Merge pull request #94 from scality/flat_config_storage

Flatten persistent storage configuration

Author: ballot-scality

ChangeLog.rst

@@ -9,6 +9,10 @@ Breaking changes
 be lost. Please see the pull-request description for manual steps required after
 upgrading a MetalK8s 0.1 cluster to MetalK8s 0.2 (:ghissue:`147`)
 
+:ghpull:`94` - flatten the storage configuration and allow more user defined
+storage related actions. Please see :ref:`upgrade_from_MetalK8s_before_0.2.0`
+(:ghissue:`153`)
+
 
 Release 0.1.2 (in development)
 ==============================

docs/architecture/storage.rst

@@ -1,2 +1,34 @@
 Storage Architecture
 ====================
+
+MetalK8s current strage architecture rely on local storage, configured with LVM
+for its purpose.
+
+A default setup, satisfying the storage needs of MetalK8s is automatically
+setup by default and can be easily extended through the various configuration
+items exposed by the tool.
+
+Glossary
+########
+
+* LVM PV: The LVM Physical Volume. This is the disk or the partition provided
+  to LVM to create the LVM Volume Group
+* LVM VG : The LVM Volume Group. This is the logical unit of LVM aggregating
+  the LVM Physical Volumes into one single logical entity
+* LVM LV: A Logical Volume. This is where the filesystem will be created.
+  Several LVM LVs can be created on a single LVM VG
+* PV : Kubernetes Persistent Volume. This is what will be consumed by a
+  Persistent Volume Claim for the Kubernetes storage needs
+* PVC : Kubernetes Persisten Volume Claim
+
+
+Goal
+####
+
+MetalK8s provides a functional Kubernetes cluster with some opinionated
+deployment for the monitoring and logging aspect.
+These deployments require storage, but we wanted to provide an easy way for
+the end user to add it's own configuration
+
+As the deployment of Kubernetes on premise is focused on dedicated hardware,
+Logical Volume Manager (LVM) has been chosen.

docs/usage/quickstart.rst

@@ -64,16 +64,73 @@ subdirectory of our inventory, we declare how to setup storage (in the
 default configuration) on hosts in the *kube-node* group, i.e. hosts on which
 Pods will be scheduled:
 
+.. code-block:: yaml
+
+    metalk8s_lvm_drives_vg_metalk8s: ['/dev/vdb']
+
+In the above, we assume every *kube-node* host has a disk available as
+:file:`/dev/vdb` which can be used to set up Kubernetes *PersistentVolumes*. For
+more information about storage, see :doc:`../architecture/storage`.
+
+.. _upgrade_from_MetalK8s_before_0.2.0:
+
+Upgrading from MetalK8s < 0.2.0
+-------------------------------
+
+The storage configuration changed in a non-backward compatible way on
+MetalK8s 0.2.0 release.
+The old configuration will trigger an error when the playbook
+:file:`playbooks/deploy.yml` is run.
+
+
+An old configuration looking like this
+
 .. code-block:: yaml
 
     metal_k8s_lvm:
       vgs:
         kubevg:
           drives: ['/dev/vdb']
 
-In the above, we assume every *kube-node* host has a disk available as
-:file:`/dev/vdb` which can be used to set up Kubernetes *PersistentVolumes*. For
-more information about storage, see :doc:`../architecture/storage`.
+would become
+
+.. code-block:: yaml
+
+    metalk8s_lvm_default_vg: False
+    metalk8s_lvm_vgs: ['kubevg']
+    metalk8s_lvm_drives_kubevg: ['/dev/vdb']
+    metalk8s_lvm_lvs_kubevg:
+      lv01:
+        size: 52G
+      lv02:
+        size: 52G
+      lv03:
+        size: 52G
+      lv04:
+        size: 11G
+      lv05:
+        size: 11G
+      lv06:
+        size: 11G
+      lv07:
+        size: 5G
+      lv08:
+        size: 5G
+
+A quick explanation of these new variables and why they are required
+
+* metalk8s_lvm_default_vg: The value *False* will ensure that we disable all
+  automatic logic behind configuring the storage
+
+* metalk8s_lvm_vgs: This is a list of the LVM VGs managed by MetalK8s
+
+* metalk8s_lvm_drives_kubevg: This variable is a concatenation of the prefix
+  *metalk8s_lvm_drives_* and the name of the LVM VG. It is used to specify
+  the drives used for this LVM VG
+
+* metalk8s_lvm_lvs_kubevg: This variable is a concatenation of the prefix
+  *metalk8s_lvm_lvs_* and the name of the LVM VG. It is used to specify
+  the LVM LVs created in this LVM VG.
 
 Entering the MetalK8s Shell
 ---------------------------

playbooks/storage-post.yml

@@ -1,6 +1,5 @@
-- hosts: kube-node
+- hosts: kube-master
   tags:
-    - lvm-storage
     - kube-pv
   roles:
-    - role: kube_lvm_storage
+    - role: kube_lvm_storageclass

playbooks/storage-pre.yml

@@ -2,4 +2,5 @@
   tags:
     - lvm-storage
   roles:
-    - role: setup_lvm
+    - role: setup_lvm_vg
+    - role: setup_lvm_lv