Adds a check that can check a request-reply service

monitor/request.go

@@ -0,0 +1,100 @@
+// Copyright 2025 The NATS 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 monitor
+
+import (
+	"regexp"
+	"time"
+
+	"github.com/nats-io/nats.go"
+)
+
+type CheckRequestOptions struct {
+	// Subject is the subject to send the request to
+	Subject string `json:"subject" yaml:"subject"`
+	// Payload is the payload to send to the service
+	Payload string `json:"payload" yaml:"payload"`
+	// Header is headers to send with the request
+	Header map[string]string `json:"header" yaml:"header"`
+	//HeaderMatch to send in the payload
+	HeaderMatch map[string]string `json:"headers" yaml:"headers"`
+	// ResponseMatch applies regular expression match against the payload
+	ResponseMatch string `json:"response_match" yaml:"response_match"`
+	// ResponseTimeWarn warns when the response takes longer than a certain time
+	ResponseTimeWarn time.Duration `json:"response_time_warn" yaml:"response_time_warn"`
+	// ResponseTimeCritical logs critical when the response takes longer than a certain time
+	ResponseTimeCritical time.Duration `json:"response_time_crit" yaml:"response_time_crit"`
+}
+
+func CheckRequest(server string, nopts []nats.Option, check *Result, timeout time.Duration, opts CheckRequestOptions) error {
+	nc, err := nats.Connect(server, nopts...)
+	if check.CriticalIfErr(err, "could not load info: %v", err) {
+		return nil
+	}
+
+	if opts.Subject == "" {
+		check.Critical("no subject specified")
+		return nil
+	}
+
+	msg := nats.NewMsg(opts.Subject)
+	msg.Data = []byte(opts.Payload)
+	for k, v := range opts.Header {
+		msg.Header.Add(k, v)
+	}
+
+	start := time.Now()
+	resp, err := nc.RequestMsg(msg, timeout)
+	since := time.Since(start)
+
+	check.Pd(&PerfDataItem{
+		Help:  "How long the request took",
+		Name:  "time",
+		Value: float64(since.Round(time.Millisecond).Seconds()),
+		Warn:  opts.ResponseTimeWarn.Seconds(),
+		Crit:  opts.ResponseTimeCritical.Seconds(),
+		Unit:  "s",
+	})
+	if check.CriticalIfErr(err, "could not send request: %v", err) {
+		return nil
+	}
+
+	if opts.ResponseMatch != "" {
+		re, err := regexp.Compile(opts.ResponseMatch)
+		if check.CriticalIfErr(err, "content regex compile failed: %v", err) {
+			return nil
+		}
+
+		if !re.Match(resp.Data) {
+			check.Critical("response does not match regexp")
+		}
+	}
+
+	for k, v := range opts.HeaderMatch {
+		rv := resp.Header.Get(k)
+		if rv != v {
+			check.Critical("invalid header %q = %q", k, rv)
+		}
+	}
+
+	if opts.ResponseTimeCritical > 0 && since > opts.ResponseTimeCritical {
+		check.Critical("response took %v", since.Round(time.Millisecond))
+	} else if opts.ResponseTimeWarn > 0 && since > opts.ResponseTimeWarn {
+		check.Warn("response took %v", since.Round(time.Millisecond))
+	}
+
+	check.OkIfNoWarningsOrCriticals("Valid response")
+
+	return nil
+}

monitor/request_test.go

@@ -0,0 +1,138 @@
+// Copyright 2025 The NATS 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 monitor_test
+
+import (
+	"regexp"
+	"testing"
+	"time"
+
+	"github.com/nats-io/jsm.go/monitor"
+	"github.com/nats-io/nats-server/v2/server"
+	"github.com/nats-io/nats.go"
+)
+
+func TestCheckRequest(t *testing.T) {
+	t.Run("Body match", func(t *testing.T) {
+		withJetStream(t, func(srv *server.Server, nc *nats.Conn) {
+			check := &monitor.Result{}
+
+			_, err := nc.Subscribe("test", func(msg *nats.Msg) {
+				msg.Respond([]byte("test payload"))
+			})
+			assertNoError(t, err)
+
+			assertNoError(t, monitor.CheckRequest(srv.ClientURL(), nil, check, time.Second, monitor.CheckRequestOptions{
+				Subject:       "test",
+				ResponseMatch: "no match",
+			}))
+			assertListIsEmpty(t, check.OKs)
+			assertListIsEmpty(t, check.Warnings)
+			assertListEquals(t, check.Criticals, "response does not match regexp")
+
+			check = &monitor.Result{}
+			assertNoError(t, monitor.CheckRequest(srv.ClientURL(), nil, check, time.Second, monitor.CheckRequestOptions{
+				Subject:       "test",
+				ResponseMatch: ".+payload",
+			}))
+			assertListIsEmpty(t, check.Criticals)
+			assertListIsEmpty(t, check.Warnings)
+			assertListEquals(t, check.OKs, "Valid response")
+		})
+	})
+
+	t.Run("Headers", func(t *testing.T) {
+		withJetStream(t, func(srv *server.Server, nc *nats.Conn) {
+			check := &monitor.Result{}
+
+			_, err := nc.Subscribe("test", func(msg *nats.Msg) {
+				rmsg := nats.NewMsg(msg.Reply)
+				rmsg.Header.Add("test", "test header")
+				msg.RespondMsg(rmsg)
+			})
+			assertNoError(t, err)
+
+			assertNoError(t, monitor.CheckRequest(srv.ClientURL(), nil, check, time.Second, monitor.CheckRequestOptions{
+				Subject:     "test",
+				HeaderMatch: map[string]string{"test": "no match", "other": "header"},
+			}))
+			assertListIsEmpty(t, check.OKs)
+			assertListIsEmpty(t, check.Warnings)
+			assertListEquals(t, check.Criticals, `invalid header "other" = ""`, `invalid header "test" = "test header"`)
+
+			check = &monitor.Result{}
+			assertNoError(t, monitor.CheckRequest(srv.ClientURL(), nil, check, time.Second, monitor.CheckRequestOptions{
+				Subject:     "test",
+				HeaderMatch: map[string]string{"test": "test header"},
+			}))
+			assertListIsEmpty(t, check.Criticals)
+			assertListIsEmpty(t, check.Warnings)
+			assertListEquals(t, check.OKs, "Valid response")
+		})
+	})
+
+	t.Run("Response Time", func(t *testing.T) {
+		withJetStream(t, func(srv *server.Server, nc *nats.Conn) {
+			check := &monitor.Result{}
+			_, err := nc.Subscribe("test", func(msg *nats.Msg) {
+				time.Sleep(500 * time.Millisecond)
+				msg.Respond([]byte("test payload"))
+			})
+			assertNoError(t, err)
+
+			assertNoError(t, monitor.CheckRequest(srv.ClientURL(), nil, check, time.Second, monitor.CheckRequestOptions{
+				Subject:              "test",
+				ResponseTimeWarn:     20 * time.Millisecond,
+				ResponseTimeCritical: time.Second,
+			}))
+			assertListIsEmpty(t, check.Criticals)
+			assertListIsEmpty(t, check.OKs)
+			if len(check.Warnings) != 1 {
+				t.Fatalf("expected 1 warning, got %d", len(check.Warnings))
+			}
+			m, err := regexp.MatchString("^response took \\d+ms", check.Warnings[0])
+			assertNoError(t, err)
+			if !m {
+				t.Fatalf("warning not match %s", check.Warnings[0])
+			}
+
+			check = &monitor.Result{}
+			assertNoError(t, monitor.CheckRequest(srv.ClientURL(), nil, check, time.Second, monitor.CheckRequestOptions{
+				Subject:              "test",
+				ResponseTimeWarn:     20 * time.Millisecond,
+				ResponseTimeCritical: 400 * time.Millisecond,
+			}))
+			assertListIsEmpty(t, check.Warnings)
+			assertListIsEmpty(t, check.OKs)
+			if len(check.Criticals) != 1 {
+				t.Fatalf("expected 1 warning, got %d", len(check.Criticals))
+			}
+			m, err = regexp.MatchString("^response took \\d+ms", check.Criticals[0])
+			assertNoError(t, err)
+			if !m {
+				t.Fatalf("warning not match %s", check.Criticals[0])
+			}
+
+			check = &monitor.Result{}
+			assertNoError(t, monitor.CheckRequest(srv.ClientURL(), nil, check, time.Second, monitor.CheckRequestOptions{
+				Subject:              "test",
+				ResponseTimeWarn:     800 * time.Millisecond,
+				ResponseTimeCritical: 1000 * time.Millisecond,
+			}))
+			assertListIsEmpty(t, check.Warnings)
+			assertListIsEmpty(t, check.Criticals)
+			assertListEquals(t, check.OKs, "Valid response")
+		})
+	})
+}

monitor/result.go

@@ -75,6 +75,12 @@ func (r *Result) Ok(format string, a ...any) {
 	r.OKs = append(r.OKs, fmt.Sprintf(format, a...))
 }
 
+func (r *Result) OkIfNoWarningsOrCriticals(format string, a ...any) {
+	if len(r.Warnings) == 0 && len(r.Criticals) == 0 {
+		r.Ok(format, a...)
+	}
+}
+
 func (r *Result) CriticalExitIfErr(err error, format string, a ...any) bool {
 	if err == nil {
 		return false

monitor/stream_msg.go

@@ -85,12 +85,10 @@ func CheckStreamMessage(server string, nopts []nats.Option, check *Result, opts
 
 	since := time.Since(ts)
 
-	if opts.AgeWarning > 0 || opts.AgeCritical > 0 {
-		if opts.AgeCritical > 0 && since > secondsToDuration(opts.AgeCritical) {
-			check.Critical("%v old", since.Round(time.Millisecond))
-		} else if opts.AgeWarning > 0 && since > secondsToDuration(opts.AgeWarning) {
-			check.Warn("%v old", time.Since(ts).Round(time.Millisecond))
-		}
+	if opts.AgeCritical > 0 && since > secondsToDuration(opts.AgeCritical) {
+		check.Critical("%v old", since.Round(time.Millisecond))
+	} else if opts.AgeWarning > 0 && since > secondsToDuration(opts.AgeWarning) {
+		check.Warn("%v old", time.Since(ts).Round(time.Millisecond))
 	}
 
 	if opts.Content != "" {
@@ -104,7 +102,7 @@ func CheckStreamMessage(server string, nopts []nats.Option, check *Result, opts
 		}
 	}
 
-	check.Ok("Valid message on %s > %s", opts.StreamName, opts.Subject)
+	check.OkIfNoWarningsOrCriticals("Valid message on %s > %s", opts.StreamName, opts.Subject)
 
 	return nil
 }