travis: deploy tarballs with static binary to GH Releases

The main usage is for alpine-chroot-install and similar scripts, so it
can depend on specific *persistent* version.

.travis.yml

@@ -8,6 +8,7 @@ env:
     - ARCH=aarch64
     - ARCH=armhf
     - ARCH=ppc64le
+
 before_install:
   - "wget 'https://raw.githubusercontent.com/alpinelinux/alpine-chroot-install/v0.5.1/alpine-chroot-install' \
         && echo '5414e27ceb85cefede5699ef2ec614f831cafd65  alpine-chroot-install' | sha1sum -c || exit 1"
@@ -25,3 +26,21 @@ script:
   - alpine src/apk.static --version
   - alpine make check
   - alpine make -C test root-tests
+
+# If building a tagged commit, create and deploy tarball with statically linked
+# apk to GitHub Releases.
+before_deploy:
+  - export PKGNAME="apk-tools-${TRAVIS_TAG#v}"
+  - alpine strip src/apk.static
+  - install -D -m 755 src/apk.static $PKGNAME/apk
+  - tar -czf $PKGNAME-$ARCH-linux.tar.gz $PKGNAME
+  - sha256sum $PKGNAME-$ARCH-linux.tar.gz > $PKGNAME-$ARCH-linux.tar.gz.sha256
+deploy:
+  provider: releases
+  api_key:
+    secure: "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"
+  file: apk-tools-*.tar.gz*
+  file_glob: true
+  skip_cleanup: true
+  on:
+    tags: true