ci: Add Jenkins pipeline

This is an experiment in using Jenkins pipelines for our CI. See similar
initiatives in coreos-assembler[1] and fedora-coreos-config[2].

For now, this only does the following testing:
- checks commit for unintended submodule bumps
- checks the minimum Rust version
- builds RPMs
- builds FCOS (with the new RPMs both for executing the build
  itself, as well as included in the built OS)

There are dummy placeholders for where we'd actually run the vmcheck
and the compose testsuites. Let's address those trickier parts as
follow-ups.

[1] https://github.com/coreos/coreos-assembler/pull/667
[2] https://github.com/coreos/fedora-coreos-config/pull/131

Closes: #1899
Approved by: cgwalters

.cci.jenkinsfile

@@ -0,0 +1,113 @@
+@Library('github.com/coreos/coreos-ci-lib@master') _
+
+stage("Build") {
+parallel rpms: {
+  coreos.pod(image: 'registry.svc.ci.openshift.org/coreos/cosa-buildroot:latest', runAsUser: 0) {
+      checkout scm
+      sh """
+        set -euo pipefail
+        ci/installdeps.sh
+        git submodule update --init
+
+        # We lose sanitizers (all the *san) here by building straight to RPMs, but we can
+        # restore those through a build opt later on. Being able to stash RPMs directly is
+        # super nice (and archiving later on will make it easy for anyone to download
+        # binaries from PRs in the future) and meshes well with the following stages.
+        export PATH="/root/.cargo/bin:\$PATH"
+        cargo install cbindgen
+        cbindgen -c rust/cbindgen.toml -o rpmostree-rust.h rust
+
+        cd packaging
+        make -f Makefile.dist-packaging rpm
+      """
+      stash includes: 'packaging/**/*.rpm', name: 'rpms'
+  }
+},
+codestyle: {
+  coreos.pod(image: 'quay.io/coreos-assembler/coreos-assembler:latest') {
+      def change = checkout scm
+      sh """
+        set -euo pipefail
+        # Jenkins by default only fetches the branch it's testing. Explicitly fetch master
+        # for ci-commitmessage-submodules.sh
+        git fetch origin +refs/heads/master:refs/remotes/origin/master
+        ci/ci-commitmessage-submodules.sh ${change.GIT_COMMIT}
+        ci/codestyle.sh
+      """
+  }
+},
+msrv: {
+  coreos.pod(image: 'registry.svc.ci.openshift.org/coreos/cosa-buildroot:latest', runAsUser: 0) {
+      checkout scm
+
+      // this corresponds to the latest Rust module available in el8
+      def MINIMUM_SUPPORTED_RUST_VERSION = "1.31.0"
+
+      sh """
+        set -euo pipefail
+        ci/installdeps.sh
+        curl https://sh.rustup.rs -sSf | sh -s -- --default-toolchain ${MINIMUM_SUPPORTED_RUST_VERSION} -y
+        PATH="\$HOME/.cargo/bin:\$PATH" ci/build.sh |& tee out.txt
+        grep ${MINIMUM_SUPPORTED_RUST_VERSION} out.txt
+        grep "checking for cargo... \$HOME/.cargo/bin/cargo" out.txt
+        grep "checking for rustc... \$HOME/.cargo/bin/rustc" out.txt
+      """
+  }
+}}
+
+stage("Build FCOS") {
+  coreos.pod(image: 'quay.io/coreos-assembler/coreos-assembler:latest', runAsUser: 0, kvm: true) {
+      unstash 'rpms'
+      sh """
+        set -euo pipefail
+
+        # install our built rpm-ostree
+        find packaging/ ! -name '*.src.rpm' -name '*.rpm' | xargs dnf install -y
+        rm -rf packaging
+
+        # and build FCOS
+        coreos-assembler init --force https://github.com/coreos/fedora-coreos-config
+        coreos-assembler build
+      """
+      stash includes: 'builds/latest/*/*.qcow2', name: 'fcos'
+  }
+}
+
+/*
+stage("Test") {
+parallel vmcheck: {
+  coreos.pod(image: 'quay.io/coreos-assembler/coreos-assembler:latest', runAsUser: 0, kvm: true) {
+      checkout scm
+      unstash 'rpms'
+      sh """
+        set -euo pipefail
+
+        # install our built rpm-ostree
+        find packaging/ ! -name '*.src.rpm' -name '*.rpm' | xargs dnf install -y
+        rm -rf packaging
+      """
+      unstash 'fcos'
+      sh """
+        set -euo pipefail
+
+        echo "standing up VMs"
+        find builds/ -name '*.qcow2'
+      """
+  }
+},
+compose: {
+  coreos.pod(image: 'quay.io/coreos-assembler/coreos-assembler:latest', runAsUser: 0, kvm: true) {
+      checkout scm
+      unstash 'rpms'
+      sh """
+        set -euo pipefail
+
+        # install our built rpm-ostree
+        find packaging/ ! -name '*.src.rpm' -name '*.rpm' | xargs dnf install -y
+        rm -rf packaging
+
+        echo "starting compose tests in supermin"
+      """
+  }
+}}
+*/

ci/ci-commitmessage-submodules.sh

@@ -30,8 +30,10 @@ cleanup_tmp() {
 }
 trap cleanup_tmp EXIT
 
+if ! [ -x /usr/bin/git ]; then
   pkg_upgrade
   pkg_install git
+fi
 
 gitdir=$(realpath $(pwd))
 # Create a temporary copy of this (using cp not git clone) so git doesn't