make node buffer configurable

node/conf/resource_limits.conf

@@ -25,6 +25,12 @@ node_profile=small
 # For no over-commit, should be (Total System Memory - 1G) / memory_limit_in_bytes
 max_active_gears=60
 
+# Node disk buffer 
+#
+# When moving a gear to a node, ensure that after a move this buffer of free disk space
+# will be left on the destination node.
+node_df_buffer=0.05
+
 # no_overcommit_active enforces max_active_gears in a more stringent manner than normal,
 # however it also adds overhead to gear creation, so should only be set to true
 # when needed, like in the case of enforcing single tenancy on a node.
@@ -136,3 +142,4 @@ limits_nproc=250        # max number of processes
 [cg_template_boosted]
   cpu_shares=256
   cpu_cfs_quota_us=200000
+

node/lib/openshift-origin-node/model/node.rb

@@ -44,6 +44,7 @@ class Node < Model
       DEFAULT_QUOTA_FILES          = '80000'
       DEFAULT_NO_OVERCOMMIT_ACTIVE = false
       DEFAULT_MAX_ACTIVE_GEARS     = 0
+      DEFAULT_NODE_DF_BUFFER       = 0.05
 
       @@resource_limits_cache = nil
 
@@ -336,6 +337,8 @@ def self.node_utilization
 
         # use max_{active_,}gears if set in resource limits, or fall back to old "apps" names
         res['max_active_gears'] = (resource.get('max_active_gears') or resource.get('max_active_apps') or DEFAULT_MAX_ACTIVE_GEARS)
+        res['node_df_buffer'] = resource.get('node_df_buffer', DEFAULT_NODE_DF_BUFFER)
+
 
         #
         # Count number of git repos and gear status counts

plugins/msg-broker/mcollective/lib/openshift/mcollective_application_container_proxy.rb

@@ -816,6 +816,20 @@ def get_node_total_size
       rpc_get_fact_direct('node_total_size').to_i
     end
 
+    # <<accessor>>
+    # Get the disk free buffer of a Node
+    #
+    # RETURNS:
+    # * Float: the disk free buffer of a Node
+    #
+    # NOTES:
+    # * method on Node
+    # * calls rpc_get_fact_direct
+    #
+    def get_node_df_buffer
+      rpc_get_fact_direct('node_df_buffer').to_f
+    end
+
     #
     # Add a component to an existing gear on the node
     #
@@ -2413,11 +2427,13 @@ def rsync_destination_container(gear, destination_container, destination_distric
       log_debug "DEBUG: Gear platform is '#{platform}'"
       destination_avail_space = destination_container.get_node_disk_free
       destination_total_space = destination_container.get_node_total_size
+      destination_df_buffer = destination_container.get_node_df_buffer.to_f
 
       # check here to make sure addition of gear to destination_container
       # will not result in > 95% full destination_container
-      if (destination_avail_space - source_used_blocks.to_f)/destination_total_space < 0.05
-        raise OpenShift::NodeUnavailableException.new("Gear '#{gear.uuid}' cannot be moved to '#{destination_container.id}'.  Not enough disk space, node would be > 95% full after move.", 140)
+      if (destination_avail_space - source_used_blocks.to_f)/destination_total_space < destination_df_buffer
+        max_value = sprintf('%.0f', (1.0 - destination_df_buffer)*100)
+        raise OpenShift::NodeUnavailableException.new("DEST_DF_BUFFER: #{destination_df_buffer} Gear '#{gear.uuid}' cannot be moved to '#{destination_container.id}'.  Not enough disk space, node would be using > #{max_value}% of it's disk space after the move.", 140)
       end
 
       log_debug "DEBUG: Creating new account for gear '#{gear.uuid}' on #{destination_container.id}"

plugins/msg-node/mcollective/facts/openshift_facts.rb

@@ -53,6 +53,7 @@ def get_node_config_value(key, default)
 Facter.add(:node_disk_free) { setcode { results['node_disk_free'] } }
 Facter.add(:node_total_size) { setcode { results['node_total_size'] } }
 Facter.add(:node_profile) { setcode { results['node_profile'] } }
+Facter.add(:node_df_buffer) { setcode { results['node_df_buffer'] } }
 Facter.add(:max_active_gears) { setcode { results['max_active_gears'] || '0' } }
 Facter.add(:no_overcommit_active) { setcode { results['no_overcommit_active'] || false } }
 Facter.add(:quota_blocks) { setcode { results['quota_blocks'] } }