[#137] FreeBSD support

Now that containerd supports FreeBSD, we can port nerdctl, too!
:rocket:. For full-fledged functionality, we will need to port

* buildkit. Status: POC is ready, need to upstream fixes to
  dependencies.
* runtime + containerd shim. runj/knast should work just fine.
* CNI bridge plugin for networking.

This change fixes FreeBSD compilation errors by renaming linux files
to unix where necessary, or otherwise introducing FreeBSD versions for
the necessary files.

Signed-off-by: Artem Khramov <akhramov@pm.me>

cmd/nerdctl/client_linux.go → cmd/nerdctl/client_unix.go

@@ -1,3 +1,6 @@
+//go:build freebsd || linux
+// +build freebsd linux
+
 /*
    Copyright The containerd Authors.
 

cmd/nerdctl/exec_freebsd.go

@@ -0,0 +1,29 @@
+//go:build freebsd
+// +build freebsd
+
+/*
+   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/opencontainers/runtime-spec/specs-go"
+)
+
+func setExecCapabilities(pspec *specs.Process) error {
+	//no op freebsd
+	return nil
+}

cmd/nerdctl/login_linux.go → cmd/nerdctl/login_unix.go

@@ -1,3 +1,6 @@
+//go:build freebsd || linux
+// +build freebsd linux
+
 /*
    Copyright The containerd Authors.
 

cmd/nerdctl/main_freebsd.go

@@ -0,0 +1,40 @@
+//go:build freebsd
+// +build freebsd
+
+/*
+   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/urfave/cli/v2"
+)
+
+func appNeedsRootlessParentMain(clicontext *cli.Context) bool {
+	return false
+}
+
+func appBashComplete(clicontext *cli.Context) {
+	return
+}
+
+func bashCompleteNamespaceNames(clicontext *cli.Context) {
+	return
+}
+
+func bashCompleteSnapshotterNames(clicontext *cli.Context) {
+	return
+}

cmd/nerdctl/run.go

@@ -25,6 +25,7 @@ import (
 	"os"
 	"path"
 	"path/filepath"
+	"runtime"
 	"strings"
 
 	"github.com/containerd/console"
@@ -315,12 +316,16 @@ func runAction(clicontext *cli.Context) error {
 	opts = append(opts,
 		oci.WithDefaultSpec(),
 		oci.WithDefaultUnixDevices,
-		oci.WithMounts([]specs.Mount{
-			{Type: "cgroup", Source: "cgroup", Destination: "/sys/fs/cgroup", Options: []string{"ro", "nosuid", "noexec", "nodev"}},
-		}),
 		WithoutRunMount(), // unmount default tmpfs on "/run": https://github.com/containerd/nerdctl/issues/157
 	)
 
+	if runtime.GOOS != "freebsd" {
+		opts = append(opts,
+			oci.WithMounts([]specs.Mount{
+				{Type: "cgroup", Source: "cgroup", Destination: "/sys/fs/cgroup", Options: []string{"ro", "nosuid", "noexec", "nodev"}},
+			}))
+	}
+
 	rootfsOpts, rootfsCOpts, ensuredImage, err := generateRootfsOpts(ctx, client, clicontext, id)
 	if err != nil {
 		return err

cmd/nerdctl/run_cgroup_freebsd.go

@@ -0,0 +1,29 @@
+//go:build freebsd
+// +build freebsd
+
+/*
+   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/oci"
+	"github.com/urfave/cli/v2"
+)
+
+func generateCgroupOpts(clicontext *cli.Context, id string) ([]oci.SpecOpts, error) {
+	return []oci.SpecOpts{}, nil
+}

cmd/nerdctl/run_freebsd.go

@@ -0,0 +1,37 @@
+//go:build freebsd
+// +build freebsd
+
+/*
+   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 (
+	"context"
+
+	"github.com/containerd/containerd/containers"
+	"github.com/containerd/containerd/oci"
+	"github.com/urfave/cli/v2"
+)
+
+func runBashComplete(clicontext *cli.Context) {
+	// noop
+}
+
+func WithoutRunMount() func(ctx context.Context, client oci.Client, c *containers.Container, s *oci.Spec) error {
+	// not valid on windows
+	return func(_ context.Context, _ oci.Client, _ *containers.Container, s *oci.Spec) error { return nil }
+}

pkg/containerinspector/containerinspector_freebsd.go

@@ -0,0 +1,32 @@
+//go:build freebsd
+// +build freebsd
+
+/*
+   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 containerinspector
+
+import (
+	"context"
+
+	"github.com/containerd/nerdctl/pkg/inspecttypes/native"
+)
+
+func inspectNetNS(ctx context.Context, pid int) (*native.NetNS, error) {
+	r := &native.NetNS{}
+
+	return r, nil
+}

pkg/defaults/defaults_freebsd.go

@@ -0,0 +1,51 @@
+//go:build freebsd
+// +build freebsd
+
+/*
+   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 defaults
+
+import (
+	gocni "github.com/containerd/go-cni"
+)
+
+const AppArmorProfileName = "nerdctl-default"
+
+func DataRoot() string {
+	return "/var/lib/nerdctl"
+}
+
+func CNIPath() string {
+	// default: /opt/cni/bin
+	return gocni.DefaultCNIDir
+}
+
+func CNINetConfPath() string {
+	return gocni.DefaultNetDir
+}
+
+func BuildKitHost() string {
+	return "unix:///run/buildkit/buildkitd.sock"
+}
+
+func CgroupManager() string {
+	return ""
+}
+
+func CgroupnsMode() string {
+	return ""
+}

pkg/infoutil/infoutil_freebsd.go

@@ -0,0 +1,26 @@
+//go:build freebsd
+// +build freebsd
+
+/*
+   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 infoutil
+
+const UnameO = "FreeBSD"
+
+func CgroupsVersion() string {
+	return ""
+}

pkg/infoutil/infoutil_linux.go

@@ -17,98 +17,11 @@
 package infoutil
 
 import (
-	"bufio"
-	"io"
-	"os"
-	"regexp"
-
-	"strings"
-
 	"github.com/containerd/cgroups"
-	"golang.org/x/sys/unix"
 )
 
-// UnameR returns `uname -r`
-func UnameR() string {
-	var utsname unix.Utsname
-	if err := unix.Uname(&utsname); err != nil {
-		// error is unlikely to happen
-		return ""
-	}
-	var s string
-	for _, f := range utsname.Release {
-		if f == 0 {
-			break
-		}
-		s += string(f)
-	}
-	return s
-}
-
-// UnameM returns `uname -m`
-func UnameM() string {
-	var utsname unix.Utsname
-	if err := unix.Uname(&utsname); err != nil {
-		// error is unlikely to happen
-		return ""
-	}
-	var s string
-	for _, f := range utsname.Machine {
-		if f == 0 {
-			break
-		}
-		s += string(f)
-	}
-	return s
-}
-
 const UnameO = "GNU/Linux"
 
-func DistroName() string {
-	f, err := os.Open("/etc/os-release")
-	if err != nil {
-		return UnameO
-	}
-	defer f.Close()
-	return distroName(f)
-}
-
-func distroName(r io.Reader) string {
-	scanner := bufio.NewScanner(r)
-	var name, version string
-	for scanner.Scan() {
-		line := scanner.Text()
-		k, v := getOSReleaseAttrib(line)
-		switch k {
-		case "PRETTY_NAME":
-			return v
-		case "NAME":
-			name = v
-		case "VERSION":
-			version = v
-		}
-	}
-	if name != "" {
-		if version != "" {
-			return name + " " + version
-		}
-		return name
-	}
-	return UnameO
-}
-
-var osReleaseAttribRegex = regexp.MustCompile(`([^\s=]+)\s*=\s*("{0,1})([^"]*)("{0,1})`)
-
-func getOSReleaseAttrib(line string) (string, string) {
-	splitBySlash := strings.SplitN(line, "#", 2)
-	l := strings.TrimSpace(splitBySlash[0])
-	x := osReleaseAttribRegex.FindAllStringSubmatch(l, -1)
-	if len(x) >= 1 && len(x[0]) > 3 {
-		return x[0][1], x[0][3]
-	}
-	return "", ""
-}
-
 func CgroupsVersion() string {
 	if cgroups.Mode() == cgroups.Unified {
 		return "2"