--eval prints exports to get env vars into current session

README.md

@@ -2,15 +2,21 @@
 
 ![Build Status](http://ci.engineerbetter.com/api/v1/teams/main/pipelines/yml2env/jobs/test/badge)
 
-Executes a command with environment variables taken from a YAML file.
+Either executes a command with environment variables taken from a YAML file, or prints a load of `export`s you can `eval`
 
-```
-yml2env <path-to-yaml-file> <command>
+```sh
+yml2env <path-to-yaml-file> [<command> | --eval]
+
+# Run command with env vars from YAML file
+$ yml2env vars.yml tests.sh
+
+# Set env vars in current shell
+$ eval "$(yml2env var.yml --eval)"
 ```
 
 ## Why?
 
-It's quite handy for using Concourse `--load-vars-from` files when running local tasks, like tests.
+It's quite handy for using Concourse `--load-vars-from` files when running local tasks, like tests. The `--eval` feature is useful when you need to get lots of stuff from the output of a Concourse Terraform resource as env vars.
 
 ## Example
 

version

@@ -1 +1 @@
-1.1.0
+1.2.0

yml2env.go

@@ -13,7 +13,7 @@ import (
 	"gopkg.in/yaml.v2"
 )
 
-var usage = "yml2env <YAML file> <command>"
+var usage = "yml2env <YAML file> [<command> | --env]"
 
 func main() {
 	args := os.Args
@@ -32,13 +32,24 @@ func main() {
 
 	bytes := loadYaml(yamlPath)
 	mapSlice := parseYaml(bytes)
+	mapSlice = uppercaseKeys(mapSlice)
 	envVars := os.Environ()
-	envVars = addUppercaseKeysToEnv(mapSlice, envVars)
+	envVars = addToEnv(mapSlice, envVars)
 
-	err, _ := run(envVars, args[2:])
-	if err != nil {
-		fmt.Fprintln(os.Stderr, err)
-		os.Exit(1)
+	if args[2] == "--eval" {
+		if len(args) > 3 {
+			fmt.Fprintln(os.Stderr, usage)
+			os.Exit(1)
+		}
+
+		printExports(mapSlice)
+		os.Exit(0)
+	} else {
+		err, _ := run(envVars, args[2:])
+		if err != nil {
+			fmt.Fprintln(os.Stderr, err)
+			os.Exit(1)
+		}
 	}
 }
 
@@ -81,15 +92,15 @@ func valueToString(item yaml.MapItem) yaml.MapItem {
 	return item
 }
 
-func addUppercaseKeysToEnv(mapSlice yaml.MapSlice, envVars []string) []string {
+func uppercaseKeys(mapSlice yaml.MapSlice) yaml.MapSlice {
 	for i := 0; i < len(mapSlice); i++ {
 		item := mapSlice[i]
 
 		if key, ok := item.Key.(string); ok {
 			key := strings.ToUpper(key)
 			item = valueToString(item)
 			if value, ok := item.Value.(string); ok {
-				envVars = env.Set(key, value, envVars)
+				mapSlice[i] = yaml.MapItem{Key: key, Value: value}
 			} else {
 				fmt.Fprintln(os.Stderr, "YAML invalid")
 				os.Exit(1)
@@ -100,6 +111,19 @@ func addUppercaseKeysToEnv(mapSlice yaml.MapSlice, envVars []string) []string {
 		}
 	}
 
+	return mapSlice
+}
+
+func addToEnv(mapSlice yaml.MapSlice, envVars []string) []string {
+	for i := 0; i < len(mapSlice); i++ {
+		item := mapSlice[i]
+
+		key, _ := item.Key.(string)
+		item = valueToString(item)
+		value, _ := item.Value.(string)
+		envVars = env.Set(key, value, envVars)
+	}
+
 	return envVars
 }
 
@@ -140,3 +164,15 @@ func determineExitCode(cmd *exec.Cmd, err error) (exitCode int) {
 
 	return
 }
+
+func printExports(mapSlice yaml.MapSlice) {
+	for i := 0; i < len(mapSlice); i++ {
+		item := mapSlice[i]
+
+		key, _ := item.Key.(string)
+		key = strings.ToUpper(key)
+		item = valueToString(item)
+		value, _ := item.Value.(string)
+		fmt.Printf("export '%s=%s'\n", key, value)
+	}
+}

yml2env_test.go

@@ -11,7 +11,7 @@ import (
 
 var _ = Describe("yml2env", func() {
 	var cliPath string
-	usage := "yml2env <YAML file> <command>"
+	usage := "yml2env <YAML file> \\[<command> | --env\\]"
 
 	BeforeSuite(func() {
 		var err error
@@ -40,35 +40,55 @@ var _ = Describe("yml2env", func() {
 		Ω(session.Err).ShouldNot(Say("foo"))
 	})
 
-	It("requires a command to invoke", func() {
-		command := exec.Command(cliPath, "fixtures/vars.yml")
-		session, err := Start(command, GinkgoWriter, GinkgoWriter)
-		Ω(err).ShouldNot(HaveOccurred())
-		Eventually(session).Should(Exit(1))
-		Ω(session.Err).Should(Say(usage))
-	})
+	Describe("running a command", func() {
+		It("requires a command to invoke", func() {
+			command := exec.Command(cliPath, "fixtures/vars.yml")
+			session, err := Start(command, GinkgoWriter, GinkgoWriter)
+			Ω(err).ShouldNot(HaveOccurred())
+			Eventually(session).Should(Exit(1))
+			Ω(session.Err).Should(Say(usage))
+		})
 
-	It("invokes the given command passing env vars from the YAML file", func() {
-		command := exec.Command(cliPath, "fixtures/vars.yml", "fixtures/script.sh")
-		session, err := Start(command, GinkgoWriter, GinkgoWriter)
-		Ω(err).ShouldNot(HaveOccurred())
-		Eventually(session).Should(Exit(0))
-		Ω(session).Should(Say("value from yaml"))
-	})
+		It("invokes the given command passing env vars from the YAML file", func() {
+			command := exec.Command(cliPath, "fixtures/vars.yml", "fixtures/script.sh")
+			session, err := Start(command, GinkgoWriter, GinkgoWriter)
+			Ω(err).ShouldNot(HaveOccurred())
+			Eventually(session).Should(Exit(0))
+			Ω(session).Should(Say("value from yaml"))
+		})
 
-	It("invokes the given command passing boolean env vars from the YAML file", func() {
-		command := exec.Command(cliPath, "fixtures/boolean.yml", "fixtures/script.sh")
-		session, err := Start(command, GinkgoWriter, GinkgoWriter)
-		Ω(err).ShouldNot(HaveOccurred())
-		Eventually(session).Should(Exit(0))
-		Ω(session).Should(Say("true"))
+		It("invokes the given command passing boolean env vars from the YAML file", func() {
+			command := exec.Command(cliPath, "fixtures/boolean.yml", "fixtures/script.sh")
+			session, err := Start(command, GinkgoWriter, GinkgoWriter)
+			Ω(err).ShouldNot(HaveOccurred())
+			Eventually(session).Should(Exit(0))
+			Ω(session).Should(Say("true"))
+		})
+
+		It("invokes the given command passing integer env vars from the YAML file", func() {
+			command := exec.Command(cliPath, "fixtures/integer.yml", "fixtures/script.sh")
+			session, err := Start(command, GinkgoWriter, GinkgoWriter)
+			Ω(err).ShouldNot(HaveOccurred())
+			Eventually(session).Should(Exit(0))
+			Ω(session).Should(Say("42"))
+		})
 	})
 
-	It("invokes the given command passing integer env vars from the YAML file", func() {
-		command := exec.Command(cliPath, "fixtures/integer.yml", "fixtures/script.sh")
-		session, err := Start(command, GinkgoWriter, GinkgoWriter)
-		Ω(err).ShouldNot(HaveOccurred())
-		Eventually(session).Should(Exit(0))
-		Ω(session).Should(Say("42"))
+	Describe("printing out exports", func() {
+		It("does not accept a subcommand", func() {
+			command := exec.Command(cliPath, "fixtures/vars.yml", "--eval", "fixtures/script.sh")
+			session, err := Start(command, GinkgoWriter, GinkgoWriter)
+			Ω(err).ShouldNot(HaveOccurred())
+			Eventually(session).Should(Exit(1))
+			Ω(session.Err).Should(Say(usage))
+		})
+
+		It("prints out an export for each var", func() {
+			command := exec.Command(cliPath, "fixtures/vars.yml", "--eval")
+			session, err := Start(command, GinkgoWriter, GinkgoWriter)
+			Ω(err).ShouldNot(HaveOccurred())
+			Eventually(session).Should(Exit(0))
+			Ω(session).Should(Say("export 'VAR_FROM_YAML=value from yaml'"))
+		})
 	})
 })