Fix potential leak, use modules, various cleanups (#29)

* Fix one potential resource leak

* Minor clean-ups and organizational improvements

* Use modules instead of dep

* Add comments for future maintainers (i.e. me)

go.mod

@@ -0,0 +1,12 @@
+module github.com/peterbourgon/fastly-exporter
+
+go 1.12
+
+require (
+	github.com/go-kit/kit v0.8.0
+	github.com/google/go-cmp v0.2.0
+	github.com/oklog/run v1.0.0
+	github.com/peterbourgon/usage v1.0.1
+	github.com/pkg/errors v0.8.0
+	github.com/prometheus/client_golang v1.0.0
+)

go.sum

@@ -0,0 +1,56 @@
+github.com/alecthomas/template v0.0.0-20160405071501-a0175ee3bccc/go.mod h1:LOuyumcjzFXgccqObfd/Ljyb9UuFJ6TxHnclSeseNhc=
+github.com/alecthomas/units v0.0.0-20151022065526-2efee857e7cf/go.mod h1:ybxpYRFXyAe+OPACYpWeL0wqObRcbAqCMya13uyzqw0=
+github.com/beorn7/perks v0.0.0-20180321164747-3a771d992973/go.mod h1:Dwedo/Wpr24TaqPxmxbtue+5NUziq4I4S80YR8gNf3Q=
+github.com/beorn7/perks v1.0.0 h1:HWo1m869IqiPhD389kmkxeTalrjNbbJTC8LXupb+sl0=
+github.com/beorn7/perks v1.0.0/go.mod h1:KWe93zE9D1o94FZ5RNwFwVgaQK1VOXiVxmqh+CedLV8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/go-kit/kit v0.8.0/go.mod h1:xBxKIO96dXMWWy0MnWVtmwkA9/13aqxPnvrjFYMA2as=
+github.com/go-logfmt/logfmt v0.3.0 h1:8HUsc87TaSWLKwrnumgC8/YconD2fJQsRJAsWaPg2ic=
+github.com/go-logfmt/logfmt v0.3.0/go.mod h1:Qt1PoO58o5twSAckw1HlFXLmHsOX5/0LbT9GBnD5lWE=
+github.com/go-stack/stack v1.8.0/go.mod h1:v0f6uXyyMGvRgIKkXu+yp6POWl0qKG85gN/melR3HDY=
+github.com/gogo/protobuf v1.1.1/go.mod h1:r8qH/GZQm5c6nD/R0oafs1akxWv10x8SbQlK7atdtwQ=
+github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
+github.com/golang/protobuf v1.3.1 h1:YF8+flBXS5eO826T4nzqPrxfhQThhXl0YzfuUPu4SBg=
+github.com/golang/protobuf v1.3.1/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
+github.com/google/go-cmp v0.2.0/go.mod h1:oXzfMopK8JAjlY9xF4vHSVASa0yLyX7SntLO5aqRK0M=
+github.com/json-iterator/go v1.1.6/go.mod h1:+SdeFBvtyEkXs7REEP0seUULqWtbJapLOCVDaaPEHmU=
+github.com/julienschmidt/httprouter v1.2.0/go.mod h1:SYymIcj16QtmaHHD7aYtjjsJG7VTCxuUUipMqKk8s4w=
+github.com/konsorten/go-windows-terminal-sequences v1.0.1/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
+github.com/kr/logfmt v0.0.0-20140226030751-b84e30acd515/go.mod h1:+0opPa2QZZtGFBFZlji/RkVcI2GknAs/DXo4wKdlNEc=
+github.com/matttproud/golang_protobuf_extensions v1.0.1/go.mod h1:D8He9yQNgCq6Z5Ld7szi9bcBfOoFv/3dc6xSMkL2PC0=
+github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
+github.com/modern-go/reflect2 v1.0.1/go.mod h1:bx2lNnkwVCuqBIxFjflWJWanXIb3RllmbCylyMrvgv0=
+github.com/mwitkow/go-conntrack v0.0.0-20161129095857-cc309e4a2223/go.mod h1:qRWi+5nqEBWmkhHvq77mSJWrCKwh8bxhgT7d/eI7P4U=
+github.com/oklog/run v1.0.0/go.mod h1:dlhp/R75TPv97u0XWUtDeV/lRKWPKSdTuV0TZvrmrQA=
+github.com/peterbourgon/usage v1.0.1 h1:Clwpoi24ldPcZdlNreEdkh/1RyV5mEnJh0A8t13d/Rk=
+github.com/peterbourgon/usage v1.0.1/go.mod h1:KBC4Y1vQmbn4b8YHk7r0TlVkByTasbseRBMSOz5o0d0=
+github.com/pkg/errors v0.8.0 h1:WdK/asTD0HN+q6hsWO3/vpuAkAr+tw6aNJNDFFf0+qw=
+github.com/pkg/errors v0.8.0/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/prometheus/client_golang v0.9.1/go.mod h1:7SWBe2y4D6OKWSNQJUaRYU/AaXPKyh/dDVn+NZz0KFw=
+github.com/prometheus/client_golang v1.0.0 h1:vrDKnkGzuGvhNAL56c7DBz29ZL+KxnoR0x7enabFceM=
+github.com/prometheus/client_golang v1.0.0/go.mod h1:db9x61etRT2tGnBNRi70OPL5FsnadC4Ky3P0J6CfImo=
+github.com/prometheus/client_model v0.0.0-20180712105110-5c3871d89910/go.mod h1:MbSGuTsp3dbXC40dX6PRTWyKYBIrTGTE9sqQNg2J8bo=
+github.com/prometheus/client_model v0.0.0-20190129233127-fd36f4220a90 h1:S/YWwWx/RA8rT8tKFRuGUZhuA90OyIBpPCXkcbwU8DE=
+github.com/prometheus/client_model v0.0.0-20190129233127-fd36f4220a90/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
+github.com/prometheus/common v0.4.1 h1:K0MGApIoQvMw27RTdJkPbr3JZ7DNbtxQNyi5STVM6Kw=
+github.com/prometheus/common v0.4.1/go.mod h1:TNfzLD0ON7rHzMJeJkieUDPYmFC7Snx/y86RQel1bk4=
+github.com/prometheus/procfs v0.0.0-20181005140218-185b4288413d/go.mod h1:c3At6R/oaqEKCNdg8wHV1ftS6bRYblBhIjjI8uT2IGk=
+github.com/prometheus/procfs v0.0.2 h1:6LJUbpNm42llc4HRCuvApCSWB/WfhuNo9K98Q9sNGfs=
+github.com/prometheus/procfs v0.0.2/go.mod h1:TjEm7ze935MbeOT/UhFTIMYKhuLP4wbCsTZCD3I8kEA=
+github.com/sirupsen/logrus v1.2.0/go.mod h1:LxeOpSwHxABJmUn/MG1IvRgCAasNZTLOkJPxbbu5VWo=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/objx v0.1.1/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
+golang.org/x/crypto v0.0.0-20180904163835-0709b304e793/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
+golang.org/x/net v0.0.0-20181114220301-adae6a3d119a/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
+golang.org/x/sync v0.0.0-20181108010431-42b317875d0f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20180905080454-ebe1bf3edb33/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20181116152217-5ac8a444bdc5 h1:mzjBh+S5frKOsOBobWIMAbXavqjmgO17k/2puhcFR94=
+golang.org/x/sys v0.0.0-20181116152217-5ac8a444bdc5/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+gopkg.in/alecthomas/kingpin.v2 v2.2.6/go.mod h1:FMv+mEhP44yOT+4EoQTLFTRgOQ1FBLkstjWtayDeSgw=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

main.go

@@ -9,12 +9,12 @@ import (
 	"os"
 	"os/signal"
 	"strings"
-	"text/tabwriter"
 	"time"
 
 	"github.com/go-kit/kit/log"
 	"github.com/go-kit/kit/log/level"
 	"github.com/oklog/run"
+	"github.com/peterbourgon/usage"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 )
 
@@ -31,7 +31,7 @@ func main() {
 		debug      = fs.Bool("debug", false, "Log debug information")
 	)
 	fs.Var(&serviceIDs, "service", "Specific Fastly service ID (optional, repeatable)")
-	fs.Usage = usageFor(fs, "fastly-exporter [flags]")
+	fs.Usage = usage.For(fs, "fastly-exporter [flags]")
 	fs.Parse(os.Args[1:])
 
 	var logger log.Logger
@@ -187,25 +187,3 @@ func (ss *stringslice) String() string {
 type httpClient interface {
 	Do(*http.Request) (*http.Response, error)
 }
-
-func usageFor(fs *flag.FlagSet, short string) func() {
-	return func() {
-		fmt.Fprintf(os.Stderr, "USAGE\n")
-		fmt.Fprintf(os.Stderr, "  %s\n", short)
-		fmt.Fprintf(os.Stderr, "\n")
-		fmt.Fprintf(os.Stderr, "FLAGS\n")
-		w := tabwriter.NewWriter(os.Stderr, 0, 2, 2, ' ', 0)
-		fs.VisitAll(func(f *flag.Flag) {
-			def := f.DefValue
-			if def == "" {
-				def = "..."
-			}
-			fmt.Fprintf(w, "\t-%s %s\t%s\n", f.Name, def, f.Usage)
-		})
-		w.Flush()
-		fmt.Fprintf(os.Stderr, "\n")
-		fmt.Fprintf(os.Stderr, "VERSION\n")
-		fmt.Fprintf(os.Stderr, "  %s\n", version)
-		fmt.Fprintf(os.Stderr, "\n")
-	}
-}

monitor.go

@@ -11,6 +11,10 @@ import (
 	"github.com/go-kit/kit/log/level"
 )
 
+// monitor polls the Fastly real-time stats API for the provided service ID on a
+// regular cadence. All received metrics are processed and given to the
+// Prometheus metrics struct. The service name label is regularly updated via
+// the name resolver. The function exits when the context is canceled.
 func monitor(ctx context.Context, client httpClient, token string, serviceID string, resolver nameResolver, metrics prometheusMetrics, postprocess func(), logger log.Logger) error {
 	var ts uint64
 	for {
@@ -23,46 +27,54 @@ func monitor(ctx context.Context, client httpClient, token string, serviceID str
 				serviceName = resolver.resolve(serviceID)
 				logger      = log.With(logger, "service_name", serviceName)
 			)
+
 			// rt.fastly.com blocks until it has data to return.
 			// It's safe to call in a (single-threaded!) hot loop.
 			u := fmt.Sprintf("https://rt.fastly.com/v1/channel/%s/ts/%d", serviceID, ts)
 			req, err := http.NewRequest("GET", u, nil)
 			if err != nil {
 				return err // fatal for sure
 			}
+
 			req.Header.Set("User-Agent", "Fastly-Exporter ("+version+")")
 			req.Header.Set("Fastly-Key", token)
 			req.Header.Set("Accept", "application/json")
 			resp, err := client.Do(req.WithContext(ctx))
 			if err != nil {
-				level.Error(logger).Log("err", err)
+				level.Error(logger).Log("during", "execute request", "err", err)
 				contextSleep(ctx, time.Second)
 				continue
 			}
+
 			var rt realtimeResponse
 			if err := json.NewDecoder(resp.Body).Decode(&rt); err != nil {
 				resp.Body.Close()
-				level.Error(logger).Log("err", err)
+				level.Error(logger).Log("during", "decode response", "err", err)
 				contextSleep(ctx, time.Second)
 				continue
 			}
 			resp.Body.Close()
+
 			rterr := rt.Error
 			if rterr == "" {
 				rterr = "<none>"
 			}
+
 			switch resp.StatusCode {
 			case http.StatusOK:
 				level.Debug(logger).Log("status_code", resp.StatusCode, "response_ts", rt.Timestamp, "err", rterr)
 				process(rt, serviceID, serviceName, metrics)
 				postprocess()
+
 			case http.StatusUnauthorized, http.StatusForbidden:
 				level.Error(logger).Log("status_code", resp.StatusCode, "response_ts", rt.Timestamp, "err", rterr, "msg", "token may be invalid")
 				contextSleep(ctx, 15*time.Second)
+
 			default:
 				level.Error(logger).Log("status_code", resp.StatusCode, "response_ts", rt.Timestamp, "err", rterr)
 				contextSleep(ctx, 5*time.Second)
 			}
+
 			ts = rt.Timestamp
 		}
 	}