feat: adding filter infrastructure + status and event filter

cmd/nerdctl/system_events.go

@@ -39,6 +39,7 @@ func newEventsCommand() *cobra.Command {
 	eventsCommand.RegisterFlagCompletionFunc("format", func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
 		return []string{"json"}, cobra.ShellCompDirectiveNoFileComp
 	})
+	eventsCommand.Flags().StringSliceP("filter", "f", []string{}, "Filter matches containers based on given conditions")
 	return eventsCommand
 }
 
@@ -51,10 +52,15 @@ func processSystemEventsOptions(cmd *cobra.Command) (types.SystemEventsOptions,
 	if err != nil {
 		return types.SystemEventsOptions{}, err
 	}
+	filters, err := cmd.Flags().GetStringSlice("filter")
+	if err != nil {
+		return types.SystemEventsOptions{}, err
+	}
 	return types.SystemEventsOptions{
 		Stdout:   cmd.OutOrStdout(),
 		GOptions: globalOptions,
 		Format:   format,
+		Filters:  filters,
 	}, nil
 }
 

cmd/nerdctl/system_events_linux_test.go

@@ -0,0 +1,111 @@
+/*
+   Copyright The containerd 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 main
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/containerd/nerdctl/v2/pkg/testutil"
+	"gotest.tools/v3/assert"
+)
+
+func testEventFilter(t *testing.T, args ...string) string {
+	t.Parallel()
+	base := testutil.NewBase(t)
+	testContainerName := testutil.Identifier(t)
+	defer base.Cmd("rm", "-f", testContainerName).Run()
+
+	fullArgs := []string{"events", "--filter"}
+	fullArgs = append(fullArgs, args...)
+	fullArgs = append(fullArgs,
+		"--format",
+		"json",
+	)
+
+	eventsCmd := base.Cmd(fullArgs...).Start()
+	base.Cmd("run", "--rm", testutil.CommonImage).Start()
+	time.Sleep(3 * time.Second)
+	return eventsCmd.Stdout()
+}
+
+func TestEventFilters(t *testing.T) {
+
+	type testCase struct {
+		name       string
+		args       []string
+		nerdctlOut string
+		dockerOut  string
+		dockerSkip bool
+	}
+	testCases := []testCase{
+		{
+			name:       "CapitializedFilter",
+			args:       []string{"event=START"},
+			nerdctlOut: "\"Status\":\"start\"",
+			dockerOut:  "\"status\":\"start\"",
+			dockerSkip: true,
+		},
+		{
+			name:       "StartEventFilter",
+			args:       []string{"event=start"},
+			nerdctlOut: "\"Status\":\"start\"",
+			dockerOut:  "\"status\":\"start\"",
+			dockerSkip: false,
+		},
+		{
+			name:       "UnsupportedEventFilter",
+			args:       []string{"event=unknown"},
+			nerdctlOut: "\"Status\":\"unknown\"",
+			dockerSkip: true,
+		},
+		{
+			name:       "StatusFilter",
+			args:       []string{"status=start"},
+			nerdctlOut: "\"Status\":\"start\"",
+			dockerOut:  "\"status\":\"start\"",
+			dockerSkip: false,
+		},
+		{
+			name:       "UnsupportedStatusFilter",
+			args:       []string{"status=unknown"},
+			nerdctlOut: "\"Status\":\"unknown\"",
+			dockerSkip: true,
+		},
+	}
+
+	for _, tc := range testCases {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			actualOut := testEventFilter(t, tc.args...)
+			errorMsg := fmt.Sprintf("%s failed;\nActual Filter Result: '%s'", tc.name, actualOut)
+
+			isDocker := testutil.GetTarget() == testutil.Docker
+			if isDocker && tc.dockerSkip {
+				t.Skip("test is incompatible with Docker")
+			}
+
+			if isDocker {
+				assert.Equal(t, true, strings.Contains(actualOut, tc.dockerOut), errorMsg)
+			} else {
+				assert.Equal(t, true, strings.Contains(actualOut, tc.nerdctlOut), errorMsg)
+			}
+		})
+	}
+}

docs/command-reference.md

@@ -1275,8 +1275,10 @@ Usage: `nerdctl events [OPTIONS]`
 Flags:
 
 - :whale: `--format`: Format the output using the given Go template, e.g, `{{json .}}`
+- :whale: `-f, --filter`: Filter containers based on given conditions
+  - :whale: `--filter event=<value>`: Event's status. Start is the only supported status.
 
-Unimplemented `docker events` flags: `--filter`, `--since`, `--until`
+Unimplemented `docker events` flags: `--since`, `--until`
 
 ### :whale: nerdctl info
 

pkg/api/types/system_types.go

@@ -37,6 +37,8 @@ type SystemEventsOptions struct {
 	GOptions GlobalCommandOptions
 	// Format the output using the given Go template, e.g, '{{json .}}
 	Format string
+	// Filter events based on given conditions
+	Filters []string
 }
 
 // SystemPruneOptions specifies options for `nerdctl system prune`.

pkg/cmd/system/events.go

@@ -48,18 +48,101 @@ type EventOut struct {
 type Status string
 
 const (
-	START   Status = "START"
-	UNKNOWN Status = "UNKNOWN"
+	START   Status = "start"
+	UNKNOWN Status = "unknown"
 )
 
+var statuses = [...]Status{START, UNKNOWN}
+
+func isStatus(status string) bool {
+	status = strings.ToLower(status)
+
+	for _, supportedStatus := range statuses {
+		if string(supportedStatus) == status {
+			return true
+		}
+	}
+
+	return false
+}
+
 func TopicToStatus(topic string) Status {
-	if strings.Contains(strings.ToUpper(topic), string(START)) {
+	if strings.Contains(strings.ToLower(topic), string(START)) {
 		return START
 	}
 
 	return UNKNOWN
 }
 
+// EventFilter for filtering events
+type EventFilter func(*EventOut) bool
+
+// generateEventFilter is similar to Podman implementation:
+// https://github.com/containers/podman/blob/189d862d54b3824c74bf7474ddfed6de69ec5a09/libpod/events/filters.go#L11
+func generateEventFilter(filter, filterValue string) (func(e *EventOut) bool, error) {
+	switch strings.ToUpper(filter) {
+	case "EVENT", "STATUS":
+		return func(e *EventOut) bool {
+			if !isStatus(string(e.Status)) {
+				return false
+			}
+
+			return strings.EqualFold(string(e.Status), filterValue)
+		}, nil
+	}
+
+	return nil, fmt.Errorf("%s is an invalid or unsupported filter", filter)
+}
+
+// parseFilter is similar to Podman implementation:
+// https://github.com/containers/podman/blob/189d862d54b3824c74bf7474ddfed6de69ec5a09/libpod/events/filters.go#L96
+func parseFilter(filter string) (string, string, error) {
+	filterSplit := strings.SplitN(filter, "=", 2)
+	if len(filterSplit) != 2 {
+		return "", "", fmt.Errorf("%s is an invalid filter", filter)
+	}
+	return filterSplit[0], filterSplit[1], nil
+}
+
+// applyFilters is similar to Podman implementation:
+// https://github.com/containers/podman/blob/189d862d54b3824c74bf7474ddfed6de69ec5a09/libpod/events/filters.go#L106
+func applyFilters(event *EventOut, filterMap map[string][]EventFilter) bool {
+	for _, filters := range filterMap {
+		match := false
+		for _, filter := range filters {
+			if filter(event) {
+				match = true
+				break
+			}
+		}
+		if !match {
+			return false
+		}
+	}
+	return true
+}
+
+// generateEventFilters is similar to Podman implementation:
+// https://github.com/containers/podman/blob/189d862d54b3824c74bf7474ddfed6de69ec5a09/libpod/events/filters.go#L11
+func generateEventFilters(filters []string) (map[string][]EventFilter, error) {
+	filterMap := make(map[string][]EventFilter)
+	for _, filter := range filters {
+		key, val, err := parseFilter(filter)
+		if err != nil {
+			return nil, err
+		}
+		filterFunc, err := generateEventFilter(key, val)
+		if err != nil {
+			return nil, err
+		}
+		filterSlice := filterMap[key]
+		filterSlice = append(filterSlice, filterFunc)
+		filterMap[key] = filterSlice
+	}
+
+	return filterMap, nil
+}
+
 // Events is from https://github.com/containerd/containerd/blob/v1.4.3/cmd/ctr/commands/events/events.go
 func Events(ctx context.Context, client *containerd.Client, options types.SystemEventsOptions) error {
 	eventsClient := client.EventService()
@@ -77,6 +160,10 @@ func Events(ctx context.Context, client *containerd.Client, options types.System
 			return err
 		}
 	}
+	filterMap, err := generateEventFilters(options.Filters)
+	if err != nil {
+		return err
+	}
 	for {
 		var e *events.Envelope
 		select {
@@ -99,37 +186,41 @@ func Events(ctx context.Context, client *containerd.Client, options types.System
 					continue
 				}
 			}
-			if tmpl != nil {
-				var data map[string]interface{}
-				err := json.Unmarshal(out, &data)
-				if err != nil {
-					log.G(ctx).WithError(err).Warn("cannot marshal Any into JSON")
-				} else {
-					_, ok := data["container_id"]
-					if ok {
-						id = data["container_id"].(string)
-					}
+			var data map[string]interface{}
+			err := json.Unmarshal(out, &data)
+			if err != nil {
+				log.G(ctx).WithError(err).Warn("cannot marshal Any into JSON")
+			} else {
+				_, ok := data["container_id"]
+				if ok {
+					id = data["container_id"].(string)
 				}
+			}
 
-				out := EventOut{e.Timestamp, id, e.Namespace, e.Topic, TopicToStatus(e.Topic), string(out)}
-				var b bytes.Buffer
-				if err := tmpl.Execute(&b, out); err != nil {
-					return err
-				}
-				if _, err := fmt.Fprintln(options.Stdout, b.String()+"\n"); err != nil {
-					return err
-				}
-			} else {
-				if _, err := fmt.Fprintln(
-					options.Stdout,
-					e.Timestamp,
-					e.Namespace,
-					e.Topic,
-					string(out),
-				); err != nil {
-					return err
+			eOut := EventOut{e.Timestamp, id, e.Namespace, e.Topic, TopicToStatus(e.Topic), string(out)}
+			match := applyFilters(&eOut, filterMap)
+			if match {
+				if tmpl != nil {
+					var b bytes.Buffer
+					if err := tmpl.Execute(&b, eOut); err != nil {
+						return err
+					}
+					if _, err := fmt.Fprintln(options.Stdout, b.String()+"\n"); err != nil {
+						return err
+					}
+				} else {
+					if _, err := fmt.Fprintln(
+						options.Stdout,
+						e.Timestamp,
+						e.Namespace,
+						e.Topic,
+						string(out),
+					); err != nil {
+						return err
+					}
 				}
 			}
+
 		}
 	}
 }