Add more alarms

This commit adds more built-in alarms to the Linux formula.

linux/meta/heka.yml

         window: 120
         periods: 0
         function: avg
+    linux_system_swap_usage_critical:
+      description: 'There is no more swap free space'
+      severity: critical
+      rules:
+      - metric: swap_free
+        relational_operator: '=='
+        threshold: 0
+        window: 60
+        periods: 0
+        function: max
+    linux_system_swap_activity_warning:
+      description: 'The swap activity is high'
+      severity: warning
+      rules:
+      - metric: swap_io_in
+        relational_operator: '>='
+        threshold: 1048576 # 1 Mb/s
+        window: 120
+        periods: 0
+        function: avg
+      - metric: swap_io_out
+        relational_operator: '>='
+        threshold: 1048576 # 1 Mb/s
+        window: 120
+        periods: 0
+        function: avg
+    linux_system_swap_usage_warning:
+      description: 'The swap free space is low'
+      severity: warning
+      rules:
+      - metric: swap_percent_used
+        relational_operator: '>='
+        threshold: 0.8
+        window: 60
+        periods: 0
+        function: avg
+    linux_system_root_fs_warning:
+      description: "The root filesystem's free space is low"
+      severity: warning
+      rules:
+      - metric: fs_space_percent_free
+        field:
+          fs: '/'
+        relational_operator: '<'
+        threshold: 10
+        window: 60
+        periods: 0
+        function: min
+    linux_system_root_fs_critical:
+      description: "The root filesystem's free space is too low"
+      severity: critical
+      rules:
+      - metric: fs_space_percent_free
+        field:
+          fs: '/'
+        relational_operator: '<'
+        threshold: 5
+        window: 60
+        periods: 0
+        function: min
+    linux_system_network_warning_dropped_rx:
+      description: 'Some received packets have been dropped'
+      severity: warning
+      rules:
+      - metric: if_dropped_rx
+        relational_operator: '>'
+        threshold: 100
+        window: 60
+        periods: 0
+        function: avg
+    linux_system_network_critical_dropped_rx:
+      description: 'Too many received packets have been dropped'
+      severity: critical
+      rules:
+      - metric: if_dropped_rx
+        relational_operator: '>'
+        threshold: 1000
+        window: 60
+        periods: 0
+        function: avg
+    linux_system_network_warning_dropped_tx:
+      description: 'Some transmitted packets have been dropped'
+      severity: warning
+      rules:
+      - metric: if_dropped_tx
+        relational_operator: '>'
+        threshold: 100
+        window: 60
+        periods: 0
+        function: avg
+    linux_system_network_critical_dropped_tx:
+      description: 'Too many transmitted packets have been dropped'
+      severity: critical
+      rules:
+      - metric: if_dropped_tx
+        relational_operator: '>'
+        threshold: 1000
+        function: avg
+        window: 60
+    linux_system_hdd_errors_critical:
+      description: 'Errors on hard drive(s) have been detected'
+      severity: critical
+      no_data_policy: okay
+      rules:
+      - metric: hdd_errors_rate
+        group_by: [device]
+        relational_operator: '>'
+        threshold: 0
+        window: 60
+        periods: 0
+        function: max
   alarm:
     linux_system_cpu:
       alerting: enabled
       triggers:
       - linux_system_cpu_warning
       - linux_system_cpu_critical
+    linux_system_swap:
+      alerting: enabled
+      triggers:
+      - linux_system_swap_usage_critical
+      - linux_system_swap_activity_warning
+      - linux_system_swap_usage_warning
+    linux_system_root_fs:
+      alerting: enabled
+      triggers:
+      - linux_system_root_fs_critical
+      - linux_system_root_fs_warning
+    linux_system_network_rx:
+      alerting: enabled
+      triggers:
+      - linux_system_network_critical_dropped_rx
+      - linux_system_network_warning_dropped_rx
+    linux_system_network_tx:
+      alerting: enabled
+      triggers:
+      - linux_system_network_critical_dropped_tx
+      - linux_system_network_warning_dropped_tx
+    linux_system_hdd_errors:
+      alerting: enabled_with_notification
+      triggers:
+      - linux_system_hdd_errors_critical