Kubernetes Kustomize: replace variable in patch file - kubernetes

Question

Given the following kustomize patch:
apiVersion: apps/v1
kind: Deployment
metadata:
name: flux
spec:
template:
spec:
containers:
- name: some-name
args:
- --some-key=some-value
...
- --git-url=https://user:${PASSWORD}#domain.de
I want to use kubectl apply -k and somehow pass a value for ${PASSWORD} which I can set from my build script.
The only solution I got to work so far was replacing the ${PASSWORD} with sed, but I would prefer a kustomize solution.

Answer 1

As #Jonas already suggested you should consider using Secret. It's nicely described in this article.
I want to use kubectl apply -k and somehow pass a value for
${PASSWORD} which I can set from my build script.
I guess your script can store the generated password as a variable or save it to some file. You can easily create a Secret as follows:
$ kustomize edit add secret sl-demo-app --from-literal=db-password=$PASSWORD
or from a file:
$ kustomize edit add secret sl-demo-app --from-file=file/path
As you can read in the mentioned article:
These commands will modify your kustomization.yaml and add a
SecretGenerator inside it.
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
bases:
- ../../base
patchesStrategicMerge:
- custom-env.yaml
- replica-and-rollout-strategy.yaml
secretGenerator:
- literals:
- db-password=12345
name: sl-demo-app
type: Opaque
kustomize build run in your project directory will create among others following Secret:
apiVersion: v1
data:
db-password: MTIzNDU=
kind: Secret
metadata:
name: sl-demo-app-6ft88t2625
type: Opaque
...
More details you can fine in the article.
If we want to use this secret from our deployment, we just have, like
before, to add a new layer definition which uses the secret.
For example, this file will mount the db-password value as
environement variables
apiVersion: apps/v1
kind: Deployment
metadata:
name: sl-demo-app
spec:
template:
spec:
containers:
- name: app
env:
- name: "DB_PASSWORD"
valueFrom:
secretKeyRef:
name: sl-demo-app
key: db.password
In your Deployment definition file it may look similar to this:
apiVersion: apps/v1
kind: Deployment
metadata:
name: flux
spec:
template:
spec:
containers:
- name: some-name
env:
- name: "PASSWORD"
valueFrom:
secretKeyRef:
name: git-secret
key: git.password
args:
- --some-key=some-value
...
- --git-url=https://user:${PASSWORD}#domain.de