common-flows

A repository containing the playbooks/roles for common tasks performed on existing clusters, ensembles, and groups of nodes once they have been provisioned. This includes tasks like:

• adding new nodes to existing clusters or ensembles
• deploying agents to new nodes but leaving the existing nodes untouched, and
• reconfiguring existing nodes/clusters/ensembles once they have been provisioned

This repository is used as a submodule by the main DataNexus repositories to provide access to these common flows from any of those repositories.

Use

To use these common roles in another GitHub repository, simply add this repository as a (git) submodule of that repository. This can be accomplished by running a command that looks something like the following:

$ git submodule add https://github.com/Datanexus/common-flows common-flows

This will create a common-flows subdirectory, then clone this repository into that common-flows subdirecory and checkout the latest commit from this repository, and create a .gitmodules file that looks something like the following:

[submodule "common-roles"]
    path = common-flows
    url = https://github.com/Datanexus/common-flows

Once the common-roles repository has been added as a submodule, the next step is to add the common-roles directory to the roles_path used by Ansible. This can be accomplished by creating an ansible.cfg file in the same directory as the playbook that will be run that looks something like this:

[defaults]
roles_path = ../:common-roles:common-flows

With the submodule added and the roles_path modified to ensure that the roles in this repository are included in the roles_path used by the ansible-playbook command, the roles in this repository can then be used in any playbooks that might be defined in the repository that this common-roles repository is being added to as a submodule.

To commit the changes made by the process of adding this repository as a submodule, you would then run a series of commands that look something like this:

$ git add common-flows ansible.cfg
    ...
$ git commit -m "adding common-flows submodule to repository"
    ...
$ git push
    ...

Cloning the resulting repository

To clone the resulting repository, simply add a --recursive flag to the git clone command that you would normally use. For example, the following command will clone the dn-solr repository from the Datanexus organization at GitHub.com (which includes this repository as a submodule):

$ git clone --recursive https://github.com/Datanexus/dn-solr

Pulling changes into the resulting repository

If this repository is modified and the developer of a repository that includes this one as a submodule wants to pull the latest changes into their repository, they can do that quite easily by using a sequence of commands that look something like this:

$ cd common-flows
$ git checkout master
    ...
$ git pull
$ cd ..
$ git add common-flows
    ...
$ git commit -m "updating common-flows submodule version"
    ...
$ git push
    ...

This sequence of commands will pull down the latest changes from the https://github.com/Datanexus/common-flows repository, update the version of the common-flows submodule that is used by the repository that depends on it, and commit that new version to that repository.