wait: add --ignore option

In the recent past, I met the frequent need to wait for a container to
exist that, at the same time, may get removed (e.g., system tests in [1]).

Add an `--ignore` option to podman-wait which will ignore errors when a
specified container is missing and mark its exit code as -1.  Also
remove ID fields from the WaitReport.  It is actually not used by
callers and removing it makes the code simpler and faster.

Once merged, we can go over the tests and simplify them.

[1] github.com/containers/podman/pull/16852

Signed-off-by: Valentin Rothberg <vrothberg@redhat.com>

cmd/podman/containers/wait.go

@@ -53,6 +53,8 @@ func waitFlags(cmd *cobra.Command) {
 	flags.StringVarP(&waitInterval, intervalFlagName, "i", "250ms", "Time Interval to wait before polling for completion")
 	_ = cmd.RegisterFlagCompletionFunc(intervalFlagName, completion.AutocompleteNone)
 
+	flags.BoolVarP(&waitOptions.Ignore, "ignore", "", false, "Ignore if a container does not exist")
+
 	conditionFlagName := "condition"
 	flags.StringSliceVar(&waitConditions, conditionFlagName, []string{}, "Condition to wait on")
 	_ = cmd.RegisterFlagCompletionFunc(conditionFlagName, common.AutocompleteWaitCondition)

docs/source/markdown/podman-wait.1.md.in

@@ -23,6 +23,10 @@ Condition to wait on (default "stopped")
 
  Print usage statement
 
+
+#### **--ignore**
+Ignore errors when a specified container is missing and mark its return code as -1.
+
 #### **--interval**, **-i**=*duration*
   Time interval to wait before polling for completion. A duration string is a sequence of decimal numbers, each with optional fraction and a unit suffix, such as "300ms", "-1.5h" or "2h45m". Valid time units are "ns", "us" (or "µs"), "ms", "s", "m", "h". Time unit defaults to "ms".
 
@@ -46,6 +50,9 @@ $ podman wait 860a4b23
 $ podman wait mywebserver myftpserver
 0
 125
+
+$ podman wait --ignore does-not-exist
+-1
 ```
 
 ## SEE ALSO

pkg/domain/entities/containers.go

@@ -52,11 +52,11 @@ type ContainerRunlabelReport struct{}
 type WaitOptions struct {
 	Condition []define.ContainerStatus
 	Interval  time.Duration
+	Ignore    bool
 	Latest    bool
 }
 
 type WaitReport struct {
-	Id       string //nolint:revive,stylecheck
 	Error    error
 	ExitCode int32
 }

pkg/domain/infra/abi/containers.go

@@ -139,13 +139,29 @@ func (ic *ContainerEngine) ContainerExists(ctx context.Context, nameOrID string,
 }
 
 func (ic *ContainerEngine) ContainerWait(ctx context.Context, namesOrIds []string, options entities.WaitOptions) ([]entities.WaitReport, error) {
-	ctrs, err := getContainersByContext(false, options.Latest, false, namesOrIds, ic.Libpod)
+	responses := make([]entities.WaitReport, 0, len(namesOrIds))
-	if err != nil {
+	if options.Latest {
-		return nil, err
+		ctr, err := ic.Libpod.GetLatestContainer()
+		if err != nil {
+			if options.Ignore && errors.Is(err, define.ErrNoSuchCtr) {
+				responses = append(responses, entities.WaitReport{ExitCode: -1})
+				return responses, nil
+			}
+			return nil, err
+		}
+		namesOrIds = append(namesOrIds, ctr.ID())
 	}
-	responses := make([]entities.WaitReport, 0, len(ctrs))
+	for _, n := range namesOrIds {
-	for _, c := range ctrs {
+		c, err := ic.Libpod.LookupContainer(n)
-		response := entities.WaitReport{Id: c.ID()}
+		if err != nil {
+			if options.Ignore && errors.Is(err, define.ErrNoSuchCtr) {
+				responses = append(responses, entities.WaitReport{ExitCode: -1})
+				continue
+			}
+			return nil, err
+		}
+
+		response := entities.WaitReport{}
 		if options.Condition == nil {
 			options.Condition = []define.ContainerStatus{define.ContainerStateStopped, define.ContainerStateExited}
 		}

pkg/domain/infra/tunnel/containers.go

@@ -38,17 +38,17 @@ func (ic *ContainerEngine) ContainerExists(ctx context.Context, nameOrID string,
 }
 
 func (ic *ContainerEngine) ContainerWait(ctx context.Context, namesOrIds []string, opts entities.WaitOptions) ([]entities.WaitReport, error) {
-	cons, err := getContainersByContext(ic.ClientCtx, false, false, namesOrIds)
+	responses := make([]entities.WaitReport, 0, len(namesOrIds))
-	if err != nil {
-		return nil, err
-	}
-	responses := make([]entities.WaitReport, 0, len(cons))
 	options := new(containers.WaitOptions).WithCondition(opts.Condition).WithInterval(opts.Interval.String())
-	for _, c := range cons {
+	for _, n := range namesOrIds {
-		response := entities.WaitReport{Id: c.ID}
+		response := entities.WaitReport{}
-		exitCode, err := containers.Wait(ic.ClientCtx, c.ID, options)
+		exitCode, err := containers.Wait(ic.ClientCtx, n, options)
 		if err != nil {
-			response.Error = err
+			if opts.Ignore && errorhandling.Contains(err, define.ErrNoSuchCtr) {
+				response.ExitCode = -1
+			} else {
+				response.Error = err
+			}
 		} else {
 			response.ExitCode = exitCode
 		}

test/system/055-rm.bats

@@ -20,6 +20,15 @@ load helpers
     run_podman rm $rand
     is "$output" "$rand" "display raw input"
     run_podman 125 inspect $rand
+    run_podman 125 wait $rand
+    run_podman wait --ignore $rand
+    is "$output" "-1" "wait --ignore will mark missing containers with -1"
+
+    if !is_remote; then
+        # remote does not support the --latest flag
+        run_podman wait --ignore --latest
+        is "$output" "-1" "wait --ignore will mark missing containers with -1"
+    fi
 }
 
 @test "podman rm - running container, w/o and w/ force" {