Add support for multiple archs in autopkgtest CI

This took **a lot** of time, as autopkgtest-build-qemu has been able to
build non-x86 for less than a release (version 5.17, unreleased),
and it isn't meant to be (easly) used on Ubuntu (and unfortunately GH
Actions only support Ubuntu).

This is extremely fragile; adding a CPU core breaks something, adding a
MB of RAM breaks something, installing recommended packages breaks
something... you get it. But it works. Beautiful, isn't it?

This currently tests amd64, arm64. armhf, i386 and ppc64el. s390x seems
unsupported by autopkgtest-build-qemu.

If you're curious to see how many trials it took, have a look at this
test branch:
github.com/Tachi107/pistache/tree/actions-autopkgtest-multiarch-test

.github/workflows/autopkgtest.yaml

@@ -5,8 +5,13 @@
 name: autopkgtest
 
 on:
-  [push, pull_request]
+  push:
+    paths-ignore: pistache.io/**
+  pull_request:
+    paths-ignore: pistache.io/**
 
+# The default Debian shell (dash) is faster than bash at running scripts, and
+# using bash when it is not needed doesn't make sense.
 defaults:
   run:
     shell: sh
@@ -15,22 +20,89 @@ jobs:
   test:
     runs-on: ubuntu-latest
 
+    strategy:
+      fail-fast: false
+      matrix:
+        arch: [ amd64, arm64, armhf, i386, ppc64el ] # , s390x
+
     steps:
     - uses: actions/checkout@v2
 
+    # The Debian repository is needed by autopkgtest-build-qemu when building
+    # for foreign architectures, since the tool tries to install
+    # linux-image-${{ matrix.arch }}, that is unavailable on Ubuntu; adding
+    # the Debian Testing repo and lowering its priority solves the issue
+    # while not risking to break the system mixing Debian and Ubuntu pkgs.
+    # The pgp key required to use the repository is downloaded through the
+    # debain-archive-keyring package, and instead of using the deprecated
+    # apt-key utility to add the keyring to the trusted ones I use the
+    # Signed-By option (deb822 source format), as recommended in the Debian
+    # wiki (https://wiki.debian.org/DebianRepository/UseThirdParty).
+    # Node.js stuff is purged since it is not needed and for whatever reason
+    # causes a warning to be generated when building autopkgtest.
+    # Also qemu-system-gui is holded to prevent installation since it is not
+    # needed, and both vmdb2 and qemu-user-static are installed from testing
+    # because the version available in Ubuntu does not work; the old vmdb2
+    # causes image generation failures for all architectures, qemu-user-static
+    # only for arm64, but causes autopkgtest to fail for armhf and ppc64el.
+    # The debian-archive.trafficmanager.net mirror is used since it is the
+    # Azure mirror, and GitHub Actions run on that network.
+    # The --no-install-recommends apt option is important, as installing
+    # recommended packages causes autopkgtest to fail for arm64 and armhf;
+    # I don't know why, I don't know how, I only know that it tooks hours to
+    # figure it out.
     - name: Install dependencies
       run: |
+        sudo apt -qq install debian-archive-keyring
+        printf 'Enabled: yes\nTypes: deb\nURIs: http://debian-archive.trafficmanager.net/debian/\nSuites: testing\nComponents: main\nSigned-By: /usr/share/keyrings/debian-archive-keyring.gpg\n' | sudo tee /etc/apt/sources.list.d/debian.sources
+        printf 'Package: *\nPin: release o=Debian,a=testing\nPin-Priority: 400\n' | sudo tee /etc/apt/preferences.d/99debian-testing
         sudo apt -qq update
-        sudo apt -qq install autopkgtest genisoimage qemu-system vmdb2 meson cppcheck debhelper-compat dh-exec libc6-dev libcurl4-openssl-dev libgtest-dev libssl-dev libstdc++6 lintian pkg-config rapidjson-dev valgrind devscripts --no-install-recommends
+        sudo apt -qq autopurge '*yarn*' '*npm*' '*node*'
+        sudo rm -rf /usr/local/lib/node_modules
+        sudo apt --assume-yes install genisoimage qemu-system vmdb2/testing devscripts --no-install-recommends qemu-user-static/testing qemu-efi-aarch64 qemu-efi-arm ovmf ovmf-ia32 && sudo apt-mark auto qemu-user-static qemu-efi-aarch64 qemu-efi-arm ovmf ovmf-ia32
+        sudo apt -qq build-dep .
 
-    - name: Build image
+    # Build and install autopkgtest from the latest master (5.17), since
+    # previous versions can't build non-x86 images. It is done in a nested /tmp
+    # directory because otherwise debuild would try to write in /, resulting in
+    # an error.
+    - name: Install autopkgtest from source
       run: |
-        sudo autopkgtest-build-qemu --size 12G testing $HOME/autopkgtest-testing.img
+        mkdir --parent /tmp/autopkgtest-build
+        curl --silent --output /tmp/autopkgtest-build/autopkgtest-master.tar --proto https --tlsv1.3 --http2-prior-knowledge https://salsa.debian.org/ci-team/autopkgtest/-/archive/master/autopkgtest-master.tar
+        tar --extract --file=/tmp/autopkgtest-build/autopkgtest-master.tar --directory=/tmp/autopkgtest-build
+        cd /tmp/autopkgtest-build/autopkgtest-master
+        sudo apt -qq build-dep . --default-release=testing
+        DEB_BUILD_OPTIONS=nocheck debuild --unsigned-source --unsigned-changes
+        sudo apt -qq install ../autopkgtest*.deb
+        cd -
+        rm -rf /tmp/autopkgtest-build
 
-    - name: Build Debian package
+    - name: Build image
+      run: sudo autopkgtest-build-qemu --architecture ${{ matrix.arch }} --size 12G testing $HOME/autopkgtest-testing.img
+
+    - name: Build Debian package source
       run: |
         ./debian/rules get-orig-source
-        debuild -S -sa -uc -us
+        dpkg-source --build .
+
+    # The increased timeout is needed because the CI can be too slow to boot
+    # the image. --dpkg-architecture is needed because autopkgtest-virt-qemu
+    # defaults to the host arch instead of reading it from the image.
+    # The ram size is set to 3072 MB because the default 1 GiB is not enough
+    # to build Pistache, the amount must be less than 4 GiB otherwise the i386
+    # image won't boot, ppc64el requires it to be aligned to 256 MiB and an
+    # amout not convertible to a GiB integer causes arm64 to fail, while extra
+    # CPU cores can't be used as they can cause arm runs to fail with the error
+    # below. Instead of explicitly calling autopkgtest-virt-qemu it should be
+    # enough to just write qemu.
+    # Currently this sometimes fails on i386 with
+    #   <VirtSubproc>: failure: timed out waiting for 'login prompt on serial
+    #     console'
+    # and on arm64 and armhf with
+    #   host login: <VirtSubproc>: failure: The VM does not start a root shell
+    #     on ttyS1 or hvc1 already. The only other supported login mechanism is
+    #     through --user and -*** the guest ttyS0
 
     - name: Run autopkgtest
-      run: autopkgtest ../pistache_*.dsc -- qemu --timeout-reboot=120 $HOME/autopkgtest-testing.img
+      run: autopkgtest ../pistache_*.dsc -- autopkgtest-virt-qemu --dpkg-architecture=${{ matrix.arch }} --timeout-reboot=120 --ram-size=3072 $HOME/autopkgtest-testing.img

README.md

@@ -8,7 +8,7 @@ SPDX-License-Identifier: Apache-2.0
 
 [![N|Solid](pistache.io/static/img/logo.png)](https://www.github.com/pistacheio/pistache)
 
-[![Build Status](https://travis-ci.org/pistacheio/pistache.svg?branch=master)](https://travis-ci.org/pistacheio/pistache)
+[![autopkgtest](https://github.com/pistacheio/pistache/actions/workflows/autopkgtest.yaml/badge.svg)](https://github.com/pistacheio/pistache/actions/workflows/autopkgtest.yaml)
 [![REUSE status](https://api.reuse.software/badge/github.com/pistacheio/pistache)](https://api.reuse.software/info/github.com/pistacheio/pistache)
 
 Pistache is a modern and elegant HTTP and REST framework for C++. It is entirely written in pure-C++17 and provides a clear and pleasant API.

tests/meson.build

@@ -53,7 +53,7 @@ foreach test_name : pistache_test_files
 				date_dep
 			]
 		),
-		timeout: 60,
+		timeout: 600,
 		workdir: meson.current_build_dir(),
 		is_parallel: false
 	)