Add log levels, new log framework, verbosity

CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased]
 ### Added
 - Support for other entrypoints other than `/bin/sh`, can specify an entrypoint for the shell command method.
+- Add logging library `glog` to allow logging at levels of severity and verbosity.
+- Can specify verbosity level of logs via the `logVerbosity` configuration option.
 ### Changed
 - Can scale ReplicaSets, ReplicationControllers and StatefulSets alongside Deployments.
 - ResourceMetrics fields have `resourceName` and `resource` rather than `deploymentName` and `deployment`. In JSON this means that only the resource name will be exposed via field `resource`.

api/api.go

@@ -22,7 +22,6 @@ package api
 import (
 	"encoding/json"
 	"fmt"
-	"log"
 	"net/http"
 
 	"github.com/go-chi/chi"
@@ -84,8 +83,7 @@ func (api *API) getMetrics(w http.ResponseWriter, r *http.Request) {
 	response, err := json.Marshal(metrics)
 	if err != nil {
 		// Should not occur, panic
-		log.Panic(err)
-		return
+		panic(err)
 	}
 	w.WriteHeader(http.StatusOK)
 	w.Write(response)
@@ -125,8 +123,7 @@ func (api *API) getEvaluation(w http.ResponseWriter, r *http.Request) {
 	response, err := json.Marshal(evaluations)
 	if err != nil {
 		// Should not occur, panic
-		log.Panic(err)
-		return
+		panic(err)
 	}
 	w.WriteHeader(http.StatusOK)
 	w.Write(response)
@@ -153,7 +150,7 @@ func apiError(w http.ResponseWriter, apiErr *Error) {
 	response, err := json.Marshal(apiErr)
 	if err != nil {
 		// Should not occur, panic
-		log.Panic(err)
+		panic(err)
 	}
 	w.WriteHeader(apiErr.Code)
 	w.Write(response)

cmd/custom-pod-autoscaler/main.go

@@ -24,17 +24,20 @@ package main
 
 import (
 	"context"
+	"flag"
 	"fmt"
 	"io/ioutil"
 	"log"
 	"net/http"
 	"os"
 	"os/exec"
 	"os/signal"
+	"strconv"
 	"syscall"
 	"time"
 
 	"github.com/go-chi/chi"
+	"github.com/golang/glog"
 	"github.com/jthomperoo/custom-pod-autoscaler/api"
 	"github.com/jthomperoo/custom-pod-autoscaler/config"
 	"github.com/jthomperoo/custom-pod-autoscaler/evaluate"
@@ -66,10 +69,23 @@ const (
 	startTimeEnvName       = "startTime"
 	minReplicasEnvName     = "minReplicas"
 	maxReplicasEnvName     = "maxReplicas"
+	logVerbosityEnvName    = "logVerbosity"
 )
 
 const defaultConfig = "/config.yaml"
 
+func init() {
+	err := flag.Set("logtostderr", "true")
+	if err != nil {
+		log.Fatalf("Fail to set log to standard error flag: %s", err)
+	}
+	err = flag.Set("v", "0")
+	if err != nil {
+		log.Fatalf("Fail to set default log verbosity flag: %s", err)
+	}
+	flag.Parse()
+}
+
 func main() {
 	// Read in environment variables
 	configPath, exists := os.LookupEnv(configEnvName)
@@ -81,33 +97,47 @@ func main() {
 	// Read in config file
 	configFileData, err := ioutil.ReadFile(configPath)
 	if err != nil {
-		log.Panic(err)
+		glog.Fatalf("Fail to read configuration file: %s", err)
 	}
 
 	// Load Custom Pod Autoscaler config
 	config, err := config.LoadConfig(configFileData, configEnvs)
 	if err != nil {
-		log.Panic(err)
+		glog.Fatalf("Fail to parse configuration: %s", err)
 	}
 
 	// Create the in-cluster Kubernetes config
 	clusterConfig, err := rest.InClusterConfig()
 	if err != nil {
-		log.Panic(err)
+		glog.Fatalf("Fail to create in-cluster Kubernetes config: %s", err)
 	}
 
 	// Set up clientset
 	clientset, err := kubernetes.NewForConfig(clusterConfig)
 	if err != nil {
-		log.Panic(err)
+		glog.Fatalf("Fail to set up Kubernetes clientset: %s", err)
 	}
 
 	// Set up dynamic client
 	dynamicClient, err := dynamic.NewForConfig(clusterConfig)
 	if err != nil {
-		log.Panic(err)
+		glog.Fatalf("Fail to set up Kubernetes dynamic client: %s", err)
+	}
+
+	// Get group resources
+	groupResources, err := restmapper.GetAPIGroupResources(clientset.Discovery())
+	if err != nil {
+		glog.Fatalf("Fail get group resources: %s", err)
 	}
 
+	// Set logging level
+	err = flag.Lookup("v").Value.Set(strconv.Itoa(int(config.LogVerbosity)))
+	if err != nil {
+		glog.Fatalf("Fail to set log verbosity: %s", err)
+	}
+
+	glog.V(1).Infoln("Setting up resources and clients")
+
 	// Unstructured converter
 	unstructuredConverted := runtime.DefaultUnstructuredConverter
 
@@ -117,13 +147,6 @@ func main() {
 		UnstructuredConverter: unstructuredConverted,
 	}
 
-	// Get group resources
-	groupResources, err := restmapper.GetAPIGroupResources(clientset.Discovery())
-	if err != nil {
-		log.Panic(err)
-	}
-
-	// Set up scaling client
 	scaleClient := scale.New(
 		clientset.RESTClient(),
 		restmapper.NewDiscoveryRESTMapper(groupResources),
@@ -159,6 +182,8 @@ func main() {
 		},
 	}
 
+	glog.V(1).Infoln("Setting up REST API")
+
 	// Set up API
 	api := &api.API{
 		Router:          chi.NewRouter(),
@@ -173,15 +198,17 @@ func main() {
 		Handler: api.Router,
 	}
 
+	glog.V(1).Infoln("Setting up autoscaler")
+
 	delayTime := config.StartTime - (time.Now().UTC().UnixNano() / int64(time.Millisecond) % config.StartTime)
 	delayStartTimer := time.NewTimer(time.Duration(delayTime) * time.Millisecond)
 
-	log.Printf("Waiting %d milliseconds before starting autoscaler\n", delayTime)
+	glog.V(0).Infof("Waiting %d milliseconds before starting autoscaler\n", delayTime)
 
 	go func() {
 		// Wait for delay to start at expected time
 		<-delayStartTimer.C
-		log.Println("Starting autoscaler")
+		glog.V(0).Infoln("Starting autoscaler")
 		// Set up time ticker with configured interval
 		ticker := time.NewTicker(time.Duration(config.Interval) * time.Millisecond)
 		// Set up shutdown channel, which will listen for UNIX shutdown commands
@@ -204,7 +231,7 @@ func main() {
 			for {
 				select {
 				case <-shutdown:
-					log.Println("Shutting down...")
+					glog.V(0).Infoln("Shutting down...")
 					// Stop API
 					ctx, cancel := context.WithCancel(context.Background())
 					defer cancel()
@@ -213,16 +240,17 @@ func main() {
 					ticker.Stop()
 					return
 				case <-ticker.C:
+					glog.V(2).Infoln("Running autoscaler")
 					err := autoscaler.Scale()
 					if err != nil {
-						log.Println(err)
+						glog.Errorln(err)
 					}
 				}
 			}
 		}()
 	}()
 
-	log.Println("Starting API")
+	glog.V(0).Infoln("Starting API")
 	// Start API
 	srv.ListenAndServe()
 }
@@ -245,6 +273,7 @@ func readEnvVars() map[string]string {
 		minReplicasEnvName,
 		maxReplicasEnvName,
 		startTimeEnvName,
+		logVerbosityEnvName,
 	}
 	configEnvs := map[string]string{}
 	for _, envName := range configEnvsNames {

codecov.yml

@@ -9,11 +9,11 @@ coverage:
   status:
     project:
       default:
-        target: auto
+        target: 80
         threshold: 1%
     patch:
       default:
-        target: auto
+        target: 80
         threshold: 1%
     changes: no
 

config/config.go

@@ -39,14 +39,15 @@ const (
 )
 
 const (
-	defaultInterval    = 15000
-	defaultHost        = "0.0.0.0"
-	defaultPort        = 5000
-	defaultNamespace   = "default"
-	defaultMinReplicas = 1
-	defaultMaxReplicas = 10
-	defaultStartTime   = 1
-	defaultRunMode     = PerPodRunMode
+	defaultInterval     = 15000
+	defaultHost         = "0.0.0.0"
+	defaultPort         = 5000
+	defaultNamespace    = "default"
+	defaultMinReplicas  = 1
+	defaultMaxReplicas  = 10
+	defaultStartTime    = 1
+	defaultRunMode      = PerPodRunMode
+	defaultLogVerbosity = 0
 )
 
 const jsonStructTag = "json"
@@ -64,6 +65,7 @@ type Config struct {
 	MaxReplicas    int32                                    `json:"maxReplicas"`
 	RunMode        string                                   `json:"runMode"`
 	StartTime      int64                                    `json:"startTime"`
+	LogVerbosity   int32                                    `json:"logVerbosity"`
 }
 
 // Method describes a method for passing data/triggerering logic, such as through a shell

config/config_test.go

@@ -38,6 +38,7 @@ const (
 	defaultMaxReplicas     = 10
 	defaultStartTime       = 1
 	defaultRunMode         = "per-pod"
+	defaultLogVerbosity    = 0
 )
 
 func TestLoadConfig(t *testing.T) {
@@ -101,6 +102,7 @@ func TestLoadConfig(t *testing.T) {
 				MinReplicas:    defaultMinReplicas,
 				MaxReplicas:    defaultMaxReplicas,
 				StartTime:      defaultStartTime,
+				LogVerbosity:   defaultLogVerbosity,
 				ScaleTargetRef: nil,
 			},
 		},
@@ -125,6 +127,7 @@ func TestLoadConfig(t *testing.T) {
 				"maxReplicas":    "6",
 				"startTime":      "0",
 				"scaleTargetRef": `{ "name": "test target name", "kind": "test target kind", "apiVersion": "test target api version"}`,
+				"logVerbosity":   "3",
 			},
 			nil,
 			&config.Config{
@@ -149,6 +152,7 @@ func TestLoadConfig(t *testing.T) {
 					Kind:       "test target kind",
 					APIVersion: "test target api version",
 				},
+				LogVerbosity: 3,
 			},
 		},
 		{
@@ -174,6 +178,7 @@ func TestLoadConfig(t *testing.T) {
 				maxReplicas: 7
 				startTime: 0
 				namespace: "test yaml namespace"
+				logVerbosity: 2
 			`, "\t", "", -1)),
 			nil,
 			nil,
@@ -202,6 +207,7 @@ func TestLoadConfig(t *testing.T) {
 						Entrypoint: "testentry",
 					},
 				},
+				LogVerbosity: 2,
 			},
 		},
 		{
@@ -230,7 +236,8 @@ func TestLoadConfig(t *testing.T) {
 				"minReplicas":2,
 				"maxReplicas":7,
 				"startTime":0,
-				"namespace":"test yaml namespace"
+				"namespace":"test yaml namespace",
+				"logVerbosity":1
 			}`),
 			nil,
 			nil,
@@ -259,6 +266,7 @@ func TestLoadConfig(t *testing.T) {
 						Entrypoint: "testentry",
 					},
 				},
+				LogVerbosity: 1,
 			},
 		},
 		{
@@ -286,6 +294,7 @@ func TestLoadConfig(t *testing.T) {
 				"minReplicas":    "3",
 				"maxReplicas":    "6",
 				"startTime":      "0",
+				"logVerbosity":   "5",
 				"scaleTargetRef": `{ "name": "test target name", "kind": "test target kind", "apiVersion": "test target api version"}`,
 			},
 			nil,
@@ -318,6 +327,7 @@ func TestLoadConfig(t *testing.T) {
 						Entrypoint: "testentry",
 					},
 				},
+				LogVerbosity: 5,
 			},
 		},
 		{
@@ -350,6 +360,7 @@ func TestLoadConfig(t *testing.T) {
 				"maxReplicas":    "6",
 				"startTime":      "0",
 				"scaleTargetRef": `{ "name": "test target name", "kind": "test target kind", "apiVersion": "test target api version"}`,
+				"logVerbosity":   "3",
 			},
 			nil,
 			&config.Config{
@@ -382,6 +393,7 @@ func TestLoadConfig(t *testing.T) {
 						Entrypoint: "testentry",
 					},
 				},
+				LogVerbosity: 3,
 			},
 		},
 	}

docs/reference/configuration.md

@@ -158,3 +158,16 @@ Default value: `1`
 This defines in milliseconds a starting point for the scaler, with the scaler running as if it started at the time provided. Allows specifying that the autoscaler must start on a multiple of the interval from the start time. For example, a startTime of `60000` would result in the autoscaler starting at the next full minute. The default value will start the autoscaler after a single millisecond, close to instantly.
 
 > Note: The scaling will not actually start until after one interval has passed.
+## logVerbosity
+Example:
+```yaml
+logVerbosity: 0
+```
+Default value: `0`  
+This defines the verbosity of the logging, allowing for debugging errors/issues. Logging will occur for all values ABOVE and including the verbosity level set.  
+Log levels:
+
+* `0` - normal.
+* `1` - verbose.
+* `2` - more verbose around high level logic such as autoscaling/rest api.
+* `3` - more verbose around lower level logic such as metric gathering and evaluation.