Commit Graph

176 Commits

Author SHA1 Message Date
Christian Schwarz
3cb1865909 chore: trace spans: use crypto/rand for generating them
math/rand.Read is deprecated in newer Go versions.

Also, it appears that crypto/rand is faster when used from multiple
goroutines: https://gist.github.com/problame/0699acd6f99db4163f26f0b8a61569f3
2024-09-08 23:19:45 +00:00
Christian Schwarz
def510abfd chore: require go 1.22/1.23, upgrade protobuf, upgrade all deps
Go upgrade:
- Go 1.23 is current => use that for release builds
- Go 1.22 is less than one year old, it's desirable to support it.
- The [`Go Toolchains`](https://go.dev/doc/toolchain) stuff is available
  in both of these (would also be in Go 1.21). That is quite nice stuff,
  but required some changes to how we versions we use in CircleCI and
  the `release-docker` Makefile target.

Protobuf upgrade:
- Go to protobuf GH release website
- Download latest locally
- run `sha256sum`
- replace existing pinned hashes
- `make generate`

Deps upgrade:
- `go get -t -u all`
- repository moves aren't handled well automatically, fix manually
- repeat until no changes
2024-09-08 20:49:09 +00:00
Christian Schwarz
08769a8752 fix: accidental use of wrong logging package 2024-09-08 12:57:58 +00:00
Denis Shaposhnikov
27012e5623
Allow same root_fs for different jobs: sinks and so on (#752)
Because some jobs add client identity to root_fs and other jobs don't do
that,
we can't reliable detect overlapping of filesystems. And and the same
time we
need an ability to use equal or overlapped root_fs for different jobs.
For
instance see this config:

```
  - name: "zdisk"
    type: "sink"
    root_fs: "zdisk/zrepl"
    serve:
      type: "local"
      listener_name: "zdisk"
```
and
```
  - name: "remote-to-zdisk"
    type: "pull"
    connect:
      type: "tls"
    root_fs: "zdisk/zrepl/remote"
```

As you can see, two jobs have overlapped root_fs, but actually datasets
are not
overlapped, because job `zdisk` save everything under
`zdisk/zrepl/localhost`,
because it adds client identity. So they actually use two different
filesystems:
`zdisk/zrepl/localhost` and `zdisk/zrepl/remote`. And we can't detect
this
situation during config check. So let's just remove this check, because
it's
admin's duty to configure correct root_fs's.

---------

Co-authored-by: Christian Schwarz <me@cschwarz.com>
2023-11-01 00:12:54 +01:00
Goran Mekic
bc5e1ede04
metric to detect filesystems rules that don't match any local dataset (#653)
This PR adds a Prometheus counter called
`zrepl_zfs_list_unmatched_user_specified_dataset_count`.
Monitor for increases of the counter to detect filesystem filter rules that
have no effect because they don't match any local filesystem.

An example use case for this is the following story:
1. Someone sets up zrepl with `filesystems` filter for `zroot/pg14<`.
2. During the upgrade to Postgres 15, they rename the dataset to `zroot/pg15`,
   but forget to update the zrepl `filesystems` filter.
3. zrepl will not snapshot / replicate the `zroot/pg15<` datasets.

Since `filesystems` rules are always evaluated on the side that has the datasets,
we can smuggle this functionality into the `zfs` module's `ZFSList` function that
is used by all jobs with a `filesystems` filter.

Dashboard changes:
- histogram with increase in $__interval, one row per job
- table with increase in $__range
- explainer text box, so, people know what the previous two are about
We had to re-arrange some panels, hence the Git diff isn't great.

closes https://github.com/zrepl/zrepl/pull/653

Co-authored-by: Christian Schwarz <me@cschwarz.com>
Co-authored-by: Goran Mekić <meka@tilda.center>
2023-05-02 22:13:52 +02:00
Tercio Filho
2b3daaf9f1
zrepl status: hide progress bar once all filesystems reach terminal state (#674)
* Added `IsTerminal` method
* Made rendering of progress bar conditional based on IsTerminal
2023-05-02 19:28:56 +02:00
Christian Schwarz
6260b75031 snapper: fix delayed snapshots caused by system suspend/resume
See explainer comment in periodic.go for details.

fixes https://github.com/zrepl/zrepl/issues/611
2022-10-27 00:19:06 +02:00
Christian Schwarz
3ffb69bfb0 config: support zrepl's day and week units for snapshotting.interval
Originally, I had a patch that would replace all usages of
time.Duration in package config with the new config.Duration
types, but:
1. these are all timeouts/retry intervals that have default values.
   Most users don't touch them, and if they do, they don't need
   day or week units.
2. go-yaml's error reporting for yaml.Unmarshaler is inferior to
   built-in types (line numbers are missing, so the error would not have
   sufficient context)

fixes https://github.com/zrepl/zrepl/issues/486
2022-10-27 00:19:06 +02:00
Yannick Dylla
1da8f848f2 snapper: support custom timestamp format
fixes https://github.com/zrepl/zrepl/issues/465
closes https://github.com/zrepl/zrepl/pull/639
2022-10-27 00:19:06 +02:00
Christian Schwarz
a6aa610165 run go1.19 gofmt and make adjustments as needed
(Go 1.19 expanded doc comment syntax)
2022-10-24 22:22:41 +02:00
Christian Schwarz
a967986a18 fixup: fix hooks unit tests
The previous commit c743c7b03f
broke the hooks unit tests.

GitHub was not configured to require passing tests for master merge.
Didn't notice it locally due to Go's test caching.
I amended this before pushing this change.
2022-10-09 15:36:00 +02:00
Christian Schwarz
c743c7b03f refactor snapper & support cron-based snapshotting
fixes https://github.com/zrepl/zrepl/issues/554
refs https://github.com/zrepl/zrepl/discussions/547#discussioncomment-1936126
2022-09-25 19:23:44 +02:00
Christian Schwarz
2d8c3692ec rework resume token validation to allow resuming from raw sends of unencrypted datasets
Before this change, resuming from an unencrypted dataset with
send.raw=true specified wouldn't work with zrepl due to overly
restrictive resume token checking.

An initial PR to fix this was made in https://github.com/zrepl/zrepl/pull/503
but it didn't address the core of the problem.
The core of the problem was that zrepl assumed that if a resume token
contained `rawok=true, compressok=true`, the resulting send would be
encrypted. But if the sender dataset was unencrypted, such a resume would
actually result in an unencrypted send.
Which could be totally legitimate but zrepl failed to recognize that.

BACKGROUND
==========

The following snippets of OpenZFS code are insightful regarding how the
various ${X}ok values in the resume token are handled:

- 6c3c5fcfbe/module/zfs/dmu_send.c (L1947-L2012)
- 6c3c5fcfbe/module/zfs/dmu_recv.c (L877-L891)
- https://github.com/openzfs/zfs/blob/6c3c5fc/lib/libzfs/libzfs_sendrecv.c#L1663-L1672

Basically, some zfs send flags make the DMU send code set some DMU send
stream featureflags, although it's not a pure mapping, i.e, which DMU
send stream flags are used depends somewhat on the dataset (e.g., is it
encrypted or not, or, does it use zstd or not).

Then, the receiver looks at some (but not all) feature flags and maps
them to ${X}ok dataset zap attributes.

These are funnelled back to the sender 1:1 through the resume_token.

And the sender turns them into lzc flags.

As an example, let's look at zfs send --raw.
if the sender requests a raw send on an unencrypted dataset, the send
stream (and hence the resume token) will not have the raw stream
featureflag set, and hence the resume token will not have the rawok
field set. Instead, it will have compressok, embedok, and depending
on whether large blocks are present in the dataset, largeblockok set.

WHAT'S ZREPL'S ROLE IN THIS?
============================

zrepl provides a virtual encrypted sendflag that is like `raw`,
but further ensures that we only send encrypted datasets.

For any other resume token stuff, it shoudn't do any checking,
because it's a futile effort to keep up with ZFS send/recv features
that are orthogonal to encryption.

CHANGES MADE IN THIS COMMIT
===========================

- Rip out a bunch of needless checking that zrepl would do during
  planning. These checks were there to give better error messages,
  but actually, the error messages created by the endpoint.Sender.Send
  RPC upon send args validation failure are good enough.
- Add platformtests to validate all combinations of
  (Unencrypted/Encrypted FS) x (send.encrypted = true | false) x (send.raw = true | false)
  for cases both non-resuming and resuming send.

Additional manual testing done:
1. With zrepl 0.5, setup with unencrypted dataset, send.raw=true specified, no send.encrypted specified.
2. Observe that regular non-resuming send works, but resuming doesn't work.
3. Upgrade zrepl to this change.
4. Observe that both regular and resuming send works.

closes https://github.com/zrepl/zrepl/pull/613
2022-09-25 17:32:02 +02:00
Cole Helbling
1df0f8912a Add --skip-cert-check flag to zrepl configcheck to prevent checking cert files
It may be desirable to check that a config is valid without checking for
the existence of certificate files (e.g. when validating a config inside
a sandbox without access to the cert files).

This will be very useful for NixOS so that we can check the config file
at nix-build time (e.g. potentially without proper permissions to read cert
files for a TLS connection).

fixes https://github.com/zrepl/zrepl/issues/467
closes https://github.com/zrepl/zrepl/pull/587
2022-07-08 20:18:41 +02:00
Christian Schwarz
2642c64303 make initial replication policy configurable (most_recent, all, fail)
Config:

```
- type: push
  ...
  conflict_resolution:
    initial_replication: most_recent | all | fali
```

The ``initial_replication`` option determines which snapshots zrepl
replicates if the filesystem has not been replicated before.
If ``most_recent`` (the default), the initial replication will only
transfer the most recent snapshot, while ignoring previous snapshots.
If all snapshots should be replicated, specify ``all``.
Use ``fail`` to make replication of the filesystem fail in case
there is no corresponding fileystem on the receiver.

Code-Level Changes, apart from the obvious:
- Rework IncrementalPath()'s return signature.
  Now returns an error for initial replications as well.
- Rename & rework it's consumer, resolveConflict().

Co-authored-by: Graham Christensen <graham@grahamc.com>

Fixes https://github.com/zrepl/zrepl/issues/550
Fixes https://github.com/zrepl/zrepl/issues/187
Closes https://github.com/zrepl/zrepl/pull/592
2022-06-26 14:36:59 +02:00
Christian Schwarz
a2b2e0fe34 daemon/control: make http server {Read,Write}Timeout envconst-configurable
refs https://github.com/zrepl/zrepl/issues/379
2021-12-18 15:14:33 +01:00
Christian Schwarz
fb6a9be954 fix encrypt-on-receive with placeholders
fixes https://github.com/zrepl/zrepl/issues/504

Problem:
  plain send + recv with root_fs encrypted + placeholders causes plain recvs
  whereas user would expect encrypt-on-recv
Reason:
  We create placeholder filesytems with -o encryption=off.
  Thus, children received below those placeholders won't inherit
  encryption of root_fs.
Fix:
  We'll have three values for `recv.placeholders.encryption: unspecified (default) | off | inherit`.
  When we create a placeholder, we will fail the operation if  `recv.placeholders.encryption = unspecified`.
  The exception is if the placeholder filesystem is to encode the client identity ($root_fs/$client_identity) in a pull job.
  Those are created in `inherit` mode if the config field is `unspecified` so that users who don't need
  placeholders are not bothered by these details.

Future Work:
  Automatically warn existing users of encrypt-on-recv about the problem
  if they are affected.
  The problem that I hit during implementation of this is that the
  `encryption` prop's `source` doesn't quite behave like other props:
  `source` is `default` for `encryption=off` and `-` when `encryption=on`.
  Hence, we can't use `source` to distinguish the following 2x2 cases:
  (1) placeholder created with explicit -o encryption=off
  (2) placeholder created without specifying -o encryption
  with
  (A) an encrypted parent at creation time
  (B) an unencrypted parent at creation time
2021-12-18 15:12:47 +01:00
Christian Schwarz
c1e2c9826f trace: hint debug env var in error when crashing due to active child tasks
refs https://github.com/zrepl/zrepl/issues/542
2021-12-05 18:57:43 +01:00
Christian Schwarz
c2fbf93365 daemon: provide os.Environ() in zrepl status
Useful for debugging.

fixes https://github.com/zrepl/zrepl/issues/534
2021-11-14 17:34:32 +01:00
Lapo Luchini
c6a9ebc71c job/active: add "last completed" metric for error reporting
use case:

    So that I can use a more resilient alerting such as "last complete was sent more than 24h ago".

fixes https://github.com/zrepl/zrepl/issues/516
closes https://github.com/zrepl/zrepl/pull/530
2021-11-10 17:35:12 +01:00
Christian Schwarz
1f0f2f8569 pruner + docs: less confusing type names, some comments, better docs for keep: not_replicated
fixes https://github.com/zrepl/zrepl/issues/524
2021-10-10 21:11:38 +02:00
Christian Schwarz
845195b7ed bandwidth limiting: fix crash with SnapJob
zrepl daemon panics when the snap job triggers

fixup for f5f269bfd5 (bandwidth limiting)
fixes #521

Oct 01 16:14:56 cstp zrepl[56563]: panic: invalid config`BandwidthLimit` field invalid: BucketCapacity must not be zero
Oct 01 16:14:56 cstp zrepl[56563]:         panic: end span: span still has active child spans
Oct 01 16:14:56 cstp zrepl[56563]: goroutine 38 [running]:
Oct 01 16:14:56 cstp zrepl[56563]: github.com/zrepl/zrepl/daemon/logging/trace.WithSpan.func2()
Oct 01 16:14:56 cstp zrepl[56563]:         /home/cs/zrepl/zrepl/daemon/logging/trace/trace.go:341 +0x2ea
Oct 01 16:14:56 cstp zrepl[56563]: github.com/zrepl/zrepl/daemon/logging/trace.WithTaskAndSpan.func1()
Oct 01 16:14:56 cstp zrepl[56563]:         /home/cs/zrepl/zrepl/daemon/logging/trace/trace_convenience.go:40 +0x2e
Oct 01 16:14:56 cstp zrepl[56563]: panic(0xcee9c0, 0xc000676730)
Oct 01 16:14:56 cstp zrepl[56563]:         /home/cs/go1.16.6/src/runtime/panic.go:965 +0x1b9
Oct 01 16:14:56 cstp zrepl[56563]: github.com/zrepl/zrepl/endpoint.NewSender(0xf5bbc0, 0xc0003840c0, 0xc0000b2c90, 0x4, 0xc0002c5958, 0x0, 0x0, 0x0, 0xc000068cf8)
Oct 01 16:14:56 cstp zrepl[56563]:         /home/cs/zrepl/zrepl/endpoint/endpoint.go:68 +0x1ec
Oct 01 16:14:56 cstp zrepl[56563]: github.com/zrepl/zrepl/daemon/job.(*SnapJob).doPrune(0xc00039e000, 0xf6e3b8, 0xc0006541b0)
Oct 01 16:14:56 cstp zrepl[56563]:         /home/cs/zrepl/zrepl/daemon/job/snapjob.go:179 +0x198
Oct 01 16:14:56 cstp zrepl[56563]: github.com/zrepl/zrepl/daemon/job.(*SnapJob).Run(0xc00039e000, 0xf6e3b8, 0xc0001d83c0)
Oct 01 16:14:56 cstp zrepl[56563]:         /home/cs/zrepl/zrepl/daemon/job/snapjob.go:127 +0x329
Oct 01 16:14:56 cstp zrepl[56563]: github.com/zrepl/zrepl/daemon.(*jobs).start.func1(0xc0006a4100, 0xf6e3b8, 0xc00022a0f0, 0xf72d18, 0xc00039e000)
Oct 01 16:14:56 cstp zrepl[56563]:         /home/cs/zrepl/zrepl/daemon/daemon.go:255 +0x15b
Oct 01 16:14:56 cstp zrepl[56563]: created by github.com/zrepl/zrepl/daemon.(*jobs).start
Oct 01 16:14:56 cstp zrepl[56563]:         /home/cs/zrepl/zrepl/daemon/daemon.go:251 +0x425
Oct 01 16:14:56 cstp systemd[1]: zrepl.service: Main process exited, code=exited, status=2/INVALIDARGUMENT
Oct 01 16:14:56 cstp systemd[1]: zrepl.service: Failed with result 'exit-code'.
2021-10-09 15:52:38 +02:00
Christian Schwarz
f5f269bfd5 send/recv: job-level bandwidth limiting
Sponsored-by: Prominic.NET, Inc.

fixes #339
2021-09-12 20:08:43 +02:00
InsanePrawn
b2c6e51a43 client/signal: Revert "add signal 'snapshot', rename existing signal 'wakeup' to 'replication'"
This was merged to master prematurely as the job components are not decoupled well enough
for these signals to be useful yet.

This reverts commit 2c8c2cfa14.

closes #452
2021-03-25 22:26:17 +01:00
Calistoc
2c8c2cfa14 add signal 'snapshot', rename existing signal 'wakeup' to 'replication' 2021-03-14 18:16:23 +01:00
Christian Schwarz
0ceea1b792 replication: simplify parallel replication variables & expose them in config
closes #140
2021-03-14 17:30:10 +01:00
InsanePrawn
393fc10a69 [#285] support setting zfs send / recv flags in the config (send: -wLcepbS, recv: -ox)
Co-authored-by: Christian Schwarz <me@cschwarz.com>
Signed-off-by: InsanePrawn <insane.prawny@gmail.com>

closes #285
closes #276
closes #24
2021-02-20 17:20:45 +01:00
Christian Schwarz
1c937e58f7 zfs.NilBool: document its purpose and move it to its own package 'nodefault' 2021-02-20 17:04:57 +01:00
Christian Schwarz
efe7b17d21 Update to protobuf v1.25 and grpc 1.35; bump CI to go1.12
From:
github.com/golang/protobuf v1.3.2
google.golang.org/grpc v1.17.0

To:
github.com/golang/protobuf v1.4.3
google.golang.org/grpc v1.35.0
google.golang.org/protobuf v1.25.0

About the two protobuf packages:
https://developers.google.com/protocol-buffers/docs/reference/go/faq
> Version v1.4.0 and higher of github.com/golang/protobuf wrap the new
implementation and permit programs to adopt the new API incrementally. For
example, the well-known types defined in github.com/golang/protobuf/ptypes are
simply aliases of those defined in the newer module. Thus,
google.golang.org/protobuf/types/known/emptypb and
github.com/golang/protobuf/ptypes/empty may be used interchangeably.

Notable Code Changes in zrepl:
- generate protobufs now contain a mutex so we can't copy them by value
  anymore
- grpc.WithDialer is deprecated => use grpc.WithContextDialer instead

Go1.12 is now actually required by some of the dependencies.
2021-01-25 00:39:01 +01:00
Mathias Fredriksson
6ac537210b daemon: avoid math/rand race by using global source
Unless we're using the global source for math/rand, (*rand.Rand).Read
should not be called concurrently. We seed the rng in daemon.Run to
avoid ambiguity or hiding global side effects inside packages.

closes #414
2021-01-25 00:16:01 +01:00
Mathias Fredriksson
48be4032a2 daemon: fix data race in snapjob pruner report
closes #416
2021-01-25 00:16:01 +01:00
Christian Schwarz
0d96627ffb [#388] trace: make WithTaskGroup actually concurrent 2021-01-24 22:28:47 +01:00
Christian Schwarz
fecc9416ab [#347] package trace: envconst-configurable debug mode 2020-09-02 22:45:44 +02:00
Christian Schwarz
a7915db4c3 [#347] package trace: printing debugString before instead of at panic (fixup e500d9e) 2020-09-02 22:45:44 +02:00
InsanePrawn
180c3d9ae1 Reformat all files with make format.
Signed-off-by: InsanePrawn <insane.prawny@gmail.com>
2020-08-31 23:57:45 +02:00
Christian Schwarz
e500d9ee26 package trace: track activeChildTasks in a set if debugEnabled=true
refs #358
2020-08-23 20:13:58 +02:00
Hans Schulz
83fdffbcef replication: prometheus metric for number of failed replications in last attempt
- package replication: metric
- Grafana panel
- wiring
- changelog

Signed-off-by: Christian Schwarz <me@cschwarz.com>

closes #341
2020-08-04 01:19:44 +02:00
Christian Schwarz
30cdc1430e replication + endpoint: replication guarantees: guarantee_{resumability,incremental,nothing}
This commit

- adds a configuration in which no step holds, replication cursors, etc. are created
- removes the send.step_holds.disable_incremental setting
- creates a new config option `replication` for active-side jobs
- adds the replication.protection.{initial,incremental} settings, each
  of which can have values
    - `guarantee_resumability`
    - `guarantee_incremental`
    - `guarantee_nothing`
  (refer to docs/configuration/replication.rst for semantics)

The `replication` config from an active side is sent to both endpoint.Sender and endpoint.Receiver
for each replication step. Sender and Receiver then act accordingly.

For `guarantee_incremental`, we add the new `tentative-replication-cursor` abstraction.
The necessity for that abstraction is outlined in https://github.com/zrepl/zrepl/issues/340.

fixes https://github.com/zrepl/zrepl/issues/340
2020-07-26 20:32:35 +02:00
Christian Schwarz
95fc299733 daemon/job: test that sample configs are buildable 2020-07-26 20:32:35 +02:00
Christian Schwarz
509185dfbe prometheus: expose zrepl version as const metric 2020-06-14 15:26:05 +02:00
Christian Schwarz
4b1b7a8561 envconst: queryable report of resolved variables + integration inot zrepl status --raw
fixes #299
refs #186
2020-06-14 15:26:05 +02:00
Christian Schwarz
1c270b7e39 add option to disable step holds for incremental sends
This is a stop-gap solution until we re-write the pruner to support
rules for removing step holds.

Note that disabling step holds for incremental sends does not affect
zrepl's guarantee that incremental replication is always possible:

Suppose you yank the external drive during an incremental @from -> @to step:

* restarting that step or future incrementals @from -> @to_later` will be possible
  because the replication cursor bookmark points to @from until the step is complete
* resuming @from -> @to will work as long as the pruner on your internal pool doesn't come around to destroy @to.
    * in that case, the replication algorithm should determine that the resumable state
      on the receiving side isuseless because @to no longer exists on the sending side,
      and consequently clear it, and restart an incremental step @from -> @to_later

refs #288
2020-06-14 15:26:05 +02:00
Christian Schwarz
292b85b5ef [#316] endpoint / replication protocol: more robust step-holds and replication cursor management
- drop HintMostRecentCommonAncestor rpc call
    - it is wrong to put faith into the active side of the replication to always make that call
      (we might not trust it, ref pull setup)
- clean up step holds + step bookmarks + replication cursor bookmarks on
  send RPC instead
    - this makes it symmetric with Receive RPC
- use a cache (endpoint.sendAbstractionsCache) to avoid the cost of
  listing the on-disk endpoint abstractions state on every step

The "create" methods for endpoint abstractions (CreateReplicationCursor, HoldStep) are now fully
idempotent and return an Abstraction.

Notes about endpoint.sendAbstractionsCache:
- fills lazily from disk state on first `Get` operation
- fill from disk is generally only attempted once
    - unless the `ListAbstractions` fails, in which case the fill from
      disk is retried on next `Get` (the current `Get` will observe a
      subset of the actual on-disk abstractions)
    - the `Invalidate` method is called
- it is a global (zrepl process-wide) cache

fixes #316
2020-06-14 15:21:36 +02:00
Christian Schwarz
10a14a8c50 [#307] add package trace, integrate it with logging, and adopt it throughout zrepl
package trace:

- introduce the concept of tasks and spans, tracked as linked list within ctx
    - see package-level docs for an overview of the concepts
    - **main feature 1**: unique stack of task and span IDs
        - makes it easy to follow a series of log entries in concurrent code
    - **main feature 2**: ability to produce a chrome://tracing-compatible trace file
        - either via an env variable or a `zrepl pprof` subcommand
        - this is not a CPU profile, we already have go pprof for that
        - but it is very useful to visually inspect where the
          replication / snapshotter / pruner spends its time
          ( fixes #307 )

usage in package daemon/logging:

- goal: every log entry should have a trace field with the ID stack from package trace

- make `logging.GetLogger(ctx, Subsys)` the authoritative `logger.Logger` factory function
    - the context carries a linked list of injected fields which
      `logging.GetLogger` adds to the logger it returns
    - `logging.GetLogger` also uses package `trace` to get the
      task-and-span-stack and injects it into the returned logger's fields
2020-05-19 11:30:02 +02:00
Christian Schwarz
7d6ee4c166 daemon: expose prometheus metrics on pprof listener (useful for debugging) 2020-05-18 19:39:27 +02:00
Christian Schwarz
70f9c6482f zfs: context propagation to ZFSListFilesystemVersions
fixup of 9568e46f05
2020-04-21 14:10:53 +02:00
Christian Schwarz
e0b5bd75f8 endpoint: refactor, fix stale holds on initial replication failure, zfs-abstractions subcmd, more efficient ZFS queries
The motivation for this recatoring are based on two independent issues:

- @JMoVS found that the changes merged as part of #259 slowed his OS X
  based installation down significantly.
  Analysis of the zfs command logging introduced in #296 showed that
  `zfs holds` took most of the execution time, and they pointed out
  that not all of those `zfs holds` invocations were actually necessary.
  I.e.: zrepl was inefficient about retrieving information from ZFS.

- @InsanePrawn found that failures on initial replication would lead
  to step holds accumulating on the sending side, i.e. they would never
  be cleaned up in the HintMostRecentCommonAncestor RPC handler.
  That was because we only sent that RPC if there was a most recent
  common ancestor detected during replication planning.
  @InsanePrawn prototyped an implementation of a `zrepl zfs-abstractions release`
  command to mitigate the situation.
  As part of that development work and back-and-forth with @problame,
  it became evident that the abstractions that #259 built on top of
  zfs in package endpoint (step holds, replication cursor,
  last-received-hold), were not well-represented for re-use in the
  `zrepl zfs-abstractions release` subocommand prototype.

This commit refactors package endpoint to address both of these issues:

- endpoint abstractions now share an interface `Abstraction` that, among
  other things, provides a uniform `Destroy()` method.
  However, that method should not be destroyed directly but instead
  the package-level `BatchDestroy` function should be used in order
  to allow for a migration to zfs channel programs in the future.

- endpoint now has a query facitilty (`ListAbstractions`) which is
  used to find on-disk
    - step holds and bookmarks
    - replication cursors (v1, v2)
    - last-received-holds
  By describing the query in a struct, we can centralized the retrieval
  of information via the ZFS CLI and only have to be clever once.
  We are "clever" in the following ways:
  - When asking for hold-based abstractions, we only run `zfs holds` on
    snapshot that have `userrefs` > 0
    - To support this functionality, add field `UserRefs` to zfs.FilesystemVersion
      and retrieve it anywhere we retrieve zfs.FilesystemVersion from ZFS.
  - When asking only for bookmark-based abstractions, we only run
    `zfs list -t bookmark`, not with snapshots.
  - Currently unused (except for CLI) per-filesystem concurrent lookup
  - Option to only include abstractions with CreateTXG in a specified range

- refactor `endpoint`'s various ZFS info  retrieval methods to use
  `ListAbstractions`

- rename the `zrepl holds list` command to `zrepl zfs-abstractions list`
- make `zrepl zfs-abstractions list` consume endpoint.ListAbstractions

- Add a `ListStale` method which, given a query template,
  lists stale holds and bookmarks.
  - it uses replication cursor has different modes
- the new `zrepl zfs-abstractions release-{all,stale}` commands can be used
  to remove abstractions of package endpoint

- Adjust HintMostRecentCommonAncestor RPC for stale-holds cleanup:
    - send it also if no most recent common ancestor exists between sender and receiver
    - have the sender clean up its abstractions when it receives the RPC
      with no most recent common ancestor, using `ListStale`
    - Due to changed semantics, bump the protocol version.

- Adjust HintMostRecentCommonAncestor RPC for performance problems
  encountered by @JMoVS
    - by default, per (job,fs)-combination, only consider cleaning
      step holds in the createtxg range
      `[last replication cursor,conservatively-estimated-receive-side-version)`
    - this behavior ensures resumability at cost proportional to the
      time that replication was donw
    - however, as explained in a comment, we might leak holds if
      the zrepl daemon stops running
    - that  trade-off is acceptable because in the presumably rare
      this might happen the user has two tools at their hand:
    - Tool 1: run `zrepl zfs-abstractions release-stale`
    - Tool 2: use env var `ZREPL_ENDPOINT_SENDER_HINT_MOST_RECENT_STEP_HOLD_CLEANUP_MODE`
      to adjust the lower bound of the createtxg range (search for it in the code).
      The env var can also be used to disable hold-cleanup on the
      send-side entirely.

supersedes closes #293
supersedes closes #282
fixes #280
fixes #278

Additionaly, we fixed a couple of bugs:

- zfs: fix half-nil error reporting of dataset-does-not-exist for ZFSListChan and ZFSBookmark

- endpoint: Sender's `HintMostRecentCommonAncestor` handler would not
  check whether access to the specified filesystem was allowed.
2020-04-18 12:26:03 +02:00
Christian Schwarz
1336c91865 zfs: introduce pkg zfs/zfscmd for command logging, status, prometheus metrics
refs #196
2020-04-05 20:47:25 +02:00
InsanePrawn
9568e46f05 zfs: use exec.CommandContext everywhere
Co-authored-by: InsanePrawn <insane.prawny@gmail.com>
2020-03-27 13:08:43 +01:00
InsanePrawn
44bd354eae Spellcheck all files
Signed-off-by: InsanePrawn <insane.prawny@gmail.com>
2020-02-24 16:06:09 +01:00