Add context to errors (#29)

This will make understanding errors simpler as we can deduce what the
origin was.

Author: Bjørn

go.mod

@@ -1,6 +1,7 @@
 module github.com/lunarway/snyk_exporter
 
 require (
+	github.com/pkg/errors v0.8.1
 	github.com/prometheus/client_golang v0.9.2
 	github.com/prometheus/common v0.0.0-20190107103113-2998b132700a
 	gopkg.in/alecthomas/kingpin.v2 v2.2.6

go.sum

@@ -23,6 +23,8 @@ github.com/matttproud/golang_protobuf_extensions v1.0.1/go.mod h1:D8He9yQNgCq6Z5
 github.com/mwitkow/go-conntrack v0.0.0-20161129095857-cc309e4a2223/go.mod h1:qRWi+5nqEBWmkhHvq77mSJWrCKwh8bxhgT7d/eI7P4U=
 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/pkg/errors v0.8.1 h1:iURUrRGxPUNPdy5/HRSm+Yj6okJ6UtLINN0Q9M4+h3I=
+github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 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=

main.go

@@ -13,6 +13,7 @@ import (
 	"syscall"
 	"time"
 
+	"github.com/pkg/errors"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/prometheus/common/log"
@@ -155,7 +156,7 @@ func runAPIPolling(done chan error, url, token string, organizationIDs []string,
 				return nil
 			})
 			if err != nil {
-				done <- err
+				done <- errors.WithMessagef(err, "organization %s (%s)", organization.Name, organization.ID)
 				return
 			}
 			gaugeResults = append(gaugeResults, results...)
@@ -175,6 +176,7 @@ func runAPIPolling(done chan error, url, token string, organizationIDs []string,
 func poll(organization org, collector func(org) error) error {
 	err := collector(organization)
 	if err != nil {
+		err = errors.Cause(err)
 		httpErr, ok := err.(*url.Error)
 		if ok {
 			if httpErr.Timeout() {
@@ -252,7 +254,7 @@ type gaugeResult struct {
 func collect(client *client, organization org) ([]gaugeResult, error) {
 	projects, err := client.getProjects(organization.ID)
 	if err != nil {
-		return nil, err
+		return nil, errors.WithMessage(err, "get projects for organization")
 	}
 
 	var gaugeResults []gaugeResult