Add a generic config and collector for custom metrics

collector/config.go

@@ -0,0 +1,53 @@
+// Copyright 2015 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package collector
+
+import (
+	"time"
+)
+
+type Config struct {
+	//the endpoint to hit to scrape metrics
+	Endpoint string `json:"endpoint"`
+
+	//holds information about different metrics that can be collected
+	MetricsConfig []MetricConfig `json:"metrics_config"`
+}
+
+// metricConfig holds information extracted from the config file about a metric
+type MetricConfig struct {
+	//the name of the metric
+	Name string `json:"name"`
+
+	//enum type for the metric type
+	MetricType MetricType `json:"metric_type"`
+
+	//data type of the metric (eg: integer, string)
+	Units string `json:"units"`
+
+	//the frequency at which the metric should be collected
+	PollingFrequency time.Duration `json:"polling_frequency"`
+
+	//the regular expression that can be used to extract the metric
+	Regex string `json:"regex"`
+}
+
+// MetricType is an enum type that lists the possible type of the metric
+type MetricType string
+
+const (
+	Counter MetricType = "counter"
+	Gauge   MetricType = "gauge"
+)

collector/config/sample_config.json

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+{
+	"endpoint" : "http://localhost:8000/nginx_status",
+	"metrics_config"  : [
+		{ "name" : "activeConnections",  
+		  "metric_type" : "gauge",
+		  "units" : "integer",
+		  "polling_frequency" : 10,
+		  "regex" : "Active connections: ([0-9]+)"			
+		},
+		{ "name" : "reading",
+		  "metric_type" : "gauge", 
+		  "units" : "integer",
+		  "polling_frequency" : 10,
+		  "regex" : "Reading: ([0-9]+) .*"	
+		},
+		{ "name" : "writing",
+                  "metric_type" : "gauge",
+                  "units" : "integer",
+                  "polling_frequency" : 10,
+                  "regex" : ".*Writing: ([0-9]+).*"
+                },
+		{ "name" : "waiting",
+                  "metric_type" : "gauge",
+                  "units" : "integer",
+                  "polling_frequency" : 10,
+                  "regex" : ".*Waiting: ([0-9]+)"
+                }
+	] 	
+
+}

collector/generic_collector.go

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+// Copyright 2015 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package collector
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"time"
+
+	"github.com/google/cadvisor/info/v2"
+)
+
+type GenericCollector struct {
+	//name of the collector
+	name string
+
+	//holds information extracted from the config file for a collector
+	configFile Config
+}
+
+//Returns a new collector using the information extracted from the configfile
+func NewCollector(collectorName string, configfile string) (*GenericCollector, error) {
+	configFile, err := ioutil.ReadFile(configfile)
+	if err != nil {
+		return nil, err
+	}
+
+	var configInJSON Config
+	err = json.Unmarshal(configFile, &configInJSON)
+	if err != nil {
+		return nil, err
+	}
+
+	//TODO : Add checks for validity of config file (eg : Accurate JSON fields)
+
+	return &GenericCollector{
+		name: collectorName, configFile: configInJSON,
+	}, nil
+}
+
+//Returns name of the collector
+func (collector *GenericCollector) Name() string {
+	return collector.name
+}
+
+//Returns collected metrics and the next collection time of the collector
+func (collector *GenericCollector) Collect() (time.Time, []v2.Metric, error) {
+	//TO BE IMPLEMENTED
+	return time.Now(), nil, nil
+}

collector/generic_collector_test.go

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+// Copyright 2015 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package collector
+
+import (
+	"io/ioutil"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestConfigWithErrors(t *testing.T) {
+	assert := assert.New(t)
+
+	//Syntax error: Missed '"' after active connections
+	invalid := `
+	{
+		"endpoint" : "host:port/nginx_status",
+		"metricsConfig"  : [
+			{
+				 "name" : "activeConnections,  
+		  		 "metricType" : "gauge",
+		 	 	 "units" : "integer",
+		  		 "pollingFrequency" : "10s",
+		    		 "regex" : "Active connections: ([0-9]+)"			
+			}
+		]
+	}
+	`
+
+	//Create a temporary config file 'temp.json' with invalid json format
+	assert.NoError(ioutil.WriteFile("temp.json", []byte(invalid), 0777))
+
+	_, err := NewCollector("tempCollector", "temp.json")
+	assert.Error(err)
+
+	assert.NoError(os.Remove("temp.json"))
+}
+
+func TestConfig(t *testing.T) {
+	assert := assert.New(t)
+
+	//Create an nginx collector using the config file 'sample_config.json'
+	collector, err := NewCollector("nginx", "config/sample_config.json")
+	assert.NoError(err)
+	assert.Equal(collector.name, "nginx")
+	assert.Equal(collector.configFile.Endpoint, "http://localhost:8000/nginx_status")
+	assert.Equal(collector.configFile.MetricsConfig[0].Name, "activeConnections")
+}