Simplify skaffold init code

[dgageot]

Each commit is a simplification. I didn't merge them to ease the review.
Also fixes #3405

[codecov]

Codecov Report

Merging #3406 into master will increase coverage by 0.06%.
The diff coverage is 85.54%.

Impacted Files	Coverage Δ
pkg/skaffold/docker/docker_init.go	100% <100%> (ø)	⬆️
pkg/skaffold/build/jib/init.go	88.13% <100%> (ø)	⬆️
pkg/skaffold/initializer/init.go	63.41% <68.57%> (+2.79%)	⬆️
pkg/skaffold/build/buildpacks/init.go	86.66% <90.9%> (-4.25%)	⬇️

[balopat]

One issue with these changes is that it will generate a bit more verbose skaffold.yaml than necessary based on our current defaults - however there is no tests ensuring this behavior yet, and it is not the end of the world. But still a bit of a regression in UX in my opinion:

diff --git a/examples/microservices/skaffold.yaml b/examples/microservices/skaffold.yaml
index f4e408246..4bd5ba5b3 100644
--- a/examples/microservices/skaffold.yaml
+++ b/examples/microservices/skaffold.yaml
@@ -1,18 +1,22 @@
-apiVersion: skaffold/v1
+apiVersion: skaffold/v2alpha1
 kind: Config
+metadata:
+  name: microservices
 build:
   artifacts:
-    - image: gcr.io/k8s-skaffold/leeroy-web
-      context: ./leeroy-web/
-    - image: gcr.io/k8s-skaffold/leeroy-app
-      context: ./leeroy-app/
+  - image: gcr.io/k8s-skaffold/leeroy-app
+    context: leeroy-app
+    docker:
+      dockerfile: Dockerfile
+  - image: gcr.io/k8s-skaffold/leeroy-web
+    context: leeroy-web
+    docker:
+      dockerfile: Dockerfile
+  tagPolicy:
+    gitCommit: {}
+  local: {}
...

vs the current version:

diff --git a/examples/microservices/skaffold.yaml b/examples/microservices/skaffold.yaml
index f4e408246..b79fcbb74 100644
--- a/examples/microservices/skaffold.yaml
+++ b/examples/microservices/skaffold.yaml
@@ -1,18 +1,15 @@
-apiVersion: skaffold/v1
+apiVersion: skaffold/v2alpha1
 kind: Config
+metadata:
+  name: microservices
 build:
   artifacts:
-    - image: gcr.io/k8s-skaffold/leeroy-web
-      context: ./leeroy-web/
-    - image: gcr.io/k8s-skaffold/leeroy-app
-      context: ./leeroy-app/
+  - image: gcr.io/k8s-skaffold/leeroy-app
+    context: leeroy-app
+  - image: gcr.io/k8s-skaffold/leeroy-web
+    context: leeroy-web

[balopat]

LGTM with the nit that this version of skaffold init doesn't respect default value setting. I would rather keep the yaml minimal when possible. WDYT?

[dgageot]

Good catch @balopat!

It used to be that only a few defaults were explicit.
Now they all are. I don't really like that,
I was thinking of having none...

Anyways, I think it’s best to add a non regression test and make sure we produce the same yaml as before. Wdyt?

[dgageot]

I changed a few things to make sure we produce the same yaml as before.

[balopat]

Nice! Good to go! Thank you for the improvements, I believe this is a much better UX to keep the yaml minimal!