libpod/containers/json: alias last -> limit

Support both `last` and `limit` for in the containers listing endpoint.
We intended to use `limit` which is also mentioned in the docs, but the
implementation ended up using `last` as the http parameter; likely being
caused by the CLI using `--last`.  To avoid any regression, we decided
for supporting both and aliasing `last`.

Fixes: #6413
Signed-off-by: Valentin Rothberg <rothberg@redhat.com>

3 files changed, 37 insertions, 3 deletions

diff --git a/pkg/api/handlers/libpod/containers.go b/pkg/api/handlers/libpod/containers.go
index 2556cdc2a..506286736 100644
--- a/pkg/api/handlers/libpod/containers.go
+++ b/pkg/api/handlers/libpod/containers.go
@@ -14,6 +14,7 @@ import (
 	"github.com/containers/libpod/pkg/ps"
 	"github.com/gorilla/schema"
 	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
 )
 
 func ContainerExists(w http.ResponseWriter, r *http.Request) {
@@ -36,7 +37,8 @@ func ListContainers(w http.ResponseWriter, r *http.Request) {
 	query := struct {
 		All       bool                `schema:"all"`
 		Filters   map[string][]string `schema:"filters"`
-		Last      int                 `schema:"last"`
+		Last      int                 `schema:"last"` // alias for limit
+		Limit     int                 `schema:"limit"`
 		Namespace bool                `schema:"namespace"`
 		Pod       bool                `schema:"pod"`
 		Size      bool                `schema:"size"`
@@ -50,11 +52,22 @@ func ListContainers(w http.ResponseWriter, r *http.Request) {
 			errors.Wrapf(err, "Failed to parse parameters for %s", r.URL.String()))
 		return
 	}
+
+	limit := query.Limit
+	// Support `last` as an alias for `limit`.  While Podman uses --last in
+	// the CLI, the API is using `limit`.  As we first used `last` in the
+	// API as well, we decided to go with aliasing to prevent any
+	// regression. See github.com/containers/libpod/issues/6413.
+	if _, found := r.URL.Query()["last"]; found {
+		logrus.Info("List containers: received `last` parameter - overwriting `limit`")
+		limit = query.Last
+	}
+
 	runtime := r.Context().Value("runtime").(*libpod.Runtime)
 	opts := entities.ContainerListOptions{
 		All:       query.All,
 		Filters:   query.Filters,
-		Last:      query.Last,
+		Last:      limit,
 		Size:      query.Size,
 		Sort:      "",
 		Namespace: query.Namespace,
diff --git a/pkg/bindings/containers/containers.go b/pkg/bindings/containers/containers.go
index 929b6bbd5..8c588bb40 100644
--- a/pkg/bindings/containers/containers.go
+++ b/pkg/bindings/containers/containers.go
@@ -35,7 +35,7 @@ func List(ctx context.Context, filters map[string][]string, all *bool, last *int
 		params.Set("all", strconv.FormatBool(*all))
 	}
 	if last != nil {
-		params.Set("last", strconv.Itoa(*last))
+		params.Set("limit", strconv.Itoa(*last))
 	}
 	if pod != nil {
 		params.Set("pod", strconv.FormatBool(*pod))
diff --git a/test/apiv2/20-containers.at b/test/apiv2/20-containers.at
index 60f6d97aa..9efebfeb9 100644
--- a/test/apiv2/20-containers.at
+++ b/test/apiv2/20-containers.at
@@ -26,6 +26,27 @@ t GET libpod/containers/json?all=true 200 \
   .[0].ExitCode=0 \
   .[0].IsInfra=false
 
+# Make sure `limit` works.
+t GET libpod/containers/json?limit=1 200 \
+  length=1 \
+  .[0].Id~[0-9a-f]\\{64\\} \
+  .[0].Image=$IMAGE \
+  .[0].Command[0]="true" \
+  .[0].State~\\\(exited\\\|stopped\\\) \
+  .[0].ExitCode=0 \
+  .[0].IsInfra=false
+
+# Make sure `last` works, which is an alias for `limit`.
+# See https://github.com/containers/libpod/issues/6413.
+t GET libpod/containers/json?last=1 200 \
+  length=1 \
+  .[0].Id~[0-9a-f]\\{64\\} \
+  .[0].Image=$IMAGE \
+  .[0].Command[0]="true" \
+  .[0].State~\\\(exited\\\|stopped\\\) \
+  .[0].ExitCode=0 \
+  .[0].IsInfra=false
+
 cid=$(jq -r '.[0].Id' <<<"$output")
 
 t DELETE libpod/containers/$cid 204