={} --portal {} --login".format(target_iqn, target_portal),
    "lsblk -n -d",
    "iscsiadm -m node --targetname={} --portal {} --logout".format(target_iqn, target_portal),
    "lsblk -n -d"
])

vol.detach()
pyrax.utils.wait_until(vol, "status", "available", interval=3, attempts=0,
                                    verbose=True)

运行 python 代码如下所示

user@ubuntu:~$ python attach.py 2> /dev/null
Current value of status: attaching (elapsed:  1.0 seconds)
Current value of status: in-use (elapsed:  4.9 seconds)

command: lsblk -n -d
 stdout: sda    8:0    0 29.8G  0 disk

command: echo InitiatorName=iqn.2008-10.org.openstack:a24b6f80-cf02-48fc-9a25-ccc3ed3fb918 > /etc/iscsi/initiatorname.iscsi

command: iscsiadm -m discovery --type sendtargets --portal 10.190.142.116:3260
 stdout: 10.190.142.116:3260,1 iqn.2010-11.com.rackspace:35abb4bb-caee-4c5e-ad53-a16f6f12ab50
 stdout: 10.69.193.1:3260,1 iqn.2010-11.com.rackspace:35abb4bb-caee-4c5e-ad53-a16f6f12ab50

command: iscsiadm -m node --targetname=iqn.2010-11.com.rackspace:35abb4bb-caee-4c5e-ad53-a16f6f12ab50 --portal 10.190.142.116:3260 --login
 stdout: Logging in to [iface: default, target: iqn.2010-11.com.rackspace:35abb4bb-caee-4c5e-ad53-a16f6f12ab50, portal: 10.190.142.116,3260] (multiple)
 stdout: Login to [iface: default, target: iqn.2010-11.com.rackspace:35abb4bb-caee-4c5e-ad53-a16f6f12ab50, portal: 10.190.142.116,3260] successful.

command: lsblk -n -d
 stdout: sda    8:0    0 29.8G  0 disk
 stdout: sdb    8:16   0   50G  0 disk

command: iscsiadm -m node --targetname=iqn.2010-11.com.rackspace:35abb4bb-caee-4c5e-ad53-a16f6f12ab50 --portal 10.190.142.116:3260 --logout
 stdout: Logging out of session [sid: 5, target: iqn.2010-11.com.rackspace:35abb4bb-caee-4c5e-ad53-a16f6f12ab50, portal: 10.190.142.116,3260]
 stdout: Logout of [sid: 5, target: iqn.2010-11.com.rackspace:35abb4bb-caee-4c5e-ad53-a16f6f12ab50, portal: 10.190.142.116,3260] successful.

command: lsblk -n -d
 stdout: sda    8:0    0 29.8G  0 disk
Current value of status: detaching (elapsed:  0.8 seconds)
Current value of status: available (elapsed:  4.7 seconds)
user@ubuntu:~$

只是，补充一点：

虽然Rackspace官方文档中没有提到

https://support.rackspace.com/how-to/attach-a-cloud-block-storage-volume-to-an-onmetal-server/

在 2015 年 8 月 5 日的 forum post 中，Rackspace 托管基础设施支持还推荐运行ning

iscsiadm -m node -T $TARGET_IQN -p $TARGET_PORTAL --op update -n node.startup -v automatic

使连接持久化，以便它在启动时自动重新启动 iSCSI 会话。

更新

关于推断新设备名称：海登少校在 blog post 中写道

[root@server-01 ~]# ls /dev/disk/by-path/

可用于查找新设备的路径。如果您想尊重任何符号链接，我想这会起作用

[root@server-01 ~]# find -L /dev/disk/by-path -maxdepth 1 -mindepth 1 -exec realpath {} \;

如何使用 pyrax 将云块存储卷附加到 OnMetal 服务器？

How to attach a Cloud Block Storage volume to an OnMetal server with pyrax?

rackspace

rackspace-cloud

pyrax