Pongo2 support

.gitignore

@@ -5,3 +5,5 @@ goenvtemplator.tar.xz
 goenvtemplator2
 goenvtemplator2-amd64
 goenvtemplator2.tar.xz
+
+vendor

README.md

@@ -98,7 +98,8 @@ and [Sprig](https://github.com/Masterminds/sprig) library.
 
 ### Built-in functions
 There are a few built in functions as well:
-  * `require (env "ENV_NAME")` - Renders an error if environments variable does not exists. If it is equal to empty string, returns empty string.  `{{ require (env "TIMEOUT_MS) }}`
+  * `{{ require (env "ENV_NAME") }}` - Renders an error if environments variable does not exists. If it is equal to empty string, returns empty string.  `{{ require (env "TIMEOUT_MS) }}`
+  * `{{ range $key, $value := envall }}{{ $key }}={{ $value }};{{ end }}` - Loop over every environment variable.
 
 ### Nested Go templates
 If you have nested Go templates there is problem with escaping. To resolve this problem you can define different 

debian/changelog

@@ -1,3 +1,10 @@
+goenvtemplator (2.1.0) UNRELEASED; urgency=medium
+
+  * Support for pongo2 template language
+  * Simple API for fast template language implementation
+
+ -- Jakub Dusek <jakub.dusek@firma.seznam.cz>  Fri, 20 Jul 2017 17:42:19 +0200
+
 goenvtemplator (2.0.0~rc3) Seznam; urgency=medium
 
   * Binary name changed to goenvtemplator2 to support dual installation of both major versions.

doc/goenvtemplator2.1

@@ -10,16 +10,49 @@ goenvtemplator2 [OPTIONS]
 goenvtemplator2 is a simple app, that can template your config files by environment variables and optionally replace itself (by exec syscall) with the application binary. So at the end your application runs directly under the process that run this tool like docker as if it was originally the entrypoint itself.
 
 .SH OPTIONS
-Possible OPTIONS are:
-  -debug-templates    Print processed templates to stdout.
-  -env-file FILE      Additional file with environment variables. Can be
-                      passed multiple times. (default [])
-  -exec COMMAND ARGS  Activates exec by command. First non-flag arguments is
-                      the command, the rest are it's arguments.
-  -template VALUE     Template (/template:/dest). Can be passed multiple
-                      times. (default [])
-  -v INT              Verbosity level.
-  -version            Prints version.
+.TP
+.BI "\-alsologtostderr"\fR
+log to standard error as well as files
+.TP
+.BI "\-delim-left \fIstring"\fR
+(text/template only) Override default left delimiter {{.
+.TP
+.BI "\-delim-right \fIstring"
+(text/template only) Override default right delimiter }}.
+.TP
+.BI "\-engine \fIstring"
+Override default text/template [supports: text/template, pongo] (default "text/template")
+.TP
+.BI "\-env-file \fIvalue"
+Additional file with environment variables. Can be passed multiple times.
+.TP
+.BI "\-exec"\fR
+Activates exec by command. First non-flag arguments is the command, the rest are it's arguments.
+.TP
+.BI "\-log_backtrace_at \fIvalue"
+when logging hits line file:N, emit a stack trace
+.TP
+.BI "\-log_dir \fIstring"
+If non-empty, write log files in this directory
+.TP
+.BI "\-logtostderr"
+log to standard error instead of files
+.TP
+.BI "\-stderrthreshold \fIvalue"
+logs at or above this threshold go to stderr
+.TP
+.BI "\-template \fIvalue"
+Template (/template:/dest). Can be passed multiple times.
+.TP
+.BI "\-v \fIvalue"
+log level for V logs
+.TP
+.BI "\-version"
+Prints version.
+.TP
+.BI "\-vmodule \fIvalue"
+comma-separated list of pattern=N settings for file-filtered logging
+
 .SH SEE ALSO
 envsubst(1), env(1)
 .SH BUGS

engine/pongo.go

@@ -0,0 +1,40 @@
+package engine
+
+import (
+	"os"
+	"strings"
+
+	"github.com/flosch/pongo2"
+	log "github.com/golang/glog"
+)
+
+type PongoTemplar struct {
+	Source string
+}
+
+func (templar *PongoTemplar) GenerateTemplate() (string, error) {
+	context := pongo2.Context{}
+
+	tmpl, err := pongo2.FromString(templar.Source)
+	if err != nil {
+		return "", err
+	}
+
+	for _, val := range os.Environ() {
+		parts := strings.SplitN(val, "=", 2)
+		key, value := parts[0], parts[1]
+
+		context[key] = value
+	}
+
+	if log.V(3) {
+		log.Info("Using context %v", context)
+	}
+
+	out, err := tmpl.Execute(context)
+	if err != nil {
+		return "", err
+	}
+
+	return out, nil
+}

engine/templar.go

@@ -0,0 +1,5 @@
+package engine
+
+type Templar interface {
+	GenerateTemplate() (string, error)
+}

engine/template.go

@@ -0,0 +1,108 @@
+package engine
+
+import (
+	"bytes"
+	"errors"
+	"flag"
+	"fmt"
+	"os"
+	"strings"
+	"text/template"
+
+	"github.com/Masterminds/sprig"
+)
+
+type TextTemplar struct {
+	Source string
+	Name   string
+}
+
+type OptionalString struct {
+	ptr *string
+}
+
+var (
+	delimLeft  string
+	delimRight string
+)
+
+func init() {
+	flag.StringVar(
+		&delimLeft,
+		"delim-left",
+		"",
+		"(text/template only) Override default left delimiter {{.",
+	)
+	flag.StringVar(
+		&delimRight,
+		"delim-right",
+		"",
+		"(text/template only) Override default right delimiter }}.",
+	)
+}
+
+func (s OptionalString) String() string {
+	if s.ptr == nil {
+		return ""
+	}
+	return *s.ptr
+}
+
+func Require(arg interface{}) (string, error) {
+	if arg == nil {
+		return "", errors.New("Required argument is missing!")
+	}
+
+	switch v := arg.(type) {
+	case string:
+		return v, nil
+	case *string:
+		if v != nil {
+			return *v, nil
+		}
+	case OptionalString:
+		if v.ptr != nil {
+			return *v.ptr, nil
+		}
+	}
+
+	return "", fmt.Errorf("Requires: unsupported type '%T'!", arg)
+}
+
+func EnvAll() (map[string]string, error) {
+	res := make(map[string]string)
+
+	for _, item := range os.Environ() {
+		split := strings.Split(item, "=")
+		res[split[0]] = strings.Join(split[1:], "=")
+	}
+
+	return res, nil
+}
+
+var funcMap = template.FuncMap{
+	"require": Require,
+	"envall":  EnvAll,
+}
+
+func (templar *TextTemplar) GenerateTemplate() (string, error) {
+	t, err := template.New(templar.Name).
+		Delims(delimLeft, delimRight).
+		Option("missingkey=error").
+		Funcs(funcMap).
+		Funcs(sprig.TxtFuncMap()).
+		Parse(templar.Source)
+
+	if err != nil {
+		return "", err
+	}
+
+	var buffer bytes.Buffer
+	// hacking because go 1.7 fails to throw error, see https://github.com/golang/go/commit/277bcbbdcd26f2d64493e596238e34b47782f98e
+	emptyHash := map[string]interface{}{}
+	if err = t.Execute(&buffer, &emptyHash); err != nil {
+		return "", err
+	}
+
+	return buffer.String(), nil
+}

glide.yaml

@@ -4,3 +4,6 @@ import:
   version: v1
 - package: github.com/Masterminds/sprig
   version: 2.8.0
+- package: github.com/flosch/pongo2
+  version: v3
+- package: github.com/golang/glog