Support setting command in go-getter plugin

This allows one to use non-kustomization remote source

examples/README.md

@@ -40,6 +40,8 @@ Advanced Usage
 
    * [secret generation](secretGeneratorPlugin.md) - Generating secrets from a plugin.
 
+   * [remote sources](goGetterGeneratorPlugin.md) - Generating from remote sources.
+
 - transformer plugins:
    * [validation transformer](validationTransformer/README.md) -
    validate resources through a transformer

examples/goGetterGeneratorPlugin.md

@@ -0,0 +1,126 @@
+# Remote Sources
+
+Kustomize supports building a [remote target], but the URLs are limited to common [Git repository specs].
+
+To extend the supported format, Kustomize has a [plugin] system that allows one to integrate third-party tools such as [hashicorp/go-getter] to "download things from a string URL suing a variety of protocols", extract the content and generated resources as part of kustomize build.
+
+[remote target]: https://github.com/kubernetes-sigs/kustomize/blob/master/examples/remoteBuild.md
+[Git repository specs]: https://github.com/kubernetes-sigs/kustomize/blob/master/pkg/git/repospec_test.go
+[plugin]: ../docs/plugins
+[hashicorp/go-getter]: https://github.com/hashicorp/go-getter
+
+## Make a place to work
+
+<!-- @makeWorkplace @goGetterTest -->
+```sh
+DEMO_HOME=$(mktemp -d)
+```
+
+## Use a remote kustomize layer
+
+Define a kustomization representing your _local_ variant (aka environment).
+
+This could involve any number of kustomizations (see other examples), but in this case just add the name prefix `my-` to all resources:
+
+<!-- @writeKustLocal @goGetterTest -->
+```sh
+cat <<'EOF' >$DEMO_HOME/my/kustomization.yaml
+namePrefix:  my-
+resources:
+- ../base
+EOF
+```
+
+It refer a remote base defined as below:
+
+<!-- @writeKustLocal @goGetterTest -->
+```sh
+cat <<'EOF' >$DEMO_HOME/base/kustomization.yaml
+generators:
+- goGetter.yaml
+EOF
+```
+
+The base refers to a generator configuration file called `goGetter.yaml`.
+
+This file lets one specify the source URL, and other things like sub path in the package, defaulting to base directory, and command to run under the path, defaulting to `kustomize build`.
+
+Create the config file `goGetter.yaml`, specifying the arbitrarily chosen name _example_:
+
+<!-- @writeGeneratorConfig @goGetterTest -->
+```sh
+cat <<'EOF' >$DEMO_HOME/base/goGetter.yaml
+apiVersion: someteam.example.com/v1
+kind: GoGetter
+metadata:
+  name: example
+url: github.com/kustless/kustomize-examples.git
+EOF
+```
+
+Because this particular YAML file is listed in the `generators:` stanza of a kustomization file, it is treated as the binding between a generator plugin - identified by the _apiVersion_ and _kind_ fields - and other fields that configure the plugin.
+
+Download the plugin to your `DEMO_HOME` and make it executable:
+
+<!-- @installPlugin @goGetterTest -->
+```sh
+plugin=plugin/someteam.example.com/v1/gogetter/GoGetter
+curl -s --create-dirs -o \
+"$DEMO_HOME/kustomize/$plugin" \
+"https://raw.githubusercontent.com/\
+kubernetes-sigs/kustomize/master/$plugin"
+
+chmod a+x $DEMO_HOME/kustomize/$plugin
+```
+
+Define a helper function to run kustomize with the correct environment and flags for plugins:
+
+<!-- @defineKustomizeIt @goGetterTest -->
+```sh
+function kustomizeIt {
+  XDG_CONFIG_HOME=$DEMO_HOME \
+  kustomize build --enable_alpha_plugins \
+    $DEMO_HOME/$1
+}
+```
+
+Finally, build the local variant.  Notice that all
+resource  names now have the `my-` prefix:
+
+<!-- @doLocal @goGetterTest -->
+```sh
+clear
+kustomizeIt my
+```
+
+Compare local variant to remote base:
+
+<!-- @doCompare @goGetterTest-->
+```sh
+diff <(kustomizeIt my) <(kustomizeIt base) | more
+```
+
+To see the unmodified but extracted sources, run kustomize on the base.  Every invocation here is re-downloading and re-build the package.
+
+<!-- @showBase @goGetterTest -->
+```sh
+kustomizeIt base
+```
+
+## Use non-kustomize remote sources
+
+Sometimes the remote sources does not include `kustomization.yaml`. To use that in the plugin, set command to override the default build.
+
+<!-- @setCommand @goGetterTest -->
+```sh
+echo "command: cat resources.yaml" >>$DEMO_HOME/base/goGetter.yaml
+```
+
+Finally, built it
+
+<!-- @finalLocal @goGetterTest -->
+```sh
+kustomizeIt my
+```
+
+and observe the transformation from remote kustomization.yaml is not included.

plugin/someteam.example.com/v1/gogetter/GoGetter

@@ -11,7 +11,8 @@
 #  metadata:
 #    name: example
 #  url: github.com/kustless/kustomize-examples.git
-#  # overlay: base  # (optional) relative path in the package
+#  # subPath: base # (optional) relative path in the package
+#  # command: cat *.yaml # (optional) build command, default `kustomize build $subPath`
 #
 # download kustomize layes and build it to stdout
 #
@@ -20,7 +21,7 @@
 #
 # TODO: cache downloads
 
-set -e
+set -ex
 
 # YAML parsing function borrowed from ChartInflator
 function parseYaml {
@@ -32,7 +33,8 @@ function parseYaml {
     local t=${v#"${v%%[![:space:]]*}"}  # trim leading space
 
     if [ "$k" == "url" ]; then url=$t
-    elif [ "$k" == "overlay" ]; then overlay=$t
+    elif [ "$k" == "subPath" ]; then subPath=$t
+    elif [ "$k" == "command" ]; then command=$t
     fi
   done <"$file"
 }
@@ -40,7 +42,13 @@ function parseYaml {
 TMP_DIR=$(mktemp -d)
 
 parseYaml $1
+
+if [ -z "$command" ]; then
+  command="kustomize build"
+fi
+
 go-getter $url $TMP_DIR/got 2> /dev/null
-kustomize build $TMP_DIR/got/$overlay
+
+(cd $TMP_DIR/got/$subPath; $command)
 
 /bin/rm -rf $TMP_DIR

plugin/someteam.example.com/v1/gogetter/GoGetter_test.go

@@ -30,7 +30,7 @@ apiVersion: someteam.example.com/v1
 kind: GoGetter
 metadata:
   name: example
-url: github.com/kustless/kustomize-examples.git
+url: github.com/kustless/kustomize-examples.git?ref=adef0a8
 `)
 
 	th.AssertActualEqualsExpected(m, `
@@ -40,6 +40,66 @@ data:
   enableRisky: "false"
 kind: ConfigMap
 metadata:
-  name: the-map
+  name: remote-cm
+`)
+}
+
+func TestGoGetterCommand(t *testing.T) {
+	tc := plugins_test.NewEnvForTest(t).Set()
+	defer tc.Reset()
+
+	tc.BuildExecPlugin(
+		"someteam.example.com", "v1", "GoGetter")
+
+	th := kusttest_test.NewKustTestPluginHarness(t, "/app")
+
+	m := th.LoadAndRunGenerator(`
+apiVersion: someteam.example.com/v1
+kind: GoGetter
+metadata:
+  name: example
+url: github.com/kustless/kustomize-examples.git?ref=adef0a8
+command: cat resources.yaml
+`)
+
+	th.AssertActualEqualsExpected(m, `
+apiVersion: v1
+data:
+  altGreeting: Good Morning!
+  enableRisky: "false"
+kind: ConfigMap
+metadata:
+  name: cm
+`)
+}
+
+
+func TestGoGetterSubPath(t *testing.T) {
+	tc := plugins_test.NewEnvForTest(t).Set()
+	defer tc.Reset()
+
+	tc.BuildExecPlugin(
+		"someteam.example.com", "v1", "GoGetter")
+
+	th := kusttest_test.NewKustTestPluginHarness(t, "/app")
+
+	m := th.LoadAndRunGenerator(`
+apiVersion: someteam.example.com/v1
+kind: GoGetter
+metadata:
+  name: example
+url: github.com/kustless/kustomize-examples.git?ref=9ca07d2
+subPath: dev
+command: kustomize build --enable_alpha_plugins
+`)
+
+	th.AssertActualEqualsExpected(m, `
+apiVersion: v1
+data:
+  altGreeting: Good Morning!
+  enableRisky: "false"
+kind: ConfigMap
+metadata:
+  name: dev-remote-cm
 `)
 }