libvirt

Overview

1. 前言

云计算离不开虚拟化,虚拟化绕不开libvirt。

因为开发虚拟机监控程序,花了一些时间学习libvirt, 这是一篇用来熟悉libvirt的博客。

2. libvirt

按照官方主页的介绍,libvirt项目是:

  • 一套用于管理虚拟化平台的工具
  • 支持C、Python、Perl、Java及其他语言
  • 使用开源license
  • 支持KVM、QEMU、Xen、Virtuozzo、VMWare ESX、LXC、BHyve及其他驱动
  • 支持Linux、FreeBSD、Windows及macOS等操作系统
  • 被许多应用使用

在Linux平台上以C/S的形式存在,libvirtd程序作为服务端管理虚拟机,接收和解析客户端请求,客户端可以是virsh命令行工具,也可以是基于libvirt库自行开发的程序。

架构如下,图片来自维基百科:

可以看到libvirt对用户屏蔽了底层hypervisor,向上提供了统一的接口。

2.1 为什么不直接使用KVM

博主在接触libvirtd前,一直都是直接使用qemu-kvm来玩虚拟机的,一般配置好参数和脚本后手动操作,控制虚拟机起停。

qemu本身也是一个模拟器,在Linux下可以利用kvm模块加速虚拟化,但qemu只是一个命令行工具,且参数多如牛毛,在用kvm调试安装黑苹果成功后,还是需要配置libvirtd实现开机自启动。

如果需要实现可编程的的虚拟机操作,我们需要:

  • 定义结构化的数据来虚拟机配置
  • 维护虚拟机的生命周期,包括创建、启动、停止、删除,并处理异常情况
  • 本地的Daemon维护虚拟机,向服务端提供API

开发和维护的工作量都不小,而libvirt不止做到这些,还提供一套虚拟化管理方案。

2.2 从virsh命令看libvirt

由于libvirt主要使用者都是云厂商的开发者,技术的应用者也不太可能公开分享实践经验。因此博主在入门时从virsh命令开始,熟悉通过virsh命令操作虚拟机后,再从API库中寻找对应的接口完成功能。

virsh帮助命令输出

  1➜  ~ virsh
  2
  3virsh [options]... [<command_string>]
  4virsh [options]... <command> [args...]
  5
  6  options:
  7    -c | --connect=URI      hypervisor connection URI
  8    -d | --debug=NUM        debug level [0-4]
  9    -e | --escape <char>    set escape sequence for console
 10    -h | --help             this help
 11    -k | --keepalive-interval=NUM
 12                            keepalive interval in seconds, 0 for disable
 13    -K | --keepalive-count=NUM
 14                            number of possible missed keepalive messages
 15    -l | --log=FILE         output logging to file
 16    -q | --quiet            quiet mode
 17    -r | --readonly         connect readonly
 18    -t | --timing           print timing information
 19    -v                      short version
 20    -V                      long version
 21         --version[=TYPE]   version, TYPE is short or long (default short)
 22  commands (non interactive mode):
 23
 24 Domain Management (help keyword 'domain')
 25    attach-device                  attach device from an XML file
 26    attach-disk                    attach disk device
 27    attach-interface               attach network interface
 28    autostart                      autostart a domain
 29    blkdeviotune                   Set or query a block device I/O tuning parameters.
 30    blkiotune                      Get or set blkio parameters
 31    blockcommit                    Start a block commit operation.
 32    blockcopy                      Start a block copy operation.
 33    blockjob                       Manage active block operations
 34    blockpull                      Populate a disk from its backing image.
 35    blockresize                    Resize block device of domain.
 36    change-media                   Change media of CD or floppy drive
 37    console                        connect to the guest console
 38    cpu-stats                      show domain cpu statistics
 39    create                         create a domain from an XML file
 40    define                         define (but don't start) a domain from an XML file
 41    desc                           show or set domain's description or title
 42    destroy                        destroy (stop) a domain
 43    detach-device                  detach device from an XML file
 44    detach-device-alias            detach device from an alias
 45    detach-disk                    detach disk device
 46    detach-interface               detach network interface
 47    domdisplay                     domain display connection URI
 48    domfsfreeze                    Freeze domain's mounted filesystems.
 49    domfsthaw                      Thaw domain's mounted filesystems.
 50    domfsinfo                      Get information of domain's mounted filesystems.
 51    domfstrim                      Invoke fstrim on domain's mounted filesystems.
 52    domhostname                    print the domain's hostname
 53    domid                          convert a domain name or UUID to domain id
 54    domif-setlink                  set link state of a virtual interface
 55    domiftune                      get/set parameters of a virtual interface
 56    domjobabort                    abort active domain job
 57    domjobinfo                     domain job information
 58    domname                        convert a domain id or UUID to domain name
 59    domrename                      rename a domain
 60    dompmsuspend                   suspend a domain gracefully using power management functions
 61    dompmwakeup                    wakeup a domain from pmsuspended state
 62    domuuid                        convert a domain name or id to domain UUID
 63    domxml-from-native             Convert native config to domain XML
 64    domxml-to-native               Convert domain XML to native config
 65    dump                           dump the core of a domain to a file for analysis
 66    dumpxml                        domain information in XML
 67    edit                           edit XML configuration for a domain
 68    event                          Domain Events
 69    inject-nmi                     Inject NMI to the guest
 70    iothreadinfo                   view domain IOThreads
 71    iothreadpin                    control domain IOThread affinity
 72    iothreadadd                    add an IOThread to the guest domain
 73    iothreaddel                    delete an IOThread from the guest domain
 74    send-key                       Send keycodes to the guest
 75    send-process-signal            Send signals to processes
 76    lxc-enter-namespace            LXC Guest Enter Namespace
 77    managedsave                    managed save of a domain state
 78    managedsave-remove             Remove managed save of a domain
 79    managedsave-edit               edit XML for a domain's managed save state file
 80    managedsave-dumpxml            Domain information of managed save state file in XML
 81    managedsave-define             redefine the XML for a domain's managed save state file
 82    memtune                        Get or set memory parameters
 83    perf                           Get or set perf event
 84    metadata                       show or set domain's custom XML metadata
 85    migrate                        migrate domain to another host
 86    migrate-setmaxdowntime         set maximum tolerable downtime
 87    migrate-getmaxdowntime         get maximum tolerable downtime
 88    migrate-compcache              get/set compression cache size
 89    migrate-setspeed               Set the maximum migration bandwidth
 90    migrate-getspeed               Get the maximum migration bandwidth
 91    migrate-postcopy               Switch running migration from pre-copy to post-copy
 92    numatune                       Get or set numa parameters
 93    qemu-attach                    QEMU Attach
 94    qemu-monitor-command           QEMU Monitor Command
 95    qemu-monitor-event             QEMU Monitor Events
 96    qemu-agent-command             QEMU Guest Agent Command
 97    reboot                         reboot a domain
 98    reset                          reset a domain
 99    restore                        restore a domain from a saved state in a file
100    resume                         resume a domain
101    save                           save a domain state to a file
102    save-image-define              redefine the XML for a domain's saved state file
103    save-image-dumpxml             saved state domain information in XML
104    save-image-edit                edit XML for a domain's saved state file
105    schedinfo                      show/set scheduler parameters
106    screenshot                     take a screenshot of a current domain console and store it into a file
107    set-lifecycle-action           change lifecycle actions
108    set-user-password              set the user password inside the domain
109    setmaxmem                      change maximum memory limit
110    setmem                         change memory allocation
111    setvcpus                       change number of virtual CPUs
112    shutdown                       gracefully shutdown a domain
113    start                          start a (previously defined) inactive domain
114    suspend                        suspend a domain
115    ttyconsole                     tty console
116    undefine                       undefine a domain
117    update-device                  update device from an XML file
118    vcpucount                      domain vcpu counts
119    vcpuinfo                       detailed domain vcpu information
120    vcpupin                        control or query domain vcpu affinity
121    emulatorpin                    control or query domain emulator affinity
122    vncdisplay                     vnc display
123    guestvcpus                     query or modify state of vcpu in the guest (via agent)
124    setvcpu                        attach/detach vcpu or groups of threads
125    domblkthreshold                set the threshold for block-threshold event for a given block device or it's backing chain element
126
127 Domain Monitoring (help keyword 'monitor')
128    domblkerror                    Show errors on block devices
129    domblkinfo                     domain block device size information
130    domblklist                     list all domain blocks
131    domblkstat                     get device block stats for a domain
132    domcontrol                     domain control interface state
133    domif-getlink                  get link state of a virtual interface
134    domifaddr                      Get network interfaces' addresses for a running domain
135    domiflist                      list all domain virtual interfaces
136    domifstat                      get network interface stats for a domain
137    dominfo                        domain information
138    dommemstat                     get memory statistics for a domain
139    domstate                       domain state
140    domstats                       get statistics about one or multiple domains
141    domtime                        domain time
142    list                           list domains
143
144 Host and Hypervisor (help keyword 'host')
145    allocpages                     Manipulate pages pool size
146    capabilities                   capabilities
147    cpu-baseline                   compute baseline CPU
148    cpu-compare                    compare host CPU with a CPU described by an XML file
149    cpu-models                     CPU models
150    domcapabilities                domain capabilities
151    freecell                       NUMA free memory
152    freepages                      NUMA free pages
153    hostname                       print the hypervisor hostname
154    hypervisor-cpu-baseline        compute baseline CPU usable by a specific hypervisor
155    hypervisor-cpu-compare         compare a CPU with the CPU created by a hypervisor on the host
156    maxvcpus                       connection vcpu maximum
157    node-memory-tune               Get or set node memory parameters
158    nodecpumap                     node cpu map
159    nodecpustats                   Prints cpu stats of the node.
160    nodeinfo                       node information
161    nodememstats                   Prints memory stats of the node.
162    nodesuspend                    suspend the host node for a given time duration
163    sysinfo                        print the hypervisor sysinfo
164    uri                            print the hypervisor canonical URI
165    version                        show version
166
167 Interface (help keyword 'interface')
168    iface-begin                    create a snapshot of current interfaces settings, which can be later committed (iface-commit) or restored (iface-rollback)
169    iface-bridge                   create a bridge device and attach an existing network device to it
170    iface-commit                   commit changes made since iface-begin and free restore point
171    iface-define                   define an inactive persistent physical host interface or modify an existing persistent one from an XML file
172    iface-destroy                  destroy a physical host interface (disable it / "if-down")
173    iface-dumpxml                  interface information in XML
174    iface-edit                     edit XML configuration for a physical host interface
175    iface-list                     list physical host interfaces
176    iface-mac                      convert an interface name to interface MAC address
177    iface-name                     convert an interface MAC address to interface name
178    iface-rollback                 rollback to previous saved configuration created via iface-begin
179    iface-start                    start a physical host interface (enable it / "if-up")
180    iface-unbridge                 undefine a bridge device after detaching its slave device
181    iface-undefine                 undefine a physical host interface (remove it from configuration)
182
183 Network Filter (help keyword 'filter')
184    nwfilter-define                define or update a network filter from an XML file
185    nwfilter-dumpxml               network filter information in XML
186    nwfilter-edit                  edit XML configuration for a network filter
187    nwfilter-list                  list network filters
188    nwfilter-undefine              undefine a network filter
189    nwfilter-binding-create        create a network filter binding from an XML file
190    nwfilter-binding-delete        delete a network filter binding
191    nwfilter-binding-dumpxml       network filter information in XML
192    nwfilter-binding-list          list network filter bindings
193
194 Networking (help keyword 'network')
195    net-autostart                  autostart a network
196    net-create                     create a network from an XML file
197    net-define                     define an inactive persistent virtual network or modify an existing persistent one from an XML file
198    net-destroy                    destroy (stop) a network
199    net-dhcp-leases                print lease info for a given network
200    net-dumpxml                    network information in XML
201    net-edit                       edit XML configuration for a network
202    net-event                      Network Events
203    net-info                       network information
204    net-list                       list networks
205    net-name                       convert a network UUID to network name
206    net-start                      start a (previously defined) inactive network
207    net-undefine                   undefine a persistent network
208    net-update                     update parts of an existing network's configuration
209    net-uuid                       convert a network name to network UUID
210
211 Node Device (help keyword 'nodedev')
212    nodedev-create                 create a device defined by an XML file on the node
213    nodedev-destroy                destroy (stop) a device on the node
214    nodedev-detach                 detach node device from its device driver
215    nodedev-dumpxml                node device details in XML
216    nodedev-list                   enumerate devices on this host
217    nodedev-reattach               reattach node device to its device driver
218    nodedev-reset                  reset node device
219    nodedev-event                  Node Device Events
220
221 Secret (help keyword 'secret')
222    secret-define                  define or modify a secret from an XML file
223    secret-dumpxml                 secret attributes in XML
224    secret-event                   Secret Events
225    secret-get-value               Output a secret value
226    secret-list                    list secrets
227    secret-set-value               set a secret value
228    secret-undefine                undefine a secret
229
230 Snapshot (help keyword 'snapshot')
231    snapshot-create                Create a snapshot from XML
232    snapshot-create-as             Create a snapshot from a set of args
233    snapshot-current               Get or set the current snapshot
234    snapshot-delete                Delete a domain snapshot
235    snapshot-dumpxml               Dump XML for a domain snapshot
236    snapshot-edit                  edit XML for a snapshot
237    snapshot-info                  snapshot information
238    snapshot-list                  List snapshots for a domain
239    snapshot-parent                Get the name of the parent of a snapshot
240    snapshot-revert                Revert a domain to a snapshot
241
242 Storage Pool (help keyword 'pool')
243    find-storage-pool-sources-as   find potential storage pool sources
244    find-storage-pool-sources      discover potential storage pool sources
245    pool-autostart                 autostart a pool
246    pool-build                     build a pool
247    pool-create-as                 create a pool from a set of args
248    pool-create                    create a pool from an XML file
249    pool-define-as                 define a pool from a set of args
250    pool-define                    define an inactive persistent storage pool or modify an existing persistent one from an XML file
251    pool-delete                    delete a pool
252    pool-destroy                   destroy (stop) a pool
253    pool-dumpxml                   pool information in XML
254    pool-edit                      edit XML configuration for a storage pool
255    pool-info                      storage pool information
256    pool-list                      list pools
257    pool-name                      convert a pool UUID to pool name
258    pool-refresh                   refresh a pool
259    pool-start                     start a (previously defined) inactive pool
260    pool-undefine                  undefine an inactive pool
261    pool-uuid                      convert a pool name to pool UUID
262    pool-event                     Storage Pool Events
263
264 Storage Volume (help keyword 'volume')
265    vol-clone                      clone a volume.
266    vol-create-as                  create a volume from a set of args
267    vol-create                     create a vol from an XML file
268    vol-create-from                create a vol, using another volume as input
269    vol-delete                     delete a vol
270    vol-download                   download volume contents to a file
271    vol-dumpxml                    vol information in XML
272    vol-info                       storage vol information
273    vol-key                        returns the volume key for a given volume name or path
274    vol-list                       list vols
275    vol-name                       returns the volume name for a given volume key or path
276    vol-path                       returns the volume path for a given volume name or key
277    vol-pool                       returns the storage pool for a given volume key or path
278    vol-resize                     resize a vol
279    vol-upload                     upload file contents to a volume
280    vol-wipe                       wipe a vol
281
282 Virsh itself (help keyword 'virsh')
283    cd                             change the current directory
284    echo                           echo arguments
285    exit                           quit this interactive terminal
286    help                           print help
287    pwd                            print the current directory
288    quit                           quit this interactive terminal
289    connect                        (re)connect to hypervisor

在virsh的帮助命令中,所有的命令被划分为以下几类:

  • domain:虚拟机管理命令,domain对应虚拟机,libvirt使用xml描述虚拟机配置。需要首先通过define将虚拟机导入libvirtd,然后才能执行start、shutdown、destroy等开机、关机、强制关机操作,domain相关的命令接收ID或Name作为参数(在每台宿主机上需唯一)。domain相关命令对应API中Domain对象的方法集合,我们首选需要获取到一个domain引用,然后才能执行操作。
  • monitor:监控命令,可获取domain的配置、运行状态、统计数据等。
  • host:宿主机管理命令,用于获取和操作宿主机。
  • interface:网卡管理命令,比较少用,一般自行管理网络,使用VXLAN、Bridge、TUN/TAP将虚拟机接入用户网络。
  • filter:防火墙管理命令,可读取xml格式定义等防火墙规则,按虚拟机网卡配置防火墙。
  • network:网络相关命令,这里指的是libvirt的网络,默认使用Bridge和TUN/TAP将虚拟机加入宿主机网络,使用DHCP和iptables为虚拟机提供网络。
  • nodedev:宿主机设备管理命令,可将宿主机设备,例如GPU、USB、PCIe设备等分配给虚拟机。
  • secret:密钥管理命令。
  • snapshot:快照管理命令。
  • pool:存储池管理命令,一个存储池内可存放多个卷。
  • volume:数据卷管理命令。

virsh命令基于libvirt库开发的,因为libvirt有着良好的API架构,熟悉virsh命令对使用API有很大的帮助。

2.3 API

官方文档链接:Reference Manual for libvirt

在目录中我们可以看到与virsh命令几乎一一对应的API。

libvirt使用C语言编写,提供稳定的C API,对其他语言的支持也是通过C API的绑定实现的,因此本地需要安装相关的C开发库,并运行libvirtd守护进程。

以Go语言和CentOS 7为例,官方Go语言库为:libvirt-go,与C库版本同步向后兼容到v1.2.0,可用于生产环境。

开发环境需要安装gcc、libvirt、libvirt-devel、centos-release-qemu-ev等,该库通过CGO调用libvrt C库,访问本地的UNIX套接字来与libvirtd通信。因此不可避免需要开发本地Daemon程序,相当于在libvirtd基础上再封装一层,但这也方便操作NFS、VXLAN、系统镜像等,实现更多自定义功能。

以获取虚拟机运行状态为例,流程通常为:

获取libvirt连接 -> 按ID获取domain -> 执行操作 -> 释放domain

如下所示:

 1conn, err := libvirt.NewConnect("qemu:///system")
 2if err != nil {
 3    ...
 4}
 5defer conn.Close()
 6doms, err := conn.ListAllDomains(libvirt.CONNECT_LIST_DOMAINS_ACTIVE)
 7if err != nil {
 8    ...
 9}
10fmt.Printf("%d running domains:\n", len(doms))
11for _, dom := range doms {
12    name, err := dom.GetName()
13    if err == nil {
14        fmt.Printf("  %s\n", name)
15    }
16    dom.Free()
17}

我们可以把常用的操作封装为函数,确保所有成功打开的连接和domain都被正确释放。

有CGO的地方,就有纯GO实现。digitalocean开源了他们内部使用的libvirt库:go-libvirt,这个库通过libvirt的RPC接口与守护进程通信,不需要引用C库,可通过网络远程调用libvirtd,唯一的缺点是不稳定。

2.4 虚拟机状态

libvirt-go提供的虚拟机状态分为当前状态state与导致当前状态的原因reason,由于含义都在源码注释中,下面整理了英文注释:

  1/**
  2 * virDomainState:
  3 *
  4 * A domain may be in different states at a given point in time
  5 */
  6typedef enum {
  7    VIR_DOMAIN_NOSTATE = 0,     /* no state */
  8    VIR_DOMAIN_RUNNING = 1,     /* the domain is running */
  9    VIR_DOMAIN_BLOCKED = 2,     /* the domain is blocked on resource */
 10    VIR_DOMAIN_PAUSED  = 3,     /* the domain is paused by user */
 11    VIR_DOMAIN_SHUTDOWN= 4,     /* the domain is being shut down */
 12    VIR_DOMAIN_SHUTOFF = 5,     /* the domain is shut off */
 13    VIR_DOMAIN_CRASHED = 6,     /* the domain is crashed */
 14    VIR_DOMAIN_PMSUSPENDED = 7, /* the domain is suspended by guest
 15                                   power management */
 16
 17# ifdef VIR_ENUM_SENTINELS
 18    VIR_DOMAIN_LAST
 19    /*
 20     * NB: this enum value will increase over time as new events are
 21     * added to the libvirt API. It reflects the last state supported
 22     * by this version of the libvirt API.
 23     */
 24# endif
 25} virDomainState;
 26
 27typedef enum {
 28    VIR_DOMAIN_NOSTATE_UNKNOWN = 0,
 29
 30# ifdef VIR_ENUM_SENTINELS
 31    VIR_DOMAIN_NOSTATE_LAST
 32# endif
 33} virDomainNostateReason;
 34
 35typedef enum {
 36    VIR_DOMAIN_RUNNING_UNKNOWN = 0,
 37    VIR_DOMAIN_RUNNING_BOOTED = 1,          /* normal startup from boot */
 38    VIR_DOMAIN_RUNNING_MIGRATED = 2,        /* migrated from another host */
 39    VIR_DOMAIN_RUNNING_RESTORED = 3,        /* restored from a state file */
 40    VIR_DOMAIN_RUNNING_FROM_SNAPSHOT = 4,   /* restored from snapshot */
 41    VIR_DOMAIN_RUNNING_UNPAUSED = 5,        /* returned from paused state */
 42    VIR_DOMAIN_RUNNING_MIGRATION_CANCELED = 6,  /* returned from migration */
 43    VIR_DOMAIN_RUNNING_SAVE_CANCELED = 7,   /* returned from failed save process */
 44    VIR_DOMAIN_RUNNING_WAKEUP = 8,          /* returned from pmsuspended due to
 45                                               wakeup event */
 46    VIR_DOMAIN_RUNNING_CRASHED = 9,         /* resumed from crashed */
 47    VIR_DOMAIN_RUNNING_POSTCOPY = 10,       /* running in post-copy migration mode */
 48
 49# ifdef VIR_ENUM_SENTINELS
 50    VIR_DOMAIN_RUNNING_LAST
 51# endif
 52} virDomainRunningReason;
 53
 54typedef enum {
 55    VIR_DOMAIN_BLOCKED_UNKNOWN = 0,     /* the reason is unknown */
 56
 57# ifdef VIR_ENUM_SENTINELS
 58    VIR_DOMAIN_BLOCKED_LAST
 59# endif
 60} virDomainBlockedReason;
 61
 62typedef enum {
 63    VIR_DOMAIN_PAUSED_UNKNOWN = 0,      /* the reason is unknown */
 64    VIR_DOMAIN_PAUSED_USER = 1,         /* paused on user request */
 65    VIR_DOMAIN_PAUSED_MIGRATION = 2,    /* paused for offline migration */
 66    VIR_DOMAIN_PAUSED_SAVE = 3,         /* paused for save */
 67    VIR_DOMAIN_PAUSED_DUMP = 4,         /* paused for offline core dump */
 68    VIR_DOMAIN_PAUSED_IOERROR = 5,      /* paused due to a disk I/O error */
 69    VIR_DOMAIN_PAUSED_WATCHDOG = 6,     /* paused due to a watchdog event */
 70    VIR_DOMAIN_PAUSED_FROM_SNAPSHOT = 7, /* paused after restoring from snapshot */
 71    VIR_DOMAIN_PAUSED_SHUTTING_DOWN = 8, /* paused during shutdown process */
 72    VIR_DOMAIN_PAUSED_SNAPSHOT = 9,      /* paused while creating a snapshot */
 73    VIR_DOMAIN_PAUSED_CRASHED = 10,     /* paused due to a guest crash */
 74    VIR_DOMAIN_PAUSED_STARTING_UP = 11, /* the domain is being started */
 75    VIR_DOMAIN_PAUSED_POSTCOPY = 12,    /* paused for post-copy migration */
 76    VIR_DOMAIN_PAUSED_POSTCOPY_FAILED = 13, /* paused after failed post-copy */
 77
 78# ifdef VIR_ENUM_SENTINELS
 79    VIR_DOMAIN_PAUSED_LAST
 80# endif
 81} virDomainPausedReason;
 82
 83typedef enum {
 84    VIR_DOMAIN_SHUTDOWN_UNKNOWN = 0,    /* the reason is unknown */
 85    VIR_DOMAIN_SHUTDOWN_USER = 1,       /* shutting down on user request */
 86
 87# ifdef VIR_ENUM_SENTINELS
 88    VIR_DOMAIN_SHUTDOWN_LAST
 89# endif
 90} virDomainShutdownReason;
 91
 92typedef enum {
 93    VIR_DOMAIN_SHUTOFF_UNKNOWN = 0,     /* the reason is unknown */
 94    VIR_DOMAIN_SHUTOFF_SHUTDOWN = 1,    /* normal shutdown */
 95    VIR_DOMAIN_SHUTOFF_DESTROYED = 2,   /* forced poweroff */
 96    VIR_DOMAIN_SHUTOFF_CRASHED = 3,     /* domain crashed */
 97    VIR_DOMAIN_SHUTOFF_MIGRATED = 4,    /* migrated to another host */
 98    VIR_DOMAIN_SHUTOFF_SAVED = 5,       /* saved to a file */
 99    VIR_DOMAIN_SHUTOFF_FAILED = 6,      /* domain failed to start */
100    VIR_DOMAIN_SHUTOFF_FROM_SNAPSHOT = 7, /* restored from a snapshot which was
101                                           * taken while domain was shutoff */
102    VIR_DOMAIN_SHUTOFF_DAEMON = 8,      /* daemon decides to kill domain
103                                           during reconnection processing */
104# ifdef VIR_ENUM_SENTINELS
105    VIR_DOMAIN_SHUTOFF_LAST
106# endif
107} virDomainShutoffReason;
108
109typedef enum {
110    VIR_DOMAIN_CRASHED_UNKNOWN = 0,     /* crashed for unknown reason */
111    VIR_DOMAIN_CRASHED_PANICKED = 1,    /* domain panicked */
112
113# ifdef VIR_ENUM_SENTINELS
114    VIR_DOMAIN_CRASHED_LAST
115# endif
116} virDomainCrashedReason;
117
118typedef enum {
119    VIR_DOMAIN_PMSUSPENDED_UNKNOWN = 0,
120
121# ifdef VIR_ENUM_SENTINELS
122    VIR_DOMAIN_PMSUSPENDED_LAST
123# endif
124} virDomainPMSuspendedReason;
125
126typedef enum {
127    VIR_DOMAIN_PMSUSPENDED_DISK_UNKNOWN = 0,
128
129# ifdef VIR_ENUM_SENTINELS
130    VIR_DOMAIN_PMSUSPENDED_DISK_LAST
131# endif
132} virDomainPMSuspendedDiskReason;

博主按照枚举数值整理如下:

  • 0:nostate,无状态
  • 1:running,运行中
    • unknown:未知
    • booted:正常开机启动
    • migrated:从其他宿主机迁移后启动
    • restored:从状态文件恢复运行
    • fromSnapshot:从快照恢复运行
    • unpaused:从挂起状态恢复运行
    • migrationCanceled:取消迁移状态后恢复运行
    • saveCancel:取消保存后恢复运行
    • wakeup:唤醒后恢复运行
    • crashed:从crash状态恢复启动
    • postCopy:复制结束后恢复启动
  • 2:blocked,因为资源阻塞
    • unknown:未知
  • 3:pause,挂起
    • unkown:未知
    • user:用户主动执行挂起
    • migration:执行迁移导致的挂起
    • save:保存虚拟机导致的挂起
    • dump:dump虚拟机导致的挂起
    • IOError:磁盘IO错误导致的挂起
    • watchdog:看门狗事件导致的挂起
    • fromSnapshot:从快照恢复后挂起
    • shuttingDown:关机时挂起
    • snapshot:创建快照时挂起
    • crash:虚拟机crash导致的挂起
    • startingUp:虚拟机正在启动
    • postCopy:post-copy迁移导致的挂起
    • postCopyFaiied:post-copy失败后的挂起
  • 4:shutdown,正在关机
    • unknown:未知
    • user:用户主动关机
  • 5:shutoff,已关闭
    • unknown:未知
    • shutdown:正常关机
    • destroyed:强制关机
    • crashed:domain crash
    • migrated:已迁移到其他host
    • saved:已保存到文件
    • failed:domain无法启动
    • fromSnapshot:从domain关闭时生成的快照恢复
    • daemon:被守护进程终结
  • 6:crash,crash
    • unknown:未知
    • panicked:domain panic
  • 7:pmsuspend,由虚拟机的电源管理挂起
    • unknown:未知

3. 写在最后

博主的负责的虚拟机监控程序涉及libvirt内容比较简单,基本仅限于上面的示例代码:获取虚拟机状态上报服务端。

状态通过调接口就可以获取,比较麻烦的是做相关测试来确定libvirtd状态与业务状态的转换关系。

如果未来有更多虚拟机相关的开发工作时,应该会再深入研究一些API内部实现。

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