Custom Installation Solutions

Cloudera hosts two types of software repositories that you can use to install products such as Cloudera Manager or CDH—parcel repositories and package repositories.

These repositories are effective solutions in most cases, but custom installation solutions are sometimes required. Using the Cloudera-hosted software repositories requires client access over the Internet. Typical installations use the latest available software. In some scenarios, these behaviors might not be desirable, such as:
  • You need to install older product versions. For example, in a CDH cluster, all hosts must run the same CDH version. After completing an initial installation, you may want to add hosts. This could be to increase the size of your cluster to handle larger tasks or to replace older hardware.
  • The hosts on which you want to install Cloudera products are not connected to the Internet, so they cannot reach the Cloudera repository. (For a parcel installation, only the Cloudera Manager Server needs Internet access, but for a package installation, all cluster hosts require access to the Cloudera repository). Most organizations partition parts of their network from outside access. Isolating network segments improves security, but can add complexity to the installation process.
In both of these cases, using an internal repository allows you to meet the needs of your organization, whether that means installing specific versions of Cloudera software or installing Cloudera software on hosts without Internet access.

Introduction to Parcels

Parcels are a packaging format that facilitate upgrading software from within Cloudera Manager. You can download, distribute, and activate a new software version all from within Cloudera Manager. Cloudera Manager downloads a parcel to a local directory. Once the parcel is downloaded to the Cloudera Manager Server host, an Internet connection is no longer needed to deploy the parcel. For detailed information about parcels, see Parcels.

If your Cloudera Manager Server does not have Internet access, you can obtain the required parcel files and put them into a parcel repository. For more information, see Configuring a Local Parcel Repository.

Understanding Package Management

Before getting into the details of how to configure a custom package management solution in your environment, it can be useful to have more information about:

Package Management Tools

Packages (rpm or deb files) help ensure that installations complete successfully by satisfying package dependencies. When you install a particular package, all other required packages are installed at the same time. For example, hadoop-0.20-hive depends on hadoop-0.20.

Package management tools, such as yum (RHEL), zypper (SLES), and apt-get (Ubuntu) are tools that can find and install required packages. For example, on a RHEL compatible system, you might run the command yum install hadoop-0.20-hive. The yum utility informs you that the Hive package requires hadoop-0.20 and offers to install it for you. zypper and apt-get provide similar functionality.

Package Repositories

Package management tools rely on package repositories to install software and resolve any dependency requirements. For information on creating an internal repository, see Configuring a Local Package Repository.

Repository Configuration Files

Information about package repositories is stored in configuration files, the location of which varies according to the package management tool.
  • RHEL compatible (yum): /etc/yum.repos.d
  • SLES (zypper): /etc/zypp/zypper.conf
  • Ubuntu (apt-get): /etc/apt/apt.conf (Additional repositories are specified using .list files in the /etc/apt/sources.list.d/ directory.)
For example, on a typical CentOS system, you might find:
ls -l /etc/yum.repos.d/
total 36
-rw-r--r--. 1 root root 1664 Dec  9  2015 CentOS-Base.repo
-rw-r--r--. 1 root root 1309 Dec  9  2015 CentOS-CR.repo
-rw-r--r--. 1 root root  649 Dec  9  2015 CentOS-Debuginfo.repo
-rw-r--r--. 1 root root  290 Dec  9  2015 CentOS-fasttrack.repo
-rw-r--r--. 1 root root  630 Dec  9  2015 CentOS-Media.repo
-rw-r--r--. 1 root root 1331 Dec  9  2015 CentOS-Sources.repo
-rw-r--r--. 1 root root 1952 Dec  9  2015 CentOS-Vault.repo
-rw-r--r--. 1 root root  951 Jun 24  2017 epel.repo
-rw-r--r--. 1 root root 1050 Jun 24  2017 epel-testing.repo
The .repo files contain pointers to one or more repositories. There are similar pointers inside configuration files for zypper and apt-get. In the following excerpt from CentOS-Base.repo, there are two repositories defined: one named Base and one named Updates. The mirrorlist parameter points to a website that has a list of places where this repository can be downloaded.
name=CentOS-$releasever - Base

#released updates
name=CentOS-$releasever - Updates

Listing Repositories

You can list the enabled repositories by running one of the following commands:
  • RHEL compatible: yum repolist
  • SLES: zypper repos
  • Ubuntu: apt-get does not include a command to display sources, but you can determine sources by reviewing the contents of /etc/apt/sources.list and any files contained in /etc/apt/sources.list.d/.
The following shows an example of the output of yum repolist on a CentOS 7 sytstem:
repo id               repo name                                           status
base/7/x86_64         CentOS-7 - Base                                      9,591
epel/x86_64           Extra Packages for Enterprise Linux 7 - x86_64      12,382
extras/7/x86_64       CentOS-7 - Extras                                      392
updates/7/x86_64      CentOS-7 - Updates                                   1,962
repolist: 24,327