Monday, 4 December 2017

Puppet - Roles and Profiles

Forgetting about Puppet for a moment - if we are to conceptually describe how our servers are built as part of a large distributed group then we would describe them initially in terms of business function - e.g. this server stores data of financial transactions, it also needs to allow certain people to login to it, it needs to be monitored etc etc - whilst another server might be described at a high level as running a web server, needs the ability to allow certain people to login etc.

The high level description of what a server does we call a role (e.g. data store role and web server role in the example above).

The technical sub-components of a role we call a profile (e.g. install postgres database module, install ldap client module, install nginx module).

We can further subdivide profiles into roles that are common to many systems, e.g. we can define . common profile that contains:

common profile -> ldap module + packages module + monitoring module + security module

then we could define a web server profile:

webserver profile -> nginx module + haproxy module

we can define multiple profiles that contain the technical building blocks which we can put together for a specific role (business function). Each server is described by one role. Each role is formed of at least one profile - usually more. Profiles can be reused multiple times in different roles.

then our role would look like:

webserver role -> common profile + webserver profile

I have a git repository that shows a simple example of using roles and profiles - puppet rolesandprofiles

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