Add a diff kustomization feature

If implemented it will permit queriying the Kubernetes API to fetch the specified
Flux Kustomization, then uses the specified path to build the overlay.
It will then ssa-dry-run apply and output the diff using homeport/dyff

Signed-off-by: Soule BA <soule@weave.works>

go.mod

@@ -12,6 +12,7 @@ require (
 	github.com/fluxcd/image-reflector-controller/api v0.15.0
 	github.com/fluxcd/kustomize-controller/api v0.19.1
 	github.com/fluxcd/notification-controller/api v0.20.1
+	github.com/fluxcd/pkg/apis/kustomize v0.3.1
 	github.com/fluxcd/pkg/apis/meta v0.10.2
 	github.com/fluxcd/pkg/runtime v0.12.3
 	github.com/fluxcd/pkg/ssa v0.10.0
@@ -20,9 +21,13 @@ require (
 	github.com/fluxcd/pkg/version v0.0.1
 	github.com/fluxcd/source-controller/api v0.20.1
 	github.com/go-git/go-git/v5 v5.4.2
+	github.com/gonvenience/bunt v1.3.2
+	github.com/gonvenience/ytbx v1.4.2
 	github.com/google/go-cmp v0.5.6
 	github.com/google/go-containerregistry v0.2.0
 	github.com/hashicorp/go-retryablehttp v0.7.0 // indirect
+	github.com/homeport/dyff v1.4.6
+	github.com/lucasb-eyer/go-colorful v1.2.0
 	github.com/manifoldco/promptui v0.9.0
 	github.com/mattn/go-shellwords v1.0.12
 	github.com/olekukonko/tablewriter v0.0.4
@@ -42,6 +47,11 @@ require (
 	sigs.k8s.io/yaml v1.3.0
 )
 
+require (
+	github.com/drone/envsubst v1.0.3
+	sigs.k8s.io/kustomize/kyaml v0.13.0
+)
+
 require (
 	cloud.google.com/go v0.81.0 // indirect
 	github.com/Azure/go-ansiterm v0.0.0-20210617225240-d185dfc1b5a1 // indirect
@@ -51,6 +61,7 @@ require (
 	github.com/Azure/go-autorest/autorest/date v0.3.0 // indirect
 	github.com/Azure/go-autorest/logger v0.2.1 // indirect
 	github.com/Azure/go-autorest/tracing v0.6.0 // indirect
+	github.com/BurntSushi/toml v0.4.1 // indirect
 	github.com/MakeNowJust/heredoc v0.0.0-20170808103936-bb23615498cd // indirect
 	github.com/Microsoft/go-winio v0.4.16 // indirect
 	github.com/PuerkitoBio/purell v1.1.1 // indirect
@@ -64,7 +75,6 @@ require (
 	github.com/evanphx/json-patch v4.12.0+incompatible // indirect
 	github.com/exponent-io/jsonpath v0.0.0-20151013193312-d6023ce2651d // indirect
 	github.com/fluxcd/pkg/apis/acl v0.0.3 // indirect
-	github.com/fluxcd/pkg/apis/kustomize v0.3.1 // indirect
 	github.com/form3tech-oss/jwt-go v3.2.3+incompatible // indirect
 	github.com/fvbommel/sortorder v1.0.1 // indirect
 	github.com/go-errors/errors v1.0.1 // indirect
@@ -76,6 +86,10 @@ require (
 	github.com/go-openapi/swag v0.19.14 // indirect
 	github.com/gogo/protobuf v1.3.2 // indirect
 	github.com/golang/protobuf v1.5.2 // indirect
+	github.com/gonvenience/neat v1.3.7 // indirect
+	github.com/gonvenience/term v1.0.1 // indirect
+	github.com/gonvenience/text v1.0.6 // indirect
+	github.com/gonvenience/wrap v1.1.0 // indirect
 	github.com/google/btree v1.0.1 // indirect
 	github.com/google/go-github/v41 v41.0.0 // indirect
 	github.com/google/go-querystring v1.1.0 // indirect
@@ -87,7 +101,6 @@ require (
 	github.com/hashicorp/errwrap v1.0.0 // indirect
 	github.com/hashicorp/go-cleanhttp v0.5.1 // indirect
 	github.com/hashicorp/go-multierror v1.1.1 // indirect
-	github.com/hashicorp/go-retryablehttp v0.6.8 // indirect
 	github.com/imdario/mergo v0.3.12 // indirect
 	github.com/inconshreveable/mousetrap v1.0.0 // indirect
 	github.com/jbenet/go-context v0.0.0-20150711004518-d14ea06fba99 // indirect
@@ -96,9 +109,13 @@ require (
 	github.com/kevinburke/ssh_config v0.0.0-20201106050909-4977a11b4351 // indirect
 	github.com/liggitt/tabwriter v0.0.0-20181228230101-89fcab3d43de // indirect
 	github.com/mailru/easyjson v0.7.6 // indirect
+	github.com/mattn/go-ciede2000 v0.0.0-20170301095244-782e8c62fec3 // indirect
+	github.com/mattn/go-isatty v0.0.14 // indirect
 	github.com/mattn/go-runewidth v0.0.7 // indirect
 	github.com/mitchellh/go-homedir v1.1.0 // indirect
+	github.com/mitchellh/go-ps v1.0.0 // indirect
 	github.com/mitchellh/go-wordwrap v1.0.0 // indirect
+	github.com/mitchellh/hashstructure v1.1.0 // indirect
 	github.com/moby/spdystream v0.2.0 // indirect
 	github.com/moby/term v0.0.0-20210610120745-9d4ed1856297 // indirect
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
@@ -109,15 +126,18 @@ require (
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/russross/blackfriday v1.5.2 // indirect
 	github.com/russross/blackfriday/v2 v2.0.1 // indirect
-	github.com/sergi/go-diff v1.1.0 // indirect
+	github.com/sergi/go-diff v1.2.0 // indirect
 	github.com/shurcooL/sanitized_anchor_name v1.0.0 // indirect
 	github.com/stretchr/testify v1.7.0 // indirect
+	github.com/texttheater/golang-levenshtein v1.0.1 // indirect
+	github.com/virtuald/go-ordered-json v0.0.0-20170621173500-b18e6e673d74 // indirect
 	github.com/xanzy/go-gitlab v0.54.3 // indirect
 	github.com/xanzy/ssh-agent v0.3.0 // indirect
 	github.com/xlab/treeprint v0.0.0-20181112141820-a009c3971eca // indirect
 	go.starlark.net v0.0.0-20200306205701-8dd3e2ee1dd5 // indirect
 	golang.org/x/net v0.0.0-20211216030914-fe4d6282115f // indirect
 	golang.org/x/oauth2 v0.0.0-20210819190943-2bc19b11175f // indirect
+	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c // indirect
 	golang.org/x/sys v0.0.0-20211029165221-6e7872819dc8 // indirect
 	golang.org/x/text v0.3.7 // indirect
 	golang.org/x/time v0.0.0-20210723032227-1f47c861a9ac // indirect
@@ -132,7 +152,6 @@ require (
 	k8s.io/kube-openapi v0.0.0-20211115234752-e816edb12b65 // indirect
 	k8s.io/utils v0.0.0-20211208161948-7d6a63dca704 // indirect
 	sigs.k8s.io/json v0.0.0-20211208200746-9f7c6b3444d2 // indirect
-	sigs.k8s.io/kustomize/kyaml v0.13.0 // indirect
 	sigs.k8s.io/structured-merge-diff/v4 v4.2.0 // indirect
 )