Bazel computes the default value of output_user_root before parsing the
flag[0]. The computation of the default value involves getting the $USER
from the environment. I don't have that variable when building with
sandbox enabled.
[0]: 9323c57607/src/main/cpp/startup_options.cc (L123-L124)
Create a many-layered Docker Image.
Implements much less than buildImage:
- Doesn't support specific uids/gids
- Doesn't support runninng commands after building
- Doesn't require qemu
- Doesn't create mutable copies of the files in the path
- Doesn't support parent images
If you want those feature, I recommend using buildLayeredImage as an
input to buildImage.
Notably, it does support:
- Caching low level, common paths based on a graph traversial
algorithm, see referencesByPopularity in
0a80233487993256e811f566b1c80a40394c03d6
- Configurable number of layers. If you're not using AUFS or not
extending the image, you can specify a larger number of layers at
build time:
pkgs.dockerTools.buildLayeredImage {
name = "hello";
maxLayers = 128;
config.Cmd = [ "${pkgs.gitFull}/bin/git" ];
};
- Parallelized creation of the layers, improving build speed.
- The contents of the image includes the closure of the configuration,
so you don't have to specify paths in contents and config.
With buildImage, paths referred to by the config were not included
automatically in the image. Thus, if you wanted to call Git, you
had to specify it twice:
pkgs.dockerTools.buildImage {
name = "hello";
contents = [ pkgs.gitFull ];
config.Cmd = [ "${pkgs.gitFull}/bin/git" ];
};
buildLayeredImage on the other hand includes the runtime closure of
the config when calculating the contents of the image:
pkgs.dockerTools.buildImage {
name = "hello";
config.Cmd = [ "${pkgs.gitFull}/bin/git" ];
};
Minor Problems
- If any of the store paths change, every layer will be rebuilt in
the nix-build. However, beacuse the layers are bit-for-bit
reproducable, when these images are loaded in to Docker they will
match existing layers and not be imported or uploaded twice.
Common Questions
- Aren't Docker layers ordered?
No. People who have used a Dockerfile before assume Docker's
Layers are inherently ordered. However, this is not true -- Docker
layers are content-addressable and are not explicitly layered until
they are composed in to an Image.
- What happens if I have more than maxLayers of store paths?
The first (maxLayers-2) most "popular" paths will have their own
individual layers, then layer #(maxLayers-1) will contain all the
remaining "unpopular" paths, and finally layer #(maxLayers) will
contain the Image configuration.
Using a simple algorithm, convert the references to a path in to a
sorted list of dependent paths based on how often they're referenced
and how deep in the tree they live. Equally-"popular" paths are then
sorted by name.
The existing writeReferencesToFile prints the paths in a simple
ascii-based sorting of the paths.
Sorting the paths by graph improves the chances that the difference
between two builds appear near the end of the list, instead of near
the beginning. This makes a difference for Nix builds which export a
closure for another program to consume, if that program implements its
own level of binary diffing.
For an example, Docker Images. If each store path is a separate layer
then Docker Images can be very efficiently transfered between systems,
and we get very good cache reuse between images built with the same
version of Nixpkgs. However, since Docker only reliably supports a
small number of layers (42) it is important to pick the individual
layers carefully. By storing very popular store paths in the first 40
layers, we improve the chances that the next Docker image will share
many of those layers.*
Given the dependency tree:
A - B - C - D -\
\ \ \ \
\ \ \ \
\ \ - E ---- F
\- G
Nodes which have multiple references are duplicated:
A - B - C - D - F
\ \ \
\ \ \- E - F
\ \
\ \- E - F
\
\- G
Each leaf node is now replaced by a counter defaulted to 1:
A - B - C - D - (F:1)
\ \ \
\ \ \- E - (F:1)
\ \
\ \- E - (F:1)
\
\- (G:1)
Then each leaf counter is merged with its parent node, replacing the
parent node with a counter of 1, and each existing counter being
incremented by 1. That is to say `- D - (F:1)` becomes `- (D:1, F:2)`:
A - B - C - (D:1, F:2)
\ \ \
\ \ \- (E:1, F:2)
\ \
\ \- (E:1, F:2)
\
\- (G:1)
Then each leaf counter is merged with its parent node again, merging
any counters, then incrementing each:
A - B - (C:1, D:2, E:2, F:5)
\ \
\ \- (E:1, F:2)
\
\- (G:1)
And again:
A - (B:1, C:2, D:3, E:4, F:8)
\
\- (G:1)
And again:
(A:1, B:2, C:3, D:4, E:5, F:9, G:2)
and then paths have the following "popularity":
A 1
B 2
C 3
D 4
E 5
F 9
G 2
and the popularity contest would result in the paths being printed as:
F
E
D
C
B
G
A
* Note: People who have used a Dockerfile before assume Docker's
Layers are inherently ordered. However, this is not true -- Docker
layers are content-addressable and are not explicitly layered until
they are composed in to an Image.
This causes problems for packages built using a bootstrap stdenv,
resulting in references to /bin/sh or even bootstrap-tools. The darwin
stdenv is much stricter about what requisites/references are allowed but
using /bin/sh on linux is also undesirable.
eg. https://hydra.nixos.org/build/81754896
$ nix-build -A xz
$ head -n1 result-bin/bin/xzdiff
#!/nix/store/yvc7kmw98kq547bnqn1afgyxm8mxdwhp-bootstrap-tools/bin/sh
This reverts commit f06942327a.
This reverts commit f777d2b719.
cc #34409
This breaks evaluation of the tested job:
attribute 'diskInterface' missing, at /nix/store/5k9kk52bv6zsvsyyvpxhm8xmwyn2yjvx-source/pkgs/build-support/vm/default.nix:316:24
This includes the initialy commit was done by @Mic92 plus a few fixes
from my side. So essentially this avoids patching statically linked
executables and also speeds up searching for ELF files altogether.
I've tested this by comparing the outputs of all the derivations which
make use of this hook using the following Nix expression:
let
getPackagesForRev = rev: with import (builtins.fetchGit {
url = ./.;
inherit rev;
}) { config.allowUnfree = true; }; [
cups-kyodialog3 elasticsearch franz gurobi javacard-devkit
masterpdfeditor maxx oracle-instantclient powershell reaper
teamviewer unixODBCDrivers.msodbcsql17 virtlyst wavebox zoom-us
];
pkgs = import <nixpkgs> {};
baseRev = "ef764eb0d8314b81a012dae04642b4766199956d";
in pkgs.runCommand "diff-contents" {
chset = pkgs.lib.zipListsWith (old: new: pkgs.runCommand "diff" {
inherit old new;
nativeBuildInputs = [ pkgs.nukeReferences ];
} ''
mkdir -p "''${NIX_STORE#/}"
cp --no-preserve=all -r "$old" "''${NIX_STORE#/}"
cp --no-preserve=all -r "$new" "''${NIX_STORE#/}"
find "''${old#/}" "''${new#/}" \
\( -type f -exec nuke-refs {} + \) -o \( -type l -delete \)
mkdir "$out"
echo "$old" > "$out/old-path"
echo "$new" > "$out/new-path"
diff -Nur "''${old#/}" "''${new#/}" > "$out/diff" || :
'') (getPackagesForRev baseRev) (getPackagesForRev "");
} ''
err=0
for c in $chset; do
if [ -s "$c/diff" ]; then
echo "$(< "$c/old-path") -> $(< "$c/new-path")" \
"differs, report: $c/diff" >&2
err=1
fi
done
[ $err -eq 0 ] && touch "$out"
''
With these changes there is only one derivation which has altered
contents, which is "franz". However the reason why it has differing
contents is not directly because of the autoPatchelfHook changes, but
because the "env-vars" file from the builder is in
"$out/opt/franz/env-vars" (Cc: @gnidorah) and we now have different
contents for NIX_CFLAGS_COMPILE and other environment variables.
I also tested this against a random static binary and the hook no longer
tries to patch it.
Merges: #47222
The "maxx" package recursively runs isExecutable on a bunch of files and
since the change to use "readelf" instead of "file" a lot of errors like
this one are printed during build:
readelf: Error: Not an ELF file - it has the wrong magic bytes at the
start
While the isExecutable was never meant to be used outside of the
autoPatchelfHook, it's still a good idea to silence the errors because
whenever readelf fails, it clearly indicates that the file in question
is not a valid ELF file.
Signed-off-by: aszlig <aszlig@nix.build>
If the ELF file is not an executable, we do not get a PT_INTERP section,
because after all, it's a *shared* library.
So instead of checking for PT_INTERP (to avoid statically linked
executables) for all ELF files, we add another check to see if it's an
executable and *only* skip it when it is and there's no PT_INTERP.
Signed-off-by: aszlig <aszlig@nix.build>
The `overrideScope` bound by `makeScope` (via special `callPackage`)
took an override in the form `super: self { … }`. But this is
dangerously close to the `self: super { … }` form used by *everything*
else, even other definitions of `overrideScope`! Since that
implementation did not even share any code either until I changed it
recently in 3cf43547f4, this inconsistency
is almost certainly an oversight and not intentional.
Unfortunately, just as the inconstency is hard to debug if one just
assumes the conventional order, any sudden fix would break existing
overrides in the same hard-to-debug way. So instead of changing the
definition a new `overrideScope'` with the conventional order is added,
and old `overrideScope` deprecated with a warning saying to use
`overrideScope'` instead. That will hopefully get people to stop using
`overrideScope`, freeing our hand to change or remove it in the future.
02c09e0171 (NixOS/nixpkgs#44558) was reverted in
c981787db9 but, as it turns out, it fixed an issue
I didn't know about at the time: the values of `propagateDoc` options were
(and now again are) inconsistent with the underlying things those wrappers wrap
(see NixOS/nixpkgs#46119), which was (and now is) likely to produce more instances
of NixOS/nixpkgs#43547, if not now, then eventually as stdenv changes.
This patch (which is a simplified version of the original reverted patch) is the
simplest solution to this whole thing: it forces wrappers to directly inspect the
outputs of the things they are wrapping instead of making stdenv guess the correct
values.
Because dates are an impurity, by default buildImage will use a static
date of one second past the UNIX Epoch. This can be a bit frustrating
when listing docker images in the CLI:
$ docker image list
REPOSITORY TAG IMAGE ID CREATED SIZE
hello latest 08c791c7846e 48 years ago 25.2MB
If you want to trade the purity for a better user experience, you can
set created to now.
pkgs.dockerTools.buildImage {
name = "hello";
tag = "latest";
created = "now";
contents = pkgs.hello;
config.Cmd = [ "/bin/hello" ];
}
and now the Docker CLI will display a reasonable date and sort the
images as expected:
$ docker image list
REPOSITORY TAG IMAGE ID CREATED SIZE
hello latest de2bf4786de6 About a minute ago 25.2MB
This commit adds test based on real-world crates (brotli).
There were a few more edge cases that were missing beforehand. Also it
turned out that we can get rid of the `finalBins` list since that will
now be handled during runtime.
The build expression got quiet large over time and to make it a bit
easier to grasp the different scripts involved in the build are now
separated from the nix file.
Cargo has a few odd (old) ways of picking source files if the `bin.path`
attribute isn't given in the Cargo.toml. This commit adds support for
some of those. The previous behaviour always defaulted to `src/main.rs`
which was not always the right choice.
Since there is look-ahead into the unpacked sources before running the
actual builder the path selection logic has to be embedded within the
build script.
`buildRustCrate` currently supports two ways of running building
binaries when processing a crate:
- Explicit definition of all the binaries (& optionally the paths to
their respective `main.rs`) and,
- if not binary was explictly configured all files matching the patterns
`src/main.rs`, `src/bin/*.rs`.
When the explicit list is given without path information paths are now
being picked from a list of candidates. The first match wins. The order
is the same as within the cargo compatibility code.
If the crate does not provide any libraries the path `src/{bin_name}.rs`
is also considered.
All underscores within the binary names are translated into dashes (`-`)
before the lookups are made. This seems to be a common convention.
Previously the Release.xz URL would show up with a new hash whenever
debian releases an update. By using archive.org we should have a stable
source for those. I wasn't able to find the equivalent in the debian
world. Maybe they don't keep all the different Release files around..
By setting useRealVendorConfig explicitly to true, the actual (slightly
modified) config generated by cargo-vendor is used.
This solves a problem, where the static vendor config in
pkgs/build-support/rust/default.nix would not sufficiently replace all
crates Cargo is looking for.
As useRealVendorConfig (and writeVendorConfig in fetchcargo) default to
false, there should be no breakage in existing cargoSha256 hashes.
Nethertheless, imho using this new feature should become standard. A
possible deprecation path could be:
- introduce this patch
- set useRealVendorConfig explicitly to false whereever cargoSha256 is
set but migration is not wanted yet.
- after some time, let writeVendorConfig default to true
- when useRealVendorConfig is true everywhere cargoSha256 is set and
enough time is passed, `assert cargoVendorDir == null ->
useRealVendorConfig;`, remove old behaviour
- after some time, remove all appearences of useRealVendorConfig and the
parameter itself
Introduce a `skawarePackages.buildPackage` function that contains the
common setup, removing a lot of duplication.
In particular, we require that the build directory has to be empty
after the `fixupPhase`, to make sure every relevant file is moved to
the outputs.
A next step would be to deduplicate the `configureFlags` attributes
and only require a `skawareInputs` field.
There's no reason `linkFarm` can't be used for symlinks in
subdirectories, except that currently it doesn't ensure the directory
of the link exists. This backwards-compatible change expands the utility
of the function.
This hopefully makes patchShebangs respect cross compilation. It
introduces the concept of the HOST_PATH. Nothing is ever executed on
it but instead used as a way to get the proper path using ‘command
-v’. Needs more testing.
/cc @ericson2314 @dtzwill
Fixes#33956Fixes#21138
* substitute(): --subst-var was silently coercing to "" if the variable does not exist.
* libffi: simplify using `checkInputs`
* pythonPackges.hypothesis, pythonPackages.pytest: simpify dependency cycle fix
* utillinux: 2.32 -> 2.32.1
https://lkml.org/lkml/2018/7/16/532
* busybox: 1.29.0 -> 1.29.1
* bind: 9.12.1-P2 -> 9.12.2
https://ftp.isc.org/isc/bind9/9.12.2/RELEASE-NOTES-bind-9.12.2.html
* curl: 7.60.0 -> 7.61.0
* gvfs: make tests run, but disable
* ilmbase: disable tests on i686. Spooky!
* mdds: fix tests
* git: disable checks as tests are run in installcheck
* ruby: disable tests
* libcommuni: disable checks as tests are run in installcheck
* librdf: make tests run, but disable
* neon, neon_0_29: make tests run, but disable
* pciutils: 3.6.0 -> 3.6.1
Semi-automatic update generated by https://github.com/ryantm/nixpkgs-update tools. This update was made based on information from https://repology.org/metapackage/pciutils/versions.
* mesa: more include fixes
mostly from void-linux (thanks!)
* npth: 1.5 -> 1.6
minor bump
* boost167: Add lockfree next_prior patch
* stdenv: cleanup darwin bootstrapping
Also gets rid of the full python and some of it's dependencies in the
stdenv build closure.
* Revert "pciutils: use standardized equivalent for canonicalize_file_name"
This reverts commit f8db20fb3a.
Patching should no longer be needed with 3.6.1.
* binutils-wrapper: Try to avoid adding unnecessary -L flags
(cherry picked from commit f3758258b8895508475caf83e92bfb236a27ceb9)
Signed-off-by: Domen Kožar <domen@dev.si>
* libffi: don't check on darwin
libffi usages in stdenv broken darwin. We need to disable doCheck for that case.
* "rm $out/share/icons/hicolor/icon-theme.cache" -> hicolor-icon-theme setup-hook
* python.pkgs.pytest: setupHook to prevent creation of .pytest-cache folder, fixes#40273
When `py.test` was run with a folder as argument, it would not only
search for tests in that folder, but also create a .pytest-cache folder.
Not only is this state we don't want, but it was also causing
collisions.
* parity-ui: fix after merge
* python.pkgs.pytest-flake8: disable test, fix build
* Revert "meson: 0.46.1 -> 0.47.0"
With meson 0.47.0 (or 0.47.1, or git)
things are very wrong re:rpath handling
resulting in at best missing libs but
even corrupt binaries :(.
When we run patchelf it masks the problem
by removing obviously busted paths.
Which is probably why this wasn't noticed immediately.
Unfortunately the binary already
has a long series of paths scribbled
in a space intended for a much smaller string;
in my testing it was something like
lengths were 67 with 300+ written to it.
I think we've reported the relevant issues upstream,
but unfortunately it appears our patches
are what introduces the overwrite/corruption
(by no longer being correct in what they assume)
This doesn't look so bad to fix but it's
not something I can spend more time on
at the moment.
--
Interestingly the overwritten string data
(because it is scribbled past the bounds)
remains in the binary and is why we're suddenly
seeing unexpected references in various builds
-- notably this is is the reason we're
seeing the "extra-utils" breakage
that entirely crippled NixOS on master
(and probably on staging before?).
Fixes#43650.
This reverts commit 305ac4dade.
(cherry picked from commit 273d68eff8)
Signed-off-by: Domen Kožar <domen@dev.si>
package-build expects the recipe file name to match the Emacs package
name. `melpaBuild` takes an extra argument `ename` for the Emacs package
name (default: `pname`, the Nix package name) which is used to name the recipe
file.
Fixes: #43893
See also: #43609
This makes the command ‘nix-env -qa -f. --arg config '{skipAliases =
true;}'’ work in Nixpkgs.
Misc...
- qtikz: use libsForQt5.callPackage
This ensures we get the right poppler.
- rewrites:
docbook5_xsl -> docbook_xsl_ns
docbook_xml_xslt -> docbook_xsl
diffpdf: fixup
With the recent update of BusyBox to version 1.29.0 in
d6aa506e3b there is now a new dependency
on libresolv.
This now throws a runtime error when executing ash, eg. whenever we do
something like this:
nix-build -E 'with import ./. {}; vmTools.runInLinuxVM hello'
The resulting error will be:
.../ash: error while loading shared libraries: libresolv.so.2: cannot
open shared object file: No such file or directory
I tried to override BusyBox with enableStatic, but that still requires
parts of glibc:
Static linking against glibc, can't use --gc-sections
Trying libraries: crypt m resolv
Library crypt is not needed, excluding it
Library m is needed, can't exclude it (yet)
Library resolv is needed, can't exclude it (yet)
Library m is needed, can't exclude it (yet)
Library resolv is needed, can't exclude it (yet)
Final link with: m resolv
In the long term maybe switching to a more minimal C library such as
musl would make more sense, but for now I just added libresolv.so to the
initrd which fixes the runtime error.
Signed-off-by: aszlig <aszlig@nix.build>
Cc: @edolstra, @rbvermaa
Signed-off-by: aszlig <aszlig@nix.build>
All package sets are simultaneously updated to accommodate changes to
package-build. Due to new restrictions in package-build, all packages using
`melpaBuild` must now provide a recipe file, even those packages which are not
included in upstream MELPA.
So far the runtimeDependencies variable has been rather useless unless
you also set dontPatchelf, because the patchelf setup hook ran *after*
the autoPatchelfHook and thus stripped off the additional RPATHs added
using runtimeDependencies.
I did this by moving the autoPatchelfHook to be run in postFixup instead
of fixupOutput, however I needed to replicate the for loop that runs the
hook on all outputs.
Until we have a way to influence order of execution for hooks I've
marked this with an XXX so that we can use fixupOutput again.
Tested this against all packages that use autoPatchelfHook using the
following and checking whether the output contains any errors concerning
shared libraries:
nix-build -E 'with import ./. { config.allowUnfree = true; };
runCommand "test-executables" {
drvs = [
masterpdfeditor franz zoom-us anydesk teamviewer maxx
oracle-instantclient cups-kyodialog3 virtlyst powershell
];
} "for i in $drvs; do for b in $i/bin/*; do \"$b\" || :; done; done"
'
Signed-off-by: aszlig <aszlig@nix.build>
Fixes: https://github.com/NixOS/nixpkgs/issues/43082
Cc: @Ericson2314
Since this is probably never the desired case and has led to actual
issues, see the comments at:
af1313e915
This might also happen when pulling a patch from GitHub or a similar web
interface without explicitly selecting the "raw" format.
Excludes and includes are implemented by passing the parameters to the
respective flags of `filterdiff`. Those were passed unescaped until now.
Since those flags expect patterns (similar to shell globs), something
like `/some/path/*` might be used to exclude or include all files in
some path. Without escaping the shell would expand the `*`, leading to
unexpected behaviour.
This commit was originally introduced as part of #41420 and then
reverted with the rest of that PR. However there was no reason to revert
his particular commit.
docker-tools tests load images without specifying any tag
value. Docker then uses the image with tag "latest" which doesn't
exist anymore since commit 39e678e24e.
In particular, this contains Firefox-related and libgcrypt updates.
Other larger rebuilds would apparently need lots of time to catch up
on Hydra, due to nontrivial rebuilds in other branches than staging.
A .la file specifies linker flags to link with the library it describes. Its
"dependency_libs" field lists the libraries that this library depends upon.
This list often contains "-l" flags without corresponding "-L" flags. Many
packages in Nixpkgs deal with this in one of these ways:
- delete .la file [1]
- clear dependency_libs [2]
- add -L flags to dependency_libs [3]
- propagate dependencies [4]
Sometimes "dependency_libs" contain wrong "-L" flags pointing to the "dev"
output with headers rather than to the main output with libraries. They have to
be edited or deleted to reduce closure size [5].
Deleting .la files is often but not always safe [6]. Atomatically deleting as
many of them as possible is complex [7]. Deleting .la files that describe
shared rather than static libraries is probably safe; but clearing their
"dependency_libs" field achieves the same effect with less potential for
unintended consequences. This is the approach that may be enabled for all
Nixpkgs.
[1] 2a79d296d3
[2] c83a530985
[3] 9e0dcf3bd9
[4] 01134e698f
[5] f6c73f1e37
[6] https://wiki.gentoo.org/wiki/Project:Quality_Assurance/Handling_Libtool_Archives
[7] https://github.com/gentoo/gentoo/blob/fb1f2435/eclass/ltprune.eclass
If there is a shared object or executable that's using
position-independent code, the file's mime type is
"application/x-pie-executable", so until this change its dependencies
wouldn't be patched.
This simply adds the mime type to the search loop.
Signed-off-by: aszlig <aszlig@nix.build>
Attributes `imageName` and `imageTag` are exposed if the image is
built by our Nix tools but not if the image is pulled. So, we expose
these attributes for convenience and homogeneity.
Skopeo used by our docker tools was patched to work in the build
sandbox (it used /var/tmp which is not available in the sandbox).
Since this temporary directory can now be set at build time, we remove
the patch from our docker tools.
The extraCommands was, previously, simply put in the body of the script
using nix expansion `${extraCommands}` (which looks exactly like bash
expansion!).
This causes issues like in #34779 where scripts will eventually create
invalid bash.
The solution is to use a script like `run-as-root`.
* * *
Fixes#34779
toPath has confusing semantics and is never necessary; it can always
either just be omitted or replaced by pre-concatenating `/.`. It has
been marked as "!!! obsolete?" for more than 10 years in a C++
comment, hopefully removing it will let us properly deprecate and,
eventually, remove it.
The hack of using `crossConfig` to enforce stricter handling of
dependencies is replaced with a dedicated `strictDeps` for that purpose.
(Experience has shown that my punning was a terrible idea that made more
difficult and embarrising to teach teach.)
Now that is is clear, a few packages now use `strictDeps`, to fix
various bugs:
- bintools-wrapper and cc-wrapper
Regression introduced in 736848723e.
This commit most certainly hasn't been tested with sandboxing enabled
and breaks not only pullImage but also the docker-tools NixOS VM test
because it doesn't find it's certificate path and also relies on
/var/tmp being there.
Fixing the certificate path is the easiest one because it can be done
via environment variable.
I've used overrideAttrs for changing the hardcoded path to /tmp (which
is available in sandboxed builds and even hardcoded in Nix), so that
whenever someone uses Skopeo from all-packages.nix the path is still
/var/tmp.
The reason why this is hardcoded to /var/tmp can be seen in a comment in
vendor/github.com/containers/image/storage/storage_image.go:
Do not use the system default of os.TempDir(), usually /tmp, because
with systemd it could be a tmpfs.
With sandboxed builds this isn't the case, however for using Nix without
NixOS this could turn into a problem if this indeed is the case.
So in the long term this needs to have a proper solution.
In addition to that, I cleaned up the expression a bit.
Tested by building dockerTools.examples.nixFromDockerHub and the
docker-tools NixOS VM test.
Signed-off-by: aszlig <aszlig@nix.build>
Cc: @nlewo, @Mic92, @Profpatsch, @globin, @LnL7
The script would parse the output of `git submodule status` but
didn't handle paths with spaces in them. This would result in the
following error when trying to determine the URL of the submodule:
error: key does not contain a section: .url
* fetchs3: add configurable name
Change the default from "foo" to the basename of the s3 URL and make it
configurable.
* fetchs3: fix error on missing credentials.session_token
The session token should default to null instead of failing
* fetchs3: make use of the region argument
Set it to null if you don't want to use it
* fetchs3: prefer local build
Fetcher-types spend more time on network than CPU
Skopeo is used to pull images from a Docker registry (instead of a
Docker deamon in a VM).
An image reference is specified with its name and its digest which is
an immutable image identifier (unlike image name and tag).
Skopeo can be used to get the digest of an image, for instance:
$ skopeo inspect docker://docker.io/nixos/nix:1.11 | jq -r '.Digest'
