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Installing Postgres software with Puppet

In this playground, we will show you how you can use Puppet to install your Postgres database setup. You will see that Puppet cannot only take care of the Postgres database software installation itself but also take care of all prerequisites.

After Puppet executed the prerequisites and Postgres database installation, we will show you that Puppet also can create your database setup..

The playground system

The playground system contains a pre-installed puppet agent. There is no server available, so to run Puppet, you have to use the puppet apply command. The playground text will guide you with this.

This system is what we call a “stem-cell” system. At this point in time, it is not predestined to become an Postgres database server. In fact, it could just as easily become a WebLogic server. All of the steps needed to make this stem-cell system become an Postgres database server are performed by Puppet.

Working in the playground

Under this text, you see the working area. You can inspect the system and issue any command you like in the terminal. In the editor window, you can see the Puppet production environment. You can edit anything you wish. The documentation tab shows the documentation for the pg_profile module.

Beware

This system will self destruct in about one hour. So please don’t use it to build or create anything you wish to keep!

Subjects in this playground

The playground contains the following sub paragraphs:
  • Puppet code for Postgres installation
  • Ensure prerequisites
  • Install the Postgres software
  • Create the database
Happy exploring!!

Puppet code for Postgres installation

We have done our best to make it as easy as possible to use Puppet to change your “stem-cell” system into a running Postgres database. Let’s look at some of the Puppet code needed to do this.

In the editor tab, go to the directory hierdata\nodes and open the file pg13.playground.enterprisemodules.com. This file contains all the node-specific data.

At the top, you see:

role: role::postgres::simple_db

This hiera definition tells Puppet that for this node, node pg13.enterprisemodules.com, we want to apply the Puppet class role::postgres::simple_db.

The role role::postgres::simple_db

Let’s see what this Puppet class is doing for us. In the editor tab, go to the directory modules\role\manifests\postgres and open the file simple_db.pp. For your convenience, we have included the contents here as well.

class role::postgres::simple_db()
{

  contain ::profile::base
  contain ::pg_profile::database

  Class['::profile::base']
  -> Class['::pg_profile::database']
}

As you can see, this role class contains (is special sort of include) two other classes. The ::profile::base class is what we call the base profile. A base profile contains all Puppet definitions you would like to apply to all nodes in your organization. It includes all the standard settings you want to apply to your system, no matter what.

The second include is the ::pg_profile::database class. This Puppet class is where all the magic happens needed to transform this node into an Postgres database.

As you can see, this is pretty easy. Let’s see it in action!

Ensure prerequisites

There are not a lot of prerequisites before you can install the postgres package. But if you wanted to change the Postgres uid of gid, or install some extra packages, the pg_profile has got you covered. The pg_profile::database Puppet class would silently take care of all prerequisites for you. For teaching purposes, we have disabled this.

In the editor tab, go to the directory hierdata\nodes and open the file pg13.playground.enterprisemodules.com. This file contains all the node-specific data.

In the top of the file you see this:

pg_profile::database::em_license:           skip
pg_profile::database::sysctl:               skip 
pg_profile::database::limits:               skip
pg_profile::database::groups_and_users:     skip
pg_profile::database::packages:             skip
pg_profile::database::db_software:          skip
pg_profile::database::db_init:              skip
pg_profile::database::db_startup:           skip
pg_profile::database::db_roles:             skip
pg_profile::database::db_definition:        skip
pg_profile::database::db_parameters:        skip
pg_profile::database::db_tablespaces:       skip
pg_profile::database::db_schemas:           skip
pg_profile::database::db_records:           skip

This is the hiera settings that tell pg_profile NOT to execute the software, autostart etc steps.

First Puppet run

With all the skips in place, let’s run Puppet and see what happens.

puppet apply site.pp 

Well, that didn’t do a lot.

Notice: Compiled catalog for pg13.playground.enterprisemodules.com in environment production in 0.25 seconds
Notice: Applied catalog in 0.13 seconds

Actually, what it did, is executing only the base profile. And in this playground, the base profile is minimal.

Re-enable all prerequisite steps.

For the next step, we are going to remove some of the skip definitions in the hiera. Open the node yaml in the editor tab and remove or comment out all lines in the second block of skips. Your hiera should look something like this now:

# pg_profile::database::em_license:           skip
# pg_profile::database::sysctl:               skip 
# pg_profile::database::limits:               skip
# pg_profile::database::groups_and_users:     skip
# pg_profile::database::packages:             skip
pg_profile::database::db_software:          skip
pg_profile::database::db_init:              skip
pg_profile::database::db_startup:           skip
pg_profile::database::db_roles:             skip
pg_profile::database::db_definition:        skip
pg_profile::database::db_parameters:        skip
pg_profile::database::db_tablespaces:       skip
pg_profile::database::db_schemas:           skip
pg_profile::database::db_records:           skip

Re-run Puppet

So now Puppet with the postgres modules executes much more of its regular steps. Let’s see what a re-run of Puppet provides us.

puppet apply site.pp 

The result is following:

Notice: Compiled catalog for pg13.playground.enterprisemodules.com in environment production in 1.27 seconds
Notice: /Stage[setup]/Easy_type::License::Available/File[/etc/puppetlabs/puppet/em_license]/ensure: created
Notice: /Stage[setup]/Easy_type::License::Available/File[/etc/puppetlabs/puppet/em_license/.gitkeep]/ensure: defined content as '{md5}d41d8cd98f00b204e9800998ecf8427e'
Notice: Applied catalog in 0.49 seconds

Because we didn’t specify any data for users, groups, packages, only the pg_profile::database::em_license class actually does something. It ensures that the EM licenses file is in the correct spot.
Wow, that is a lot more. Puppet now:

All prerequisites needed for a successful Postgres database server installation are now fulfilled.

Next up: Install the Postgres software itself.

Install the Postgres software

With all of the prerequisites done, it is time to install some Oracle software.

In the editor tab, go to the directory hierdata\nodes and open the file pg13.playground.enterprisemodules.com.yaml. This file contains all the node-specific data.

Let’s comment out the skip for the step pg_profile::database::db_software as well now . Meaning: next Puppet run, DO execute the software installation.
Your hiera should look something like this now:

#
# pg_profile::database::em_license:           skip
# pg_profile::database::sysctl:               skip 
# pg_profile::database::limits:               skip
# pg_profile::database::groups_and_users:     skip
# pg_profile::database::packages:             skip
# pg_profile::database::db_software:          skip
#

Re-run Puppet

Let’s see what Puppet has got in store for us now and re-run Puppet.

puppet apply site.pp 

The output should look similar to the following:

Notice: Compiled catalog for pg13.playground.enterprisemodules.com in environment production in 0.33 seconds
Notice: Ensure Postgres software version 13
Notice: /Stage[main]/Pg_profile::Database::Db_software/File[/etc/pki/rpm-gpg/RPM-GPG-KEY-PGDG-13]/ensure: defined content as '{md5}b45f4ff074210f1c72422bced5501338'
Notice: /Stage[main]/Pg_profile::Database::Db_software/Yumrepo[yum.postgresql.org]/ensure: created
Notice: /Stage[main]/Pg_profile::Database::Db_software/Package[postgresql13-server]/ensure: created
Notice: Applied catalog in 10.49 seconds

So, now pg_profile will execute all of the steps required to install the Postgres software. Since it has already taken care of the prerequisites in the previous Puppet run, it will detect everything already in place and report no additional changes.

For the actual Oracle software installation, it executes these steps:
1) Make sure that Postgres repo gpg key is installed.
2) Add Postgres repository.
3) Install postgresql server package.
5) Install additional packages.

Re-run Puppet and check idempotency

What happens now if we run Puppet again?

puppet apply site.pp 

Puppet detects everything is in its desired state (configured as described in your Puppet manifests and hierarchy settings) and changes nothing. It is idempotent.

Next up: Create a database.

Create the database

Last, but certainly not least, we will have to ensure the database is available to the users.

In the editor tab, go to the directory hierdata\nodes and open the file pg13.playground.enterprisemodules.com.yaml. This file contains all the node-specific data.

If you take a look at the third block of settings (lines 8 through 15), they should like this for now:

pg_profile::database::db_init:              skip
pg_profile::database::db_startup:           skip
pg_profile::database::db_roles:             skip
pg_profile::database::db_definition:        skip
pg_profile::database::db_parameters:        skip
pg_profile::database::db_tablespaces:       skip
pg_profile::database::db_schemas:           skip
pg_profile::database::db_records:           skip

This tell’s Puppet to skip all database steps. Like I explained before, this is here for teaching purposes. Let’s remove or comment out all of these skips, so Puppet will apply a full manifest that ensures the creation of the database and other Database objects.

Make sure yaml file now looks like this:

# pg_profile::database::db_init:              skip
# pg_profile::database::db_startup:           skip
# pg_profile::database::db_roles:             skip
# pg_profile::database::db_definition:        skip
# pg_profile::database::db_parameters:        skip
# pg_profile::database::db_tablespaces:       skip
# pg_profile::database::db_schemas:           skip
# pg_profile::database::db_records:           skip
#

Re-run Puppet

Let’s see what Puppet has in store for us now, as we re-run Puppet via the terminal window:

puppet apply site.pp
Notice: Compiled catalog for pg13.playground.enterprisemodules.com in environment production in 0.69 seconds
Notice: Ensure Postgres software version 13
Notice: Ensure Postgres initial setup
Notice: Ensure Postgres database start
Notice: Ensure Postgres database(s) testdb@localhost
Notice: /Stage[main]/Pg_profile::Database::Db_init/Exec[Initialize Postgres Database]/returns: executed successfully
Notice: /Stage[main]/Pg_profile::Database::Db_init/Pg_register[localhost]/default: defined 'default' as 'true'
Notice: /Stage[main]/Pg_profile::Database::Db_init/Pg_register[localhost]/user: defined 'user' as 'postgres'
Notice: /Stage[main]/Pg_profile::Database::Db_init/Pg_register[localhost]/os_user: defined 'os_user' as 'postgres'
Notice: /Stage[main]/Pg_profile::Database::Db_init/Pg_register[localhost]/database: defined 'database' as 'postgres'
Notice: /Stage[main]/Pg_profile::Database::Db_init/Pg_register[localhost]/connect_string: defined 'connect_string' as ''
Notice: /Stage[main]/Pg_profile::Database::Db_init/Pg_register[localhost]/daemonized: defined 'daemonized' as 'false'
Notice: /Stage[main]/Profile::Db_startup/Exec[run_postgres]/returns: executed successfully
Notice: /Stage[main]/Pg_profile::Database::Db_definition/Pg_database[testdb@localhost]/ensure: created
Notice: /Stage[main]/Pg_profile::Database::Db_definition/Pg_register[testdb]/default: defined 'default' as 'false'
Notice: /Stage[main]/Pg_profile::Database::Db_definition/Pg_register[testdb]/user: defined 'user' as 'postgres'
Notice: /Stage[main]/Pg_profile::Database::Db_definition/Pg_register[testdb]/os_user: defined 'os_user' as 'postgres'
Notice: /Stage[main]/Pg_profile::Database::Db_definition/Pg_register[testdb]/database: defined 'database' as 'testdb'
Notice: /Stage[main]/Pg_profile::Database::Db_definition/Pg_register[testdb]/connect_string: defined 'connect_string' as ''
Notice: /Stage[main]/Pg_profile::Database::Db_definition/Pg_register[testdb]/daemonized: defined 'daemonized' as 'false'
Notice: Applied catalog in 12.86 seconds

After this Puppet run, you’ll see that database postgres@localhost has been created and is running on your playground system.

Re-run Puppet and check idempotency

And again, let’s see what happens if we run Puppet one last time:

puppet apply site.pp 

Puppet detects everything is at its desired state, as described in your Puppet manifests and hierarchy settings. No changes will be done to the system. Another example of the built-in idempotency.

Next up: Introspecting your database

You like it?

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If you have any questions, don’t hesitate to contact us.

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