stack.sh fails on CentOS8 because mod_wsgi not found

[Hirotaka Wakabayashi]

Hello devstack-team,

I get an error because the mod_wsgi package does not exist[2] when I run devstack on my CentOS 8[1]. I think we should use python3-mod_wsgi instead of mod_wsgi because the ChangeLog of python3-mod_wsgi-4.6.4-4 obsoletes mod_wsgi[3].

Thanks in advance,
Hirotaka Wakabayashi

[1] My CentOS8
```
NAME="CentOS Linux"
VERSION="8 (Core)"
ID="centos"
ID_LIKE="rhel fedora"
VERSION_ID="8"
PLATFORM_ID="platform:el8"
PRETTY_NAME="CentOS Linux 8 (Core)"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:centos:centos:8"
HOME_URL="https://www.centos.org/"
BUG_REPORT_URL="https://bugs.centos.org/"

CENTOS_MANTISBT_PROJECT="CentOS-8"
CENTOS_MANTISBT_PROJECT_VERSION="8"
REDHAT_SUPPORT_PRODUCT="centos"
REDHAT_SUPPORT_PRODUCT_VERSION="8"
```

[2] The error log
```
+ functions-common:sudo_with_proxies:2288 : sudo http_proxy= https_proxy= no_proxy= dnf install -y httpd mod_wsgi
Last metadata expiration check: 0:09:39 ago on Tue 30 Jun 2020 08:00:05 AM JST.
Package httpd-2.4.37-21.module_el8.2.0+382+15b0afa8.x86_64 is already installed.
No match for argument: mod_wsgi
Error: Unable to find a match: mod_wsgi
```

[3] python3-mod_wsgi-4.6.4-4 ChangeLog
```
2019-12-04 - Lubos Uhliarik <email address hidden> - 4.6.4-4
- Resolves: #1779705 - python3-mod_wsgi: Remove the Provides and Obsoletes for the name `mod_wsgi`
```
https://centos.pkgs.org/8/centos-appstream-x86_64/python3-mod_wsgi-4.6.4-4.el8.x86_64.rpm.html

[Hirotaka Wakabayashi (hiwkby)]

Hello again,

My solution is here. Please see the lines around "install_apache_wsgi". I can submit a patch if no problems.

```
$ git diff
diff --git a/lib/apache b/lib/apache
index 41c2e3d8..12dceb35 100644
--- a/lib/apache
+++ b/lib/apache
@@ -100,7 +100,7 @@ function install_apache_uwsgi {
                         uwsgi-plugin-python \
                         uwsgi-plugin-python3 \
                         libapache2-mod-proxy-uwsgi
- elif [[ $os_VENDOR == "Fedora" ]]; then
+ elif is_fedora; then
         # Note httpd comes with mod_proxy_uwsgi and it is loaded by
         # default; the mod_proxy_uwsgi package actually conflicts now.
         # See:
@@ -109,7 +109,7 @@ function install_apache_uwsgi {
         # Thus there is nothing else to do after this install
         install_package uwsgi \
                         uwsgi-plugin-python3
- elif [[ $os_VENDOR =~ openSUSE ]]; then
+ elif is_suse; then
         install_package uwsgi \
                         uwsgi-python3 \
                         apache2-mod_uwsgi
@@ -123,8 +123,14 @@ function install_apache_uwsgi {
         pip_install uwsgi
         pip download uwsgi -c $REQUIREMENTS_DIR/upper-constraints.txt
         local uwsgi
- uwsgi=$(ls uwsgi*)
- tar xvf $uwsgi
+ if [ -f uW*.tar.gz ] ; then
+ mkdir uwsgi-latest
+ uwsgi=$(ls uW*.tar.gz)
+ tar xvf $uwsgi -C uwsgi-latest
+ else
+ uwsgi=$(ls uwsgi*)
+ tar xvf $uwsgi
+ fi
         cd uwsgi*/apache2
         sudo $apxs -i -c mod_proxy_uwsgi.c
         popd
@@ -161,7 +167,7 @@ function install_apache_wsgi {
         fi
     elif is_fedora; then
         sudo rm -f /etc/httpd/conf.d/000-*
- install_package httpd mod_wsgi
+ install_package httpd python3-mod_wsgi
         # For consistency with Ubuntu, switch to the worker mpm, as
         # the default is event
         sudo sed -i '/mod_mpm_prefork.so/s/^/#/g' /etc/httpd/conf.modules.d/00-mpm.conf
```

Thanks in advance,
Hirotaka Wakabayashi

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/738965

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/738965
Committed: https://git.openstack.org/cgit/openstack/devstack/commit/?id=1e26508983a1ebf2c23560395ffca8b1f6f79462
Submitter: Zuul
Branch: master

commit 1e26508983a1ebf2c23560395ffca8b1f6f79462
Author: Hirotaka Wakabayashi <email address hidden>
Date: Thu Jul 2 06:19:21 2020 +0000

    Use python3-mod-wsgi instead of mod_wsgi on CentOS8

    This fixes a stack.sh execution error on CentOS8. We should use
    python3-mod_wsgi instead of mod_wsgi since mod_wsgi is replaced by
    python3-mod_wsgi. The following change may affect this issue.
    https://git.centos.org/rpms/mod_wsgi/c/4a746b53e9e3fef74b227e016e785449160871b8?branch=c8s

    Change-Id: I5344ecf519e1a79091b6158c2d711d09b21fae0c
    Closes-Bug: #1885645

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/ussuri
Review: https://review.opendev.org/746590

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/746590
Committed: https://git.openstack.org/cgit/openstack/devstack/commit/?id=96c2aa13fe9345bef31ef053faae334e2663a509
Submitter: Zuul
Branch: stable/ussuri

commit 96c2aa13fe9345bef31ef053faae334e2663a509
Author: Hirotaka Wakabayashi <email address hidden>
Date: Thu Jul 2 06:19:21 2020 +0000

    Use python3-mod-wsgi instead of mod_wsgi on CentOS8

    This fixes a stack.sh execution error on CentOS8. We should use
    python3-mod_wsgi instead of mod_wsgi since mod_wsgi is replaced by
    python3-mod_wsgi. The following change may affect this issue.
    https://git.centos.org/rpms/mod_wsgi/c/4a746b53e9e3fef74b227e016e785449160871b8?branch=c8s

    Change-Id: I5344ecf519e1a79091b6158c2d711d09b21fae0c
    Closes-Bug: #1885645
    (cherry picked from commit 1e26508983a1ebf2c23560395ffca8b1f6f79462)