Add strict flag to agent (#196)

* Add strict flag to agent

Agent will hard fail if a data gatherer is defined for a missing CRD.

Related [#510](jetstack/preflight-platform#510)

Signed-off-by: oluwole.fadeyi <[email protected]>

* Adds new type of error and changed strict flag

New error type: CRDNotFoundError
This is to catch the edge case that when a CRD is not found
the backoff loop should not be retried

The strict flag has been changed to hard fail if an error of any type
is returned, including if a CRD is not found

Signed-off-by: Jamie Leppard <[email protected]>

* Improves error handling

Error from CRDNotFoundError is now not appeneded to dgError
if not in strict mode.
Strict mode no longer iterates over a multi error but checks to see if
any errors are present at all

Signed-off-by: Jamie Leppard <[email protected]>

* Changes CRDNotFoundError to ConfigError

The CRDNotFound error in the k8s package has been
changed to a more general ConfigError in the local package

Signed-off-by: Jamie Leppard <[email protected]>

* Added new error package for datagatherers

The config error has been moved to a new package dedicated to
error associated with data gatherers

Signed-off-by: Jamie Leppard <[email protected]>

Co-authored-by: oluwole.fadeyi <[email protected]>
Co-authored-by: Jamie Leppard <[email protected]>

Author: 3 people

cmd/agent.go

@@ -79,5 +79,12 @@ func init() {
 		10*time.Minute,
 		"Max time for retrying failed data gatherers (given as XhYmZs).",
 	)
+	agentCmd.PersistentFlags().BoolVarP(
+		&agent.StrictMode,
+		"strict",
+		"",
+		false,
+		"Runs agent in strict mode. No retry attempts will be made for a missing data gatherer's data.",
+	)
 
 }

pkg/agent/run.go

@@ -17,6 +17,7 @@ import (
 	"github.com/jetstack/preflight/api"
 	"github.com/jetstack/preflight/pkg/client"
 	"github.com/jetstack/preflight/pkg/datagatherer"
+	dgerror "github.com/jetstack/preflight/pkg/datagatherer/error"
 	"github.com/jetstack/preflight/pkg/version"
 	"github.com/spf13/cobra"
 )
@@ -42,6 +43,9 @@ var InputPath string
 // BackoffMaxTime is the maximum time for which data gatherers will be retried
 var BackoffMaxTime time.Duration
 
+// StrictMode flag causes the agent to fail at the first attempt
+var StrictMode bool
+
 // Run starts the agent process
 func Run(cmd *cobra.Command, args []string) {
 	ctx := context.Background()
@@ -207,8 +211,17 @@ func gatherData(ctx context.Context, config Config) []*api.DataReading {
 			}
 			dgData, err := dg.Fetch()
 			if err != nil {
-				err = fmt.Errorf("%s: %v", k, err)
-				dgError = multierror.Append(dgError, err)
+				if _, ok := err.(*dgerror.ConfigError); ok {
+					if StrictMode {
+						err = fmt.Errorf("%s: %v", k, err)
+						dgError = multierror.Append(dgError, err)
+					} else {
+						log.Printf("%s: %v", k, err)
+					}
+				} else {
+					err = fmt.Errorf("%s: %v", k, err)
+					dgError = multierror.Append(dgError, err)
+				}
 				continue
 			} else {
 				completedDataGatherers[k] = true
@@ -238,13 +251,21 @@ func gatherData(ctx context.Context, config Config) []*api.DataReading {
 		return dgError.ErrorOrNil()
 	}
 
-	err := backoff.RetryNotify(getReadings, backOff, notify)
-	if err != nil {
-		log.Println(err)
-		log.Printf("This will not be retried")
+	if StrictMode {
+		err := getReadings()
+		if err != nil {
+			log.Fatalf("%v", err)
+		}
 	} else {
-		log.Printf("All data gatherers successfull")
+		err := backoff.RetryNotify(func() error { return getReadings() }, backOff, notify)
+		if err != nil {
+			log.Println(err)
+			log.Printf("This will not be retried")
+		} else {
+			log.Printf("Finished gathering data")
+		}
 	}
+
 	return readings
 }
 

pkg/datagatherer/error/error.go

@@ -0,0 +1,14 @@
+package dgerror
+
+import (
+	"fmt"
+)
+
+// ConfigError is the error type for a misconfiguration. e.g. A missing CRD
+type ConfigError struct {
+	Err string
+}
+
+func (e *ConfigError) Error() string {
+	return fmt.Sprintf("%s", e.Err)
+}

pkg/datagatherer/k8s/dynamic.go

@@ -6,7 +6,9 @@ import (
 	"strings"
 
 	"github.com/jetstack/preflight/pkg/datagatherer"
+	dgerror "github.com/jetstack/preflight/pkg/datagatherer/error"
 	"github.com/pkg/errors"
+	statusError "k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/fields"
@@ -139,7 +141,12 @@ func (g *DataGathererDynamic) Fetch() (interface{}, error) {
 			FieldSelector: g.fieldSelector,
 		})
 		if err != nil {
-			return nil, errors.WithStack(err)
+			if statusErr, ok := err.(*statusError.StatusError); ok {
+				if statusErr.Status().Code == 404 {
+					return nil, &dgerror.ConfigError{Err: err.Error()}
+				}
+			}
+			return nil, err
 		}
 		list.Object = namespaceList.Object
 		list.Items = append(list.Items, namespaceList.Items...)