added env substitution to the cft files..

resources/user-data-env.yaml

@@ -0,0 +1,9 @@
+UserData: 
+    "Fn::Base64": !Sub |
+        #!/bin/bash
+        yum install -y aws-cfn-bootstrap
+        ${Local::IncludeEnv TEMP_ENV_VAL}
+        /opt/aws/bin/cfn-init -v --region ${AWS::Region} --stack ${AWS::StackName} --resource ECSLaunchConfiguration
+        /opt/aws/bin/cfn-signal -e $? --region ${AWS::Region} --stack ${AWS::StackName} --resource ECSAutoScalingGroup
+UserData2-${Local::IncludeEnv TEMP_ENV_VAL}:
+    temp: !Local::IncludeEnv TEMP_ENV_VAL

utils/include_env.go

@@ -0,0 +1,56 @@
+package utils
+
+import (
+	"bufio"
+	"bytes"
+	"io"
+	"os"
+	"regexp"
+
+	log "github.com/Sirupsen/logrus"
+)
+
+var (
+	// Matches literal string: ${Local::IncludeEnv <key>}
+	// example:   ${Local::IncludeEnv HOME}
+	literalIncludeEnvRe = regexp.MustCompile(`\${[ ]*Local::IncludeEnv[ ]+([[:ascii:]]+)}`)
+	// Matches tag  !Local::IncludeEnv <key>
+	// for example:   !Local::IncludeEnv HOME
+	valueIncludeEnvTagRe = regexp.MustCompile(`!Local::IncludeEnv[ ]+([[:ascii:]]+)`)
+)
+
+func ApplyIncludeEnvDirective(reader io.Reader) []byte {
+	output := bytes.NewBuffer([]byte{})
+	scanner := bufio.NewScanner(reader)
+	for scanner.Scan() {
+		line := scanner.Bytes()
+
+		loc := literalIncludeEnvRe.FindIndex(line)
+		tagLoc := valueIncludeEnvTagRe.FindIndex(line)
+
+		if len(loc) == 2 {
+			envName := string(literalIncludeEnvRe.FindSubmatch(line)[1])
+			log.Debugf("loading include env: %s", envName)
+
+			output.Write(line[0:loc[0]])
+			envValue := os.Getenv(envName)
+			output.WriteString(envValue)
+			output.Write(line[loc[1]:])
+
+		} else if len(tagLoc) == 2 {
+			envName := string(valueIncludeEnvTagRe.FindSubmatch(line)[1])
+			log.Debugf("loading include env: %s", envName)
+
+			output.Write(line[0:tagLoc[0]])
+			envValue := os.Getenv(envName)
+			output.WriteString(envValue)
+			output.Write(line[tagLoc[1]:])
+
+		} else {
+			output.Write(line)
+		}
+
+		output.WriteByte('\n')
+	}
+	return output.Bytes()
+}

utils/include_env_test.go

@@ -0,0 +1,51 @@
+//
+// Copyright 2016 Capital One Services, LLC
+//
+// 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.
+//
+// SPDX-Copyright: Copyright (c) Capital One Services, LLC
+// SPDX-License-Identifier: Apache-2.0
+//
+package utils
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+var expectedEnvIncl = `UserData: 
+    "Fn::Base64": !Sub |
+        #!/bin/bash
+        yum install -y aws-cfn-bootstrap
+        something
+        /opt/aws/bin/cfn-init -v --region ${AWS::Region} --stack ${AWS::StackName} --resource ECSLaunchConfiguration
+        /opt/aws/bin/cfn-signal -e $? --region ${AWS::Region} --stack ${AWS::StackName} --resource ECSAutoScalingGroup
+UserData2-something:
+    temp: something
+`
+
+func TestApplyIncludeEnvDirective(t *testing.T) {
+	fname := "../resources/" + "user-data-env.yaml"
+	TemporaryChdir("../resources", func() {
+		f, err := os.Open(fname)
+		assert.Nil(t, err)
+		defer f.Close()
+		var result []byte
+		TemporaryEnv("TEMP_ENV_VAL", "something", func() {
+			result = ApplyIncludeEnvDirective(f)
+		})
+
+		assert.Equal(t, expectedEnvIncl, string(result))
+	})
+}

utils/util.go

@@ -315,3 +315,19 @@ func MaxInt(x, y int) int {
 	}
 	return y
 }
+
+// testing util
+
+func TemporaryEnv(name, value string, runIt func()) {
+	old, ok := os.LookupEnv(name)
+	os.Setenv(name, value)
+	defer func() {
+		if !ok {
+			os.Unsetenv(name)
+		} else {
+			os.Setenv(name, old)
+		}
+	}()
+
+	runIt()
+}

utils/util_test.go

@@ -19,11 +19,13 @@ package utils
 
 import (
 	"io/ioutil"
+	"os"
 	"path/filepath"
 	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 const (
@@ -124,3 +126,29 @@ func TestSpecialFnIncludeLinesMissingFile(t *testing.T) {
 	assert.Equal(t, valid, string(cftJson))
 
 }
+
+func TestTemporaryEnvNew(t *testing.T) {
+	const key = "TEMP_ENV_1"
+	require.Equal(t, "", os.Getenv(key))
+	TemporaryEnv(key, "asdf", func() {
+		require.Equal(t, "asdf", os.Getenv(key))
+	})
+	require.Equal(t, "", os.Getenv(key))
+	v, ok := os.LookupEnv(key)
+	require.False(t, ok)
+	require.Equal(t, "", v)
+}
+
+func TestTemporaryEnvExisting(t *testing.T) {
+	const key = "TEMP_ENV_2"
+	os.Setenv(key, "qwerty")
+
+	require.Equal(t, "qwerty", os.Getenv(key))
+	TemporaryEnv(key, "asdf", func() {
+		require.Equal(t, "asdf", os.Getenv(key))
+	})
+	require.Equal(t, "qwerty", os.Getenv(key))
+	v, ok := os.LookupEnv(key)
+	require.True(t, ok)
+	require.Equal(t, "qwerty", v)
+}