Add CentOS 8 support

* Add "centos" element, a CentOS version-independent element. This is in
  line with the same work done for RHEL in Stein cycle.
* Deprecate the centos7 element. CentOS 7 support itself it not
  deprecated though. The new "centos" element provides the same support
  level as the "centos7" element.
* Add functional testing

The default CentOS version is 8. You can adjust it using the DIB_RELEASE
environment variable.

Change-Id: I373ba2296c4613765676e59aabd9c651345298d1

.zuul.d/jobs.yaml

@@ -42,6 +42,7 @@
     vars:
       dib_functests:
         - centos7/build-succeeds
+        - centos/8-build-succeeds
         - opensuse/build-succeeds
         - opensuse/opensuse15-build-succeeds
         - fedora/build-succeeds

diskimage_builder/elements/centos/README.rst

@@ -0,0 +1,26 @@
+======
+centos
+======
+
+Use CentOS cloud images as the baseline for built disk images.
+
+For further details see the redhat-common README.
+
+Environment Variables
+---------------------
+
+DIB_DISTRIBUTION_MIRROR:
+   :Required: No
+   :Default: None
+   :Description: To use a CentOS Yum mirror, set this variable to the mirror URL
+                 before running bin/disk-image-create. This URL should point to
+                 the directory containing the ``7/8`` directories.
+   :Example: ``DIB_DISTRIBUTION_MIRROR=http://amirror.com/centos``
+
+DIB_CLOUD_IMAGES:
+  :Required: No
+  :Description: Set the desired URL to fetch the images from.  ppc64le:
+                Currently the CentOS community is working on providing the
+                ppc64le images. Until then you'll need to set this to a local
+                image file.
+  :Example: ``DIB_CLOUD_IMAGES=/path/to/my/centos/8/CentOS-8-GenericCloud-x86_64.qcow2``

diskimage_builder/elements/centos/element-deps

@@ -0,0 +1,5 @@
+cache-url
+redhat-common
+rpm-distro
+source-repositories
+yum

diskimage_builder/elements/centos/environment.d/10-centos-distro-name.bash

@@ -0,0 +1,2 @@
+export DISTRO_NAME=centos
+export DIB_RELEASE=${DIB_RELEASE:-8}

diskimage_builder/elements/centos/environment.d/11-yum-dnf.bash

@@ -0,0 +1,7 @@
+# since CentOS 8, dnf is the yum replacement.
+
+if [[ ${DIB_RELEASE} == '8' ]]; then
+    export YUM=dnf
+elif [[ ${DIB_RELEASE} == '7' ]]; then
+    export YUM=yum
+fi

diskimage_builder/elements/centos/pre-install.d/01-set-centos-mirror

@@ -0,0 +1,23 @@
+#!/bin/bash
+
+if [ ${DIB_DEBUG_TRACE:-0} -gt 0 ]; then
+    set -x
+fi
+set -eu
+set -o pipefail
+
+DIB_DISTRIBUTION_MIRROR=${DIB_DISTRIBUTION_MIRROR:-}
+
+[ -n "$DIB_DISTRIBUTION_MIRROR" ] || exit 0
+
+# Only set the mirror for the Base, Extras and Updates repositories
+# The others aren't enabled and do not exist on all mirrors
+if [[ ${DIB_RELEASE} == '7' ]]; then
+    sed -e "s|^#baseurl=http[s]*://mirror.centos.org/centos|baseurl=$DIB_DISTRIBUTION_MIRROR|;/^mirrorlist=/d" -i /etc/yum.repos.d/CentOS-Base.repo
+elif [[ ${DIB_RELEASE} == '8' ]]; then
+    sed -e "s|^#baseurl=http[s]*://mirror.centos.org/|baseurl=$DIB_DISTRIBUTION_MIRROR|;/^mirrorlist=/d" -i /etc/yum.repos.d/CentOS-Base.repo
+    sed -e "s|^#baseurl=http[s]*://mirror.centos.org/|baseurl=$DIB_DISTRIBUTION_MIRROR|;/^mirrorlist=/d" -i /etc/yum.repos.d/CentOS-AppStream.repo
+    sed -e "s|^#baseurl=http[s]*://mirror.centos.org/|baseurl=$DIB_DISTRIBUTION_MIRROR|;/^mirrorlist=/d" -i /etc/yum.repos.d/CentOS-centosplus.repo
+    sed -e "s|^#baseurl=http[s]*://mirror.centos.org/|baseurl=$DIB_DISTRIBUTION_MIRROR|;/^mirrorlist=/d" -i /etc/yum.repos.d/CentOS-Extras.repo
+    sed -e "s|^#baseurl=http[s]*://mirror.centos.org/|baseurl=$DIB_DISTRIBUTION_MIRROR|;/^mirrorlist=/d" -i /etc/yum.repos.d/CentOS-PowerTools.repo
+fi

diskimage_builder/elements/centos/pre-install.d/02-set-machine-id

@@ -0,0 +1,23 @@
+#!/bin/bash
+
+if [ ${DIB_DEBUG_TRACE:-0} -gt 0 ]; then
+    set -x
+fi
+set -eu
+set -o pipefail
+
+# Set a machine-id.  The .qcow2 image doesn't have one, and sometimes
+# one will get made (if systemd is upgraded as part of the build
+# process) and sometimes not.  The problem is that certain kernel
+# install scripts bail silently without it; kernel packages end up
+# being installed but the initramfs etc isn't copied into place.
+#
+# Note this is cleared out in the sysprep role.
+#
+# See also:
+#  768c5e188c1b4bff01da14a49b96b51301db4c03 : similar thing for fedora
+#  https://bugzilla.redhat.com/show_bug.cgi?id=1737355 : upstream bug
+#  https://bugzilla.redhat.com/show_bug.cgi?id=1486124 : unresolved
+#   bug about kernel install requiring machine-id
+
+systemd-machine-id-setup

diskimage_builder/elements/centos/root.d/10-centos-cloud-image

@@ -0,0 +1,62 @@
+#!/bin/bash
+
+if [ ${DIB_DEBUG_TRACE:-0} -gt 0 ]; then
+    set -x
+fi
+set -eu
+set -o pipefail
+
+[ -n "$ARCH" ]
+[ -n "$TARGET_ROOT" ]
+
+if [[ "${DIB_RELEASE}" = 7 ]]; then
+    if [[ "amd64 x86_64" =~ "$ARCH" ]]; then
+        ARCH="x86_64"
+        DIB_CLOUD_IMAGES=${DIB_CLOUD_IMAGES:-http://cloud.centos.org/centos/${DIB_RELEASE}/images}
+    elif [[ "arm64 aarch64" =~ "$ARCH" ]]; then
+        ARCH="aarch64"
+        DIB_CLOUD_IMAGES=${DIB_CLOUD_IMAGES:-http://cloud.centos.org/altarch/${DIB_RELEASE}/images/aarch64}
+    elif [[ "ppc64le" =~ "$ARCH" ]]; then
+        DIB_CLOUD_IMAGES=${DIB_CLOUD_IMAGES:-http://cloud.centos.org/altarch/${DIB_RELEASE}/images/ppc64le}
+    else
+        echo 'centos root element only support the x86_64, aarch64 and ppc64le values for $ARCH'
+        exit 1
+    fi
+else
+    if [[ "amd64 x86_64 arm64 aarch64 ppc64le" =~ "$ARCH" ]]; then
+        if [[ "amd64" =~ "$ARCH" ]]; then
+            ARCH="x86_64"
+        elif [[ "arm64" =~ "$ARCH" ]]; then
+            ARCH="aarch64"
+        fi
+        DIB_CLOUD_IMAGES=${DIB_CLOUD_IMAGES:-http://cloud.centos.org/centos/${DIB_RELEASE}/${ARCH}/images}
+    else
+        echo 'centos root element only support the x86_64, aarch64 and ppc64le values for $ARCH'
+        exit 1
+    fi
+
+fi
+
+DIB_LOCAL_IMAGE=${DIB_LOCAL_IMAGE:-}
+
+if [ -n "$DIB_LOCAL_IMAGE" ]; then
+    IMAGE_LOCATION=$DIB_LOCAL_IMAGE
+    # No need to copy a local image into the cache directory, so just specify
+    # the cached path as the original path.
+    CACHED_IMAGE=$IMAGE_LOCATION
+    BASE_IMAGE_FILE=$(basename $DIB_LOCAL_IMAGE)
+    BASE_IMAGE_TAR=$BASE_IMAGE_FILE.tgz
+else
+    DIB_FLAVOR=${DIB_FLAVOR:-GenericCloud}
+    if [[ "${DIB_RELEASE}" = 7 ]]; then
+        BASE_IMAGE_FILE=${BASE_IMAGE_FILE:-CentOS-${DIB_RELEASE}-${ARCH}-${DIB_FLAVOR}.qcow2.xz}
+    else
+        LATEST_IMAGE_FILE=$(curl -s https://cloud.centos.org/centos/${DIB_RELEASE}/${ARCH}/images/ | grep -o "CentOS-${DIB_RELEASE}-${DIB_FLAVOR}-.[^>]*.qcow2" | head -1)
+        BASE_IMAGE_FILE=${BASE_IMAGE_FILE:-$LATEST_IMAGE_FILE}
+    fi
+    BASE_IMAGE_TAR=$BASE_IMAGE_FILE.tgz
+    IMAGE_LOCATION=$DIB_CLOUD_IMAGES/$BASE_IMAGE_FILE
+    CACHED_IMAGE=$DIB_IMAGE_CACHE/$BASE_IMAGE_FILE
+fi
+
+$TMP_HOOKS_PATH/bin/extract-image $BASE_IMAGE_FILE $BASE_IMAGE_TAR $IMAGE_LOCATION $CACHED_IMAGE

diskimage_builder/elements/centos/test-elements/8-build-succeeds/README.rst

@@ -0,0 +1 @@
+Centos 8 test

diskimage_builder/elements/centos/test-elements/8-build-succeeds/element-deps

@@ -0,0 +1,3 @@
+base
+epel
+openstack-ci-mirrors

diskimage_builder/elements/centos/test-elements/8-build-succeeds/environment.d/10-set-distro.bash

@@ -0,0 +1 @@
+export DIB_RELEASE='8'

diskimage_builder/elements/centos/test-elements/8-build-succeeds/test-output-formats

@@ -0,0 +1 @@
+qcow2

diskimage_builder/elements/centos7/README.rst

@@ -1,6 +1,13 @@
 =======
 centos7
 =======
+
+.. warning::
+
+   This element is deprecated and is left only for backward compatibility.
+   Use the `centos` element instead. Note that you should set DIB_RELEASE to 7
+   to indicate which release you are using. Please read the notes.
+
 Use CentOS 7 cloud images as the baseline for built disk images.
 
 For further details see the redhat-common README.

diskimage_builder/elements/centos7/element-deps

@@ -1,5 +1 @@
-cache-url
+centos
-redhat-common
-rpm-distro
-source-repositories
-yum

diskimage_builder/elements/centos7/environment.d/00-centos7-element-deprecation.bash

@@ -0,0 +1 @@
+echo "The centos7 element is deprecated and will be removed in future releases. Use the centos element instead."

diskimage_builder/elements/centos7/environment.d/09-centos7-distro-name.bash

@@ -0,0 +1,7 @@
+# For backward compat (centos vs centos7)
+export DIB_FLAVOR=${DIB_RELEASE:-GenericCloud}
+export DIB_RELEASE=7
+
+# Useful for elements that work with fedora (dnf) & centos
+export YUM=${YUM:-yum}
+

diskimage_builder/elements/centos7/pre-install.d/01-set-centos-mirror

@@ -1,15 +0,0 @@
-#!/bin/bash
-
-if [ ${DIB_DEBUG_TRACE:-0} -gt 0 ]; then
-    set -x
-fi
-set -eu
-set -o pipefail
-
-DIB_DISTRIBUTION_MIRROR=${DIB_DISTRIBUTION_MIRROR:-}
-
-[ -n "$DIB_DISTRIBUTION_MIRROR" ] || exit 0
-
-# Only set the mirror for the Base, Extras and Updates repositories
-# The others arn't enabled and do not exist on all mirrors
-sed -e "s|^#baseurl=http[s]*://mirror.centos.org/centos|baseurl=$DIB_DISTRIBUTION_MIRROR|;/^mirrorlist=/d" -i /etc/yum.repos.d/CentOS-Base.repo

diskimage_builder/elements/centos7/root.d/10-centos7-cloud-image

@@ -1,42 +0,0 @@
-#!/bin/bash
-
-if [ ${DIB_DEBUG_TRACE:-0} -gt 0 ]; then
-    set -x
-fi
-set -eu
-set -o pipefail
-
-[ -n "$ARCH" ]
-[ -n "$TARGET_ROOT" ]
-
-if [[ "amd64 x86_64" =~ "$ARCH" ]]; then
-    ARCH="x86_64"
-    DIB_CLOUD_IMAGES=${DIB_CLOUD_IMAGES:-http://cloud.centos.org/centos/7/images}
-elif [[ "arm64 aarch64" =~ "$ARCH" ]]; then
-    ARCH="aarch64"
-    DIB_CLOUD_IMAGES=${DIB_CLOUD_IMAGES:-http://cloud.centos.org/altarch/7/images/aarch64}
-elif [[ "ppc64le" =~ "$ARCH" ]]; then
-    DIB_CLOUD_IMAGES=${DIB_CLOUD_IMAGES:-http://cloud.centos.org/altarch/7/images/ppc64le}
-else
-    echo 'centos7 root element only support the x86_64, aarch64 and ppc64le values for $ARCH'
-    exit 1
-fi
-
-DIB_LOCAL_IMAGE=${DIB_LOCAL_IMAGE:-}
-
-if [ -n "$DIB_LOCAL_IMAGE" ]; then
-    IMAGE_LOCATION=$DIB_LOCAL_IMAGE
-    # No need to copy a local image into the cache directory, so just specify
-    # the cached path as the original path.
-    CACHED_IMAGE=$IMAGE_LOCATION
-    BASE_IMAGE_FILE=$(basename $DIB_LOCAL_IMAGE)
-    BASE_IMAGE_TAR=$BASE_IMAGE_FILE.tgz
-else
-    DIB_CENTOS7_CLOUD_RELEASE=${DIB_CENTOS7_CLOUD_RELEASE:-GenericCloud}
-    BASE_IMAGE_FILE=${BASE_IMAGE_FILE:-CentOS-7-${ARCH}-$DIB_CENTOS7_CLOUD_RELEASE.qcow2.xz}
-    BASE_IMAGE_TAR=$BASE_IMAGE_FILE.tgz
-    IMAGE_LOCATION=$DIB_CLOUD_IMAGES/$BASE_IMAGE_FILE
-    CACHED_IMAGE=$DIB_IMAGE_CACHE/$BASE_IMAGE_FILE
-fi
-
-$TMP_HOOKS_PATH/bin/extract-image $BASE_IMAGE_FILE $BASE_IMAGE_TAR $IMAGE_LOCATION $CACHED_IMAGE

releasenotes/notes/add-centos-8-support-4fd28eb04e11ba43.yaml

@@ -0,0 +1,8 @@
+---
+features:
+  - Added CentOS 8 support.
+deprecations:
+  - |
+    The ``centos7`` element is deprecated and is left only for backward
+    compatibility. Use the ``centos`` element instead. Note that you should set
+    ``DIB_RELEASE`` to ``7`` when using the ``centos`` element.