kpt live diff is noisy and contains irrelevant changes

[phanimarupaka]

I made a small change to nginx package(bumped up replicas), but the live diff shows very verbose output. I expect this diff to be more precise and show me what I need to see.

➜  nginx git:(main) ✗ kpt live status
deployment.apps/my-nginx is Current: Deployment is available. Replicas: 2
service/my-nginx-svc is Current: Service is ready

➜  nginx git:(main) ✗ git diff
diff --git a/deployment.yaml b/deployment.yaml
index cf5dfe5..edc0bb0 100644
--- a/deployment.yaml
+++ b/deployment.yaml
@@ -18,7 +18,7 @@ metadata:
     env: dev
   name: my-nginx
 spec:
-  replicas: 2
+  replicas: 3
   selector:
     matchLabels:
       app: my-nginx

➜  nginx git:(main) ✗ kpt live diff
diff -u -N /var/folders/jx/jtq50wxs2h7g1xftcm79qwrw00pyt1/T/LIVE-508913543/apps.v1.Deployment.default.my-nginx /var/folders/jx/jtq50wxs2h7g1xftcm79qwrw00pyt1/T/MERGED-303310138/apps.v1.Deployment.default.my-nginx
--- /var/folders/jx/jtq50wxs2h7g1xftcm79qwrw00pyt1/T/LIVE-508913543/apps.v1.Deployment.default.my-nginx	2021-05-07 11:30:26.000000000 -0700
+++ /var/folders/jx/jtq50wxs2h7g1xftcm79qwrw00pyt1/T/MERGED-303310138/apps.v1.Deployment.default.my-nginx	2021-05-07 11:30:26.000000000 -0700
@@ -2,12 +2,11 @@
kind: Deployment
metadata:
  annotations:
-    config.k8s.io/owning-inventory: 1ba35c28fbca811486a6e2c7b74e371245665307-1619805875784412000
    deployment.kubernetes.io/revision: "1"
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"apps/v1","kind":"Deployment","metadata":{"annotations":{"config.k8s.io/owning-inventory":"1ba35c28fbca811486a6e2c7b74e371245665307-1619805875784412000"},"labels":{"env":"dev"},"name":"my-nginx","namespace":"default"},"spec":{"replicas":2,"selector":{"matchLabels":{"app":"my-nginx","env":"dev"}},"template":{"metadata":{"labels":{"app":"my-nginx","env":"dev"}},"spec":{"containers":[{"image":"nginx:1.14.1","name":"nginx","ports":[{"containerPort":80}]}]}}}}
  creationTimestamp: "2021-05-07T18:30:06Z"
-  generation: 1
+  generation: 2
  labels:
    env: dev
  managedFields:
@@ -17,14 +16,12 @@
      f:metadata:
        f:annotations:
          .: {}
-          f:config.k8s.io/owning-inventory: {}
          f:kubectl.kubernetes.io/last-applied-configuration: {}
        f:labels:
          .: {}
          f:env: {}
      f:spec:
        f:progressDeadlineSeconds: {}
-        f:replicas: {}
        f:revisionHistoryLimit: {}
        f:selector:
          f:matchLabels:
@@ -100,6 +97,14 @@
    manager: kube-controller-manager
    operation: Update
    time: "2021-05-07T18:30:22Z"
+  - apiVersion: apps/v1
+    fieldsType: FieldsV1
+    fieldsV1:
+      f:spec:
+        f:replicas: {}
+    manager: kpt
+    operation: Update
+    time: "2021-05-07T18:30:26Z"
  name: my-nginx
  namespace: default
  resourceVersion: "38967"
@@ -107,7 +112,7 @@
  uid: a00cdca6-f4b6-48fb-b1a5-e967cb014f5d
spec:
  progressDeadlineSeconds: 600
-  replicas: 2
+  replicas: 3
  revisionHistoryLimit: 10
  selector:
    matchLabels:
diff -u -N /var/folders/jx/jtq50wxs2h7g1xftcm79qwrw00pyt1/T/LIVE-508913543/v1.Service.default.my-nginx-svc /var/folders/jx/jtq50wxs2h7g1xftcm79qwrw00pyt1/T/MERGED-303310138/v1.Service.default.my-nginx-svc
--- /var/folders/jx/jtq50wxs2h7g1xftcm79qwrw00pyt1/T/LIVE-508913543/v1.Service.default.my-nginx-svc	2021-05-07 11:30:26.000000000 -0700
+++ /var/folders/jx/jtq50wxs2h7g1xftcm79qwrw00pyt1/T/MERGED-303310138/v1.Service.default.my-nginx-svc	2021-05-07 11:30:26.000000000 -0700
@@ -2,7 +2,6 @@
kind: Service
metadata:
  annotations:
-    config.k8s.io/owning-inventory: 1ba35c28fbca811486a6e2c7b74e371245665307-1619805875784412000
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"v1","kind":"Service","metadata":{"annotations":{"config.k8s.io/owning-inventory":"1ba35c28fbca811486a6e2c7b74e371245665307-1619805875784412000"},"labels":{"app":"nginx","env":"dev"},"name":"my-nginx-svc","namespace":"default"},"spec":{"ports":[{"port":80}],"selector":{"app":"my-nginx","env":"dev"},"type":"LoadBalancer"}}
  creationTimestamp: "2021-05-07T18:30:06Z"
@@ -16,7 +15,6 @@
      f:metadata:
        f:annotations:
          .: {}
-          f:config.k8s.io/owning-inventory: {}
          f:kubectl.kubernetes.io/last-applied-configuration: {}
        f:labels:
          .: {}
exit status 1

[frankfarzan]

The core UX issue is that with even with no human authored changes, you see diff like this.

[mortent]

The diff shown with kpt live diff shows the diff between the local configuration and the actual configuration found in the apiserver. Due to defaulted fields, fields managed by other controllers, and values added by the apiserver, there can be substantial differences from the local configuration. This is the expected behavior and aligned with how kubectl diff works.

One possible way to reduce some of the noise would be if we could allow users to suppress the managedFields information, as it tends to be very verbose. There have been some changes in kubectl around this: kubernetes/kubernetes#90066

Another issue with kpt live diff is that it currently doesn't consider resources deleted from the local state: #412

[mortent]

We have removed the kpt live diff command, so closing this issue.