Switch to kingpin

Signed-off-by: rustyclock <rustyclock@protonmail.com>

README.md

@@ -34,18 +34,24 @@ $ cat example/data.json
             "count": 3,
             "some_boolean": false,
             "state": "ACTIVE"
-        },
+        }
-    ]
+    ],
+    "location": "mars"
 }
 
-$ cat example/config.yml
+$ cat examples/config.yml
+---
+metrics:
 - name: example_global_value
   path: $.counter
+  help: Example of a top-level global value scrape in the json
   labels:
     environment: beta # static label
+    location: $.location          # dynamic label
 
 - name: example_value
   type: object
+  help: Example of sub-level value scrapes from a json
   path: $.values[*]?(@.state == "ACTIVE")
   labels:
     environment: beta # static label
@@ -55,10 +61,13 @@ $ cat example/config.yml
     count: $.count # dynamic value
     boolean: $.some_boolean
 
+headers:
+  X-Dummy: my-test-header
+
 $ python -m SimpleHTTPServer 8000 &
 Serving HTTP on 0.0.0.0 port 8000 ...
 
-$ ./json_exporter examples/config.yml &
+$ ./json_exporter --config.file examples/config.yml &
 
 $ curl "http://localhost:7979/probe?target=http://localhost:8000/examples/data.json" | grep ^example
 example_global_value{environment="beta",location="mars"} 1234
@@ -78,10 +87,9 @@ Then head over to http://localhost:9090/graph?g0.range_input=1h&g0.expr=example_
 
 ```console
 docker run \
-  -v config.yml:/config.yml
+  -v $PWD/examples/config.yml:/config.yml
   quay.io/prometheuscommunity/json-exporter \
-    http://example.com/target.json \
+    --config.file /config.yml
-    /config.yml
 ```
 
 # See Also

cmd/main.go

@@ -16,7 +16,6 @@ package cmd
 import (
 	"context"
 	"encoding/json"
-	"fmt"
 	"net/http"
 	"os"
 	"time"
@@ -28,48 +27,32 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/prometheus/common/promlog"
+	"github.com/prometheus/common/promlog/flag"
 	"github.com/prometheus/common/version"
-	"github.com/urfave/cli"
+	"gopkg.in/alecthomas/kingpin.v2"
 )
 
 var (
-	defaultOpts = []cli.Flag{
+	configFile    = kingpin.Flag("config.file", "JSON exporter configuration file.").Default("config.yml").ExistingFile()
-		cli.IntFlag{
+	listenAddress = kingpin.Flag("web.listen-address", "The address to listen on for HTTP requests.").Default(":7979").String()
-			Name:  "port",
+	configCheck   = kingpin.Flag("config.check", "If true validate the config file and then exit.").Default().Bool()
-			Usage: "The port number used to expose metrics via http",
-			Value: 7979,
-		},
-		cli.StringFlag{
-			Name:  "log-level",
-			Usage: "Set Logging level",
-			Value: "info",
-		},
-	}
 )
 
-func MakeApp() *cli.App {
+func Run() {
-
-	app := cli.NewApp()
-	app.Name = "json_exporter"
-	app.Usage = "A prometheus exporter for scraping metrics from JSON REST API endpoints"
-	app.UsageText = "[OPTIONS] CONFIG_PATH"
-	app.Action = main
-	app.Flags = defaultOpts
-
-	return app
-}
-
-func main(c *cli.Context) {
 
 	promlogConfig := &promlog.Config{}
+
+	flag.AddFlags(kingpin.CommandLine, promlogConfig)
+	kingpin.Version(version.Print("json_exporter"))
+	kingpin.HelpFlag.Short('h')
+	kingpin.Parse()
 	logger := promlog.New(promlogConfig)
 
 	level.Info(logger).Log("msg", "Starting json_exporter", "version", version.Info()) //nolint:errcheck
 	level.Info(logger).Log("msg", "Build context", "build", version.BuildContext())    //nolint:errcheck
 
-	internal.Init(logger, c)
+	level.Info(logger).Log("msg", "Loading config file", "file", *configFile) //nolint:errcheck
-
+	config, err := config.LoadConfig(*configFile)
-	config, err := config.LoadConfig(c.Args()[0])
 	if err != nil {
 		level.Error(logger).Log("msg", "Error loading config", "err", err) //nolint:errcheck
 		os.Exit(1)
@@ -78,13 +61,17 @@ func main(c *cli.Context) {
 	if err != nil {
 		level.Error(logger).Log("msg", "Failed to marshal config to JOSN", "err", err) //nolint:errcheck
 	}
-	level.Info(logger).Log("msg", "Loaded config file", "config", configJson) //nolint:errcheck
+	level.Info(logger).Log("msg", "Loaded config file", "config", string(configJson)) //nolint:errcheck
+
+	if *configCheck {
+		os.Exit(0)
+	}
 
 	http.Handle("/metrics", promhttp.Handler())
 	http.HandleFunc("/probe", func(w http.ResponseWriter, req *http.Request) {
 		probeHandler(w, req, logger, config)
 	})
-	if err := http.ListenAndServe(fmt.Sprintf(":%d", c.Int("port")), nil); err != nil {
+	if err := http.ListenAndServe(*listenAddress, nil); err != nil {
 		level.Error(logger).Log("msg", "failed to start the server", "err", err) //nolint:errcheck
 	}
 }

go.mod

@@ -9,5 +9,6 @@ require (
 	github.com/prometheus/client_golang v1.7.1
 	github.com/prometheus/common v0.10.0
 	github.com/urfave/cli v1.22.4
+	gopkg.in/alecthomas/kingpin.v2 v2.2.6
 	gopkg.in/yaml.v2 v2.3.0
 )

internal/collector.go

@@ -14,10 +14,7 @@
 package internal
 
 import (
-	"context"
 	"fmt"
-	"io/ioutil"
-	"net/http"
 	"strconv"
 
 	"github.com/go-kit/kit/log"
@@ -171,32 +168,3 @@ func extractLabels(logger log.Logger, json []byte, l map[string]string) map[stri
 	}
 	return labels
 }
-
-func FetchJson(ctx context.Context, logger log.Logger, endpoint string, headers map[string]string) ([]byte, error) {
-	client := &http.Client{}
-	req, err := http.NewRequest("GET", endpoint, nil)
-	req = req.WithContext(ctx)
-	if err != nil {
-		level.Error(logger).Log("msg", "Failed to create request", "err", err) //nolint:errcheck
-		return nil, err
-	}
-
-	for key, value := range headers {
-		req.Header.Add(key, value)
-	}
-	if req.Header.Get("Accept") == "" {
-		req.Header.Add("Accept", "application/json")
-	}
-	resp, err := client.Do(req)
-	if err != nil {
-		return nil, fmt.Errorf("failed to fetch json from endpoint;endpoint:<%s>,err:<%s>", endpoint, err)
-	}
-	defer resp.Body.Close()
-
-	data, err := ioutil.ReadAll(resp.Body)
-	if err != nil {
-		return nil, fmt.Errorf("failed to read response body;err:<%s>", err)
-	}
-
-	return data, nil
-}

internal/init.go

@@ -1,44 +0,0 @@
-// Copyright 2020 The Prometheus 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 internal
-
-import (
-	"os"
-
-	"github.com/go-kit/kit/log"
-	"github.com/go-kit/kit/log/level"
-	"github.com/prometheus-community/json_exporter/config"
-	"github.com/urfave/cli"
-)
-
-func Init(logger log.Logger, c *cli.Context) {
-	args := c.Args()
-
-	if len(args) < 1 {
-		cli.ShowAppHelp(c)                                     //nolint:errcheck
-		level.Error(logger).Log("msg", "Not enough arguments") //nolint:errcheck
-		os.Exit(1)
-	}
-
-	var (
-		configPath = args[0]
-	)
-
-	_, err := config.LoadConfig(configPath)
-
-	if err != nil {
-		level.Error(logger).Log("msg", "Failed to load config") //nolint:errcheck
-		os.Exit(1)
-	}
-}

internal/util.go

@@ -14,11 +14,16 @@
 package internal
 
 import (
+	"context"
 	"fmt"
+	"io/ioutil"
 	"math"
+	"net/http"
 	"strconv"
 	"strings"
 
+	"github.com/go-kit/kit/log"
+	"github.com/go-kit/kit/log/level"
 	"github.com/kawamuray/jsonpath"
 	"github.com/prometheus-community/json_exporter/config"
 	"github.com/prometheus/client_golang/prometheus"
@@ -100,3 +105,32 @@ func CreateMetricsList(r *prometheus.Registry, c config.Config) ([]JsonGaugeColl
 	}
 	return metrics, nil
 }
+
+func FetchJson(ctx context.Context, logger log.Logger, endpoint string, headers map[string]string) ([]byte, error) {
+	client := &http.Client{}
+	req, err := http.NewRequest("GET", endpoint, nil)
+	req = req.WithContext(ctx)
+	if err != nil {
+		level.Error(logger).Log("msg", "Failed to create request", "err", err) //nolint:errcheck
+		return nil, err
+	}
+
+	for key, value := range headers {
+		req.Header.Add(key, value)
+	}
+	if req.Header.Get("Accept") == "" {
+		req.Header.Add("Accept", "application/json")
+	}
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("failed to fetch json from endpoint;endpoint:<%s>,err:<%s>", endpoint, err)
+	}
+	defer resp.Body.Close()
+
+	data, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read response body;err:<%s>", err)
+	}
+
+	return data, nil
+}

main.go

@@ -14,14 +14,9 @@
 package main
 
 import (
-	"os"
-
 	"github.com/prometheus-community/json_exporter/cmd"
 )
 
 func main() {
-	err := cmd.MakeApp().Run(os.Args)
+	cmd.Run()
-	if err != nil {
-		os.Exit(1)
-	}
 }