Commit graph

1444 commits

Author SHA1 Message Date
Eelco Dolstra
c60715e937
Ignore broken "Deriver: unknown-deriver" fields in .narinfo
These were generated by a legacy tool.
2017-03-28 13:08:13 +02:00
Eelco Dolstra
895a74a814
LocalFSStore::getBuildLog(): Handle corrupted logs 2017-03-21 19:23:35 +01:00
Eelco Dolstra
e1e49c58e1
Only use cache.nixos.org when the store is /nix/store
This is consistent with the behaviour of the old
download-from-binary-cache substituter.
2017-03-21 17:59:18 +01:00
Eelco Dolstra
ecbc3fedd3
Require signatures by default
This corresponds to the NixOS default.
2017-03-21 15:10:48 +01:00
Eelco Dolstra
4bb38591e5
Restore cache.nixos.org as the default substituter
Fixes #1283.
2017-03-21 15:06:46 +01:00
Eelco Dolstra
f8b84a3b8c
Move istringstream_nocopy to a separate file 2017-03-21 14:43:03 +01:00
Eelco Dolstra
3229f85585
Honor $NIX_SSHOPTS again
NixOps needs this.
2017-03-21 14:35:50 +01:00
Eelco Dolstra
20df50d8e1
Merge branch 'darwin-s3-binary-cache-store' of https://github.com/shlevy/nix 2017-03-20 17:46:35 +01:00
Eelco Dolstra
287084d688
ssh:// -> ssh-ng://, legacy-ssh:// -> ssh:// 2017-03-16 14:19:32 +01:00
Eelco Dolstra
c5b83d8913
copyPaths(): Use queryValidPaths() to reduce SSH latency 2017-03-16 13:50:01 +01:00
Eelco Dolstra
91d67692cf
copyPaths(): Don't query path info for a path the target already has
For example, this cuts "nix-copy-closure --from" on a NixOS system
closure from 15.9s to 0.5s.
2017-03-16 12:05:51 +01:00
Eelco Dolstra
ea7fa88131
LegacySSHStore: Provide a faster implementation of computeFSClosure()
This avoids the latency of the standard implementation, which can make
a huge difference (e.g. 16.5s -> 0.5s on a NixOS system closure).
2017-03-16 11:44:52 +01:00
Eelco Dolstra
7a716ef2a5
Fix nix-copy-closure --to 2017-03-16 10:58:48 +01:00
Eelco Dolstra
0ec7f47b00
Remove "killing process <pid>" messages
They convey no useful information.
2017-03-16 10:52:28 +01:00
Eelco Dolstra
3f35612c04
More precise compression settings 2017-03-15 17:20:19 +01:00
Eelco Dolstra
25dff2b7db
runProgram(): Distinguish between empty input and no input
For example, if we call brotli with an empty input, it shouldn't read
from the caller's stdin.
2017-03-15 16:50:19 +01:00
Eelco Dolstra
042975ea8e
Compress NAR listings using the "text-compression" method
So if "text-compression=br", the .ls file in S3 will get a
Content-Encoding of "br". Brotli appears to compress better than xz
for this kind of file and is natively supported by browsers.
2017-03-15 16:50:19 +01:00
Eelco Dolstra
45c70382ac
S3BinaryCacheStore: Set Content-Type
This is necessary for serving log files to browsers.
2017-03-15 16:50:19 +01:00
Eelco Dolstra
8b1d65bebe
S3BinaryCacheStore: Support compression of narinfo and log files
You can now set the store parameter "text-compression=br" to compress
textual files in the binary cache (i.e. narinfo and logs) using
Brotli. This sets the Content-Encoding header; the extension of
compressed files is unchanged.

You can separately specify the compression of log files using
"log-compression=br". This is useful when you don't want to compress
narinfo files for backward compatibility.
2017-03-15 16:49:28 +01:00
Eelco Dolstra
e8186085e0
Add support for brotli compression
Build logs on cache.nixos.org are compressed using Brotli (since this
allows them to be decompressed automatically by Chrome and Firefox),
so it's handy if "nix log" can decompress them.
2017-03-15 16:49:06 +01:00
Eelco Dolstra
532d73d5d8
BinaryCacheStore: Implement getBuildLog()
We assume that build logs are stored under log/<drv>, e.g.

  /nix/store/q7ab198v13p0f8x8wgnd75dva7d5mip6-friday-devil-0.1.1.1.drv

maps to

  https://cache.nixos.org/log/q7ab198v13p0f8x8wgnd75dva7d5mip6-friday-devil-0.1.1.1.drv
2017-03-15 16:48:29 +01:00
Eelco Dolstra
0afeb7f51e
Store: Add a method for getting build logs
This allows various Store implementations to provide different ways to
get build logs. For example, BinaryCacheStore can get the build logs
from the binary cache.

Also, remove the log-servers option since we can use substituters for
this.
2017-03-15 16:48:29 +01:00
Shea Levy
96443e94a1 Merge branch 'configurable-aws-region' 2017-03-12 10:01:11 -04:00
Shea Levy
93f863be96 Add option to disable import-from-derivation completely, even if the drv is already realized 2017-03-08 08:46:12 -05:00
Shea Levy
3cc18d3753 Properly set the caFile for aws-sdk-cpp s3 2017-03-06 14:30:35 -05:00
Shea Levy
4fc30922cf istringstream_nocopy: Implement in a standards-compliant way.
Fixes the problem mentioned in e6a61b8da7

See #1135
2017-03-06 13:03:02 -05:00
Shea Levy
5789eaa3f4 Add aws-region param to S3 store URLs 2017-03-03 16:12:17 -05:00
Eelco Dolstra
d1158bb816
Cache connection failures 2017-03-03 19:36:01 +01:00
Eelco Dolstra
8490ee37a6
SSHMaster: Make thread-safe 2017-03-03 19:28:27 +01:00
Eelco Dolstra
d3eb1cf3bb
build-remote: Don't use a SSH master
This is unnecessary because we make only one connection.
2017-03-03 19:23:20 +01:00
Eelco Dolstra
577ebeaefb
Improve SSH handling
* Unify SSH code in SSHStore and LegacySSHStore.

* Fix a race starting the SSH master. We now wait synchronously for
  the SSH master to finish starting. This prevents the SSH clients
  from starting their own connections.

* Don't use a master if max-connections == 1.

* Add a "max-connections" store parameter.

* Add a "compress" store parameter.
2017-03-03 19:05:50 +01:00
Eelco Dolstra
2f992692e2
Fix fatal "broken pipe" error when $NIX_BUILD_HOOK is missing 2017-03-03 15:40:06 +01:00
Eelco Dolstra
fa125b9b28
TeeSink: Pre-reserve string space
When receiving a very large file, this can prevent the string from
having tobe copied, which temporarily doubles memory consumption.
2017-03-01 16:16:04 +01:00
Eelco Dolstra
f61f67ddee
RemoteStore::addToStore(): Send NAR rather than string containing NAR
This allows the NAR to be streamed in the future (though we're not
doing that yet).
2017-03-01 16:07:15 +01:00
Eelco Dolstra
07a0b8ca67
Tweak message 2017-03-01 14:52:16 +01:00
Eelco Dolstra
c4a40949d9
Handle importing NARs containing files greater than 4 GiB
Also templatize readInt() to work for various integer types.
2017-03-01 13:52:54 +01:00
Eelco Dolstra
0780805246
Fix building against older curl versions
http://hydra.nixos.org/build/49490928
2017-02-28 14:03:43 +01:00
Eelco Dolstra
fd86dd93dd
Improve SQLite busy handling 2017-02-28 13:59:11 +01:00
Eelco Dolstra
34b12bad59
NarInfoDiskCache: Handle SQLite busy errors 2017-02-28 13:44:11 +01:00
Eelco Dolstra
80027144ae
In SQLite errors, include the database path
This is necessary because we have multiple SQLite databases (e.g. the
binary cache cache).
2017-02-28 13:20:12 +01:00
Eelco Dolstra
7251d048fa
Support auto-configuration of build-max-jobs
"build-max-jobs" and the "-j" option can now be set to "auto" to use
the number of CPUs in the system. (Unlike build-cores, it doesn't use
0 to imply auto-configuration, because a) magic values are a bad idea
in general; b) 0 is a legitimate value used to disable local
building.)

Fixes #1198.
2017-02-28 12:54:50 +01:00
Eelco Dolstra
3fab1f04a7
_SC_NPROCESSORS_ONLN -> std:🧵:hardware_concurrency() 2017-02-27 16:01:54 +01:00
Eelco Dolstra
3cb0387d3f
Retry downloads on HTTP/2 stream errors
Issue #1254.
2017-02-27 14:36:09 +01:00
Eelco Dolstra
e76df9bd52
Register content-addressability assertion for fixed outputs 2017-02-24 16:39:53 +01:00
Eelco Dolstra
1c718f80d3
Verify content-addressability assertions at registration time 2017-02-24 16:38:14 +01:00
Dan Peebles
e7cb2847ab Explicitly model all settings and fail on unrecognized ones
Previously, the Settings class allowed other code to query for string
properties, which led to a proliferation of code all over the place making
up new options without any sort of central registry of valid options. This
commit pulls all those options back into the central Settings class and
removes the public get() methods, to discourage future abuses like that.

Furthermore, because we know the full set of options ahead of time, we
now fail loudly if someone enters an unrecognized option, thus preventing
subtle typos. With some template fun, we could probably also dump the full
set of options (with documentation, defaults, etc.) to the command line,
but I'm not doing that yet here.
2017-02-22 20:19:25 -05:00
Eelco Dolstra
f023f64f40
RemoteStore::addToStore(): Pass content-addressability assertion
... and use this in Downloader::downloadCached(). This fixes

  $ nix-build https://nixos.org/channels/nixos-16.09-small/nixexprs.tar.xz -A hello
  error: cannot import path ‘/nix/store/csfbp1s60dkgmk9f8g0zk0mwb7hzgabd-nixexprs.tar.xz’ because it lacks a valid signature
2017-02-22 16:58:00 +01:00
Eelco Dolstra
8b1b5f9a12
Handle CURLE_RECV_ERROR as a transient error
This fixes

  unable to download ‘https://cache.nixos.org/nar/077h8ji74y9b0qx7rjk71xd80vjqp6q5gy137r553jlvdlxdcdlk.nar.xz’: HTTP error 200 (curl error: Failure when receiving data from the peer)
2017-02-21 16:04:47 +01:00
Eelco Dolstra
99bbddedb1
Fix building without S3 support
http://hydra.nixos.org/build/49031196/nixlog/2/raw
2017-02-21 13:15:07 +01:00
Eelco Dolstra
df66d346df
Log AWS retries 2017-02-21 11:50:31 +01:00
Eelco Dolstra
302386f775
Support netrc in <nix/fetchurl.nix>
This allows <nix/fetchurl.nix> to fetch private Git/Mercurial
repositories, e.g.

  import <nix/fetchurl.nix> {
    url = https://edolstra@bitbucket.org/edolstra/my-private-repo/get/80a14018daed.tar.bz2;
    sha256 = "1mgqzn7biqkq3hf2697b0jc4wabkqhmzq2srdymjfa6sb9zb6qs7";
  }

where /etc/nix/netrc contains:

  machine bitbucket.org
  login edolstra
  password blabla...

This works even when sandboxing is enabled.

To do: add unpacking support (i.e. fetchzip functionality).
2017-02-16 15:51:50 +01:00
Eelco Dolstra
cde4b60919
Move netrcFile to Settings
Also get rid of Settings::processEnvironment(), it appears to be
useless.
2017-02-16 14:50:41 +01:00
Eelco Dolstra
40f0e3b366
Include "curl" in the User-Agent header
Some sites (e.g. BitBucket) give a helpful 401 error when trying to
download a private archive if the User-Agent contains "curl", but give
a redirect to a login page otherwise (so for instance
"nix-prefetch-url" will succeed but produce useless output).
2017-02-16 13:55:43 +01:00
Eelco Dolstra
d1139ff36b Merge pull request #1215 from k0001/netrc-1
Add netrc-file support
2017-02-16 12:45:44 +01:00
Eelco Dolstra
9ff9c3f2f8
Add support for s3:// URIs
This adds support for s3:// URIs in all places where Nix allows URIs,
e.g. in builtins.fetchurl, builtins.fetchTarball, <nix/fetchurl.nix>
and NIX_PATH. It allows fetching resources from private S3 buckets,
using credentials obtained from the standard places (i.e. AWS_*
environment variables, ~/.aws/credentials and the EC2 metadata
server). This may not be super-useful in general, but since we already
depend on aws-sdk-cpp, it's a cheap feature to add.
2017-02-14 14:20:00 +01:00
Renzo Carbonara
e2257d4eeb Documentation. 2017-02-09 18:16:09 +01:00
Tuomas Tynkkynen
2cd468874f Include config.h implicitly with '-include config.h' in CFLAGS
Because config.h can #define things like _FILE_OFFSET_BITS=64 and not
every compilation unit includes config.h, we currently compile half of
Nix with _FILE_OFFSET_BITS=64 and other half with _FILE_OFFSET_BITS
unset. This causes major havoc with the Settings class on e.g. 32-bit ARM,
where different compilation units disagree with the struct layout.

E.g.:

diff --git a/src/libstore/globals.cc b/src/libstore/globals.cc
@@ -166,6 +166,8 @@ void Settings::update()
     _get(useSubstitutes, "build-use-substitutes");
+    fprintf(stderr, "at Settings::update(): &useSubstitutes = %p\n", &nix::settings.useSubstitutes);
     _get(buildUsersGroup, "build-users-group");
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -138,6 +138,8 @@ void RemoteStore::initConnection(Connection & conn)
 void RemoteStore::setOptions(Connection & conn)
 {
+    fprintf(stderr, "at RemoteStore::setOptions(): &useSubstitutes = %p\n", &nix::settings.useSubstitutes);
     conn.to << wopSetOptions

Gave me:

at Settings::update(): &useSubstitutes = 0xb6e5c5cb
at RemoteStore::setOptions(): &useSubstitutes = 0xb6e5c5c7

That was not a fun one to debug!
2017-02-08 21:51:02 +02:00
Eelco Dolstra
6f4682ad36
Merge branch 'nix-copy-closure-c++' of https://github.com/shlevy/nix 2017-02-07 20:47:45 +01:00
Eelco Dolstra
caa5793b4a
Add a LegacySSHStore that uses nix-store --serve
This is useful for nix-copy-closure.
2017-02-07 19:29:21 +01:00
Eelco Dolstra
f38224e924
copyStorePath(): Don't require signatures for "trusted" stores
For example, SSH stores could be trusted.
2017-02-07 19:29:21 +01:00
Eelco Dolstra
fa07558a06
Provide default implementations for a couple of Store methods 2017-02-07 19:29:21 +01:00
Eelco Dolstra
7a58ad0ef5
SSHStore: uri -> host 2017-02-07 19:20:15 +01:00
Eelco Dolstra
612aeb2df5
Cleanup 2017-02-07 19:16:25 +01:00
Renzo Carbonara
e6e74f987f Add netrc-file support 2017-02-02 13:24:20 +01:00
Eelco Dolstra
1351b0df87
exportReferencesGraph: Only export in JSON format when in structured mode
This prevents breaking compatibility with builders that read
"closure.*", since they would accidentally pick up the new JSON files.
2017-02-02 12:20:28 +01:00
Eelco Dolstra
7a65b2470e
Restore default signal handling in child processes
In particular, this fixes Ctrl-C in nix-shell sessions.
2017-02-01 13:00:21 +01:00
Eelco Dolstra
cb1951e746
Periodically purge binary-cache.sqlite 2017-01-27 15:19:33 +01:00
Eelco Dolstra
211bc7f0e6
Implement TTL for binary cache lookups 2017-01-27 13:17:08 +01:00
Eelco Dolstra
f57a38b109
Remove unused NARExistence table 2017-01-27 12:57:49 +01:00
Eelco Dolstra
c2b0d8749f
exportReferencesGraph: Export more complete info in JSON format
This writes info about every path in the closure in the same format as
‘nix path-info --json’. Thus it also includes NAR hashes and sizes.

Example:

  [
    {
      "path": "/nix/store/10h6li26i7g6z3mdpvra09yyf10mmzdr-hello-2.10",
      "narHash": "sha256:0ckdc4z20kkmpqdilx0wl6cricxv90lh85xpv2qljppcmz6vzcxl",
      "narSize": 197648,
      "references": [
        "/nix/store/10h6li26i7g6z3mdpvra09yyf10mmzdr-hello-2.10",
        "/nix/store/27binbdy296qvjycdgr1535v8872vz3z-glibc-2.24"
      ],
      "closureSize": 20939776
    },
    {
      "path": "/nix/store/27binbdy296qvjycdgr1535v8872vz3z-glibc-2.24",
      "narHash": "sha256:1nfn3m3p98y1c0kd0brp80dn9n5mycwgrk183j17rajya0h7gax3",
      "narSize": 20742128,
      "references": [
        "/nix/store/27binbdy296qvjycdgr1535v8872vz3z-glibc-2.24"
      ],
      "closureSize": 20742128
    }
  ]

Fixes #1134.
2017-01-26 20:41:08 +01:00
Eelco Dolstra
6de33a9c67
Add support for passing structured data to builders
Previously, all derivation attributes had to be coerced into strings
so that they could be passed via the environment. This is lossy
(e.g. lists get flattened, necessitating configureFlags
vs. configureFlagsArray, of which the latter cannot be specified as an
attribute), doesn't support attribute sets at all, and has size
limitations (necessitating hacks like passAsFile).

This patch adds a new mode for passing attributes to builders, namely
encoded as a JSON file ".attrs.json" in the current directory of the
builder. This mode is activated via the special attribute

  __structuredAttrs = true;

(The idea is that one day we can set this in stdenv.mkDerivation.)

For example,

  stdenv.mkDerivation {
    __structuredAttrs = true;
    name = "foo";
    buildInputs = [ pkgs.hello pkgs.cowsay ];
    doCheck = true;
    hardening.format = false;
  }

results in a ".attrs.json" file containing (sans the indentation):

  {
    "buildInputs": [],
    "builder": "/nix/store/ygl61ycpr2vjqrx775l1r2mw1g2rb754-bash-4.3-p48/bin/bash",
    "configureFlags": [
      "--with-foo",
      "--with-bar=1 2"
    ],
    "doCheck": true,
    "hardening": {
      "format": false
    },
    "name": "foo",
    "nativeBuildInputs": [
      "/nix/store/10h6li26i7g6z3mdpvra09yyf10mmzdr-hello-2.10",
      "/nix/store/4jnvjin0r6wp6cv1hdm5jbkx3vinlcvk-cowsay-3.03"
    ],
    "propagatedBuildInputs": [],
    "propagatedNativeBuildInputs": [],
    "stdenv": "/nix/store/f3hw3p8armnzy6xhd4h8s7anfjrs15n2-stdenv",
    "system": "x86_64-linux"
  }

"passAsFile" is ignored in this mode because it's not needed - large
strings are included directly in the JSON representation.

It is up to the builder to do something with the JSON
representation. For example, in bash-based builders, lists/attrsets of
string values could be mapped to bash (associative) arrays.
2017-01-26 20:40:33 +01:00
Eelco Dolstra
b1f001538e
Fix assertion failure when a path is locked
Fixes:

  nix-store: src/libstore/build.cc:3649: void nix::Worker::run(const Goals&): Assertion `!awake.empty()' failed.
2017-01-26 20:40:33 +01:00
Eelco Dolstra
951357e5fb
UserLock: Fix multi-threaded access to a global variable 2017-01-26 20:40:33 +01:00
Eelco Dolstra
a55f589720
openLockFile: Return an AutoCloseFD 2017-01-26 20:40:33 +01:00
Eelco Dolstra
c0f2f4eeef
UserLock: Make more RAII-ish 2017-01-26 20:40:33 +01:00
Eelco Dolstra
a529c740d2
Moving more code out of DerivationGoal::startBuilder() 2017-01-26 20:40:33 +01:00
Eelco Dolstra
e8c43abd9a
On HTTP errors, also show the curl error
This is a hopefully temporary measure to diagnose the intermittent
"HTTP error 200" failures.
2017-01-26 20:40:32 +01:00
Eelco Dolstra
4425a5c547
Move exportReferencesGraph into a separate method
startBuilder() is getting rather obese.
2017-01-26 20:40:32 +01:00
Eelco Dolstra
e3bf228c92
Enable verbose curl output
Closes #1182.
2017-01-24 13:57:01 +01:00
Shea Levy
bfa41eb671 nix-copy-closure: Implement in C++.
Tests fail currently because the database is not given proper hashes in the VM
2017-01-20 09:47:58 -05:00
Eelco Dolstra
8af062f372 Merge pull request #981 from shlevy/build-remote-c++
build-remote: Implement in C++
2017-01-19 18:21:55 +01:00
Eelco Dolstra
21948deed9
Kill builds when we get EOF on the log FD
This closes a long-time bug that allowed builds to hang Nix
indefinitely (regardless of timeouts) simply by doing

  exec > /dev/null 2>&1; while true; do true; done

Now, on EOF, we just send SIGKILL to the child to make sure it's
really gone.
2017-01-19 17:16:14 +01:00
Eelco Dolstra
2579e32c2b
Use std::unique_ptr for HookInstance 2017-01-19 17:06:04 +01:00
Eelco Dolstra
cc3b93c991
Handle SIGINT etc. via a sigwait() signal handler thread
This allows other threads to install callbacks that run in a regular,
non-signal context. In particular, we can use this to signal the
downloader thread to quit.

Closes #1183.
2017-01-17 18:21:02 +01:00
Eelco Dolstra
8079ab87a2 AutoCloseDir: Use std::unique_ptr 2017-01-16 22:39:27 +01:00
Eelco Dolstra
2b9d0a99cb AutoDeleteArray -> std::unique_ptr
Also, switch to C++14 for std::make_unique.
2017-01-16 22:24:49 +01:00
Eelco Dolstra
7adb986e35 Merge pull request #1139 from Mic92/master
Simplify remouting with MS_PRIVATE in sandbox build
2017-01-09 16:46:59 +01:00
Eelco Dolstra
b6b142b4b1
Provide /var/run/nscd/socket in the sandbox
Otherwise sandbox builds can fail, e.g.

  $ NIX_REMOTE=local?root=/tmp/nix nix-build '<nixpkgs>' -A hello --option build-use-substitutes false
  ...
  downloading ‘http://ftpmirror.gnu.org/bash/bash-4.3-patches/bash43-047’...
  error: unable to download ‘http://ftpmirror.gnu.org/bash/bash-4.3-patches/bash43-047’: Couldn't resolve host name (6)
2017-01-02 14:46:37 +01:00
Eelco Dolstra
d0a2db17d9
Call Aws::InitAPI
This is required now.
2016-12-22 17:39:49 +01:00
Eelco Dolstra
786ee585b8
Add comment 2016-12-22 17:39:49 +01:00
Eelco Dolstra
3a4bd320c2
Revert "Merge branch 'seccomp' of https://github.com/aszlig/nix"
This reverts commit 9f3f2e21ed, reversing
changes made to 47f587700d.
2016-12-19 11:52:57 +01:00
Eelco Dolstra
05862209de
Revert "Give root a valid home directory"
This reverts commit ec7d498b72.
2016-12-19 11:49:03 +01:00
Eelco Dolstra
ec7d498b72
Give root a valid home directory
Some programs barf if the current user has a non-writable home
directory, e.g. http://hydra.nixos.org/build/44818144.
2016-12-15 15:56:08 +01:00
Eelco Dolstra
9f3f2e21ed
Merge branch 'seccomp' of https://github.com/aszlig/nix 2016-12-15 12:04:45 +01:00
Eelco Dolstra
47f587700d
Probably fix a segfault in PathLocks 2016-12-09 13:26:43 +01:00
Eelco Dolstra
b30d1e7ada
Don't delete .check directories of running builds
We need to keep them around for diffoscope.
2016-12-08 21:38:58 +01:00
Eelco Dolstra
88ef77226e
Fix warning on 32-bit systems
http://hydra.nixos.org/build/44628517
2016-12-08 20:37:58 +01:00
Eelco Dolstra
e629a17cc1
Fix build
http://hydra.nixos.org/build/44628517
2016-12-08 20:36:14 +01:00
Eelco Dolstra
fe1162a805
S3BinaryCacheStore: Ensure it only builds on Linux 2016-12-08 15:35:46 +01:00
Eelco Dolstra
e6a61b8da7
Fix S3BinaryCacheStore
It failed with

   AWS error uploading ‘6gaxphsyhg66mz0a00qghf9nqf7majs2.ls.xz’: Unable to parse ExceptionName: MissingContentLength Message: You must provide the Content-Length HTTP header.

possibly because the istringstream_nocopy introduced in
0d2ebb4373 doesn't supply the seek
method that the AWS library expects. So bring back the old version,
but only for S3BinaryCacheStore.
2016-12-08 15:31:27 +01:00