[CI:BUILD] Packit: Enable Copr builds on PR and commit to main

This commit adds Packit configuration files which will trigger rpm
builds on copr:`rhcontainerbot/packit-builds` on every PR as well as on
copr:`rhcontainerbot/podman-next` on every commit to main branch.

This commit will ensure main branch is always buildable on all supported
Fedora and CentOS Stream versions for aarch64 and x86_64.
TODO: enable build checks for s390x and ppc64le while ensuring they
don't take too long to build.

The packit builds reuse `buildah.spec.rpkg` present upstream and are
thus independent of Fedora / CentOS dist-git.

This change will remove the need for the current webhook based triggering
of rpm builds on rhcontainerbot/podman-next after commit to main.
That will be instead handled by the `trigger: commit` action added in this
PR. New builds will continue to get posted to the same link so users
don't need to change any existing copr repo configuration.

[NO NEW TESTS NEEDED]

Signed-off-by: Lokesh Mandvekar <lsm5@fedoraproject.org>

.packit.sh

@@ -0,0 +1,28 @@
+#!/usr/bin/env bash
+
+# This script handles any custom processing of the spec file generated using the `post-upstream-clone`
+# action and gets used by the fix-spec-file action in .packit.yaml.
+
+set -eo pipefail
+
+# Get Version from define/types.go in HEAD
+VERSION=$(grep ^$'\tVersion' define/types.go | cut -d\" -f2 | sed -e 's/-/~/')
+
+# Generate source tarball from HEAD
+git archive --prefix=buildah-$VERSION/ -o buildah-$VERSION.tar.gz HEAD
+
+# RPM Spec modifications
+
+# Use the Version from define/types.go in rpm spec
+sed -i "s/^Version:.*/Version: $VERSION/" buildah.spec
+
+# Use Packit's supplied variable in the Release field in rpm spec.
+# buildah.spec is generated using `rpkg spec --outdir ./` as mentioned in the
+# `post-upstream-clone` action in .packit.yaml.
+sed -i "s/^Release:.*/Release: $PACKIT_RPMSPEC_RELEASE%{?dist}/" buildah.spec
+
+# Use above generated tarball as Source in rpm spec
+sed -i "s/^Source:.*.tar.gz/Source: buildah-$VERSION.tar.gz/" buildah.spec
+
+# Use the right build dir for autosetup stage in rpm spec
+sed -i "s/^%setup.*/%autosetup -Sgit -n %{name}-$VERSION/" buildah.spec

.packit.yaml

@@ -0,0 +1,30 @@
+---
+# See the documentation for more information:
+# https://packit.dev/docs/configuration/
+
+# Build targets can be found at:
+# https://copr.fedorainfracloud.org/coprs/rhcontainerbot/packit-builds/
+
+specfile_path: buildah.spec
+
+jobs:
+  - &copr
+    job: copr_build
+    trigger: pull_request
+    owner: rhcontainerbot
+    project: packit-builds
+    enable_net: true
+    srpm_build_deps:
+      - make
+      - rpkg
+    actions:
+      post-upstream-clone:
+        - "rpkg spec --outdir ./"
+      fix-spec-file:
+        - "bash .packit.sh"
+
+  - <<: *copr
+    # Run on commit to main branch
+    trigger: commit
+    branch: main
+    project: podman-next

buildah.go

@@ -26,8 +26,7 @@ const (
 	// Package is the name of this package, used in help output and to
 	// identify working containers.
 	Package = define.Package
-	// Version for the Package.  Bump version in contrib/rpm/buildah.spec
-	// too.
+	// Version for the Package.
 	Version = define.Version
 	// The value we use to identify what type of information, currently a
 	// serialized Builder structure, we are using as per-container state.

define/types.go

@@ -28,8 +28,7 @@ const (
 	// Package is the name of this package, used in help output and to
 	// identify working containers.
 	Package = "buildah"
-	// Version for the Package.  Bump version in contrib/rpm/buildah.spec
-	// too.
+	// Version for the Package. Also used by .packit.sh for Packit builds.
 	Version = "1.30.0-dev"
 
 	// DefaultRuntime if containers.conf fails.