devmapper: add no_devmapper build tag

Signed-off-by: Maksym Pavlenko <makpav@amazon.com>

BUILDING.md

@@ -104,6 +104,7 @@ make generate
 > * `no_btrfs`: A build tag disables building the btrfs snapshot driver.
 > * `no_cri`: A build tag disables building Kubernetes [CRI](http://blog.kubernetes.io/2016/12/container-runtime-interface-cri-in-kubernetes.html) support into containerd.
 > See [here](https://github.com/containerd/cri-containerd#build-tags) for build tags of CRI plugin.
+> * `no_devmapper`: A build tag disables building the device mapper snapshot driver.
 >
 > For example, adding `BUILDTAGS=no_btrfs` to your environment before calling the **binaries**
 > Makefile target will disable the btrfs driver within the containerd Go build.

cmd/containerd/builtins_devmapper_linux.go

@@ -0,0 +1,21 @@
+// +build !no_devmapper
+
+/*
+   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 _ "github.com/containerd/containerd/snapshots/devmapper"

cmd/containerd/builtins_linux.go

@@ -22,7 +22,6 @@ import (
 	_ "github.com/containerd/containerd/runtime/v1/linux"
 	_ "github.com/containerd/containerd/runtime/v2"
 	_ "github.com/containerd/containerd/runtime/v2/runc/options"
-	_ "github.com/containerd/containerd/snapshots/devmapper"
 	_ "github.com/containerd/containerd/snapshots/native"
 	_ "github.com/containerd/containerd/snapshots/overlay"
 	_ "github.com/containerd/zfs"