Add helper image merger to merge yaml files

[lukaszo]

Description

Changes proposed in this pull request:

• Add helper image merger to merge yaml files

Testing

Build image

docker build -t merger .

Create few yaml files:

input.yaml:

a: 1

additional:yaml:

b: 2

extra.yaml:

c: 3

Run merger

docker run --mount src=`pwd`,target=/yamls,type=bind -e OUT=/yamls/all.yaml merger

Check the output file:
all.yaml

input:
  a: 1
additional:
  b: 2
extra:
  c: 3

Related issue(s)

#419

[mszostok]

Tested and works good 👍 but please address small comments

• Please update the main README: https://github.com/capactio/capact/blob/926517cc92f3680868fadf2e2b1ab821b987859b/hack/images/README.md
  (you can also get rid of this structure)
• Please add this image also here:

  capact/Makefile

  Line 22 in b3228c7

  INFRA = json-go-gen graphql-schema-linter jinja2

[mszostok]

Suggested change

	└── merger # The image that contains yaml merger helper scriptyaml merger helper script
	└── merger # The image that contains YAML merger helper

hm.. sth was merged here 🤔 😜

NOTE:
I also thought about not changing the input YAML files, or maybe put them in /yamls/processed/*. Now when you executed the docker run.. twice then it will generate different output. So maybe in the future if we will implement argo retry for failed step it may cause some not deterministic output. On the other hand, we have a copy of artifacts, so maybe it will work properly. For now it can stay as it is 👍

[lukaszo]

From what I see, during argo retry the pod is recreated(with the same name) and artifacts are downloaded again. We should be good here