prepare for new config file version

config/config.go

@@ -0,0 +1,78 @@
+// Copyright 2016 The grok_exporter Authors
+//
+// 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 config
+
+import (
+	"fmt"
+	"github.com/fstab/grok_exporter/config/v1"
+	"github.com/fstab/grok_exporter/config/v2"
+	"io/ioutil"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+// Example config: See ./example/config.yml
+
+func LoadConfigFile(filename string) (*v2.Config, string, error) {
+	content, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return nil, "", fmt.Errorf("Failed to load %v: %v", filename, err.Error())
+	}
+	cfg, warn, err := LoadConfigString(content)
+	if err != nil {
+		return nil, "", fmt.Errorf("Failed to load %v: %v", filename, err.Error())
+	}
+	return cfg, warn, nil
+}
+
+func LoadConfigString(content []byte) (*v2.Config, string, error) {
+	version, warn, err := findVersion(content)
+	if err != nil {
+		return nil, "", err
+	}
+	cfg, err := unmarshal(content, version)
+	return cfg, warn, err
+}
+
+func findVersion(content []byte) (int, string, error) {
+	versionExpr := regexp.MustCompile(`general:\s*config_version:[\t\f ]*(\S+)`)
+	versionInfo := versionExpr.FindStringSubmatch(string(content))
+	if len(versionInfo) == 2 {
+		version, err := strconv.Atoi(strings.TrimSpace(versionInfo[1]))
+		if err != nil {
+			return 0, "", fmt.Errorf("invalid 'general' configuration: '%v' is not a valid 'config_version'.", versionInfo[1])
+		}
+		return version, "", nil
+	} else { // no version found
+		warn := "No config_version found in config file. " +
+			"Assuming it is a config file for grok_exporter <= 0.1.4, using \"config_version: 1\". " +
+			"grok_exporter still supports \"config_version 1\", " +
+			"but you should consider updating your configuration. " +
+			"Use the '-showconfig' command line option to view your configuration in the current format."
+		return 1, warn, nil
+	}
+}
+
+func unmarshal(content []byte, version int) (*v2.Config, error) {
+	switch version {
+	case 1:
+		return v1.Unmarshal(content)
+	case 2:
+		return v2.Unmarshal(content)
+	default:
+		return nil, fmt.Errorf("config_version %v is not supported.", version)
+	}
+}

config/config_test.go

@@ -0,0 +1,71 @@
+// Copyright 2016 The grok_exporter Authors
+//
+// 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 config
+
+import (
+	"strings"
+	"testing"
+)
+
+const exampleConfig = `
+general:
+    config_version: 2
+input:
+    type: file
+    path: x/x/x
+    readall: true
+grok:
+    patterns_dir: b/c
+metrics:
+    - type: counter
+      name: test_count_total
+      help: Dummy help message.
+      match: Some text here, then a %{DATE}.
+      labels:
+          - grok_field_name: a
+            prometheus_label: b
+          - grok_field_name: c
+            prometheus_label: d
+server:
+    protocol: https
+    port: 1111
+`
+
+func TestVersionDetection(t *testing.T) {
+	expectVersion(t, exampleConfig, 2, false)
+	expectVersion(t, strings.Replace(exampleConfig, "config_version: 2", "config_version: 1", 1), 1, false)
+	expectVersion(t, strings.Replace(exampleConfig, "config_version: 2", "config_version:", 1), 1, true)
+	expectVersion(t, strings.Replace(exampleConfig, "config_version: 2", "", 1), 1, true)
+	_, _, err := findVersion([]byte(strings.Replace(exampleConfig, "config_version: 2", "config_version: a", 1)))
+	if err == nil {
+		t.Fatalf("Expected error, because 'a' is not a number.")
+	}
+}
+
+func expectVersion(t *testing.T, config string, expectedVersion int, warningExpected bool) {
+	version, warn, err := findVersion([]byte(config))
+	if err != nil {
+		t.Fatalf("unexpected error while getting version info: %v", err.Error())
+	}
+	if warningExpected && len(warn) == 0 {
+		t.Fatalf("didn't get warning for unversioned config file")
+	}
+	if !warningExpected && len(warn) > 0 {
+		t.Fatalf("unexpected warning: %v", warn)
+	}
+	if version != expectedVersion {
+		t.Fatalf("expected version %v, but found %v", expectedVersion, version)
+	}
+}

config/v1/configV1.go

@@ -0,0 +1,98 @@
+// Copyright 2016 The grok_exporter Authors
+//
+// 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 v1
+
+import (
+	"fmt"
+	"github.com/fstab/grok_exporter/config/v2"
+	"gopkg.in/yaml.v2"
+)
+
+func Unmarshal(config []byte) (*v2.Config, error) {
+	v1cfg := &Config{}
+	err := yaml.Unmarshal(config, v1cfg)
+	if err != nil {
+		return nil, fmt.Errorf("invalid configuration: %v", err.Error())
+	}
+	v2cfg := &v2.Config{
+		Input:   v1cfg.Input,
+		Grok:    v1cfg.Grok,
+		Metrics: convertMetrics(*v1cfg.Metrics),
+		Server:  v1cfg.Server,
+	}
+	v2cfg.AddDefaults()
+	err = v2cfg.Validate()
+	if err != nil {
+		return nil, err
+	}
+	return v2cfg, nil
+}
+
+func convertMetrics(v1metrics []*MetricConfig) *v2.MetricsConfig {
+	if len(v1metrics) == 0 {
+		return nil
+	}
+	v2metrics := make([]*v2.MetricConfig, len(v1metrics))
+	for i, v1metric := range v1metrics {
+		v2metrics[i] = &v2.MetricConfig{
+			Type:       v1metric.Type,
+			Name:       v1metric.Name,
+			Help:       v1metric.Help,
+			Match:      v1metric.Match,
+			Value:      v1metric.Value,
+			Cumulative: v1metric.Cumulative,
+			Buckets:    v1metric.Buckets,
+			Quantiles:  v1metric.Quantiles,
+		}
+		if len(v1metric.Labels) > 0 {
+			v2metrics[i].Labels = make([]v2.Label, len(v1metric.Labels))
+			for j, v1label := range v1metric.Labels {
+				v2metrics[i].Labels[j] = v2.Label{
+					GrokFieldName:   v1label.GrokFieldName,
+					PrometheusLabel: v1label.PrometheusLabel,
+				}
+			}
+		}
+	}
+	result := v2.MetricsConfig(v2metrics)
+	return &result
+}
+
+type Config struct {
+	// For sections that don't differ between v1 and v2, we reference v2 directly here.
+	Input   *v2.InputConfig  `yaml:",omitempty"`
+	Grok    *v2.GrokConfig   `yaml:",omitempty"`
+	Metrics *MetricsConfig   `yaml:",omitempty"`
+	Server  *v2.ServerConfig `yaml:",omitempty"`
+}
+
+type MetricsConfig []*MetricConfig
+
+type MetricConfig struct {
+	Type       string              `yaml:",omitempty"`
+	Name       string              `yaml:",omitempty"`
+	Help       string              `yaml:",omitempty"`
+	Match      string              `yaml:",omitempty"`
+	Value      string              `yaml:",omitempty"`
+	Cumulative bool                `yaml:",omitempty"`
+	Buckets    []float64           `yaml:",flow,omitempty"`
+	Quantiles  map[float64]float64 `yaml:",flow,omitempty"`
+	Labels     []Label             `yaml:",omitempty"`
+}
+
+type Label struct {
+	GrokFieldName   string `yaml:"grok_field_name,omitempty"`
+	PrometheusLabel string `yaml:"prometheus_label,omitempty"`
+}