Add generate command

A command that reads a folder with ServiceLevelObjectives and output files with the corresponding Prometheus Rules

Signed-off-by: ArthurSens <arthursens2005@gmail.com>

generate.go

@@ -0,0 +1,85 @@
+/*
+Copyright 2021 Pyrra 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 main
+
+import (
+	"io/ioutil"
+	"path/filepath"
+
+	"github.com/go-kit/log"
+	"github.com/go-kit/log/level"
+	monitoringv1 "github.com/prometheus-operator/prometheus-operator/pkg/apis/monitoring/v1"
+	"github.com/pyrra-dev/pyrra/kubernetes/api/v1alpha1"
+	"sigs.k8s.io/yaml"
+)
+
+func cmdGenerate(logger log.Logger, configFiles, prometheusFolder string) int {
+
+	fs, err := ioutil.ReadDir(configFiles)
+	if err != nil {
+		level.Error(logger).Log("msg", "getting files names", "err", err)
+		return 1
+	}
+	for _, file := range fs {
+		if !file.IsDir() {
+			fileName := file.Name()
+			bytes, err := ioutil.ReadFile(filepath.Join(configFiles, fileName))
+			if err != nil {
+				level.Error(logger).Log("msg", "failed to read file", "file", fileName, "err", err)
+				return 1
+			}
+
+			var config v1alpha1.ServiceLevelObjective
+			if err := yaml.UnmarshalStrict(bytes, &config); err != nil {
+				level.Error(logger).Log("msg", "failed to unmarshal objective", "file", fileName, "err", err)
+				return 1
+			}
+
+			objective, err := config.Internal()
+			increases, err := objective.IncreaseRules()
+			if err != nil {
+				level.Error(logger).Log("msg", "failed to get increase rules", "err", err)
+				return 1
+			}
+			burnrates, err := objective.Burnrates()
+			if err != nil {
+				level.Error(logger).Log("msg", "failed to get burn rate rules", "err", err)
+				return 1
+			}
+
+			rule := monitoringv1.PrometheusRuleSpec{
+				Groups: []monitoringv1.RuleGroup{increases, burnrates},
+			}
+
+			bytes, err = yaml.Marshal(rule)
+			if err != nil {
+				level.Error(logger).Log("msg", "failed to marshal recording rules", "err", err)
+				return 1
+			}
+
+			_, f := filepath.Split(fileName)
+			path := filepath.Join(prometheusFolder, f)
+
+			if err := ioutil.WriteFile(path, bytes, 0o644); err != nil {
+				level.Error(logger).Log("msg", "failed to write file", "path", path, "err", err)
+				return 1
+			}
+		}
+	}
+
+	return 0
+}

main.go

@@ -64,6 +64,10 @@ var CLI struct {
 		MetricsAddr   string `default:":8080" help:"The address the metric endpoint binds to."`
 		ConfigMapMode bool   `default:"false" help:"If the generated recording rules should instead be saved to config maps in the default Prometheus format."`
 	} `cmd:"" help:"Runs Pyrra's Kubernetes operator and backend for the API."`
+	Generate struct {
+		ConfigFiles      string `default:"/etc/pyrra/*.yaml" help:"The folder where Pyrra finds the config files to use."`
+		PrometheusFolder string `default:"/etc/prometheus/pyrra/" help:"The folder where Pyrra writes the generates Prometheus rules and alerts."`
+	} `cmd:"" help:"Read SLO config files and outputs them to stdout in the Prometheus rules format."`
 }
 
 func main() {
@@ -126,6 +130,8 @@ func main() {
 		code = cmdFilesystem(logger, reg, client, CLI.Filesystem.ConfigFiles, CLI.Filesystem.PrometheusFolder)
 	case "kubernetes":
 		code = cmdKubernetes(logger, CLI.Kubernetes.MetricsAddr, CLI.Kubernetes.ConfigMapMode)
+	case "generate":
+		code = cmdGenerate(logger, CLI.Generate.ConfigFiles, CLI.Generate.PrometheusFolder)
 	}
 	os.Exit(code)
 }