Merge pull request #314 from michaelsauter/experiment/override

Implement config override

.gitmodules

@@ -28,3 +28,6 @@
 [submodule "vendor/github.com/stretchr/testify"]
 	path = vendor/github.com/stretchr/testify
 	url = https://github.com/stretchr/testify
+[submodule "vendor/github.com/imdario/mergo"]
+	path = vendor/github.com/imdario/mergo
+	url = https://github.com/imdario/mergo.git

CHANGELOG.md

@@ -2,6 +2,12 @@
 
 ## Unreleased
 
+* Allow to override configuration by another configuration file. By default,
+  Crane is looking for e.g. `crane.override.yml` if the config file in use is
+  `crane.yml`. This can be customized via `--override`/`CRANE_OVERRIDE`.
+
+  _@michaelsauter_
+
 ## 2.10.3 (2016-10-27)
 
 * Add `--debug` flag to `crane mac-sync start` which turns on verbose logging

README.md

@@ -23,6 +23,7 @@ continuous integration.
   * [Hooks](#hooks)
   * [Parallelism](#parallelism)
   * [Container Prefixes](#container-prefixes)
+  * [Override configuration](#override-configuration)
   * [Override image tag](#override-image-tag)
   * [Generate command](#generate-command)
   * [YAML advanced usage](#yaml-advanced-usage)
@@ -489,6 +490,12 @@ in parallel, e.g. for CI builds. Container prefixes can also be supplied by the
 `CRANE_PREFIX` environment variable.
 
 
+### Override configuration
+The configuration can be overriden by another configuration file. By default,
+Crane is looking for e.g. `crane.override.yml` if the config file in use is
+`crane.yml`. This can be customized via `--override`/`CRANE_OVERRIDE`.
+
+
 ### Override image tag
 By using a the `--tag` flag, it is possible to globally overrides image tags. If
 you specify `--tag 2.0-rc2`, an image name `repo/app:1.0` is treated as

crane/cli.go

@@ -20,6 +20,10 @@ var (
 		"config",
 		"Location of config file.",
 	).Short('c').PlaceHolder("~/crane.yaml").String()
+	overrideFlag = app.Flag(
+		"override",
+		"Location of override file.",
+	).String()
 	prefixFlag = app.Flag(
 		"prefix",
 		"Container prefix.",
@@ -238,7 +242,7 @@ func isDryRun() bool {
 
 func commandAction(targetFlag string, wrapped func(unitOfWork *UnitOfWork), mightStartRelated bool) {
 
-	cfg = NewConfig(*configFlag, *prefixFlag, *tagFlag)
+	cfg = NewConfig(*configFlag, *overrideFlag, *prefixFlag, *tagFlag)
 	allowed = allowedContainers(*excludeFlag, *onlyFlag)
 	dependencyMap := cfg.DependencyMap()
 	target, err := NewTarget(dependencyMap, targetFlag)
@@ -388,7 +392,7 @@ func runCli() {
 		}, false)
 
 	case syncStartCommand.FullCommand():
-		cfg = NewConfig(*configFlag, *prefixFlag, *tagFlag)
+		cfg = NewConfig(*configFlag, *overrideFlag, *prefixFlag, *tagFlag)
 		sync := cfg.MacSync(*syncStartVolumeArg)
 		if sync == nil {
 			printErrorf("ERROR: No such sync configured: %s.", *syncStartVolumeArg)
@@ -397,7 +401,7 @@ func runCli() {
 		sync.Start(*syncStartDebugFlag)
 
 	case syncStopCommand.FullCommand():
-		cfg = NewConfig(*configFlag, *prefixFlag, *tagFlag)
+		cfg = NewConfig(*configFlag, *overrideFlag, *prefixFlag, *tagFlag)
 		sync := cfg.MacSync(*syncStopVolumeArg)
 		if sync == nil {
 			printErrorf("ERROR: No such sync configured: %s.", *syncStartVolumeArg)
@@ -406,7 +410,7 @@ func runCli() {
 		sync.Stop()
 
 	case syncStatusCommand.FullCommand():
-		cfg = NewConfig(*configFlag, *prefixFlag, *tagFlag)
+		cfg = NewConfig(*configFlag, *overrideFlag, *prefixFlag, *tagFlag)
 		w := new(tabwriter.Writer)
 		w.Init(os.Stdout, 0, 8, 1, '\t', 0)
 		fmt.Fprintln(w, "VOLUME\tCONTAINER\tSTATUS")

crane/config.go

@@ -14,6 +14,7 @@ import (
 	"strconv"
 	"strings"
 	"time"
+	"github.com/imdario/mergo"
 )
 
 type Config interface {
@@ -117,6 +118,31 @@ func readConfig(filename string) *config {
 	return unmarshal(data, ext)
 }
 
+func findOverride(filename, override string) string {
+	if len(override) > 0 {
+		if !path.IsAbs(override) {
+			override = path.Join(path.Dir(filename), override)
+		}
+		if _, err := os.Stat(override); err == nil {
+			return override
+		} else {
+			panic(StatusError{fmt.Errorf("Override %v not found", override), 78})
+		}
+	}
+
+	overrideFile := ""
+	lastIndex := strings.LastIndex(filename, ".")
+	if lastIndex > 0 {
+		overrideFile = filename[:lastIndex] + ".override" + filename[lastIndex:]
+	} else {
+		overrideFile = filename + ".override"
+	}
+	if _, err := os.Stat(overrideFile); err == nil {
+		return overrideFile
+	}
+	return ""
+}
+
 // displaySyntaxError will display more information
 // such as line and error type given an error and
 // the data that was unmarshalled.
@@ -164,13 +190,23 @@ func unmarshal(data []byte, ext string) *config {
 // location.
 // Containers will be ordered so that they can be
 // brought up and down with Docker.
-func NewConfig(location string, prefix string, tag string) Config {
+func NewConfig(location string, override string, prefix string, tag string) Config {
 	var config *config
 	configFile := findConfig(location)
 	if isVerbose() {
 		printInfof("Using configuration file `%s`\n", configFile)
 	}
-	config = readConfig(configFile)
+	configBase := readConfig(configFile)
+	overrideFile := findOverride(configFile, override)
+	if len(overrideFile) > 0 {
+		if isVerbose() {
+			printInfof("Using override file `%s`\n", overrideFile)
+		}
+		config = readConfig(overrideFile)
+		mergo.Merge(config, configBase)
+	} else {
+		config = configBase
+	}
 	config.path = path.Dir(configFile)
 	config.initialize()
 	config.validate()