Add containerd connection info to info endpoint (API v1.46)

This will be used in the next commit to test that changes are propagated
to the containerd store.
It is also just generally useful for debugging purposes.

- docs/api: update version history
- daemon: add fillContainerdInfo utility
- api: update swagger file with new types

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
Signed-off-by: Bjorn Neergaard <bjorn.neergaard@docker.com>
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

api/server/router/system/system_routes.go

@@ -97,6 +97,10 @@ func (s *systemRouter) getInfo(ctx context.Context, w http.ResponseWriter, r *ht
 				info.Runtimes[k] = system.RuntimeWithStatus{Runtime: rt.Runtime}
 			}
 		}
+		if versions.LessThan(version, "1.46") {
+			// Containerd field introduced in API v1.46.
+			info.Containerd = nil
+		}
 		if versions.GreaterThanOrEqualTo(version, "1.42") {
 			info.KernelMemory = false
 		}

api/swagger.yaml

@@ -5824,6 +5824,58 @@ definitions:
         example:
           - "/etc/cdi"
           - "/var/run/cdi"
+      Containerd:
+        $ref: "#/definitions/ContainerdInfo"
+        x-nullable: true
+
+  ContainerdInfo:
+    description: |
+      Information for connecting to the containerd instance that is used by the daemon.
+      This is included for debugging purposes only.
+    type: "object"
+    properties:
+      Address:
+        description: "The address of the containerd socket."
+        type: "string"
+        example: "/run/containerd/containerd.sock"
+      Namespaces:
+        description: |
+          The namespaces that the daemon uses for running containers and
+          plugins in containerd. These namespaces can be configured in the
+          daemon configuration, and are considered to be used exclusively
+          by the daemon, Tampering with the containerd instance may cause
+          unexpected behavior.
+
+          As these namespaces are considered to be exclusively accessed
+          by the daemon, it is not recommended to change these values,
+          or to change them to a value that is used by other systems,
+          such as cri-containerd.
+        type: "object"
+        properties:
+          Containers:
+            description: |
+              The default containerd namespace used for containers managed
+              by the daemon.
+
+              The default namespace for containers is "moby", but will be
+              suffixed with the `<uid>.<gid>` of the remapped `root` if
+              user-namespaces are enabled and the containerd image-store
+              is used.
+            type: "string"
+            default: "moby"
+            example: "moby"
+          Plugins:
+            description: |
+              The default containerd namespace used for plugins managed by
+              the daemon.
+
+              The default namespace for plugins is "plugins.moby", but will be
+              suffixed with the `<uid>.<gid>` of the remapped `root` if
+              user-namespaces are enabled and the containerd image-store
+              is used.
+            type: "string"
+            default: "plugins.moby"
+            example: "plugins.moby"
 
   # PluginsInfo is a temp struct holding Plugins name
   # registered with docker daemon. It is used by Info struct

api/types/system/info.go

@@ -75,6 +75,8 @@ type Info struct {
 	DefaultAddressPools []NetworkAddressPool `json:",omitempty"`
 	CDISpecDirs         []string
 
+	Containerd *ContainerdInfo `json:",omitempty"`
+
 	// Legacy API fields for older API versions.
 	legacyFields
 
@@ -85,6 +87,43 @@ type Info struct {
 	Warnings []string
 }
 
+// ContainerdInfo holds information about the containerd instance used by the daemon.
+type ContainerdInfo struct {
+	// Address is the path to the containerd socket.
+	Address string `json:",omitempty"`
+	// Namespaces is the containerd namespaces used by the daemon.
+	Namespaces ContainerdNamespaces
+}
+
+// ContainerdNamespaces reflects the containerd namespaces used by the daemon.
+//
+// These namespaces can be configured in the daemon configuration, and are
+// considered to be used exclusively by the daemon,
+//
+// As these namespaces are considered to be exclusively accessed
+// by the daemon, it is not recommended to change these values,
+// or to change them to a value that is used by other systems,
+// such as cri-containerd.
+type ContainerdNamespaces struct {
+	// Containers holds the default containerd namespace used for
+	// containers managed by the daemon.
+	//
+	// The default namespace for containers is "moby", but will be
+	// suffixed with the `<uid>.<gid>` of the remapped `root` if
+	// user-namespaces are enabled and the containerd image-store
+	// is used.
+	Containers string
+
+	// Plugins holds the default containerd namespace used for
+	// plugins managed by the daemon.
+	//
+	// The default namespace for plugins is "moby", but will be
+	// suffixed with the `<uid>.<gid>` of the remapped `root` if
+	// user-namespaces are enabled and the containerd image-store
+	// is used.
+	Plugins string
+}
+
 type legacyFields struct {
 	ExecutionDriver string `json:",omitempty"` // Deprecated: deprecated since API v1.25, but returned for older versions.
 }

daemon/info.go

@@ -82,7 +82,9 @@ func (daemon *Daemon) SystemInfo(ctx context.Context) (*system.Info, error) {
 
 	daemon.fillContainerStates(v)
 	daemon.fillDebugInfo(ctx, v)
+	daemon.fillContainerdInfo(v, &cfg.Config)
 	daemon.fillAPIInfo(v, &cfg.Config)
+
 	// Retrieve platform specific info
 	if err := daemon.fillPlatformInfo(ctx, v, sysInfo, cfg); err != nil {
 		return nil, err
@@ -227,6 +229,22 @@ func (daemon *Daemon) fillDebugInfo(ctx context.Context, v *system.Info) {
 	v.NFd = fileutils.GetTotalUsedFds(ctx)
 	v.NGoroutines = runtime.NumGoroutine()
 	v.NEventsListener = daemon.EventsService.SubscribersCount()
+
+}
+
+// fillContainerdInfo provides information about the containerd configuration
+// for debugging purposes.
+func (daemon *Daemon) fillContainerdInfo(v *system.Info, cfg *config.Config) {
+	if cfg.ContainerdAddr == "" {
+		return
+	}
+	v.Containerd = &system.ContainerdInfo{
+		Address: cfg.ContainerdAddr,
+		Namespaces: system.ContainerdNamespaces{
+			Containers: cfg.ContainerdNamespace,
+			Plugins:    cfg.ContainerdPluginNamespace,
+		},
+	}
 }
 
 func (daemon *Daemon) fillAPIInfo(v *system.Info, cfg *config.Config) {

docs/api/version-history.md

@@ -17,6 +17,9 @@ keywords: "API, Docker, rcli, REST, documentation"
 
 [Docker Engine API v1.46](https://docs.docker.com/engine/api/v1.46/) documentation
 
+* `GET /info` now includes a `Containerd` field containing information about
+  the location of the containerd API socket and containerd namespaces used
+  by the daemon to run containers and plugins.
 * `POST /containers/create` field `NetworkingConfig.EndpointsConfig.DriverOpts`,
   and `POST /networks/{id}/connect` field `EndpointsConfig.DriverOpts`, now
   support label `com.docker.network.endpoint.sysctls` for setting per-interface