tooling: add gci tool to standardize import order

The imports are ordered in 4 sections:
 - standard lib
 - default imports
 - prefix(github.com/openshift)
 - blank imports (_ <import_path>)

CONTRIBUTING.md

@@ -57,6 +57,13 @@ The coding style suggested by the Golang community is used in installer. See the
 
 Terraform has similar standards, and you can run `terraform fmt` to rewrite Terraform files to the canonical format.
 
+### Import order
+
+The Golang import statements are organized into 4 sections: standard, default, prefix("github.com/openshift"), and blank imports with the [gci tool][gci-tool]. To automatically sort the imports run:
+```sh
+hack/go-fmt.sh .
+```
+
 ## Commit Message Format
 
 We follow a rough convention for commit messages that is designed to answer two
@@ -95,6 +102,7 @@ Some unit tests use mocks that are generated with gomock. If the underlying inte
 hack/go-genmock.sh
 ```
 
+[gci-tool]: https://github.com/daixiang0/gci
 [golang-style]: https://github.com/golang/go/wiki/CodeReviewComments
 [new-issue]: https://github.com/openshift/installer/issues/new
 [podman-install]: https://podman.io/getting-started/installation

hack/go-fmt.sh

@@ -1,7 +1,9 @@
 #!/bin/sh
 if [ "$IS_CONTAINER" != "" ]; then
+  gci_repo=github.com/daixiang0/gci
   for TARGET in "${@}"; do
     find "${TARGET}" -name '*.go' ! -path '*/vendor/*' ! -path '*/.build/*' -exec gofmt -s -w {} \+
+    find "${TARGET}" -name '*.go' ! -path '*/vendor/*' ! -path '*/.build/*' -exec go run "$gci_repo" write -s standard -s default -s "prefix(github.com/openshift)" -s blank --skip-generated {} \+
   done
   git diff --exit-code
 else

tools.go

@@ -6,13 +6,12 @@
 
 package tools
 
-import (
-	// dependency of hack/go-lint.sh
-	_ "golang.org/x/lint"
-
-	// dependency of generating CRD for install-config
-	_ "sigs.k8s.io/controller-tools/cmd/controller-gen"
-
+import ( // dependency of hack/go-fmt.sh
+	_ "github.com/daixiang0/gci"
 	// used to generate mocks
 	_ "github.com/golang/mock/mockgen"
+	// dependency of hack/go-lint.sh
+	_ "golang.org/x/lint"
+	// dependency of generating CRD for install-config
+	_ "sigs.k8s.io/controller-tools/cmd/controller-gen"
 )