Add the ability to filter by metric tags

README.md

@@ -79,13 +79,46 @@ want to add support for another service or third-party API.
 There are 3 configuration options that are configurable per plugin:
 
 * **pass**: An array of strings that is used to filter metrics generated by the
-current plugin. Each string in the array is tested as a prefix against metrics
+current plugin. Each string in the array is tested as a prefix against metric names
 and if it matches, the metric is emitted.
-* **drop**: The inverse of pass, if a metric matches, it is not emitted.
+* **drop**: The inverse of pass, if a metric name matches, it is not emitted.
+* **tagpass**: tag names and arrays of strings that are used to filter metrics by
+the current plugin. Each string in the array is tested as an exact match against
+the tag name, and if it matches the metric is emitted.
+* **tagdrop**: The inverse of tagpass. If a tag matches, the metric is not emitted.
+This is tested on metrics that have passed the tagpass test.
 * **interval**: How often to gather this metric. Normal plugins use a single
 global interval, but if one particular plugin should be run less or more often,
 you can configure that here.
 
+### Plugin Configuration Examples
+
+```
+# Read metrics about disk usage by mount point
+[disk]
+interval = "1m" # Run at a 1 minute interval instead of the default
+
+[disk.tagpass]
+# These tag conditions are OR, not AND.
+# If the (filesystem is ext4 or xfs) or (the path is /opt or /home) then the metric passes
+fstype = [ "ext4", "xfs" ]
+path = [ "/opt", "/home" ]
+
+[postgresql]
+
+[postgresql.tagdrop]
+# Don't report stats about the database name 'testdatabase'
+db = [ "testdatabase" ]
+
+```
+
+```
+[disk]
+# Don't report stats about the following filesystem types
+[disk.tagdrop]
+fstype = [ "nfs", "tmpfs", "ecryptfs" ]
+```
+
 ## Plugins
 
 This section is for developers that want to create new collection plugins.

accumulator.go

@@ -32,7 +32,7 @@ func (bp *BatchPoints) Add(measurement string, val interface{}, tags map[string]
 	measurement = bp.Prefix + measurement
 
 	if bp.Config != nil {
-		if !bp.Config.ShouldPass(measurement) {
+		if !bp.Config.ShouldPass(measurement, tags) {
 			return
 		}
 	}
@@ -71,7 +71,7 @@ func (bp *BatchPoints) AddValuesWithTime(
 	measurement = bp.Prefix + measurement
 
 	if bp.Config != nil {
-		if !bp.Config.ShouldPass(measurement) {
+		if !bp.Config.ShouldPass(measurement, tags) {
 			return
 		}
 	}

config.go

@@ -51,18 +51,28 @@ func (c *Config) Plugins() map[string]*ast.Table {
 	return c.plugins
 }
 
+// The name of a tag, and the values on which to filter
+type TagFilter struct {
+	Name   string
+	Filter []string
+}
+
 // ConfiguredPlugin containing a name, interval, and drop/pass prefix lists
+// Also lists the tags to filter
 type ConfiguredPlugin struct {
 	Name string
 
 	Drop []string
 	Pass []string
 
+	TagDrop []TagFilter
+	TagPass []TagFilter
+
 	Interval time.Duration
 }
 
 // ShouldPass returns true if the metric should pass, false if should drop
-func (cp *ConfiguredPlugin) ShouldPass(measurement string) bool {
+func (cp *ConfiguredPlugin) ShouldPass(measurement string, tags map[string]string) bool {
 	if cp.Pass != nil {
 		for _, pat := range cp.Pass {
 			if strings.HasPrefix(measurement, pat) {
@@ -83,6 +93,32 @@ func (cp *ConfiguredPlugin) ShouldPass(measurement string) bool {
 		return true
 	}
 
+	if cp.TagPass != nil {
+		for _, pat := range cp.TagPass {
+			if tagval, ok := tags[pat.Name]; ok {
+				for _, filter := range pat.Filter {
+					if filter == tagval {
+						return true
+					}
+				}
+			}
+		}
+		return false
+	}
+
+	if cp.TagDrop != nil {
+		for _, pat := range cp.TagDrop {
+			if tagval, ok := tags[pat.Name]; ok {
+				for _, filter := range pat.Filter {
+					if filter == tagval {
+						return false
+					}
+				}
+			}
+		}
+		return true
+	}
+
 	return true
 }
 
@@ -140,9 +176,47 @@ func (c *Config) ApplyPlugin(name string, v interface{}) (*ConfiguredPlugin, err
 			}
 		}
 
+		if node, ok := tbl.Fields["tagpass"]; ok {
+			if subtbl, ok := node.(*ast.Table); ok {
+				for name, val := range subtbl.Fields {
+					if kv, ok := val.(*ast.KeyValue); ok {
+						tagfilter := &TagFilter{Name: name}
+						if ary, ok := kv.Value.(*ast.Array); ok {
+							for _, elem := range ary.Value {
+								if str, ok := elem.(*ast.String); ok {
+									tagfilter.Filter = append(tagfilter.Filter, str.Value)
+								}
+							}
+						}
+						cp.TagPass = append(cp.TagPass, *tagfilter)
+					}
+				}
+			}
+		}
+
+		if node, ok := tbl.Fields["tagdrop"]; ok {
+			if subtbl, ok := node.(*ast.Table); ok {
+				for name, val := range subtbl.Fields {
+					if kv, ok := val.(*ast.KeyValue); ok {
+						tagfilter := &TagFilter{Name: name}
+						if ary, ok := kv.Value.(*ast.Array); ok {
+							for _, elem := range ary.Value {
+								if str, ok := elem.(*ast.String); ok {
+									tagfilter.Filter = append(tagfilter.Filter, str.Value)
+								}
+							}
+						}
+						cp.TagDrop = append(cp.TagDrop, *tagfilter)
+					}
+				}
+			}
+		}
+
 		delete(tbl.Fields, "drop")
 		delete(tbl.Fields, "pass")
 		delete(tbl.Fields, "interval")
+		delete(tbl.Fields, "tagdrop")
+		delete(tbl.Fields, "tagpass")
 		return cp, toml.UnmarshalTable(tbl, v)
 	}
 

plugins/system/disk.go

@@ -24,9 +24,9 @@ func (s *DiskStats) Gather(acc plugins.Accumulator) error {
 
 	for _, du := range disks {
 		tags := map[string]string{
-			"path": du.Path,
+			"path":   du.Path,
+			"fstype": du.Fstype,
 		}
-
 		acc.Add("total", du.Total, tags)
 		acc.Add("free", du.Free, tags)
 		acc.Add("used", du.Total-du.Free, tags)

plugins/system/ps.go

@@ -63,6 +63,7 @@ func (s *systemPS) DiskUsage() ([]*disk.DiskUsageStat, error) {
 
 	for _, p := range parts {
 		du, err := disk.DiskUsage(p.Mountpoint)
+		du.Fstype = p.Fstype
 		if err != nil {
 			return nil, err
 		}

plugins/system/ps/disk/disk.go

@@ -6,6 +6,7 @@ import (
 
 type DiskUsageStat struct {
 	Path              string  `json:"path"`
+	Fstype            string  `json:"fstype"`
 	Total             uint64  `json:"total"`
 	Free              uint64  `json:"free"`
 	Used              uint64  `json:"used"`

plugins/system/ps/disk/disk_test.go

@@ -59,6 +59,7 @@ func TestDisk_io_counters(t *testing.T) {
 func TestDiskUsageStat_String(t *testing.T) {
 	v := DiskUsageStat{
 		Path:              "/",
+		Fstype:            "ext4",
 		Total:             1000,
 		Free:              2000,
 		Used:              3000,
@@ -68,7 +69,7 @@ func TestDiskUsageStat_String(t *testing.T) {
 		InodesFree:        6000,
 		InodesUsedPercent: 49.1,
 	}
-	e := `{"path":"/","total":1000,"free":2000,"used":3000,"used_percent":50.1,"inodes_total":4000,"inodes_used":5000,"inodes_free":6000,"inodes_used_percent":49.1}`
+	e := `{"path":"/","fstype":"ext4","total":1000,"free":2000,"used":3000,"used_percent":50.1,"inodes_total":4000,"inodes_used":5000,"inodes_free":6000,"inodes_used_percent":49.1}`
 	if e != fmt.Sprintf("%v", v) {
 		t.Errorf("DiskUsageStat string is invalid: %v", v)
 	}

plugins/system/system_test.go

@@ -48,6 +48,7 @@ func TestSystemStats_GenerateStats(t *testing.T) {
 
 	du := &disk.DiskUsageStat{
 		Path:        "/",
+		Fstype:      "ext4",
 		Total:       128,
 		Free:        23,
 		InodesTotal: 1234,
@@ -195,7 +196,8 @@ func TestSystemStats_GenerateStats(t *testing.T) {
 	require.NoError(t, err)
 
 	tags := map[string]string{
-		"path": "/",
+		"path":   "/",
+		"fstype": "ext4",
 	}
 
 	assert.True(t, acc.CheckTaggedValue("total", uint64(128), tags))