Add util functions to set/unset env variables

Proposed util functions can set variable amount of env vars at once,
covered with unit tests and handles possible errors in more convenient
way.

Change-Id: Ibd31f528fba1b10be49d1e8cc5e5f29c6b3d902a
Signed-off-by: Ruslan Aliev <raliev@mirantis.com>

pkg/util/env.go

@@ -0,0 +1,48 @@
+/*
+ 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
+
+     https://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 util
+
+import (
+	"os"
+
+	"opendev.org/airship/airshipctl/pkg/log"
+)
+
+// EnvVar is an object to store key:value pairs to set/unset environment variables
+type EnvVar struct {
+	Key   string
+	Value string
+}
+
+// Setenv is used to set variable number of env variables, if an error occurs it will be printed to logger
+func Setenv(envVars ...EnvVar) {
+	for _, envVar := range envVars {
+		if err := os.Setenv(envVar.Key, envVar.Value); err != nil {
+			log.Printf("unable to set '%s' env variable, reason '%s'", envVar.Key, err.Error())
+		}
+	}
+}
+
+// Unsetenv is used to unset variable number of env variables, if an error occurs it will be printed to logger
+func Unsetenv(envVars ...EnvVar) {
+	for _, envVar := range envVars {
+		if err := os.Unsetenv(envVar.Key); err != nil {
+			// Unsetenv on Unix never returns an error [1], so we can't emulate it in unit tests and
+			// this error message will never be printed
+			// [1] https://golang.org/src/syscall/env_unix.go
+			log.Printf("unable to unset '%s' env variable, reason '%s'", envVar.Key, err.Error())
+		}
+	}
+}

pkg/util/env_test.go

@@ -0,0 +1,116 @@
+/*
+ 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
+
+     https://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 util_test
+
+import (
+	"bytes"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"opendev.org/airship/airshipctl/pkg/log"
+	"opendev.org/airship/airshipctl/pkg/util"
+)
+
+func TestSetenv(t *testing.T) {
+	tests := []struct {
+		name        string
+		input       []util.EnvVar
+		expectedOut string
+	}{
+		{
+			name: "success one env",
+			input: []util.EnvVar{{
+				Key:   "AIRSHIPCTL_TEST_KEY",
+				Value: "AIRSHIPCTL_TEST_VALUE",
+			}},
+			expectedOut: "",
+		},
+		{
+			name: "success multiple envs",
+			input: []util.EnvVar{{
+				Key:   "AIRSHIPCTL_TEST_KEY_1",
+				Value: "AIRSHIPCTL_TEST_VALUE_1",
+			}, {
+				Key:   "AIRSHIPCTL_TEST_KEY_2",
+				Value: "AIRSHIPCTL_TEST_VALUE_2"}},
+			expectedOut: "",
+		},
+		{
+			name: "fail to set",
+			input: []util.EnvVar{{
+				Key: "invalid_key\x00",
+			}},
+			expectedOut: "unable to set 'invalid_key\x00' env variable, reason 'setenv: invalid argument'",
+		},
+	}
+
+	buf := &bytes.Buffer{}
+	log.Init(false, buf)
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			buf.Reset()
+			util.Setenv(tt.input...)
+			require.Contains(t, buf.String(), tt.expectedOut)
+			if tt.expectedOut == "" {
+				for _, key := range tt.input {
+					require.Equal(t, key.Value, os.Getenv(key.Key))
+				}
+			}
+		})
+	}
+}
+
+func TestUnsetenv(t *testing.T) {
+	tests := []struct {
+		name        string
+		input       []util.EnvVar
+		expectedOut string
+	}{
+		{
+			name: "success one env",
+			input: []util.EnvVar{{
+				Key: "AIRSHIPCTL_TEST_KEY",
+			}},
+			expectedOut: "",
+		},
+		{
+			name: "success multiple envs",
+			input: []util.EnvVar{{
+				Key: "AIRSHIPCTL_TEST_KEY_1",
+			}, {
+				Key: "AIRSHIPCTL_TEST_KEY_2"}},
+			expectedOut: "",
+		},
+	}
+
+	buf := &bytes.Buffer{}
+	log.Init(false, buf)
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			buf.Reset()
+			util.Unsetenv(tt.input...)
+			require.Contains(t, buf.String(), tt.expectedOut)
+			if tt.expectedOut == "" {
+				for _, key := range tt.input {
+					require.Equal(t, "", os.Getenv(key.Key))
+				}
+			}
+		})
+	}
+}