feat: Possibility to use custom env variables in templates (#165)

CHANGELOG.md

@@ -12,6 +12,12 @@ The format is based on [Keep a Changelog][keepachangelog] and this project adher
 - `--config-file` flag is not global anymore (use `error-pages (serve|build) --config-file ...` instead of `error-pages --config-file ... (serve|build) ...`) [#163]
 - Flags `--verbose`, `--debug` and `--log-json` are deprecated, use `--log-level` and `--log-format` instead [#163]
 
+### Added
+
+- Possibility to use custom env variables in templates [#164], [#165]
+
+[#164]:https://github.com/tarampampam/error-pages/issues/164
+[#165]:https://github.com/tarampampam/error-pages/pull/165
 [#163]:https://github.com/tarampampam/error-pages/pull/163
 
 ## v2.19.0

internal/tpl/render.go

@@ -10,6 +10,7 @@ import (
 	"time"
 
 	"github.com/pkg/errors"
+
 	"github.com/tarampampam/error-pages/internal/version"
 )
 
@@ -30,6 +31,7 @@ var tplFnMap = template.FuncMap{ //nolint:gochecknoglobals
 
 		return 0
 	},
+	"env": os.Getenv,
 }
 
 var ErrClosed = errors.New("closed")

internal/tpl/render_test.go

@@ -2,18 +2,25 @@ package tpl_test
 
 import (
 	"math/rand"
+	"os"
 	"strconv"
 	"sync"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
 	"github.com/tarampampam/error-pages/internal/tpl"
 )
 
 func Test_Render(t *testing.T) {
 	renderer := tpl.NewTemplateRenderer()
 	defer func() { _ = renderer.Close() }()
 
+	require.NoError(t, os.Setenv("TEST_ENV_VAR", "unit-test"))
+
+	defer func() { require.NoError(t, os.Unsetenv("TEST_ENV_VAR")) }()
+
 	for name, tt := range map[string]struct {
 		giveContent string
 		giveProps   tpl.Properties
@@ -67,6 +74,11 @@ func Test_Render(t *testing.T) {
 			giveProps:   tpl.Properties{L10nDisabled: true},
 			wantContent: "Y",
 		},
+
+		"env": {
+			giveContent: `{{ env "TEST_ENV_VAR" }}`,
+			wantContent: "unit-test",
+		},
 	} {
 		t.Run(name, func(t *testing.T) {
 			content, err := renderer.Render([]byte(tt.giveContent), tt.giveProps)