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+# Scaffolding for decomposing large roles
+
+## Why?
+
+Currently we have roles that are very large and encompass a lot of different
+components. This makes for a lot of logic required within the role, can
+create complex conditionals, and increases the learning curve for the role.
+
+## How?
+
+Creating a guide on how to approach breaking up a large role into smaller,
+component based, roles. Also describe how to develop new roles, to avoid creating
+large roles.
+
+## Proposal
+
+Create a new guide or append to the current contributing guide a process for
+identifying large roles that can be split up, and how to compose smaller roles
+going forward.
+
+### Large roles
+
+A role should be considered for decomposition if it:
+
+1) Configures/installs more than one product.
+1) Can configure multiple variations of the same product that can live
+side by side.
+1) Has different entry points for upgrading and installing a product
+
+Large roles should be responsible for:
+
+1) Composing smaller roles to provide a full solution such as an Openshift Master
+1) Ensuring that smaller roles are called in the correct order if necessary
+1) Calling smaller roles with their required variables
+1) Performing prerequisite tasks that small roles may depend on being in place
+(openshift_logging certificate generation for example)
+
+### Small roles
+
+A small role should be able to:
+
+1) Be deployed independently of other products (this is different than requiring
+being installed after other base components such as OCP)
+1) Be self contained and able to determine facts that it requires to complete
+1) Fail fast when facts it requires are not available or are invalid
+1) "Make it so" based on provided variables and anything that may be required
+as part of doing such (this should include data migrations)
+
+### Example using decomposition of openshift_logging
+
+The `openshift_logging` role was created as a port from the deployer image for
+the `3.5` deliverable. It was a large role that created the service accounts,
+configmaps, secrets, routes, and deployment configs/daemonset required for each
+of its different components (Fluentd, Kibana, Curator, Elasticsearch).
+
+It was possible to configure any of the components independently of one another,
+up to a point. However, it was an all of nothing installation and there was a
+need from customers to be able to do things like just deploy Fluentd.
+
+Also being able to support multiple versions of configuration files would become
+increasingly messy with a large role. Especially if the components had changes
+at different intervals.
+
+#### Folding of responsibility
+
+There was a duplicate of work within the installation of three of the four logging
+components where there was a possibility to deploy both an 'operations' and
+'non-operations' cluster side-by-side. The first step was to collapse that
+duplicate work into a single path and allow a variable to be provided to
+configure such that either possibility could be created.
+
+#### Consolidation of responsibility
+
+The generation of OCP objects required for each component were being created in
+the same task file, all Service Accounts were created at the same time, all secrets,
+configmaps, etc. The only components that were not generated at the same time were
+the deployment configs and the daemonset. The second step was to make the small
+roles self contained and generate their own required objects.
+
+#### Consideration for prerequisites
+
+Currently the Aggregated Logging stack generates its own certificates as it has
+some requirements that prevent it from utilizing the OCP cert generation service.
+In order to make sure that all components were able to trust one another as they
+did previously, until the cert generation service can be used, the certificate
+generation is being handled within the top level `openshift_logging` role and
+providing the location of the generated certificates to the individual roles.
+
+#### Snippets
+
+openshift_logging/tasks/install_logging.yaml
+```
+- name: Install logging
+  include: "{{ role_path }}/tasks/install_support.yaml"
+  when: openshift_hosted_logging_install | default(true) | bool
+
+
+## Elasticsearch
+- include_role:
+    name: openshift_logging_elasticsearch
+  vars:
+    generated_certs_dir: "{{openshift.common.config_base}}/logging"
+
+- include_role:
+    name: openshift_logging_elasticsearch
+  vars:
+    generated_certs_dir: "{{openshift.common.config_base}}/logging"
+    openshift_logging_es_ops_deployment: true
+  when:
+  - openshift_logging_use_ops | bool
+
+
+## Kibana
+- include_role:
+    name: openshift_logging_kibana
+  vars:
+    generated_certs_dir: "{{openshift.common.config_base}}/logging"
+
+- include_role:
+    name: openshift_logging_kibana
+  vars:
+    generated_certs_dir: "{{openshift.common.config_base}}/logging"
+    openshift_logging_kibana_ops_deployment: true
+  when:
+  - openshift_logging_use_ops | bool
+
+
+## Curator
+- include_role:
+    name: openshift_logging_curator
+  vars:
+    generated_certs_dir: "{{openshift.common.config_base}}/logging"
+
+- include_role:
+    name: openshift_logging_curator
+  vars:
+    generated_certs_dir: "{{openshift.common.config_base}}/logging"
+    openshift_logging_curator_ops_deployment: true
+  when:
+  - openshift_logging_use_ops | bool
+
+
+## Fluentd
+- include_role:
+    name: openshift_logging_fluentd
+  vars:
+    generated_certs_dir: "{{openshift.common.config_base}}/logging"
+
+- include: update_master_config.yaml
+```
+
+openshift_logging/tasks/install_support.yaml [old]
+```
+---
+# This is the base configuration for installing the other components
+- name: Check for logging project already exists
+  command: >
+    {{ openshift.common.client_binary }} --config={{ mktemp.stdout }}/admin.kubeconfig get project {{openshift_logging_namespace}} --no-headers
+  register: logging_project_result
+  ignore_errors: yes
+  when: not ansible_check_mode
+  changed_when: no
+
+- name: "Create logging project"
+  command: >
+    {{ openshift.common.admin_binary }} --config={{ mktemp.stdout }}/admin.kubeconfig new-project {{openshift_logging_namespace}}
+  when: not ansible_check_mode and "not found" in logging_project_result.stderr
+
+- name: Create logging cert directory
+  file: path={{openshift.common.config_base}}/logging state=directory mode=0755
+  changed_when: False
+  check_mode: no
+
+- include: generate_certs.yaml
+  vars:
+    generated_certs_dir: "{{openshift.common.config_base}}/logging"
+
+- name: Create temp directory for all our templates
+  file: path={{mktemp.stdout}}/templates state=directory mode=0755
+  changed_when: False
+  check_mode: no
+
+- include: generate_secrets.yaml
+  vars:
+    generated_certs_dir: "{{openshift.common.config_base}}/logging"
+
+- include: generate_configmaps.yaml
+
+- include: generate_services.yaml
+
+- name: Generate kibana-proxy oauth client
+  template: src=oauth-client.j2 dest={{mktemp.stdout}}/templates/oauth-client.yaml
+  vars:
+    secret: "{{oauth_secret}}"
+  when: oauth_secret is defined
+  check_mode: no
+  changed_when: no
+
+- include: generate_clusterroles.yaml
+
+- include: generate_rolebindings.yaml
+
+- include: generate_clusterrolebindings.yaml
+
+- include: generate_serviceaccounts.yaml
+
+- include: generate_routes.yaml
+```
+
+openshift_logging/tasks/install_support.yaml [new]
+```
+---
+# This is the base configuration for installing the other components
+- name: Set logging project
+  oc_project:
+    state: present
+    name: "{{ openshift_logging_namespace }}"
+
+- name: Create logging cert directory
+  file: path={{openshift.common.config_base}}/logging state=directory mode=0755
+  changed_when: False
+  check_mode: no
+
+- include: generate_certs.yaml
+  vars:
+    generated_certs_dir: "{{openshift.common.config_base}}/logging"
+
+- name: Create temp directory for all our templates
+  file: path={{mktemp.stdout}}/templates state=directory mode=0755
+  changed_when: False
+  check_mode: no
+```
+
+# Limitations
+
+There will always be exceptions for some of these rules, however the majority of
+roles should be able to fall within these guidelines.
+
+# Additional considerations
+
+Playbooks including playbooks (link to rteague's presentation?)