Release notes
=============


0.9 (2017-09-01)
----------------

- [feature] Allow managing host memory with a "maximum total" of memory that
  can be configured on VMs (-m switch). This is not based on actual RAM usage or availability but planned and configured values of currently running VMs!

  If a VM shall be inmigrated or started and the host would go beyond the
  'vm-max-total-memory' setting with that VM then the action will fail.

- [locking] Fix locking by moving to a separate lockfile and ensuring that
  reentrant use of locks is handled correctly. Also, provide upgrade scenario
  by additionally using the existing lock files.

- [locking] Ensure we rewrite the config file only when locked to reduce
  attack surface of the old mechanism while still upgrading.

- [logging] Improve logging with more specific debug output.

- [logging] Log the specific commandline that each Qemu process is started
  with to aid debugging.

- [logging] Switch logging from UTC to local server time. This has proven much
  more confusing as our other on-disk logs are in server time.

- [logging] Do not crash on broken logging (i.e. disk full or STDIO missing)
  to avoid accidentally crashing a VM just because the controlling script runs into issues.

- [logging] Add VM name prefixes also for stack dumps and tracebacks.

- [consul] Ensure that consul event handling doesn't fail the process when
  a thread fails. (Might be snake oil but doesn't hurt.)

- [consul] Reduce consul event handling pool from 10 to 3 to reduce strain on
  multiple parallel migrations.

- [ceph] Properly close RBD volume references to avoid librbd crash.

- [ceph] Ensure we don't open unnecessary duplicate RBD image handles.

- [qemu] Increase Qemu QMP timeout to 5 minutes to tolerate latency during
  migration cleanup as the QMP handler runs in the main thread and could be
  blocked for a long period.

- [migration] Improve outgoing migrations connecting to the incoming server:
  simplify code and reduce unnecessary waiting periods. Better error output.

- [migration] Improve live migration: skip compression, enable unlimited
  bandwidth, and use ephemeral ports to avoid running into TCP timing issues when retrying live migrations quickly.

- [config] Clean up default-option handling for some config options: we used
  two different styles of defaults. They have been unified into a single
  "default.conf" that gets loaded first.


0.8.11 (2017-05-29)
-------------------

- Add thousands separator in logging to live migration log to allow easier
  optical inspection.

- Improve fsfreeze timeout handling: this can take quite a while and if we
  are too eager then we end up quickly in unstable states.

- Improve error and debug logging.

- Improve resilience of continuing locally after a failed migration.


0.8.10 (2017-04-12)
-------------------

- Improve logging: include PID of the running process to help detect and
  understand potential conflicts in parallel runs.

- Try harder to catch errors and retry correctly when resetting communication
  with an agent.

- Add another layer to protect the guest agent by acquiring an exclusive lock
  on the guest agent socket file.

- Keep trying to ensure a VM is unfrozen during regular `ensure` calls.


0.8.9 (2017-04-07)
------------------

- Improve guest agent communication. The guest agent may be in an
  inconsistent state that causes it to hang. We've seen this happening
  where we froze machines and then have the agent be inconsistent.

  This now properly resets the agent connection upon a sync by sending
  the recommend "wrong" UTF-8 byte that guarantees to interrupt the
  guest agent's JSON parser.

- Improve logging output when destroying a VM because of an inconsistent
  state. (#25158)


0.8.8 (2016-11-18)
------------------

- Bugfix: migrations that ran into a timeout because the remote side
  did not respond accidentally unlocked and cleaned up without shutting
  the VM down properly. This resulted in multiple instances of a single VM.

0.8.7 (2016-11-11)
------------------

- Don't change anything if a VM is marked online but no KVM host is assigned
  (#23965).
- Refactor Agent.ensure() for improved reliability and readability.
- Decline to create a consistent snapshot if a VM is offline.
- Speed up tests a bit.
- Don't spawn unqualified partprobe invocations in parallel.
- Make debug level logging a bit less verbose.


0.8.6 (2016-11-04)
------------------

- Break inconsistent Ceph locks if the host holding an old lock is sure that a
  VM is not running anymore (#23695).
- Migration compatibility between Qemu 2.5 and 2.7 (#23695).
- Always clean up unused resources like Consul service registrations and run
  files.
- Improve error reporting and logging.


0.8.5 (2016-10-31)
------------------

- Fixed a major bug with event processing: the consul event processor was
  using the multiprocessing.pool API incorrectly. This wasn't caught by the
  tests and resulted in silent "no ops" of all event processing mechanisms.


0.8.4 (2016-10-31)
------------------

- Waiting for Qemu to shutdown gracefully was not expecting a socket error,
  which caused restarts to fail (cleanly). #24434

- Limit the number of parallel processed consul events to avoid
  overloading the host. Can be configured in the fc-qemu config file through::

    [consul]
    event-threads = <INT>

  The default is 10 threads.

- Lower the overhead of processing a consul config change event: do not
  activate Ceph and Qemu connections and do not perform scrubbing (ensure)
  when the config hasn't changed. Ceph and Qemu connections aren't needed in
  that case and scrubbing is expected to be performed in a separate task from
  a scheduler, not from an event handler that is supposed to only respond to
  changes.

- Provide a default for the binary-generation counter to allow smooth
  upgrades from previous versions.


0.8.3 (2016-10-23)
------------------

- Lower the guest agent timeout to help the tests complete faster and also
  stay responsive if the guest shouldn't have an agent available either
  yet, or currently, or generally.

- Provide a Qemu config template variable that will determine the most current
  Qemu machine type, given a prefix to filter for.

- Provide a "binary generation counter" that is a) injected a boot
  (to /tmp/fc-data/qemu-binary-generation-booted) and b) updated during every
  "ensure" command (to /run/qemu-binary-generation-current). The guest should
  use a difference between those files to schedule a cold reboot (i.e. a
  shutdown) to restart with a fresh Qemu binary.


0.8.2 (2016-09-20)
------------------

- Switch from using multiprocessing to threaded management of multiple consul
  VM event handlers to reduce Python startup overhead when processing many VMs
  in a single location. Also remove the sleep time.

- Fix log error in consul snapshot event handling. Improve the test coverage
  for consul event handling.

- Remove superfluous VM name handling where a VM config file could be
  specified instead of a VM name. This was causing obfuscation in the code
  and was barely used anyway.

- Allow using the telnet command even when fc.qemu _thinks_ that the VM
  is not running. This command is helpful for debugging and blocking it
  is a useless seatbelt.

- Do not log QMP connection errors as the are extremely common and expected.


0.8.1 (2016-09-11)
------------------

- Explicitly add logging to /var/log/fc-qemu.log. Do not filter
  log output there: we always want all the information we can get.

0.8 (2016-09-08)
----------------

- Introduce `fc-qemu telnet` command: a shortcut to connect to the human
  monitor port without having to look up the port from a config manually.

- Switch the monitor automation from using the telnet port to using the QMP
  socket. This should be a _lot_ more reliable. This also fixes a previous
  race condition where a migration status check may intermittently fail and
  then break a migration unnecessarily.

- Update vagrant environment to check against Qemu 2.6.

- Revamp output formatting to use Hynek's great structlog library.

- Limit a few more commands to specific VM states: stop only when running.

- Implement IOPS limiting either based on VM-specific ENC data,
  a Ceph pool default, or a global default. This limits IOPS for all disks
  (individually, no groups, yet) in a VM and maintains this over time.

- Rework Ceph volume unlocking: if a client owns a lock then breaking it
  will cause an immediate disconnect of the rbd/rados connection to avoid
  it sending further data updates. This can happen to us if we're setting
  up the locks on an inmigration and then have to give them up again if the
  migration fails.

0.7.22 (2016-07-21)
-------------------

- Fix bug in `fc-qemu restart` which causes mkfs.xfs for tmp to fail.


0.7.21 (2016-06-20)
-------------------

- Moderate swap and tmp volume sizes so that they do not scale linearly for very
  large VMs. #21961


0.7.20 (2016-05-03)
-------------------

- More logging output to help diagnosing a rare lock recovery failure
  (#21345).
- Remove shrink-vm. R.I.P. (#14222).


0.7.19 (2016-04-08)
-------------------

- Fix a race condition: when continuously polling monitor status to determine
  whether a VM is running, also consider the option that the VM was about
  to shutdown and the monitor has gone away.


0.7.18 (2016-04-04)
-------------------

- Another brownbag release: the snapshot refactoring wasn't tested properly
  if snapshots actually existed.


0.7.17 (2016-04-04)
-------------------

- Fix unicode/str issue: consul json decoded into unicode but librbd requires
  a plain string.

0.7.16 (2016-03-31)
-------------------

- Fix regression in snapshot taking.


0.7.15 (2016-03-20)
-------------------

- Account for different mkfs options for XFS and mkfs.ext4 (#19079).
- Improved Vagrant VM bootstrapping.
- Refactor classes in hazmat/{ceph.py,volume.py} (#19079).
- Use the "rbd_pool" ENC option to allow VM-specific selection of the RBD pool
  instead of deriving it from the resource group name.
- Improve success rate of recovering from failed migrations properly: certain
  conditions would result in only partially released locks from the target
  leading to inconsistent states.

0.7.14 (2016-01-21)
-------------------

- Use XFS for tmp partitions (#17873).
- Drop super-floppy setup von vdc and use a proper partition table instead
  (#17873).
- Fix file permissions for ENC seed JSON file.


0.7.13 (2015-12-10)
-------------------

- Ignore consul requests for VMs with missing configuration (#18841).
- Speed up initial NTP sync in Vagrant to avoid failing Ceph tests due to
  unsynced MONs.
- Refine Ceph.unlock() to remove own locks in a best-effort manner. This is
  needed to recover from incomplete migrations (#18771).
- Improve error handling with failed monitor connections.


0.7.12 (2015-11-11)
-------------------

- Improve error handling during migration.
- Fix timeout during fsfreeze that leads to locked up VMs (#18917).


0.7.11 (2015-11-04)
-------------------

- Switch `aio` setting in default qemu.vm.cfg to "threads". This will keep
  fc-qemu compatible with future Qemu versions (#18743).
- Improve logging.
- Place initial copy of ENC data in `/tmp/fc-data/enc.json`.


0.7.10 (2015-08-12)
-------------------

- Refactor system-wide configuration code.
- Create swap and tmp partition with proper filesystem labels (#16783).
- Fix rare race condition during tmp volume creation.
- Set filesystem labels for swap and tmp volumes (#17078).


0.7.9 (2015-08-03)
------------------

- Add "snapshot" command. Can be triggered from command line and
  via consul.


0.7.8 (2015-07-27)
------------------

- Improve detection of running instances.

- Broaden check for monitor connection to handle dual stack
  environments.


0.7.7 (2015-07-14)
------------------

- Fix migration issue: we ended up de-registering at the wrong time.


0.7.6 (2015-07-01)
------------------

- Quickfix: newer mkfs.ext4 versions need a '-F' flag to overwrite
  filesystems (#14920).


0.7.5 (2015-07-01)
------------------

- Spawn individual VM actions usings multiprocessing. Wait until all migrations
  are done (#14920).
- Increase allowed migration downtime to keep migration time for busy VMs in
  bounds (#14920).
- Fix exception handling errors during Consul event processing (#14920).
- Give udev mapping a bit to settle.
- Improve log readability.


0.7.4 (2015-06-02)
------------------

- Rectify brown-bag release.
- Fix some unnoticed, arbitrary test failures.


0.7.3 (2015-06-02)
------------------

- Make event processing from consul fork for each VM and return the
  master process early to avoid blocking the consul agent.

- More logging related to migrations.


0.7.2 (2015-05-26)
------------------

- Adapt to QEMU 2.2.1: uses now stdvga by default (#15748).


0.7.1 (2015-05-20)
------------------

- Fix bug with inmigration Consul service registration (#15313).
- Change KV name name space for nodes from "vm/" to "node/" (#14920).


0.7 (2015-05-18)
----------------

- Consul service registration (#15313).
- Coordinate migration via Consul (#15313).


0.6.4 (2015-02-27)
------------------

- Tolerate "setup" as an intermediate migration status as encountered in the
  wild.


0.6.3 (2015-02-19)
------------------

- Improve pid file parser to deal correctly with trailing lines and empty pid
  files.
- Ensure that exceptions are properly logged if they occur directly after
  daemonizing (e.g., in Agent.__init__()) (#13867).


0.6.2 (2015-01-22)
------------------

- Relax PyYaml and psutil version requirements to accommodate to the Flying
  Circus managed platform.


0.6.1 (2015-01-22)
------------------

- Improve logging and error messages (#13867).
- Fix unwanted behaviour during error conditions (#13867).


0.6 (2015-01-15)
----------------

- Implement live migration. Use "inmigrate" and "outmigrate" commands
  to coordinate the process (#13229).
- Note that the qemu.cfg.in template has changed!
- Improve test coverage.


0.5.1 (2014-11-22)
------------------

- Bugfix: remove Ceph discard call since it seems to be unstable (#13414).
- Improve operability by reworking what is logged to fc-qemu.log.


0.5 (2014-11-21)
----------------

- Root filesystem shrink during VM start (#13414).
- Add 'force-unlock' action to break stale locks (e.g., after a VM host went
  down).


0.4.3 (2014-11-13)
------------------

- Read Qemu config file template from `/etc/qemu/qemu.vm.cfg.in`.
- Fix tests and documentation.


0.4.2 (2014-11-12)
------------------

- Rate limit entropy transfer from host to guest (#13751).
- Add 'restart' command to simplify VM restarts.


0.4.1 (2014-09-24)
------------------

- Do not require the PID to match the machine name for determining
  online status. This caused issues for VMs with names longer than 11
  characters: http://status.flyingcircus.io/incidents/3j8wsrszlx2w


0.4 (2014-09-16)
----------------

- Allow selecting the specific command line to call for creating a VM
  using a config file + formatting syntax.

- Add test coverage to show that we gracefully recover from crashed VMs
  upon a subsequent 'ensure'.

0.3 (2014-09-13)
----------------

- Refactor and rename to 'fc.qemu'.
  Integrate most functionality that was previously placed in our
  init scripts and localconfig (fc.agent) utilities.

- Add a lot of test coverage.


0.2.6 (2014-08-21)
------------------

- Fix incoming VM detection for an already locked _and_ started VM.


0.2.5 (2014-08-20)
------------------

* Implement a safety-belt to prohibit migrating VMs that have not
  yet been started with the supported /run/kvm.*.cfg.in format.

