How to programmatically install the latest epel-release rpm, without knowing its version number? - centos

Question

My first post here, but I googled around and cannot find a simple way to do this.
I have a program which automatically configures new CentOS Linux servers as they come online. As part of the process it installs the latest version of epel-release rpm.
The command I use looks like this:
$ rpm -Uvh http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-7.noarch.rpm && \
yum clean all
This works great... until they change the rpm file to epel-release-6-8.noarch, then epel-release-6-9.noarch, and so on. They seem to update the version every 3-4 months. This is a problem, because if the repository updates the epel-release version number, my scripts will fail because it has no idea what that version should be.
I failed to find a link that might redirect to the latest epel rpm file, so I have no choice but to hard-code the version into my install scripts, and change it when they fail.
Anyone know a simple (non-hard-coded) way to download the latest epel rpm without knowing the version number? I'm hoping for a way that does not involve dong a curl on the repo file list and grep'ing the url, but curious what anyone might suggest?

Answer 1

The following script will do the trick:
cat <<EOM >/etc/yum.repos.d/epel-bootstrap.repo
[epel]
name=Bootstrap EPEL
mirrorlist=http://mirrors.fedoraproject.org/mirrorlist?repo=epel-\$releasever&arch=\$basearch
failovermethod=priority
enabled=0
gpgcheck=0
EOM
yum --enablerepo=epel -y install epel-release
rm -f /etc/yum.repos.d/epel-bootstrap.repo
It should work on RHEL/CentOS 5 and 6. I didn't test version 4.

Answer 2

The EPEL project has recently implemented "latest" symlinks for the epel-release package.
https://dl.fedoraproject.org/pub/epel/epel-release-latest-5.noarch.rpm
​https://dl.fedoraproject.org/pub/epel/epel-release-latest-6.noarch.rpm
https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
See https://fedorahosted.org/epel/ticket/8#comment:12

Answer 3

Do it right from the shell:
$ EPEL_BASEURL=http://dl.fedoraproject.org/pub/epel/$(awk '/rhel/ {print $2}' /etc/rpm/macros.dist)/$(uname -p)/
$ rpm -ivh $EPEL_BASEURL$(curl -s $EPEL_BASEURL | grep epel-release | awk -F'<|>' '{print $5}')
Retrieving http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
warning: /var/tmp/rpm-tmp.zRXE1U: Header V3 RSA/SHA256 Signature, key ID 0608b895: NOKEY
Preparing... ########################################### [100%]
1:epel-release ########################################### [100%]
I've tested this on CentOS 6.4, 6.5 and 6.6 and RHEL 6.5 and 6.6, but the contents of /etc/rpm/macros.dist and the HTML code from http://dl.fedoraproject.org should be consistent on all platforms, so this should work on all platforms.
For posterity's sake, here it is with more detail:
$ EPEL_BASEURL=http://dl.fedoraproject.org/pub/epel/$(awk '/rhel/ {print $2}' /etc/rpm/macros.dist)/$(uname -p)/
# http://dl.fedoraproject.org/pub/epel/6/x86_64/
$ EPEL_RELEASE_RPM=$(curl -s $EPEL_BASEURL | grep epel-release | awk -F'<|>' '{print $5}')
# epel-release-6-8.noarch.rpm
$ EPEL_RELEASE_RPMURL=$EPEL_BASEURL$EPEL_RELEASE_RPM
# http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
$ rpm -ivh $EPEL_RELEASE_RPMURL
Retrieving http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
warning: /var/tmp/rpm-tmp.ep6xy3: Header V3 RSA/SHA256 Signature, key ID 0608b895: NOKEY
Preparing... ########################################### [100%]
1:epel-release ########################################### [100%]