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>

filesystem.go

@@ -170,53 +170,11 @@ func cmdFilesystem(logger log.Logger, reg *prometheus.Registry, promClient api.C
 					level.Debug(logger).Log("msg", "reading", "file", f)
 					reconcilesTotal.Inc()
 
-					bytes, err := ioutil.ReadFile(f)
+					objective, err := objectiveAsRuleFile(f, prometheusFolder)
 					if err != nil {
 						reconcilesErrors.Inc()
-						return fmt.Errorf("failed to read file %q: %w", f, err)
+						return fmt.Errorf("failed to create rule file %q: %w", f, err)
 					}
-
-					var config v1alpha1.ServiceLevelObjective
-					if err := yaml.UnmarshalStrict(bytes, &config); err != nil {
-						reconcilesErrors.Inc()
-						return fmt.Errorf("failed to unmarshal objective %q: %w", f, err)
-					}
-
-					objective, err := config.Internal()
-					if err != nil {
-						reconcilesErrors.Inc()
-						return fmt.Errorf("failed to get objective: %w", err)
-					}
-
-					increases, err := objective.IncreaseRules()
-					if err != nil {
-						reconcilesErrors.Inc()
-						return fmt.Errorf("failed to get increase rules: %w", err)
-					}
-					burnrates, err := objective.Burnrates()
-					if err != nil {
-						reconcilesErrors.Inc()
-						return fmt.Errorf("failed to get burn rate rules: %w", err)
-					}
-
-					rule := monitoringv1.PrometheusRuleSpec{
-						Groups: []monitoringv1.RuleGroup{increases, burnrates},
-					}
-
-					bytes, err = yaml.Marshal(rule)
-					if err != nil {
-						reconcilesErrors.Inc()
-						return fmt.Errorf("failed to marshal recording rules: %w", err)
-					}
-
-					_, file := filepath.Split(f)
-					path := filepath.Join(prometheusFolder, file)
-
-					if err := ioutil.WriteFile(path, bytes, 0o644); err != nil {
-						reconcilesErrors.Inc()
-						return fmt.Errorf("failed to write file %q: %w", path, err)
-					}
-
 					objectives.Set(objective)
 
 					reload <- struct{}{} // Trigger a Prometheus reload
@@ -353,3 +311,49 @@ func (f FilesystemObjectiveServer) GetREDRequests(ctx context.Context, expr, gro
 func (f FilesystemObjectiveServer) GetREDErrors(ctx context.Context, expr, grouping string, i, i2 int32) (openapiserver.ImplResponse, error) {
 	return openapiserver.ImplResponse{}, errEndpointNotImplemented
 }
+
+// objectiveAsRuleFile reads a ServiceLevelObjective YAML manifest and outputs the corresponding
+// Prometheus rules as a file in the desired directory.
+func objectiveAsRuleFile(file, prometheusFolder string) (slo.Objective, error) {
+	bytes, err := ioutil.ReadFile(file)
+	if err != nil {
+		return slo.Objective{}, fmt.Errorf("failed to read file %q: %w", file, err)
+	}
+
+	var config v1alpha1.ServiceLevelObjective
+	if err := yaml.UnmarshalStrict(bytes, &config); err != nil {
+		return slo.Objective{}, fmt.Errorf("failed to unmarshal objective %q: %w", file, err)
+	}
+
+	if err != nil {
+		return slo.Objective{}, fmt.Errorf("failed to get objective: %w", err)
+	}
+
+	objective, err := config.Internal()
+	increases, err := objective.IncreaseRules()
+	if err != nil {
+		return slo.Objective{}, fmt.Errorf("failed to get increase rules: %w", err)
+	}
+	burnrates, err := objective.Burnrates()
+	if err != nil {
+		return slo.Objective{}, fmt.Errorf("failed to get burn rate rules: %w", err)
+	}
+
+	rule := monitoringv1.PrometheusRuleSpec{
+		Groups: []monitoringv1.RuleGroup{increases, burnrates},
+	}
+
+	bytes, err = yaml.Marshal(rule)
+	if err != nil {
+		return slo.Objective{}, fmt.Errorf("failed to marshal recording rules: %w", err)
+	}
+
+	_, f := filepath.Split(file)
+	path := filepath.Join(prometheusFolder, f)
+
+	if err := ioutil.WriteFile(path, bytes, 0o644); err != nil {
+		return slo.Objective{}, fmt.Errorf("failed to write file %q: %w", path, err)
+	}
+
+	return objective, nil
+}

generate.go

@@ -0,0 +1,43 @@
+/*
+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"
+)
+
+func cmdGenerate(logger log.Logger, configFiles, prometheusFolder string) int {
+	fs, err := ioutil.ReadDir(configFiles)
+	if err != nil {
+		level.Error(logger).Log("msg", "failed to read config-files directory", "err", err)
+		return 1
+	}
+	for _, file := range fs {
+		if !file.IsDir() {
+			_, err := objectiveAsRuleFile(filepath.Join(configFiles, file.Name()), prometheusFolder)
+			if err != nil {
+				level.Error(logger).Log("msg", "failed generating rule files", "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 rewrites them as Prometheus rules and alerts."`
 }
 
 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)
 }