f789aa7baf
Currently, qemu-ga may die/get killed/go away for whatever reason after guest-fsfreeze-freeze has been issued, and before guest-fsfreeze-thaw has been issued. This means the only way to unfreeze the guest is via VNC/network/console access, but obtaining that access after-the-fact can often be very difficult when filesystems are frozen. Logins will almost always hang, for instance. In many cases the only recourse would be to reboot the guest without any quiescing of volatile state, which makes this a corner-case worth giving some attention to. A likely failsafe for this situation would be to use a watchdog to restart qemu-ga if it goes away. There are some precautions qemu-ga needs to take in order to avoid immediately hanging itself on I/O, however, namely, we must disable logging and defer to processing/creation of user-specific logfiles, along with creation of the pid file if we're running as a daemon. We also need to disable non-fsfreeze-safe commands, as we normally would when processing the guest-fsfreeze-freeze command. To track when we need to do this in a way that persists between multiple invocations of qemu-ga, we create a file on the guest filesystem before issuing the fsfreeze, and delete it when doing the thaw. On qemu-ga startup, we check for the existance of this file to determine the need to take the above precautions. We're forced to do it this way since a more traditional approach such as reading/writing state to a dedicated state file will cause access/modification time updates, respectively, both of which will hang if the file resides on a frozen filesystem. Both can occur even if relatime is enabled. Checking for file existence will not update the access time, however, so it's a safe way to check for fsfreeze state. An actual watchdog-based restart of qemu-ga can itself cause an access time update that would thus hang the invocation of qemu-ga, but the logic to workaround that can be handled via the watchdog, so we don't address that here (for relatime we'd periodically touch the qemu-ga binary if the file $qga_statedir/qga.state.isfrozen is not present, this avoids qemu-ga updates or the 1 day relatime threshold causing an access-time update if we try to respawn qemu-ga shortly after it goes away) Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
483 lines
12 KiB
Python
483 lines
12 KiB
Python
# *-*- Mode: Python -*-*
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##
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#
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# Echo back a unique integer value, and prepend to response a
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# leading sentinel byte (0xFF) the client can check scan for.
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#
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# This is used by clients talking to the guest agent over the
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# wire to ensure the stream is in sync and doesn't contain stale
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# data from previous client. It must be issued upon initial
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# connection, and after any client-side timeouts (including
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# timeouts on receiving a response to this command).
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#
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# After issuing this request, all guest agent responses should be
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# ignored until the response containing the unique integer value
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# the client passed in is returned. Receival of the 0xFF sentinel
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# byte must be handled as an indication that the client's
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# lexer/tokenizer/parser state should be flushed/reset in
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# preparation for reliably receiving the subsequent response. As
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# an optimization, clients may opt to ignore all data until a
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# sentinel value is receiving to avoid unecessary processing of
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# stale data.
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#
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# Similarly, clients should also precede this *request*
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# with a 0xFF byte to make sure the guest agent flushes any
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# partially read JSON data from a previous client connection.
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#
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# @id: randomly generated 64-bit integer
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#
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# Returns: The unique integer id passed in by the client
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#
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# Since: 1.1
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# ##
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{ 'command': 'guest-sync-delimited'
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'data': { 'id': 'int' },
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'returns': 'int' }
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##
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# @guest-sync:
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#
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# Echo back a unique integer value
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#
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# This is used by clients talking to the guest agent over the
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# wire to ensure the stream is in sync and doesn't contain stale
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# data from previous client. All guest agent responses should be
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# ignored until the provided unique integer value is returned,
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# and it is up to the client to handle stale whole or
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# partially-delivered JSON text in such a way that this response
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# can be obtained.
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#
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# In cases where a partial stale response was previously
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# received by the client, this cannot always be done reliably.
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# One particular scenario being if qemu-ga responses are fed
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# character-by-character into a JSON parser. In these situations,
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# using guest-sync-delimited may be optimal.
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#
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# For clients that fetch responses line by line and convert them
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# to JSON objects, guest-sync should be sufficient, but note that
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# in cases where the channel is dirty some attempts at parsing the
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# response may result in a parser error.
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#
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# Such clients should also precede this command
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# with a 0xFF byte to make sure the guest agent flushes any
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# partially read JSON data from a previous session.
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#
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# @id: randomly generated 64-bit integer
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#
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# Returns: The unique integer id passed in by the client
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-sync'
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'data': { 'id': 'int' },
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'returns': 'int' }
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##
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# @guest-ping:
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#
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# Ping the guest agent, a non-error return implies success
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-ping' }
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##
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# @GuestAgentCommandInfo:
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#
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# Information about guest agent commands.
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#
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# @name: name of the command
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#
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# @enabled: whether command is currently enabled by guest admin
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#
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# Since 1.1.0
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##
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{ 'type': 'GuestAgentCommandInfo',
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'data': { 'name': 'str', 'enabled': 'bool' } }
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##
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# @GuestAgentInfo
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#
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# Information about guest agent.
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#
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# @version: guest agent version
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#
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# @supported_commands: Information about guest agent commands
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#
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# Since 0.15.0
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##
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{ 'type': 'GuestAgentInfo',
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'data': { 'version': 'str',
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'supported_commands': ['GuestAgentCommandInfo'] } }
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##
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# @guest-info:
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#
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# Get some information about the guest agent.
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#
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# Returns: @GuestAgentInfo
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-info',
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'returns': 'GuestAgentInfo' }
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##
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# @guest-shutdown:
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#
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# Initiate guest-activated shutdown. Note: this is an asynchronous
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# shutdown request, with no guaruntee of successful shutdown. Errors
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# will be logged to guest's syslog.
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#
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# @mode: #optional "halt", "powerdown" (default), or "reboot"
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#
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# Returns: Nothing on success
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-shutdown', 'data': { '*mode': 'str' } }
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##
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# @guest-file-open:
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#
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# Open a file in the guest and retrieve a file handle for it
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#
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# @filepath: Full path to the file in the guest to open.
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#
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# @mode: #optional open mode, as per fopen(), "r" is the default.
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#
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# Returns: Guest file handle on success.
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-file-open',
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'data': { 'path': 'str', '*mode': 'str' },
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'returns': 'int' }
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##
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# @guest-file-close:
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#
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# Close an open file in the guest
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#
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# @handle: filehandle returned by guest-file-open
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#
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# Returns: Nothing on success.
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-file-close',
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'data': { 'handle': 'int' } }
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##
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# @GuestFileRead
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#
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# Result of guest agent file-read operation
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#
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# @count: number of bytes read (note: count is *before*
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# base64-encoding is applied)
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#
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# @buf-b64: base64-encoded bytes read
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#
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# @eof: whether EOF was encountered during read operation.
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#
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# Since: 0.15.0
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##
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{ 'type': 'GuestFileRead',
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'data': { 'count': 'int', 'buf-b64': 'str', 'eof': 'bool' } }
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##
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# @guest-file-read:
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#
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# Read from an open file in the guest. Data will be base64-encoded
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#
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# @handle: filehandle returned by guest-file-open
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#
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# @count: #optional maximum number of bytes to read (default is 4KB)
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#
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# Returns: @GuestFileRead on success.
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-file-read',
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'data': { 'handle': 'int', '*count': 'int' },
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'returns': 'GuestFileRead' }
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##
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# @GuestFileWrite
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#
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# Result of guest agent file-write operation
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#
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# @count: number of bytes written (note: count is actual bytes
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# written, after base64-decoding of provided buffer)
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#
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# @eof: whether EOF was encountered during write operation.
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#
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# Since: 0.15.0
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##
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{ 'type': 'GuestFileWrite',
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'data': { 'count': 'int', 'eof': 'bool' } }
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##
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# @guest-file-write:
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#
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# Write to an open file in the guest.
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#
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# @handle: filehandle returned by guest-file-open
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#
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# @buf-b64: base64-encoded string representing data to be written
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#
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# @count: #optional bytes to write (actual bytes, after base64-decode),
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# default is all content in buf-b64 buffer after base64 decoding
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#
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# Returns: @GuestFileWrite on success.
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-file-write',
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'data': { 'handle': 'int', 'buf-b64': 'str', '*count': 'int' },
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'returns': 'GuestFileWrite' }
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##
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# @GuestFileSeek
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#
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# Result of guest agent file-seek operation
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#
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# @position: current file position
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#
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# @eof: whether EOF was encountered during file seek
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#
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# Since: 0.15.0
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##
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{ 'type': 'GuestFileSeek',
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'data': { 'position': 'int', 'eof': 'bool' } }
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##
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# @guest-file-seek:
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#
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# Seek to a position in the file, as with fseek(), and return the
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# current file position afterward. Also encapsulates ftell()'s
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# functionality, just Set offset=0, whence=SEEK_CUR.
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#
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# @handle: filehandle returned by guest-file-open
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#
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# @offset: bytes to skip over in the file stream
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#
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# @whence: SEEK_SET, SEEK_CUR, or SEEK_END, as with fseek()
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#
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# Returns: @GuestFileSeek on success.
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-file-seek',
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'data': { 'handle': 'int', 'offset': 'int', 'whence': 'int' },
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'returns': 'GuestFileSeek' }
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##
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# @guest-file-flush:
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#
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# Write file changes bufferred in userspace to disk/kernel buffers
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#
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# @handle: filehandle returned by guest-file-open
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#
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# Returns: Nothing on success.
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-file-flush',
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'data': { 'handle': 'int' } }
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##
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# @GuestFsFreezeStatus
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#
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# An enumation of filesystem freeze states
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#
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# @thawed: filesystems thawed/unfrozen
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#
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# @frozen: all non-network guest filesystems frozen
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#
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# Since: 0.15.0
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##
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{ 'enum': 'GuestFsfreezeStatus',
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'data': [ 'thawed', 'frozen' ] }
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##
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# @guest-fsfreeze-status:
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#
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# Get guest fsfreeze state. error state indicates
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#
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# Returns: GuestFsfreezeStatus ("thawed", "frozen", etc., as defined below)
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#
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# Note: This may fail to properly report the current state as a result of
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# some other guest processes having issued an fs freeze/thaw.
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-fsfreeze-status',
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'returns': 'GuestFsfreezeStatus' }
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##
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# @guest-fsfreeze-freeze:
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#
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# Sync and freeze all freezable, local guest filesystems
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#
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# Returns: Number of file systems currently frozen. On error, all filesystems
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# will be thawed.
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-fsfreeze-freeze',
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'returns': 'int' }
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##
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# @guest-fsfreeze-thaw:
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#
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# Unfreeze all frozen guest filesystems
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#
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# Returns: Number of file systems thawed by this call
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#
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# Note: if return value does not match the previous call to
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# guest-fsfreeze-freeze, this likely means some freezable
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# filesystems were unfrozen before this call, and that the
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# filesystem state may have changed before issuing this
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# command.
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-fsfreeze-thaw',
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'returns': 'int' }
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##
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# @guest-suspend-disk
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#
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# Suspend guest to disk.
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#
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# This command tries to execute the scripts provided by the pm-utils package.
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# If it's not available, the suspend operation will be performed by manually
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# writing to a sysfs file.
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#
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# For the best results it's strongly recommended to have the pm-utils
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# package installed in the guest.
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#
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# Returns: nothing on success
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# If suspend to disk is not supported, Unsupported
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#
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# Notes: o This is an asynchronous request. There's no guarantee a response
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# will be sent
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# o It's strongly recommended to issue the guest-sync command before
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# sending commands when the guest resumes
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#
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# Since: 1.1
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##
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{ 'command': 'guest-suspend-disk' }
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##
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# @guest-suspend-ram
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#
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# Suspend guest to ram.
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#
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# This command tries to execute the scripts provided by the pm-utils package.
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# If it's not available, the suspend operation will be performed by manually
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# writing to a sysfs file.
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#
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# For the best results it's strongly recommended to have the pm-utils
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# package installed in the guest.
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#
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# IMPORTANT: guest-suspend-ram requires QEMU to support the 'system_wakeup'
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# command. Thus, it's *required* to query QEMU for the presence of the
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# 'system_wakeup' command before issuing guest-suspend-ram.
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#
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# Returns: nothing on success
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# If suspend to ram is not supported, Unsupported
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#
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# Notes: o This is an asynchronous request. There's no guarantee a response
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# will be sent
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# o It's strongly recommended to issue the guest-sync command before
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# sending commands when the guest resumes
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#
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# Since: 1.1
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##
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{ 'command': 'guest-suspend-ram' }
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##
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# @guest-suspend-hybrid
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#
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# Save guest state to disk and suspend to ram.
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#
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# This command requires the pm-utils package to be installed in the guest.
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#
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# IMPORTANT: guest-suspend-hybrid requires QEMU to support the 'system_wakeup'
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# command. Thus, it's *required* to query QEMU for the presence of the
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# 'system_wakeup' command before issuing guest-suspend-hybrid.
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#
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# Returns: nothing on success
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# If hybrid suspend is not supported, Unsupported
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#
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# Notes: o This is an asynchronous request. There's no guarantee a response
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# will be sent
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# o It's strongly recommended to issue the guest-sync command before
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# sending commands when the guest resumes
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#
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# Since: 1.1
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##
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{ 'command': 'guest-suspend-hybrid' }
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##
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# @GuestIpAddressType:
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#
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# An enumeration of supported IP address types
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#
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# @ipv4: IP version 4
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#
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# @ipv6: IP version 6
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#
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# Since: 1.1
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##
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{ 'enum': 'GuestIpAddressType',
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'data': [ 'ipv4', 'ipv6' ] }
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##
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# @GuestIpAddress:
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#
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# @ip-address: IP address
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#
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# @ip-address-type: Type of @ip-address (e.g. ipv4, ipv6)
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#
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# @prefix: Network prefix length of @ip-address
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#
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# Since: 1.1
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##
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{ 'type': 'GuestIpAddress',
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'data': {'ip-address': 'str',
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'ip-address-type': 'GuestIpAddressType',
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'prefix': 'int'} }
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##
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# @GuestNetworkInterface:
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#
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# @name: The name of interface for which info are being delivered
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#
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# @hardware-address: Hardware address of @name
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#
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# @ip-addresses: List of addresses assigned to @name
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#
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# Since: 1.1
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##
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{ 'type': 'GuestNetworkInterface',
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'data': {'name': 'str',
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'*hardware-address': 'str',
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'*ip-addresses': ['GuestIpAddress'] } }
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##
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# @guest-network-get-interfaces:
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#
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# Get list of guest IP addresses, MAC addresses
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# and netmasks.
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#
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# Returns: List of GuestNetworkInfo on success.
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#
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# Since: 1.1
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##
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{ 'command': 'guest-network-get-interfaces',
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'returns': ['GuestNetworkInterface'] }
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