Add --max-problems flag to pint watch

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## v0.8.1
 
+### Added
+
+- Added `--max-problems` flag to `pint watch` command.
+
 ### Changed
 
 - Updated Prometheus modules to [v2.33.0](https://github.com/prometheus/prometheus/releases/tag/v2.33.0).

README.md

@@ -76,6 +76,14 @@ scrape_configs:
       - targets: ['localhost:8080']
 ```
 
+Available metrics:
+
+- `pint_problem` - exported for every problem detected by pint.
+  To avoid exposing too many metrics at once pass `--max-problems` flag to watch command.
+  When set pint will expose only up to `--max-problems` value number of `pint_problem` metrics.
+- `pint_problems` - this metric is the total number of all problems detected by pint,
+  including those not exported due to `--max-problems` flag.
+
 ## Release Notes
 
 See [CHANGELOG.md](/CHANGELOG.md) for history of changes.

cmd/pint/tests/0042_watch_metrics.txt

@@ -275,6 +275,9 @@ pint_check_iterations_total
 pint_problem{kind="alerting",lines="8",name="comparison",problem="alert query doesn't have any condition, it will always fire if the metric exists",reporter="promql/comparison",severity="warning"}
 pint_problem{kind="recording",lines="2",name="broken",problem="syntax error: no arguments for aggregate expression provided",reporter="promql/syntax",severity="fatal"}
 pint_problem{kind="recording",lines="5",name="aggregate",problem="job label is required and should be preserved when aggregating \"^.+$\" rules, remove job from without()",reporter="promql/aggregate",severity="warning"}
+# HELP pint_problems Total number of problems reported by pint
+# TYPE pint_problems gauge
+pint_problems
 # HELP prometheus_template_text_expansion_failures_total The total number of template text expansion failures.
 # TYPE prometheus_template_text_expansion_failures_total counter
 prometheus_template_text_expansion_failures_total

cmd/pint/tests/0048_watch_limit.txt

@@ -0,0 +1,34 @@
+exec bash -x ./test.sh &
+
+pint.ok watch --listen=:6048 --max-problems=2 --pidfile=pint.pid rules
+cmp curl.txt metrics.txt
+
+-- test.sh --
+sleep 5
+curl -s http://127.0.0.1:6048/metrics | grep -E '^pint_problem' > curl.txt
+cat pint.pid | xargs kill
+
+-- rules/1.yml --
+- record: broken
+  expr: foo / count())
+
+- record: aggregate
+  expr: sum(foo) without(job)
+
+- alert: comparison
+  expr: foo
+
+-- .pint.hcl --
+rule {
+    match {
+      kind = "recording"
+    }
+    aggregate ".+" {
+        keep = [ "job" ]
+    }
+}
+
+-- metrics.txt --
+pint_problem{kind="alerting",lines="8",name="comparison",problem="alert query doesn't have any condition, it will always fire if the metric exists",reporter="promql/comparison",severity="warning"} 1
+pint_problem{kind="recording",lines="2",name="broken",problem="syntax error: no arguments for aggregate expression provided",reporter="promql/syntax",severity="fatal"} 1
+pint_problems 3

cmd/pint/watch.go

@@ -9,6 +9,7 @@ import (
 	_ "net/http/pprof"
 	"os"
 	"os/signal"
+	"sort"
 	"strings"
 	"sync"
 	"syscall"
@@ -27,9 +28,10 @@ import (
 )
 
 const (
-	intervalFlag = "interval"
-	listenFlag   = "listen"
-	pidfileFlag  = "pidfile"
+	intervalFlag    = "interval"
+	listenFlag      = "listen"
+	pidfileFlag     = "pidfile"
+	maxProblemsFlag = "max-problems"
 )
 
 var watchCmd = &cli.Command{
@@ -54,6 +56,12 @@ var watchCmd = &cli.Command{
 			Aliases: []string{"p"},
 			Usage:   "Write pid file to this path",
 		},
+		&cli.IntFlag{
+			Name:    maxProblemsFlag,
+			Aliases: []string{"m"},
+			Value:   0,
+			Usage:   "Maximum number of problems to report on metrics, 0 - no limit",
+		},
 	},
 }
 
@@ -100,7 +108,7 @@ func actionWatch(c *cli.Context) (err error) {
 	}
 
 	// start HTTP server for metrics
-	collector := newProblemCollector(cfg, paths)
+	collector := newProblemCollector(cfg, paths, c.Int(maxProblemsFlag))
 	prometheus.MustRegister(collector)
 	prometheus.MustRegister(checkDuration)
 	prometheus.MustRegister(checkIterationsTotal)
@@ -179,14 +187,16 @@ func startTimer(ctx context.Context, cfg config.Config, workers int, interval ti
 }
 
 type problemCollector struct {
-	lock    sync.Mutex
-	cfg     config.Config
-	paths   []string
-	summary *reporter.Summary
-	problem *prometheus.Desc
+	lock        sync.Mutex
+	cfg         config.Config
+	paths       []string
+	summary     *reporter.Summary
+	problem     *prometheus.Desc
+	problems    *prometheus.Desc
+	maxProblems int
 }
 
-func newProblemCollector(cfg config.Config, paths []string) *problemCollector {
+func newProblemCollector(cfg config.Config, paths []string, maxProblems int) *problemCollector {
 	return &problemCollector{
 		cfg:   cfg,
 		paths: paths,
@@ -196,6 +206,13 @@ func newProblemCollector(cfg config.Config, paths []string) *problemCollector {
 			[]string{"kind", "name", "severity", "reporter", "problem", "lines"},
 			prometheus.Labels{},
 		),
+		problems: prometheus.NewDesc(
+			"pint_problems",
+			"Total number of problems reported by pint",
+			[]string{},
+			prometheus.Labels{},
+		),
+		maxProblems: maxProblems,
 	}
 }
 
@@ -231,7 +248,8 @@ func (c *problemCollector) Collect(ch chan<- prometheus.Metric) {
 		return
 	}
 
-	done := map[string]struct{}{}
+	done := map[string]prometheus.Metric{}
+	keys := []string{}
 
 	for _, report := range c.summary.Reports {
 		kind := "invalid"
@@ -264,11 +282,21 @@ func (c *problemCollector) Collect(ch chan<- prometheus.Metric) {
 		}
 
 		key := out.String()
-		if _, ok := done[key]; ok {
-			continue
+		if _, ok := done[key]; !ok {
+			done[key] = metric
+			keys = append(keys, key)
 		}
+	}
+
+	ch <- prometheus.MustNewConstMetric(c.problems, prometheus.GaugeValue, float64(len(done)))
 
-		ch <- metric
-		done[key] = struct{}{}
+	sort.Strings(keys)
+	var reported int
+	for _, key := range keys {
+		ch <- done[key]
+		reported++
+		if c.maxProblems > 0 && reported >= c.maxProblems {
+			break
+		}
 	}
 }