Make kubelet expand var refs in cmd, args, env

pkg/kubelet/container/helpers.go

@@ -22,6 +22,8 @@ import (
 
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
+	"github.com/GoogleCloudPlatform/kubernetes/third_party/golang/expansion"
+
 	"github.com/golang/glog"
 )
 
@@ -90,3 +92,32 @@ func HashContainer(container *api.Container) uint64 {
 	util.DeepHashObject(hash, *container)
 	return uint64(hash.Sum32())
 }
+
+// EnvVarsToMap constructs a map of environment name to value from a slice
+// of env vars.
+func EnvVarsToMap(envs []EnvVar) map[string]string {
+	result := map[string]string{}
+	for _, env := range envs {
+		result[env.Name] = env.Value
+	}
+
+	return result
+}
+
+func ExpandContainerCommandAndArgs(container *api.Container, envs []EnvVar) (command []string, args []string) {
+	mapping := expansion.MappingFuncFor(EnvVarsToMap(envs))
+
+	if len(container.Command) != 0 {
+		for _, cmd := range container.Command {
+			command = append(command, expansion.Expand(cmd, mapping))
+		}
+	}
+
+	if len(container.Args) != 0 {
+		for _, arg := range container.Args {
+			args = append(args, expansion.Expand(arg, mapping))
+		}
+	}
+
+	return command, args
+}

pkg/kubelet/container/helpers_test.go

@@ -0,0 +1,136 @@
+/*
+Copyright 2015 The Kubernetes Authors All rights reserved.
+
+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 container
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
+)
+
+func TestEnvVarsToMap(t *testing.T) {
+	vars := []EnvVar{
+		{
+			Name:  "foo",
+			Value: "bar",
+		},
+		{
+			Name:  "zoo",
+			Value: "baz",
+		},
+	}
+
+	varMap := EnvVarsToMap(vars)
+
+	if e, a := len(vars), len(varMap); e != a {
+		t.Error("Unexpected map length; expected: %v, got %v", e, a)
+	}
+
+	if a := varMap["foo"]; a != "bar" {
+		t.Errorf("Unexpected value of key 'foo': %v", a)
+	}
+
+	if a := varMap["zoo"]; a != "baz" {
+		t.Errorf("Unexpected value of key 'zoo': %v", a)
+	}
+}
+
+func TestExpandCommandAndArgs(t *testing.T) {
+	cases := []struct {
+		name            string
+		container       *api.Container
+		envs            []EnvVar
+		expectedCommand []string
+		expectedArgs    []string
+	}{
+		{
+			name:      "none",
+			container: &api.Container{},
+		},
+		{
+			name: "command expanded",
+			container: &api.Container{
+				Command: []string{"foo", "$(VAR_TEST)", "$(VAR_TEST2)"},
+			},
+			envs: []EnvVar{
+				{
+					Name:  "VAR_TEST",
+					Value: "zoo",
+				},
+				{
+					Name:  "VAR_TEST2",
+					Value: "boo",
+				},
+			},
+			expectedCommand: []string{"foo", "zoo", "boo"},
+		},
+		{
+			name: "args expanded",
+			container: &api.Container{
+				Args: []string{"zap", "$(VAR_TEST)", "$(VAR_TEST2)"},
+			},
+			envs: []EnvVar{
+				{
+					Name:  "VAR_TEST",
+					Value: "hap",
+				},
+				{
+					Name:  "VAR_TEST2",
+					Value: "trap",
+				},
+			},
+			expectedArgs: []string{"zap", "hap", "trap"},
+		},
+		{
+			name: "both expanded",
+			container: &api.Container{
+				Command: []string{"$(VAR_TEST2)--$(VAR_TEST)", "foo", "$(VAR_TEST3)"},
+				Args:    []string{"foo", "$(VAR_TEST)", "$(VAR_TEST2)"},
+			},
+			envs: []EnvVar{
+				{
+					Name:  "VAR_TEST",
+					Value: "zoo",
+				},
+				{
+					Name:  "VAR_TEST2",
+					Value: "boo",
+				},
+				{
+					Name:  "VAR_TEST3",
+					Value: "roo",
+				},
+			},
+			expectedCommand: []string{"boo--zoo", "foo", "roo"},
+			expectedArgs:    []string{"foo", "zoo", "boo"},
+		},
+	}
+
+	for _, tc := range cases {
+		actualCommand, actualArgs := ExpandContainerCommandAndArgs(tc.container, tc.envs)
+
+		if e, a := tc.expectedCommand, actualCommand; !reflect.DeepEqual(e, a) {
+			t.Errorf("%v: unexpected command; expected %v, got %v", tc.name, e, a)
+		}
+
+		if e, a := tc.expectedArgs, actualArgs; !reflect.DeepEqual(e, a) {
+			t.Errorf("%v: unexpected args; expected %v, got %v", tc.name, e, a)
+		}
+
+	}
+}