Set up Travis to build modified packages

.travis.yml

+sudo: required
+install:
+  - sudo .travis/install-alpine
+  - sudo .travis/setup-alpine
+script: |
+  source .travis/common.sh
+  alpine_run $ALPINE_USER .travis/build-pkgs

.travis/abuild-apk

+#!/bin/sh
+
+exec /usr/bin/abuild-apk --no-progress $@

.travis/build-pkgs

+#!/bin/sh
+# vim: set ts=4:
+set -eu
+
+. "$(dirname "$0")"/common.sh
+
+# Prints names of top-level directories (i.e. repositories) that has been
+# changed/created in the specified revisions.
+changed_repos() {
+	local commit_ish="$1"
+
+	git diff-tree --name-only "$commit_ish" | grep -v '^\..*' || echo ''
+}
+
+# Prints names of repo's subdirs (i.e. abuilds) that contains APKBUILDs which
+# has been changed/created in the specified revisions. The abuild names are
+# printed in a build order.
+changed_abuilds() {
+	local repo="$1"
+	local commit_ish="$2"
+
+	# Get names of repo's subdirectories with modified APKBUILD.
+	local aports="$(git diff-tree -r --relative="$repo" --name-only "$commit_ish" -- '*APKBUILD' \
+					| xargs -I% dirname % | xargs)"
+
+	# Sort abuilds by build order.
+	ap builddirs -d "$(pwd)/$repo" $aports 2>/dev/null | xargs -I% basename %
+}
+
+
+cd "$CLONE_DIR"
+
+# Workarounds for oddities of TRAVIS_COMMIT_RANGE that:
+#   - may be empty when pushing single commit,
+#   - uses triple-dot range instead of double-dot that we need,
+#   - contains SHA of old (unreachable) commit when rebasing.
+commit_range="$(echo "${TRAVIS_COMMIT_RANGE:-}" | sed -E 's/\.{3}/../')"
+if ! git rev-parse "$commit_range" >/dev/null 2>&1; then
+	commit_range="$(git rev-parse HEAD^1)..HEAD"
+fi
+
+failed_pkgs=''
+successful_pkgs=''
+
+
+title "Building abuilds that has been modified/added between $commit_range\n"
+
+echo 'Diffstat:'
+git --no-pager diff --color --stat "$commit_range"
+
+for repo in $(changed_repos "$commit_range"); do
+	for pkgname in $(changed_abuilds "$repo" "$commit_range"); do
+		qname="$repo/$pkgname"
+
+		fold_start "$pkgname" "Building package $qname"
+
+		if APKBUILD="$qname/APKBUILD" abuild -fr; then
+			successful_pkgs="$successful_pkgs $qname"
+		else
+			failed_pkgs="$failed_pkgs $qname"
+		fi
+		fold_end "$pkgname"
+	done
+done
+
+printf '\n----\n'
+if [ -n "$successful_pkgs" ]; then
+	print -s1 -c2 "Successfully build packages:$successful_pkgs\n"
+fi
+if [ -n "$failed_pkgs" ]; then
+	die "Failed to build packages:$failed_pkgs"
+
+elif [ -z "$successful_pkgs" ]; then
+	die 'No packages found to be build.'
+fi

.travis/common.sh

+# vim: set ts=4:
+
+readonly ALPINE_ROOT='/mnt/alpine'
+readonly ALPINE_USER='alpine'
+readonly CLONE_DIR="${CLONE_DIR:-$(pwd)}"
+
+# Runs commands inside the Alpine chroot.
+alpine_run() {
+	local user="${1:-root}"
+	local cmd="${2:-sh}"
+
+	local _sudo=
+	[ "$(id -u)" -eq 0 ] || _sudo='sudo'
+
+	$_sudo chroot "$ALPINE_ROOT" /usr/bin/env -i su -l $user \
+		sh -c "cd $CLONE_DIR; $cmd"
+}
+
+die() {
+	print -s1 -c1 "$@\n" 1>&2
+	exit 1
+}
+
+# Marks start of named folding section for Travis and prints title.
+fold_start() {
+	local name="$1"
+	local title="$2"
+
+	printf "\ntravis_fold:start:$name "
+	print -s1 -c6 "> $title\n"
+}
+
+# Marks end of the named folding section.
+fold_end() {
+	local name="$1"
+
+	printf "travis_fold:end:$name\n"
+}
+
+# Prints formatted and colored text.
+print() {
+	local style=0
+	local fcolor=9
+
+	local opt; while getopts 's:c:' opt; do
+		case "$opt" in
+			s) style="$OPTARG";;
+			c) fcolor="$OPTARG";;
+		esac
+	done
+
+	shift $(( OPTIND - 1 ))
+	local text="$@"
+
+	printf "\033[${style};3${fcolor}m$text\033[0m"
+}
+
+title() {
+	printf '\n'
+	print -s1 -c6 "==> $@\n"
+}

.travis/install-alpine

+#!/bin/sh
+# vim: set ts=4:
+set -eu
+
+. "$(dirname "$0")"/common.sh
+
+APK_TOOLS_URI='https://repository.fit.cvut.cz/mirrors/alpine/v3.3/main/x86_64/apk-tools-static-2.6.5-r1.apk'
+APK_TOOLS_SHA256='03162d70e6d42eea77624a8da76d69e665ca19aa834361c3652414f111884636'
+
+
+title 'Downloading apk-tools-static'
+
+cd /tmp
+wget "$APK_TOOLS_URI"
+echo "$APK_TOOLS_SHA256  $(basename "$APK_TOOLS_URI")" | sha256sum -c
+tar -xzf $(basename "$APK_TOOLS_URI")
+
+
+title 'Installing Alpine Linux'
+
+mkdir -p "$ALPINE_ROOT"/etc/apk
+cd "$ALPINE_ROOT"
+
+cp "$CLONE_DIR"/.travis/repositories etc/apk/repositories
+cp /etc/resolv.conf etc/resolv.conf
+
+/tmp/sbin/apk.static \
+	--root . --allow-untrusted --update-cache --initdb --no-progress \
+	add alpine-base
+
+mount -t proc none proc
+mount --rbind /sys sys
+mount --rbind /dev dev

.travis/repositories

+https://repository.fit.cvut.cz/mirrors/alpine/edge/main
+https://repository.fit.cvut.cz/mirrors/alpine/edge/community
+https://repository.fit.cvut.cz/mirrors/alpine/edge/testing

.travis/setup-alpine

+#!/bin/sh
+# vim: set ts=4:
+set -eu
+
+. "$(dirname "$0")"/common.sh
+
+title 'Setting up Alpine Linux'
+
+mkdir -p "${ALPINE_ROOT}${CLONE_DIR}"
+mount --bind "$CLONE_DIR" "${ALPINE_ROOT}${CLONE_DIR}"
+
+alpine_run <<-EOF
+	apk add alpine-sdk lua-aports
+
+	adduser -G users -s /bin/sh -D $ALPINE_USER
+	addgroup $ALPINE_USER abuild
+	addgroup $ALPINE_USER wheel
+
+	echo '%wheel ALL=(ALL) NOPASSWD: ALL' > /etc/sudoers.d/wheel
+
+	sed -i 's/JOBS=[0-9]*/JOBS=$(nproc)/' /etc/abuild.conf
+
+	mkdir -p /var/cache/distfiles
+	chmod a+w /var/cache/distfiles
+
+	# Hack to disable apk's progress bar.
+	install -m755 -D .travis/abuild-apk /usr/local/bin/abuild-apk
+EOF
+
+# This key will not be used anywhere, just to make abuild happy...
+alpine_run $ALPINE_USER <<-EOF
+	abuild-keygen -ain
+EOF