CentOS 7.2 network install fail [Solved]
Sunday, June 5. 2016
I was about to upgrade an old CentOS 6 box into 7. It was all planned, backups taken, necessary information gathered and USB stick prepared with 7.2 DVD image in it. A shutdown and boot from the installation USB, bunch of settings, date/time, keyboard, network, but Däng! No dice.
My initial attempt was to install from USB, but for some reason the server didn't see the USB volume as a valid installation source. No problem, I thought, let's go for network-install then. The interface was already up and the box could reach Internet ok. Installing from a mirror shouldn't take too long. But no. All I could accomplish was a "Error setting up base repository". I went googling about this and found CentOS 7.2 Netinstall Guide – Network Installation Screenshots.
First I set up installation source as On the network: http://mirror.centos.org/centos/7.2.1511/os/x86_64/ and then This URL refers to a mirror list: Checked. No avail. It took about 8 minutes to get the error, but this approach failed miserably. What /tmp/packaging.log had was:
ERR packaging: failed to grab repo metadata for anaconda: Cannot find a valid baseurl for repo: anaconda
ERR packaging: metadata download for repo anaconda failed after 10 retries
Argh! 8 minutes to determine, that the thing didn't work. 
There was plenty of time to plan for the next move. I went to see CentOS mirror list, and picked the local Finnish mirror at nic.FUNET. Setting that as source: http://ftp.funet.fi/pub/mirrors/centos.org/7.2.1511/os/x86_64/ and with This URL refers to a mirror list: set as Unchecked got me butkus, /tmp/packaging.log had:
ERR packaging: failed to grab repo metadata for anaconda: failure: repodata/6990209f63a9fd811f13e830ac3c6de4c5d70a42b1c6873e4329b523d394c3bd-primary.xml.gz from anaconda: [Errno 256] No more mirrors to try.
http://ftp.funet.fi/pub/mirrors/centos.org/7.2.1511/os/x86_64/repodata/
6990209f63a9fd811f13e830ac3c6de4c5d70a42b1c6873e4329b523d394c3bd-primary.xml.gz: [Errno 14] HTTP Error 404 - Not Found
Finally a tangible result. Obviously the HTTP/404 was correct. There is no such file in that directory. It took me about 15 seconds to determine, that the URL should be http://ftp.funet.fi/pub/mirrors/centos.org/7.2.1511/os/x86_64/repodata/
0e54cd65abd3621a0baf9a963eafb1a0ffd53603226f02aadce59635329bc937-primary.xml.gz. Something was off in the installer metadata. But where?
I checked treeinfo at http://ftp.funet.fi/pub/mirrors/centos.org/7.2.1511/os/x86_64/.treeinfo, but no avail. Then my poking around landed at /var/run/install/repo/repodata. It has among others, a file named repomd.xml. Looking at the network version from http://ftp.funet.fi/pub/mirrors/centos.org/7.2.1511/os/x86_64/repodata/repomd.xml made everything clear as crystal.
- Drive had:
- revision 1449702798
- 6990209f63a9fd811f13e830ac3c6de4c5d70a42b1c6873e4329b523d394c3bd, the file that doesn't exist in the mirror
- Network had:
- revision 1449700451
- 0e54cd65abd3621a0baf9a963eafb1a0ffd53603226f02aadce59635329bc937, the file that does exist
But how to fix this?
My initial attempt was to wget http://ftp.funet.fi/pub/mirrors/centos.org/7.2.1511/os/x86_64/repodata/repomd.xml into /var/run/install/repo/repodata and retry, but that didn't change anything, still the same frustrating error after 10 minute delay.
I rebooted the box and relized, that my change persisted on the USB-drive. Whoa! 
Anyway, I got things cooking this time. Finally the base repository was accepted, I got to go make installation selection and got the install forward.
What the hell was going on there? Where did the incorrect repomd.xml come from? It isn't in the installation image. Or it is, but it comes from a place I didn't find. Whatever it is, there is something seriously off in the process. Why doesn't the installer try to get the most recent version from the network. It is a network install, after all!! After frustrating couple hours later than anticipated, I finally got the box upgraded. Hopefully this information saves you that time.
Rebecca on :