openstack/swift - swift - OpenDev: Free Software Needs Free Tools

* Add new configuration option log_address.
Change-Id: I636bd4116687629c997b70a0d804b7ed4bc46032

Expand recon middleware to include support for account and container
servers in addition to the existing object servers. Also add support
for retrieving recent information from auditors, replicators, and
updaters. In the case of certain checks (such as container auditors)
the stats returned are only for the most recent path processed.
The middleware has also been refactored and should now also handle
errors better in cases where stats are unavailable.
While new check's have been added the output from pre-existing
check's has not changed. This should allow existing 3rd party
utilities such as the Swift ZenPack to continue to function.
Change-Id: Ib9893a77b9b8a2f03179f2a73639bc4a6e264df7

Long explanation, but hopefully answers any questions.
We don't like changing the default behavior of Swift unless there's a
really good reason and, up until now, I've tried doing this with this
new db_preallocation setting.
For clusters with dedicated account/container servers that usually
have fewer disks overall but SSD for speed, having db_preallocation
on will gobble up disk space quite quickly and the fragmentation it's
designed to fight isn't that big a speed impact to SSDs anyway.
For clusters with account/container servers spread across all servers
along with object servers usually having standard disks for cost,
having db_preallocation off will cause very fragmented database files
impacting speed, sometimes dramatically.
Weighing these two negatives, it seems the second is the lesser evil.
The first can cause disks to fill up and disable the cluster. The
second will cause performance degradation, but the cluster will still
function.
Furthermore, if just one piece of code that touches all databases
runs with db_preallocation on, it's effectively on for the whole
cluster. We discovered this most recently when we finally configured
everything within the Swift codebase to have db_preallocation off,
only to find out Slogging didn't know about the new setting and so
ran with it on and starting filling up SSDs.
So that's why I'm proposing this change to the default behavior.
We will definitely need to post a prominent notice of this change
with the next release.
Change-Id: I48a43439264cff5d03c14ec8787f718ee44e78ea

Documentation, including a list of metrics reported and their semantics,
is in the Admin Guide in a new section, "Reporting Metrics to StatsD".
An optional "metric prefix" may be configured which will be prepended to
every metric name sent to StatsD.
Here is the rationale for doing a deep integration like this versus only
sending metrics to StatsD in middleware. It's the only way to report
some internal activities of Swift in a real-time manner. So to have one
way of reporting to StatsD and one place/style of configuration, even
some things (like, say, timing of PUT requests into the proxy-server)
which could be logged via middleware are consistently logged the same
way (deep integration via the logger delegate methods).
When log_statsd_host is configured, get_logger() injects a
swift.common.utils.StatsdClient object into the logger as
logger.statsd_client. Then a set of delegate methods on LogAdapter
either pass through to the StatsdClient object or become no-ops. This
allows StatsD logging to look like:
 self.logger.increment('some.metric.here')
and do the right thing in all cases and with no messy conditional logic.
I wanted to use the pystatsd module for the StatsD client, but the
version on PyPi is lagging the git repo (and is missing both the prefix
functionality and timing_since() method). So I wrote my
swift.common.utils.StatsdClient. The interface is the same as
pystatsd.Client, but the code was written from scratch. It's pretty
simple, and the tests I added cover it. This also frees Swift from an
optional dependency on the pystatsd module, making this feature easier
to enable.
There's test coverage for the new code and all existing tests continue
to pass.
Refactored out _one_audit_pass() method in swift/account/auditor.py and
swift/container/auditor.py.
Fixed some misc. PEP8 violations.
Misc test cleanups and refactorings (particularly the way "fake logging"
is handled).
Change-Id: Ie968a9ae8771f59ee7591e2ae11999c44bfe33b2

Change-Id: I41356ee250c9088a2387b0d493586dd990a04ac3

Added option to disable SQLite db preallocation. This can be very
useful on pure ssd account/container servers where the extra space is
worth more than the lesser fragmentation.
Change-Id: I8fbb028a9b6143775b25b343e97896497a8b63a9

Object versioning in swift is implemented by setting a flag on the container
to tell swift to version all objects in the container. The flag is the
``X-Versions-Location`` header on the container, and its value is the
container where the versions are stored.
When data is ``PUT`` into a versioned container (a container with the
versioning flag turned on), the existing data in the file is redirected to a
new object and the data in the ``PUT`` request is saved as the data for the
versioned object. The new object name (for the previous version) is
``<versions_container>/<object_name>/<timestamp>``, where the timestamp is
generated by converting the ``Last-Modified`` header value of the current
version to a unix timestamp.
A ``GET`` to a versioned object will return the current version of the object
without having to do any request redirects or metadata lookups.
Change-Id: I4fcd723145e02bbb2ec1d3ad356713f5dea43b8b

Note: I'd like to get this released as soon as possible as it is a
data durability issue.
1) Orders nodes so that none get starved (see code and footnote).
2) New max_diffs setting that caps how long the replicator will spend
 trying to sync a given database per pass so the other databases
 don't get starved.
3) Replaces run_pause with the more standard "interval", which means
 the replicator won't pause unless it takes less than the interval
 set.
Change-Id: I986742229e65031df88f5251ca61746b7c8d2bde