Installing Packages on CentOS Offline

Not long ago I ran into a problem I had never faced before. I had to install some packages on a CentOS machine that had no internet access — and to skip the details, it was impossible to have internet access due to security policies. I only had SSH access, and that was the challenge: install these packages with no internet.

The dependency problem

At first it seemed like a simple task. As I usually do when I need an RPM, I went to pkgs.org, downloaded the RPM, uploaded it via SCP, and voilà. That’s when I ran into the real problem. In this case, let’s try to install kwrite:

rpm -ivh kwrite-4.10.5-6.el7.x86_64.rpm

error: Failed dependencies:
    kate-part(x86-64) = 4.10.5-6.el7 is needed by kwrite-4.10.5-6.el7.x86_64
    kde-runtime >= 4.10.5 is needed by kwrite-4.10.5-6.el7.x86_64

Solving this is simple: go back to pkgs.org and download the dependencies. But in these cases, the easiest approach would be to use YUM directly:

yum install kwrite-4.10.5-6.el7.x86_64.rpm

YUM would automatically find and install the dependencies. But as I mentioned, I have no internet access and can’t use YUM normally.

The only option was to find the dependencies, download the RPMs, and install them. And that task, while it sounds simple, is not. At the first level the package had 12 dependencies, and when trying to install the first dependency, that new package had its own dependencies, which in turn had more dependencies. In a quick count, I had to install more than 100 packages.

Installing everything manually was far from optimal.

The solution: repotrack + createrepo

Looking around online I found two key tools:

yumdownloader — downloads first-level dependencies (not useful for this case).
repotrack — downloads all dependencies recursively.

Step 1 — Start a CentOS machine with internet

The download process must be done on a CentOS machine with the same characteristics and with internet access. This ensures the downloaded packages are compatible with the target system.

Step 2 — Identify the package with yum search

yum search kwrite

Loaded plugins: fastestmirror, langpacks
============================= N/S matched: kwrite ==============================
kwrite.x86_64 : Text Editor

Once we have the package name: kwrite.x86_64.

Step 3 — Download all dependencies with repotrack

# Basic usage:
# repotrack -p [directory] [package]

repotrack -p /home/b4rt/kwrite kwrite.x86_64

Downloading GConf2-3.2.6-8.el7.i686.rpm
Downloading GConf2-3.2.6-8.el7.x86_64.rpm
Downloading OpenEXR-libs-1.7.1-7.el7.x86_64.rpm
Downloading OpenEXR-libs-1.7.1-7.el7.i686.rpm
...

-p — directory where the RPMs will be downloaded.
kwrite.x86_64 — package name.

In this case 707 dependencies were downloaded (377 MB):

find /home/b4rt/kwrite/ -type f -print | wc -l
707

du -mh /home/b4rt/kwrite/
377M    /home/b4rt/kwrite/

Step 4 — Create the local repository with createrepo

createrepo /home/b4rt/kwrite/

Spawning worker 0 with 118 pkgs
Spawning worker 1 with 118 pkgs
Spawning worker 2 with 118 pkgs
Spawning worker 3 with 118 pkgs
Spawning worker 4 with 118 pkgs
Spawning worker 5 with 117 pkgs
Workers Finished
Saving Primary metadata
Saving file lists metadata
Saving other metadata
Generating sqlite DBs
Sqlite DBs complete

createrepo generates a repodata directory inside the RPM directory. This directory has the necessary structure (XML, SQLite) to use it as a CentOS repository.

Now compress the directory and it’s ready to move to the target server:

tar -zcvf kwrite.tar.gz /home/b4rt/kwrite/

Step 5 — Configure the repository on the offline server

After uploading the file to the target server (via SCP or however you prefer), decompress it:

tar -zxvf kwrite.tar.gz -C /home/

Now create a .repo file pointing to our local repository. It must be located in /etc/yum.repos.d/:

vim /etc/yum.repos.d/repo_b4rt.repo

File contents:

[local]
name=repo_b4rt
baseurl=file:///home/kwrite
enabled=1
gpgcheck=0

Field	Description
`name`	Repository name
`baseurl`	Local path to the repository
`enabled`	`1` active, `0` inactive
`gpgcheck`	`1` validates GPG signatures, `0` disabled (required for local repos)

Step 6 — Install the package from the local repository

Verify YUM can find it (disabling internet repos and enabling only the local one):

yum search \
  --disablerepo=base \
  --disablerepo=extras \
  --disablerepo=updates \
  --disablerepo=epel \
  --enablerepo=local \
  kwrite

=============================== N/S matched: kwrite ===============================
kwrite.x86_64 : Text Editor

Now install the package:

yum install \
  --disablerepo=base \
  --disablerepo=extras \
  --disablerepo=updates \
  --disablerepo=epel \
  --enablerepo=local \
  kwrite

As we’ve just seen, our package is now installed and we know how to create local repositories for completely offline installations.

The process of generating the repository is somewhat tedious, so I wrote a Python script that tracks dependencies, creates the repository, and compresses the directory — everything is ready to move to the target server.

It requires Python 3.5+. You can clone it from github.com/bl00dyb4rt/Tracker.