Allow env var interpolation in `set` and `values` (#20)

* Allow env var interpolation in `set` and `values`

* Use go templating instead of regex

* Re-add 'env' section for backwards compatibility

* Fix typo

README.md

@@ -23,23 +23,25 @@ repositories:
 
 charts:
   # Published chart example
-  - name: vault                          # helm deployment name
-    namespace: vault                     # target namespace
-    chart: roboll/vault-secret-manager   # chart reference (repository)
-    values: [ vault.yaml ]               # value files (--values)
-    set:                                 # values (--set)
+  - name: vault                            # helm deployment name
+    namespace: vault                       # target namespace
+    chart: roboll/vault-secret-manager     # chart reference (repository)
+    values: [ vault.yaml ]                 # value files (--values)
+    set:                                   # values (--set)
       - name: address
         value: https://vault.example.com
-    env:                                 # values (--set) but value will be pulled from environment variables. Will throw an error if the environment variable is not set.
       - name: db.password
-        value: DB_PASSWORD               # $DB_PASSOWRD needs to be set in the calling environment ex: export DB_PASSWORD='password1'
+        value: {{ env "DB_PASSWORD" }}                   # value taken from environment variable. Will throw an error if the environment variable is not set. $DB_PASSWORD needs to be set in the calling environment ex: export DB_PASSWORD='password1'
+      - name: proxy.domain
+        value: "{{ env \"PLATFORM_ID\" }}.my-domain.com" # Interpolate environment variable with a fixed string
 
   # Local chart example
-  - name: grafana                         # helm deployment name
-    namespace: another                    # target namespace
-    chart: ../my-charts/grafana           # chart reference (relative path to manifest)
+  - name: grafana                            # helm deployment name
+    namespace: another                       # target namespace
+    chart: ../my-charts/grafana              # chart reference (relative path to manifest)
     values:
-    - ../../my-values/grafana/values.yaml # Values file (relative path to manifest)
+    - "../../my-values/grafana/values.yaml"             # Values file (relative path to manifest)
+    - "./values/{{ env \"PLATFORM_ENV\" }}/config.yaml" # Values file taken from path with environment variable. $PLATFORM_ENV must be set in the calling environment.
 
 ```
 

state/state.go

@@ -8,12 +8,14 @@ import (
 	"path/filepath"
 	"strings"
 	"sync"
+	"text/template"
 
 	"github.com/roboll/helmfile/helmexec"
 
 	yaml "gopkg.in/yaml.v1"
 	"path"
 	"regexp"
+	"bytes"
 )
 
 type HelmState struct {
@@ -28,14 +30,16 @@ type RepositorySpec struct {
 }
 
 type ChartSpec struct {
-	Chart   string `yaml:"chart"`
-	Version string `yaml:"version"`
-	Verify  bool   `yaml:"verify"`
+	Chart     string `yaml:"chart"`
+	Version   string `yaml:"version"`
+	Verify    bool   `yaml:"verify"`
 
 	Name      string     `yaml:"name"`
 	Namespace string     `yaml:"namespace"`
 	Values    []string   `yaml:"values"`
 	SetValues []SetValue `yaml:"set"`
+
+	// The 'env' section is not really necessary any longer, as 'set' would now provide the same functionality
 	EnvValues []SetValue `yaml:"env"`
 }
 
@@ -59,6 +63,41 @@ func ReadFromFile(file string) (*HelmState, error) {
 	return &state, nil
 }
 
+var /* const */
+	stringTemplateFuncMap = template.FuncMap{
+		"env": getEnvVar,
+	}
+
+var /* const */
+	stringTemplate = template.New("stringTemplate").Funcs(stringTemplateFuncMap)
+
+func getEnvVar(envVarName string) (string, error) {
+	envVarValue, isSet := os.LookupEnv(envVarName)
+
+	if !isSet {
+		errMsg := fmt.Sprintf("Environment Variable '%s' is not set. Please make sure it is set and try again.", envVarName)
+		return "", errors.New(errMsg)
+	}
+
+	return envVarValue, nil
+}
+
+func renderTemplateString(s string) (string, error) {
+	var t, parseErr = stringTemplate.Parse(s)
+	if parseErr != nil {
+		return "", parseErr
+	}
+
+	var tplString bytes.Buffer
+	var execErr = t.Execute(&tplString, nil)
+
+	if execErr != nil {
+		return "", execErr
+	}
+
+	return tplString.String(), nil
+}
+
 func (state *HelmState) SyncRepos(helm helmexec.Interface) []error {
 	var wg sync.WaitGroup
 	errs := []error{}
@@ -203,15 +242,28 @@ func flagsForChart(basePath string, chart *ChartSpec) ([]string, error) {
 	}
 	for _, value := range chart.Values {
 		valfile := filepath.Join(basePath, value)
-		flags = append(flags, "--values", valfile)
+		valfileRendered, err := renderTemplateString(valfile)
+		if err != nil {
+			return nil, err
+		}
+		flags = append(flags, "--values", valfileRendered)
 	}
 	if len(chart.SetValues) > 0 {
 		val := []string{}
 		for _, set := range chart.SetValues {
-			val = append(val, fmt.Sprintf("%s=%s", set.Name, set.Value))
+			renderedValue, err := renderTemplateString(set.Value)
+			if err != nil {
+				return nil, err
+			}
+			val = append(val, fmt.Sprintf("%s=%s", set.Name, renderedValue))
 		}
 		flags = append(flags, "--set", strings.Join(val, ","))
 	}
+
+	/***********
+	 * START 'env' section for backwards compatibility
+	 ***********/
+	// The 'env' section is not really necessary any longer, as 'set' would now provide the same functionality
 	if len(chart.EnvValues) > 0 {
 		val := []string{}
 		envValErrs := []string{}
@@ -231,5 +283,9 @@ func flagsForChart(basePath string, chart *ChartSpec) ([]string, error) {
 		}
 		flags = append(flags, "--set", strings.Join(val, ","))
 	}
+	/**************
+	 * END 'env' section for backwards compatibility
+	 **************/
+
 	return flags, nil
 }