add support for cgroupv2

logstash-core/lib/logstash/instrument/periodic_poller/cgroup.rb

@@ -38,21 +38,26 @@ def override(other)
     end
 
     ## `/proc/self/cgroup` contents look like this
-    # 5:cpu,cpuacct:/
-    # 4:cpuset:/
-    # 2:net_cls,net_prio:/
-    # 0::/user.slice/user-1000.slice/session-932.scope
-    ## e.g. N:controller:/path-to-info
-    # we find the controller and path
-    # we skip the line without a controller e.g. 0::/path
-    # we assume there are these symlinks:
-    # `/sys/fs/cgroup/cpu` -> `/sys/fs/cgroup/cpu,cpuacct
-    # `/sys/fs/cgroup/cpuacct` -> `/sys/fs/cgroup/cpu,cpuacct
+    # cgroupv1 (per-controller hierarchies):
+    #   5:cpu,cpuacct:/
+    #   4:cpuset:/
+    #   2:net_cls,net_prio:/
+    #   0::/user.slice/user-1000.slice/session-932.scope
+    # cgroupv2 (unified hierarchy):
+    #   0::/path
+    #
+    # For v1, we find the controller and path from lines matching N:controller:/path.
+    # We assume these symlinks exist:
+    #   `/sys/fs/cgroup/cpu` -> `/sys/fs/cgroup/cpu,cpuacct`
+    #   `/sys/fs/cgroup/cpuacct` -> `/sys/fs/cgroup/cpu,cpuacct`
+    # For v2, the 0::/path line identifies the cgroup path under the unified
+    # hierarchy at /sys/fs/cgroup. Data files (cpu.stat, cpu.max) live there.
 
     CGROUP_FILE = "/proc/self/cgroup"
     CPUACCT_DIR = "/sys/fs/cgroup/cpuacct"
     CPU_DIR = "/sys/fs/cgroup/cpu"
     CRITICAL_PATHS = [CGROUP_FILE, CPUACCT_DIR, CPU_DIR]
+    CGROUP_V2_DIR = "/sys/fs/cgroup"
 
     CONTROLLER_CPUACCT_LABEL = "cpuacct"
     CONTROLLER_CPU_LABEL = "cpu"
@@ -88,6 +93,38 @@ def controller_groups
       end
     end
 
+    class CGroupV2Resources
+      CGROUP_V2_RE = Regexp.compile("^0::(/.*)")
+
+      def cgroup_available?
+        path = resolve_v2_path
+        return false if path.nil?
+        cpu_override = Override.new("ls.cgroup.cpu.path.override")
+        resolved = cpu_override.override(path)
+        ::File.exist?(::File.join(CGROUP_V2_DIR, resolved, "cpu.stat"))
+      end
+
+      def controller_groups
+        path = resolve_v2_path
+        return {} if path.nil?
+        {
+          CONTROLLER_CPU_LABEL => CpuResourceV2.new(path),
+          CONTROLLER_CPUACCT_LABEL => CpuAcctResourceV2.new(path)
+        }
+      end
+
+      private
+
+      def resolve_v2_path
+        return nil unless ::File.exist?(CGROUP_FILE)
+        IO.readlines(CGROUP_FILE).each do |line|
+          match = CGROUP_V2_RE.match(line.strip)
+          return match[1] if match
+        end
+        nil
+      end
+    end
+
     module ControllerResource
       attr_reader :base_path, :override, :offset_path
 
@@ -138,6 +175,27 @@ def cpuacct_usage
       end
     end
 
+    class CpuAcctResourceV2
+      include LogStash::Util::Loggable
+      include ControllerResource
+      def initialize(original_path)
+        common_initialize(CGROUP_V2_DIR, "ls.cgroup.cpuacct.path.override", original_path)
+      end
+
+      def to_hash
+        {:control_group => offset_path, :usage_nanos => cpuacct_usage}
+      end
+      private
+      def cpuacct_usage
+        lines = call_if_file_exists(:read_lines, "cpu.stat", [])
+        lines.each do |line|
+          fields = line.split(/\s+/)
+          return fields[1].to_i * 1000 if fields.first == "usage_usec"
+        end
+        -1
+      end
+    end
+
     class CpuResource
       include LogStash::Util::Loggable
       include ControllerResource
@@ -170,6 +228,52 @@ def build_cpu_stats_hash
       end
     end
 
+    class CpuResourceV2
+      include LogStash::Util::Loggable
+      include ControllerResource
+      def initialize(original_path)
+        common_initialize(CGROUP_V2_DIR, "ls.cgroup.cpu.path.override", original_path)
+      end
+
+      def to_hash
+        {
+          :control_group => offset_path,
+          :cfs_period_micros => cfs_period_us,
+          :cfs_quota_micros => cfs_quota_us,
+          :stat => build_cpu_stats_hash
+        }
+      end
+      private
+      def cfs_period_us
+        read_cpu_max[1]
+      end
+
+      def cfs_quota_us
+        read_cpu_max[0]
+      end
+
+      def read_cpu_max
+        @cpu_max ||= begin
+          line = call_if_file_exists(:read_lines, "cpu.max", []).first
+          if line.nil?
+            [-1, -1]
+          else
+            parts = line.split(/\s+/)
+            quota = parts[0] == "max" ? -1 : parts[0].to_i
+            period = parts[1].to_i
+            [quota, period]
+          end
+        end
+      end
+
+      def build_cpu_stats_hash
+        stats = CpuStatsV2.new
+        lines = call_if_file_exists(:read_lines, "cpu.stat", [])
+        stats.update(lines)
+        stats.to_hash
+      end
+    end
+
     class UnimplementedResource
       attr_reader :controller, :original_path
 
@@ -210,19 +314,47 @@ def to_hash
       end
     end
 
+    class CpuStatsV2
+      def initialize
+        @number_of_elapsed_periods = -1
+        @number_of_times_throttled = -1
+        @time_throttled_nanos = -1
+      end
+
+      def update(lines)
+        lines.each do |line|
+          fields = line.split(/\s+/)
+          next unless fields.size > 1
+          case fields.first
+          when "nr_periods" then @number_of_elapsed_periods = fields[1].to_i
+          when "nr_throttled" then @number_of_times_throttled = fields[1].to_i
+          when "throttled_usec" then @time_throttled_nanos = fields[1].to_i * 1000
+          end
+        end
+      end
+
+      def to_hash
+        {
+          :number_of_elapsed_periods => @number_of_elapsed_periods,
+          :number_of_times_throttled => @number_of_times_throttled,
+          :time_throttled_nanos => @time_throttled_nanos
+        }
+      end
+    end
+
     CGROUP_RESOURCES = CGroupResources.new
+    CGROUP_V2_RESOURCES = CGroupV2Resources.new
 
     class << self
       def get_all
-        unless CGROUP_RESOURCES.cgroup_available?
-          logger.debug("One or more required cgroup files or directories not found: #{CRITICAL_PATHS.join(', ')}")
-          return
-        end
+        resolve_resources unless @resolved
+        return nil if @active_resources.nil?
 
-        groups = CGROUP_RESOURCES.controller_groups
+        groups = @active_resources.controller_groups
 
         if groups.empty?
-          logger.debug("The main cgroup file did not have any controllers: #{CGROUP_FILE}")
+          logger.debug("#{@active_label}: no controllers found") unless @logged_empty
+          @logged_empty = true
           return
         end
 
@@ -231,15 +363,33 @@ def get_all
           next unless controller.implemented?
           cgroups_stats[name.to_sym] = controller.to_hash
         end
-        cgroups_stats
+        cgroups_stats.empty? ? nil : cgroups_stats
       rescue => e
-        logger.debug("Error, cannot retrieve cgroups information", :exception => e.class.name, :message => e.message, :backtrace => e.backtrace.take(4)) if logger.debug?
+        logger.debug("Error, cannot retrieve #{@active_label} cgroups information", :exception => e.class.name, :message => e.message, :backtrace => e.backtrace.take(4)) if logger.debug?
         nil
       end
 
       def get
         get_all
       end
+
+      private
+
+      def resolve_resources
+        @resolved = true
+        if CGROUP_RESOURCES.cgroup_available?
+          @active_resources = CGROUP_RESOURCES
+          @active_label = "cgroupv1"
+          logger.debug("using cgroupv1")
+        elsif CGROUP_V2_RESOURCES.cgroup_available?
+          @active_resources = CGROUP_V2_RESOURCES
+          @active_label = "cgroupv2"
+          logger.debug("using cgroupv2")
+        else
+          @active_resources = nil
+          logger.debug("no cgroup support detected (neither v1 nor v2)")
+        end
+      end
     end
   end
 end end end