snapTools.makeSnap: init

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Graham Christensen 2019-06-18 18:51:58 +02:00
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@ -16,6 +16,7 @@
<xi:include href="functions/fhs-environments.xml" />
<xi:include href="functions/shell.xml" />
<xi:include href="functions/dockertools.xml" />
<xi:include href="functions/snaptools.xml" />
<xi:include href="functions/appimagetools.xml" />
<xi:include href="functions/prefer-remote-fetch.xml" />
<xi:include href="functions/nix-gitignore.xml" />

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@ -0,0 +1,74 @@
<section xmlns="http://docbook.org/ns/docbook"
xmlns:xlink="http://www.w3.org/1999/xlink"
xmlns:xi="http://www.w3.org/2001/XInclude"
xml:id="sec-pkgs-snapTools">
<title>pkgs.snapTools</title>
<para>
<varname>pkgs.snapTools</varname> is a set of functions for creating
Snapcraft images. Snap and Snapcraft is not used to perform these operations.
</para>
<section xml:id="ssec-pkgs-snapTools-makeSnap-signature">
<title>The makeSnap Function</title>
<para>
<function>makeSnap</function> takes a single named argument,
<parameter>meta</parameter>. This argument mirrors
<link xlink:href="https://docs.snapcraft.io/snap-format">the upstream
<filename>snap.yaml</filename> format</link> exactly.
</para>
<para>
The <parameter>base</parameter> should not be be specified, as
<function>makeSnap</function> will force set it.
</para>
<para>
Currently, <function>makeSnap</function> does not support creating GUI
stubs.
</para>
</section>
<section xml:id="ssec-pkgs-snapTools-build-a-snap-hello">
<title>Build a Hello World Snap</title>
<example xml:id="ex-snapTools-buildSnap-hello">
<title>Making a Hello World Snap</title>
<para>
The following expression packages GNU Hello as a Snapcraft snap.
</para>
<programlisting><xi:include href="../../pkgs/build-support/snap/example-hello.nix" parse="text" /></programlisting>
<para>
<command>nix-build</command> this expression and install it with
<command>snap install ./result --dangerous</command>.
<command>hello</command> will now be the Snapcraft version of the package.
</para>
</example>
</section>
<section xml:id="ssec-pkgs-snapTools-build-a-snap-firefox">
<title>Build a Hello World Snap</title>
<example xml:id="ex-snapTools-buildSnap-firefox">
<title>Making a Graphical Snap</title>
<para>
Graphical programs require many more integrations with the host. This
example uses Firefox as an example, because it is one of the most
complicated programs we could package.
</para>
<programlisting><xi:include href="../../pkgs/build-support/snap/example-firefox.nix" parse="text" /></programlisting>
<para>
<command>nix-build</command> this expression and install it with
<command>snap install ./result --dangerous</command>.
<command>nix-example-firefox</command> will now be the Snapcraft version of
the Firefox package.
</para>
<para>
The specific meaning behind plugs can be looked up in the
<link xlink:href="https://docs.snapcraft.io/supported-interfaces">Snapcraft
interface documentation</link>.
</para>
</example>
</section>
</section>

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{ callPackage, hello }:
{
makeSnap = callPackage ./make-snap.nix { };
}

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let
inherit (import <nixpkgs> { }) snapTools firefox;
in snapTools.makeSnap {
meta = {
name = "nix-example-firefox";
summary = firefox.meta.description;
architectures = [ "amd64" ];
apps.nix-example-firefox = {
command = "${firefox}/bin/firefox";
plugs = [
"pulseaudio"
"camera"
"browser-support"
"avahi-observe"
"cups-control"
"desktop"
"desktop-legacy"
"gsettings"
"home"
"network"
"mount-observe"
"removable-media"
"x11"
];
};
confinement = "strict";
};
}

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let
inherit (import <nixpkgs> { }) snapTools hello;
in snapTools.makeSnap {
meta = {
name = "hello";
summary = hello.meta.description;
description = hello.meta.longDescription;
architectures = [ "amd64" ];
confinement = "strict";
apps.hello.command = "${hello}/bin/hello";
};
}

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{
runCommand, squashfsTools, closureInfo, lib, jq, writeText
}:
{
# The meta parameter is the contents of the `snap.yaml`, NOT the
# `snapcraft.yaml`.
#
# - `snap.yaml` is what is inside of the final Snap,
# - `snapcraft.yaml` is used by `snapcraft` to build snaps
#
# Since we skip the `snapcraft` tool, we skip the `snapcraft.yaml`
# file. For more information:
#
# https://docs.snapcraft.io/snap-format
#
# Note: unsquashfs'ing an existing snap from the store can be helpful
# for determining what you you're missing.
#
meta
}: let
snap_yaml = let
# Validate the snap's meta contains a name.
# Also: automatically set the `base` parameter and the layout for
# the `/nix` bind.
validate = { name, ... } @ args:
args // {
# Combine the provided arguments with the required options.
# base: built from https://github.com/NixOS/snapd-nix-base
# and published as The NixOS Foundation on the Snapcraft store.
base = "nix-base";
layout = (args.layout or {}) // {
# Bind mount the Snap's root nix directory to `/nix` in the
# execution environment's filesystem namespace.
"/nix".bind = "$SNAP/nix";
};
};
in writeText "snap.yaml"
(builtins.toJSON (validate meta));
# These are specifically required by snapd, so don't change them
# unless you've verified snapcraft / snapd can handle them. Best bet
# is to just mirror this list against how snapcraft creates images.
# from: https://github.com/snapcore/snapcraft/blob/b88e378148134383ffecf3658e3a940b67c9bcc9/snapcraft/internal/lifecycle/_packer.py#L96-L98
mksquashfs_args = [
"-noappend" "-comp" "xz" "-no-xattrs" "-no-fragments"
# Note: We want -all-root every time, since all the files are
# owned by root anyway. This is true for Nix, but not true for
# other builds.
# from: https://github.com/snapcore/snapcraft/blob/b88e378148134383ffecf3658e3a940b67c9bcc9/snapcraft/internal/lifecycle/_packer.py#L100
"-all-root"
];
in runCommand "squashfs.img" {
nativeBuildInputs = [ squashfsTools jq ];
closureInfo = closureInfo {
rootPaths = [ snap_yaml ];
};
} ''
root=$PWD/root
mkdir $root
(
# Put the snap.yaml in to `/meta/snap.yaml`, setting the version
# to the hash part of the store path
mkdir $root/meta
version=$(echo $out | cut -d/ -f4 | cut -d- -f1)
cat ${snap_yaml} | jq ". + { version: \"$version\" }" \
> $root/meta/snap.yaml
)
(
# Copy the store closure in to the root
mkdir -p $root/nix/store
cat $closureInfo/store-paths | xargs -I{} cp -r {} $root/nix/store/
)
# Generate the squashfs image.
mksquashfs $root $out \
${lib.concatStringsSep " " mksquashfs_args}
''

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@ -175,6 +175,8 @@ in
dockerTools = callPackage ../build-support/docker { };
snapTools = callPackage ../build-support/snap { };
nix-prefetch-docker = callPackage ../build-support/docker/nix-prefetch-docker.nix { };
docker-compose = python3Packages.callPackage ../applications/virtualization/docker-compose {};