fix first pass rendering crash on syntax error (#374)

README.md

@@ -402,7 +402,7 @@ environments:
 
 releases:
 
-{{ if (eq .Environment.Name "production" }}
+{{ if eq .Environment.Name "production" }}
 - name: newrelic-agent
   # snip
 {{ end }}

main.go

@@ -3,16 +3,15 @@ package main
 import (
 	"bytes"
 	"fmt"
+	"io/ioutil"
 	"log"
 	"os"
+	"os/exec"
 	"os/signal"
 	"path/filepath"
 	"sort"
-	"syscall"
-
-	"io/ioutil"
-
 	"strings"
+	"syscall"
 
 	"github.com/roboll/helmfile/args"
 	"github.com/roboll/helmfile/environment"
@@ -22,7 +21,6 @@ import (
 	"github.com/urfave/cli"
 	"go.uber.org/zap"
 	"go.uber.org/zap/zapcore"
-	"os/exec"
 )
 
 const (
@@ -726,8 +724,12 @@ func (r *twoPassRenderer) renderEnvironment(content []byte) environment.Environm
 
 	// parse as much as we can, tolerate errors, this is a preparse
 	yamlBuf, err := firstPassRenderer.RenderTemplateContentToBuffer(content)
-	if err != nil && logger != nil {
+	if err != nil && r.logger != nil {
 		r.logger.Debugf("first-pass rendering input of \"%s\":\n%s", r.filename, prependLineNumbers(string(content)))
+		if yamlBuf == nil { // we have a template syntax error, let the second parse report
+			r.logger.Debugf("template syntax error: %v", err)
+			return firstPassEnv
+		}
 	}
 	c := state.NewCreator(r.logger, r.reader, r.abs)
 	c.Strict = false

main_test.go

@@ -2,10 +2,12 @@ package main
 
 import (
 	"fmt"
+	"os"
 	"path/filepath"
 	"strings"
 	"testing"
 
+	"github.com/roboll/helmfile/helmexec"
 	"github.com/roboll/helmfile/state"
 	"gopkg.in/yaml.v2"
 )
@@ -16,7 +18,7 @@ func makeRenderer(readFile func(string) ([]byte, error), env string) *twoPassRen
 		env:       env,
 		namespace: "namespace",
 		filename:  "",
-		logger:    logger,
+		logger:    helmexec.NewLogger(os.Stdout, "debug"),
 		abs:       filepath.Abs,
 	}
 }
@@ -228,3 +230,27 @@ func TestReadFromYaml_RenderTemplateWithNamespace(t *testing.T) {
 		t.Errorf("release name should be namespace-myrelease")
 	}
 }
+
+func TestReadFromYaml_HelfileShouldBeResilentToTemplateErrors(t *testing.T) {
+	yamlContent := []byte(`environments:
+  staging:
+	production:
+
+releases:
+{{ if (eq .Environment.Name "production" }}  # notice syntax error: unclosed left paren
+- name: prod-myrelease
+{{ else }}
+- name: myapp
+{{ end }}
+  chart: mychart
+`)
+	fileReader := func(filename string) ([]byte, error) {
+		return yamlContent, nil
+	}
+
+	r := makeRenderer(fileReader, "staging")
+	_, err := r.renderTemplate(yamlContent)
+	if err == nil {
+		t.Fatalf("wanted error, none returned")
+	}
+}