*: fix errcheck errors

Signed-off-by: Simon Pasquier <spasquie@redhat.com>

.golangci.yml

@@ -2,10 +2,15 @@ run:
   deadline: 10m
 
 linters:
-  disable-all: true
   enable:
   - golint
-  - gosimple
-  - govet
-  - staticcheck
-  - unused
+
+issues:
+  exclude-rules:
+  - path: _test.go
+    linters:
+    - errcheck
+
+linters-settings:
+  errcheck:
+    exclude: scripts/errcheck_excludes.txt

cmd/operator/main.go

@@ -206,7 +206,8 @@ func init() {
 
 func Main() int {
 	versionutil.RegisterFlags()
-	flagset.Parse(os.Args[1:])
+	// No need to check for errors because Parse would exit on error.
+	_ = flagset.Parse(os.Args[1:])
 
 	if versionutil.ShouldPrintVersion() {
 		versionutil.Print(os.Stdout, "prometheus-operator")

example/alertmanger-webhook/main.go

@@ -20,7 +20,7 @@ import (
 )
 
 func main() {
-	http.ListenAndServe(":5001", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+	_ = http.ListenAndServe(":5001", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		fmt.Println("Alertmanager Notification Payload Received")
 	}))
 }

pkg/alertmanager/operator.go

@@ -887,12 +887,15 @@ func (c *Operator) selectAlertmanagerConfigs(ctx context.Context, am *monitoring
 	}
 
 	for _, ns := range namespaces {
-		c.alrtCfgInfs.ListAllByNamespace(ns, amConfigSelector, func(obj interface{}) {
+		err := c.alrtCfgInfs.ListAllByNamespace(ns, amConfigSelector, func(obj interface{}) {
 			k, ok := c.keyFunc(obj)
 			if ok {
 				amConfigs[k] = obj.(*monitoringv1alpha1.AlertmanagerConfig)
 			}
 		})
+		if err != nil {
+			return nil, errors.Wrapf(err, "failed to list alertmanager configs in namespace %s", ns)
+		}
 	}
 
 	var rejected int

pkg/prometheus/operator.go

@@ -1633,12 +1633,15 @@ func (c *Operator) selectServiceMonitors(ctx context.Context, p *monitoringv1.Pr
 	level.Debug(c.logger).Log("msg", "filtering namespaces to select ServiceMonitors from", "namespaces", strings.Join(namespaces, ","), "namespace", p.Namespace, "prometheus", p.Name)
 
 	for _, ns := range namespaces {
-		c.smonInfs.ListAllByNamespace(ns, servMonSelector, func(obj interface{}) {
+		err := c.smonInfs.ListAllByNamespace(ns, servMonSelector, func(obj interface{}) {
 			k, ok := c.keyFunc(obj)
 			if ok {
 				serviceMonitors[k] = obj.(*monitoringv1.ServiceMonitor)
 			}
 		})
+		if err != nil {
+			return nil, errors.Wrapf(err, "failed to list service monitors in namespace %s", ns)
+		}
 	}
 
 	var rejected int
@@ -1729,12 +1732,15 @@ func (c *Operator) selectPodMonitors(ctx context.Context, p *monitoringv1.Promet
 	level.Debug(c.logger).Log("msg", "filtering namespaces to select PodMonitors from", "namespaces", strings.Join(namespaces, ","), "namespace", p.Namespace, "prometheus", p.Name)
 
 	for _, ns := range namespaces {
-		c.pmonInfs.ListAllByNamespace(ns, podMonSelector, func(obj interface{}) {
+		err := c.pmonInfs.ListAllByNamespace(ns, podMonSelector, func(obj interface{}) {
 			k, ok := c.keyFunc(obj)
 			if ok {
 				podMonitors[k] = obj.(*monitoringv1.PodMonitor)
 			}
 		})
+		if err != nil {
+			return nil, errors.Wrapf(err, "failed to list pod monitors in namespace %s", ns)
+		}
 	}
 
 	var rejected int
@@ -1817,11 +1823,14 @@ func (c *Operator) selectProbes(ctx context.Context, p *monitoringv1.Prometheus,
 	level.Debug(c.logger).Log("msg", "filtering namespaces to select Probes from", "namespaces", strings.Join(namespaces, ","), "namespace", p.Namespace, "prometheus", p.Name)
 
 	for _, ns := range namespaces {
-		c.probeInfs.ListAllByNamespace(ns, bMonSelector, func(obj interface{}) {
+		err := c.probeInfs.ListAllByNamespace(ns, bMonSelector, func(obj interface{}) {
 			if k, ok := c.keyFunc(obj); ok {
 				probes[k] = obj.(*monitoringv1.Probe)
 			}
 		})
+		if err != nil {
+			return nil, errors.Wrapf(err, "failed to list probes in namespace %s", ns)
+		}
 	}
 
 	var rejected int

scripts/errcheck_excludes.txt

@@ -0,0 +1,5 @@
+// Any error in HTTP handlers is handled by the server itself.
+(net/http.ResponseWriter).Write
+
+// Never check for logger errors.
+(github.com/go-kit/kit/log.Logger).Log

test/instrumented-sample-app/main.go

@@ -71,7 +71,7 @@ func main() {
 
 	fmt.Printf("listening for metric requests on '%v' protected via basic auth or bearer token\n", address)
 
-	http.ListenAndServe(address, nil)
+	_ = http.ListenAndServe(address, nil)
 }
 
 func handler(w http.ResponseWriter, r *http.Request) {