Got a few warnings from my IDE about redundant type conversions,
so I decided to look into it. Added the unconvert linter to our
checks, and fixed the violations. Added two ignore comments as I
wasn't sure about whether they'd change the semantics of the code.
Signed-off-by: Anders Eknert <anders@eknert.com>
With this change, the disk backend (badger) becomes available for
use with the OPA runtime properly:
It can be configured using the `storage.disk` key in OPA's config
(see included documentation).
When enabled,
- any data or policies stored with OPA will persist over restarts
- per-query metrics related to disk usage are reported
- Prometheus metrics per storage operation are exported
The main intention behind this feature is to optimize memory usage:
OPA can now operate on more data than fits into the allotted memory
resources. It is NOT meant to be used as a primary source of truth:
there are no backup/restore or desaster recovery procedures -- you
MUST secure the means to restore the data stored with OPA's disk
storage by yourself.
See also #4014. Future improvements around bundle loading are
planned.
Some notes on details:
storage/disk: impose same locking regime used with inmem
With this setup, we'll ensure:
- there is only one open write txn at a time
- there are any number of open read txns at a time
- writes are blocked when reads are inflight
- during a commit (and triggers being run), no read txns can be created
This is to ensure the same atomic policy update semantics when using
'disk" as we have with "inmem". We're basically opting out of badger's
currency control and transactionality guarantees. This is because we
cannot piggy back on that to ensure the atomic update we want.
There might be other ways -- using subscribers, and blocking in some
other place -- but this one seems preferrable since it mirrors inmem.
Part of the problem is ErrTxnTooLarge, and committing and renewing
txns when it occurs: that, which is the prescribed solution to txns
growing too big, also means that reads can see half of the "logical"
transaction having been committed, while the rest is still getting
processed.
Another approach would have been using `WriteBatch`, but that won't
let us read from the batch, only apply Set and Delete operations.
We currently need to read (via an iterator) to figure out if we
need to delete keys to replace something in the store. There is
no DropPrefix operation on the badger txn, or the WriteBatch API.
storage/disk: remove commit-and-renew-txn code for txn-too-big errors
This would break transactional guarantees we care about: while there
can be only one write transaction at a time, read transactions may
happen while a write txn is underway -- with this commit-and-reset
logic, those would read partial data.
Now, the error will be returned to the caller. The maximum txn size
depends on the size of memtables, and could be tweaked manually.
In general, the caller should try to push multiple smaller increments
of the data.
storage/disk: implement noop MakeDir
The MakeDir operation as implemented in the backend-agnostic storage
code has become an issue with the disk store: to write /foo/bar/baz,
we'd have to read /foo (among other subdirs), and that can be _much_
work for the disk backend. With inmem, it's cheap, so this wasn't
problematic before.
Some of the storage/disk/txn.go logic had to be adjusted to properly
do the MakeDir steps implicitly.
The index argument addition to patch() in storage/disk/txn.go was
necessary to keep the error messages conforming to the previous
code path: previously, conflicts (arrays indexed as objects) would
be surfaced in the MakeDir step, now it's entangled with the patch
calculation.
storage/disk: check ctx.Err() in List/Get operations
This won't abort reading a single key, but it will abort iterations.
storage/disk: support patterns in partitions
There is a potential clash here: "*", the path wildcard, is
a valid path section. However, it only affects the case when
a user would want to have a partition at
/foo/*/bar
and would really mean "*", and not the wildcard.
Storing data at /foo/*/bar with a literal "*" won't be treated
differently than storing something at /fo/xyz/bar.
storage/disk: keep per-txn-type histograms of stats
This is done by reading off the metrics on commit, and shovelling
their numbers into the prometheus collector.
NOTE: if you were to share a metrics object among multiple transactions,
the results would be skewed, as it's not reset. However, our server
handlers don't do that.
storage/disk: opt out of badger's conflict detection
With only one write transaction in flight at any time, the situation
that badger guards against cannot happen:
A transaction has written to a key after the current, to-be-committed
transaction has last read that key from the store.
Since it can't happen, we can ignore the bookkeeping involved. This
improves the time it takes to overwrite existing keys.
Signed-off-by: Stephan Renatus <stephan.renatus@gmail.com>
golint is deprecated. The author of the code no longer supports the
codebase. golangci-lint is faster than golint, and is in use by other
opa repositories (e.g. Gatekeeper).
This commit changes tools.go to reference golangci (so it ends up in
vendor) and modifies check-lint to use golangci instead.
Breaking API Changes:
- plugins/rest/rest.go: Fix typo "AllowInsureTLS" -> "AllowInsecureTLS"
- storage/errors.go: Removed unused IndexingNotSupportedErr
Signed-off-by: Will Beason <willbeason@google.com>
It's often useful to be able to create a hierarchical structure in one
shot in storage. Previously this functionality was implemented in the
server, but it's better off implemented in the storage package.
Signed-off-by: Torin Sandall <torinsandall@gmail.com>
These changes update the storage layer to support
multi-reader/single-writer txns:
- Writers can read their own writes
- Writers can rollback changes
- Readers only see writes after a successful commit
- Readers can progress during a write txn and only block during a commit
These changes also refactor the trigger interface to better support
transactions.
This is a large change set that contains a few backwards incompatible
changes. Summary of breaking changes:
- Remove storage.Storage in favour of storage.Store interface.
- Remove mount support.
- Remove storage of compiled policies.
- Modify storage.Store to support rollback.
- Modify storage.Store to support raw policy storage.
- Modify storage.Store to support indexing.
- Refactor error codes to use strings instead of ints.
- Simplify error messages throughout.
- Ensure location set on all expressions. There were a couple locations
in the parser/compiler where locations were not being set.
- Fallback to rule location in topdown in case location not set. This
ensures that users get useful locations for API requests with paths
that refer to virtual docs exactly.
Also add Find function to ast.Value. Useful for extracting values
dynamically. Eventually can support JSON pointers.
Fixes#237
These changes refactor the storage layer to use storage.Path instead of ast.Ref
for Read/Write/Begin/Unmount/Mount operations.
Previously, the storage layer used ast.Ref values to refer to locations in
storage. Use of ast.Ref introduced unnecessary complexity for storage plugins
as they had to be aware of various details (e.g., array indices specified as
ast.Number/float64 values, potentially nested references, etc.) that were
unnecessary given that ast.Ref values passed to the storage layer were
intended represent JSON pointers.
These changes also remove the need for storage plugins to be aware of where
they are mounted. That is, the paths passed to the read call will be relative
to the mount point.
The remaining dependencies on the ast package from the storage package are for
(1) indexing and (2) policy storage. It may be possible to further decouple
these packages by revisiting how indexing is done and treating policies as
blobs.
Fixes#159
This is small change that allows callers to issue GET /data and receive the
full extent of OPA's data. Secondly, this allows callers to set the data
in OPA with one request (e.g., for initialization).
Anders Eknert