Use default UNIX env when image has no environment

Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com>

oci/spec_opts.go

@@ -333,7 +333,11 @@ func WithImageConfigArgs(image Image, args []string) SpecOpts {
 
 		setProcess(s)
 		if s.Linux != nil {
-			s.Process.Env = replaceOrAppendEnvValues(config.Env, s.Process.Env)
+			defaults := config.Env
+			if len(defaults) == 0 {
+				defaults = defaultUnixEnv
+			}
+			s.Process.Env = replaceOrAppendEnvValues(defaults, s.Process.Env)
 			cmd := config.Cmd
 			if len(args) > 0 {
 				cmd = args

oci/spec_opts_unix_test.go

@@ -0,0 +1,72 @@
+// +build !windows
+
+/*
+   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 oci
+
+import (
+	"context"
+	"testing"
+
+	"github.com/containerd/containerd/containers"
+	"github.com/containerd/containerd/namespaces"
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+	specs "github.com/opencontainers/runtime-spec/specs-go"
+)
+
+func TestWithImageConfigNoEnv(t *testing.T) {
+	t.Parallel()
+	var (
+		s   Spec
+		c   = containers.Container{ID: "TestWithImageConfigNoEnv"}
+		ctx = namespaces.WithNamespace(context.Background(), "test")
+	)
+
+	err := populateDefaultUnixSpec(ctx, &s, c.ID)
+	if err != nil {
+		t.Fatal(err)
+	}
+	// test hack: we don't want to test the WithAdditionalGIDs portion of the image config code
+	s.Windows = &specs.Windows{}
+
+	img, err := newFakeImage(ocispec.Image{
+		Config: ocispec.ImageConfig{
+			Entrypoint: []string{"create", "--namespace=test"},
+			Cmd:        []string{"", "--debug"},
+		},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	opts := []SpecOpts{
+		WithImageConfigArgs(img, []string{"--boo", "bar"}),
+	}
+
+	// verify that if an image has no environment that we get a default Unix path
+	expectedEnv := []string{"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"}
+
+	for _, opt := range opts {
+		if err := opt(nil, nil, nil, &s); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	if err := assertEqualsStringArrays(s.Process.Env, expectedEnv); err != nil {
+		t.Fatal(err)
+	}
+}