Initial commit

Author: antelman107

README.md

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+# What is it?
+GO package to deal with complex configs provided through environment variables.
+
+# Why we need it?
+In dockerized applications and by https://12factor.net/ recommendation
+we have to pass configuration for our GO program through environment variables.
+
+It is easy if configuration consists of simple values (strings, numbers, boolean, etc), something like this:
+
+```json
+{
+      "login":"user",
+      "password":"somepass",
+      "mfa_enabled": true
+}
+```
+
+In this case we could use several environment variables like  `APP_LOGIN="user" APP_PASSWORD="somepass"`.
+
+But how do we work for complex configuration 
+that consists of arrays of objects? For example:
+```json
+{
+      "nodes":[
+            {
+                  "url":"http://1.localhost/",
+                  "priority":1,
+                  "enabled":true
+            },
+            {
+                  "url":"http://2.localhost/",
+                  "priority":2,
+                  "enabled":false
+            }
+      ]
+}
+```
+
+It is difficult to split this configuration to several environment variables.
+
+This package is aimed to deal with such configs.
+
+Just put the config into single environment variable.
+It could be multiline, but work with single line is simplier.
+
+Running program example:
+
+```bash
+
+CONFIG={"nodes":[{"url":"http:\/\/1.localhost\/","priority":1,"enabled":true},{"url":"http:\/\/2.localhost\/","priority":2,"enabled":false}]} ./app
+```
+
+Program code example:
+```GO
+import jsonEnvGo "github.com/antelman107/json-env-go"
+
+type Config  struct {
+	Nodes []struct {
+		URL      string `json:"url"`
+		Priority int    `json:"priority"`
+		Enabled  bool   `json:"enabled"`
+	} `json:"nodes"`
+}
+
+func main() {
+      var cfg Config
+      if err := jsonEnvGo.DecodeConfigFromEnv(envName, &cfg); err != nil {
+            logger.Error(err)
+            return
+      }
+      
+      // cfg now filled, do something with it
+      // ...
+}
+```
+
+

decode.go

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+package decode
+
+import (
+	"encoding/json"
+	"os"
+)
+
+func DecodeConfigFromEnv(envName string, target interface{}) error {
+	return json.Unmarshal([]byte(os.Getenv(envName)), &target)
+}

decode_test.go

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+package decode
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestDecode(t *testing.T) {
+	envName := "CONFIG"
+	env := `{"a":"1","b":"2"}`
+
+	type config struct {
+		A string `json:"a"`
+		B string `json:"b"`
+	}
+
+	os.Setenv(envName, env)
+
+	var a config
+	if err := DecodeConfigFromEnv(envName, &a); err != nil {
+		panic(err)
+	}
+
+	assert.Equal(t, config{ A: "1", B:"2"}, a)
+}

go.mod

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+module github.com/antelman107/json-env-go
+
+go 1.14
+
+require github.com/stretchr/testify v1.6.1

go.sum

@@ -0,0 +1,11 @@
+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.6.1 h1:hDPOHmpOpP40lSULcqw7IrRb/u7w6RpDC9399XyoNd0=
+github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=