envgen v1

.gitignore

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+.DS_Store
+.idea

README.md

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+# envgen
+
+_envgen_ is CLI tool that generates .env files for subpackages in your project based on a configuration file.
+
+The purpose of this tool is to:
+ - avoid using a bash script: harder to maintain, test, lacks the safety 
+ of a statically typed and compiled language like Go;
+ - provide flexibility and ease of use/reuse: additional features can be 
+ easily added and made available to projects already using the tool.
+
+### Usage
+
+`$ envgen config.yaml`
+
+Here's the structure of the configuration file:
+
+```yaml
+branchVarName: CIRCLE_BRANCH
+branchVarDefault: develop
+
+branches:
+  - name: develop
+    suffix: _DEV
+  - name: staging
+    suffix: _STG
+
+packages:
+  - package: awesome-crawler
+    variables:
+      - AC_THRESHOLD
+      - AC_TITLE
+  - package: web-server
+    variables:
+      - WS_PORT
+      - WS_ADDRESS
+
+globals:
+  - V_DATABASE
+```
+
+Configuration details:
+
+| Key               | Description |
+| ----------------- |:-------------:|
+| branchVarName     | name of the env var that contains the CI branch (CIRCLE_BRANCH), for CircleCI |
+| branchVarDefault  | default value of `branchVarName` |
+| branches          | list of branches and their suffixes |
+| packages          | list of subpackages |
+| packages.package  | subpackage path to where the .env file will be written |
+| packages.variables| subpackage environment variables to generate |
+| globals           | list of variables that are environment independent and global to all subpackages |
+
+For each entry in the `packages` array, a `.env` file will be created in the path `package`, 
+with the variables defined in `variables` and `globals`.
+
+#### Example:
+
+Project structure:
+```
+├── bla.go 
+├── awesome-crawler
+│   └── index.js
+└── web-server
+    └── index.html
+```
+
+Loaded env vars:
+```
+CIRCLE_BRANCH=develop
+V_DATABASE=somedburl
+WS_ADDRESS_DEV=www.sample.web
+WS_PORT_DEV=1234
+AC_TITLE_DEV=sometitle 
+AC_THRESHOLD_DEV=50
+```
+
+Resulting structure:
+```
+├── bla.go 
+├── awesome-crawler
+│   ├── .env
+│   └── index.js
+└── web-server
+    ├── .env
+    └── index.html
+```
+
+Content of awesome-crawler/.env:
+```
+V_DATABASE=somedburl
+AC_TITLE=sometitle
+AC_THRESHOLD=50
+```
+
+Content of web-server/.env:
+```
+V_DATABASE=somedburl
+WS_ADDRESS=www.sample.web
+WS_PORT=1234
+```

cmd/envgen.go

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+package cmd
+
+import (
+	"fmt"
+	"github.com/spf13/cobra"
+	"io/ioutil"
+	"os"
+
+	"gopkg.in/yaml.v2"
+)
+
+type ConfBranches struct {
+	Name   string `yaml:"name"`
+	Suffix string `yaml:"suffix"`
+}
+
+type ConfPackages struct {
+	Package   string   `yaml:"package"`
+	Variables []string `yaml:"variables"`
+}
+
+type GeneratorConfig struct {
+	BranchVarName    string         `yaml:"branchVarName"`
+	BranchVarDefault string         `yaml:"branchVarDefault"`
+	Branches         []ConfBranches `yaml:"branches"`
+	Packages         []ConfPackages `yaml:"packages"`
+	Globals          []string       `yaml:"globals"`
+}
+
+type Generator struct {
+	conf         GeneratorConfig
+	branchSuffix string
+}
+
+var rootCmd = &cobra.Command{
+	Version:       "1.0.0",
+	SilenceErrors: true,
+	Use:           "envgen <configFilePath>",
+	Short:         "envgen generates env files for sub packages",
+	Long:          "envgen is CLI tool that generates .env files for subpackages in your project based on a configuration file",
+	Args:          cobra.ExactArgs(1),
+	RunE:          generateEnvFiles,
+}
+
+func Execute() {
+	rootCmd.SetErr(errorWriter{})
+	if err := rootCmd.Execute(); err != nil {
+		rootCmd.PrintErr(err)
+		os.Exit(1)
+	}
+}
+
+func generateEnvFiles(cmd *cobra.Command, args []string) error {
+	gen := &Generator{}
+	err := gen.loadConfig(args[0])
+	if err != nil {
+		return err
+	}
+
+	logInfo("Starting env files generation")
+	fmt.Println()
+
+	globals, err := getVariablesValues(gen.conf.Globals, "")
+	if err != nil {
+		return err
+	}
+
+	for _, g := range gen.conf.Packages {
+		pkg := g.Package
+		logInfo("> Loading variables for " + pkg)
+
+		// generate package specific vars
+		packageVars, err := getVariablesValues(g.Variables, gen.branchSuffix)
+		if err != nil {
+			return err
+		}
+
+		// append globals
+		packageVars = append(packageVars, globals...)
+
+		logInfo("> Writing env file for " + pkg)
+		err = writeFile(fmt.Sprintf("%s/.env", pkg), packageVars)
+		if err != nil {
+			return err
+		}
+
+		logInfo("> Done generating env file for " + pkg)
+		fmt.Println()
+	}
+
+	logInfo("Finished env files generation!")
+	return nil
+}
+
+func getVariablesValues(envVars []string, suffix string) ([]string, error) {
+	vars := []string{}
+	for _, v := range envVars {
+		val, ok := os.LookupEnv(v + suffix)
+		if !ok {
+			err := fmt.Errorf("missing variable %s", v)
+			return nil, err
+		}
+
+		vars = append(vars, fmt.Sprintf("%s=%s", v, val))
+	}
+
+	return vars, nil
+}
+
+// loadConfig loads the configuration from the provided yaml file
+// into the instance of the Generator. It also determines the branch suffix property.
+func (g *Generator) loadConfig(filepath string) error {
+	config := &GeneratorConfig{}
+	file, err := ioutil.ReadFile(filepath)
+	if err != nil {
+		return err
+	}
+
+	err = yaml.Unmarshal(file, config)
+	if err != nil {
+		return err
+	}
+
+	g.conf = *config
+
+	g.branchSuffix, err = g.findBranchSuffix()
+	if err != nil {
+		return fmt.Errorf("missing branch suffix")
+	}
+
+	return nil
+}
+
+// findBranchSuffix determines the branch suffix to use, depending on the current CI branch
+func (g *Generator) findBranchSuffix() (string, error) {
+	branch := getEnv(g.conf.BranchVarName, "", g.conf.BranchVarDefault)
+
+	for _, b := range g.conf.Branches {
+		if b.Name == branch {
+			return b.Suffix, nil
+		}
+	}
+
+	return "", fmt.Errorf("could not find branch suffix")
+}
+
+// getEnv looks up for a loaded environment variable.
+// An optional suffix may be passed, as well as a default value to return if the env var is not loaded.
+func getEnv(key string, suffix string, defaultVal string) string {
+	if value, exists := os.LookupEnv(key + suffix); exists {
+		return value
+	}
+
+	return defaultVal
+}
+
+// writeFile writes a slice of strings into a file, separated by new lines
+func writeFile(path string, vars []string) error {
+	file, err := os.Create(path)
+	if err != nil {
+		return err
+	}
+
+	defer file.Close()
+
+	sep := "\n"
+	for _, line := range vars {
+		if _, err = file.WriteString(line + sep); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}

cmd/log.go

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+package cmd
+
+import (
+	"fmt"
+	"os"
+)
+
+const (
+	InfoColor    = "\033[1;34m%s\033[0m\n"
+	ErrorColor   = "\033[1;31m%s\033[0m\n"
+)
+
+func printLog(color string, msg interface{}) {
+	fmt.Printf(color, msg)
+}
+
+func logInfo(msg interface{}) {
+	printLog(InfoColor, msg)
+}
+
+type errorWriter struct {}
+func (w errorWriter) Write(p []byte) (n int, err error) {
+	return fmt.Fprintf(os.Stdout, ErrorColor, p)
+}

go.mod

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+module envgen
+
+go 1.14
+
+require (
+	github.com/fsnotify/fsnotify v1.4.9 // indirect
+	github.com/mitchellh/mapstructure v1.2.2 // indirect
+	github.com/pelletier/go-toml v1.7.0 // indirect
+	github.com/spf13/afero v1.2.2 // indirect
+	github.com/spf13/cast v1.3.1 // indirect
+	github.com/spf13/cobra v1.0.0
+	github.com/spf13/jwalterweatherman v1.1.0 // indirect
+	github.com/spf13/pflag v1.0.5 // indirect
+	github.com/spf13/viper v1.6.3 // indirect
+	golang.org/x/sys v0.0.0-20200413165638-669c56c373c4 // indirect
+	golang.org/x/text v0.3.2 // indirect
+	gopkg.in/ini.v1 v1.55.0 // indirect
+	gopkg.in/yaml.v2 v2.2.8
+)