Use kustomize to set hostPath path - kubernetes

Question

Is it possible to use kustomize to specify a volume hostPath from an env variable?
I have a Kubernetes manifest that describes my deployment consisting of a container.
During development, I use a different image (that contains dev tools) and mount code from my host into the container. This way I can make code changes without having to re-deploy.
I'm using a patchStategicMerge to replace the production image, with the one I want to use during dev and mount the code into the container i.e.
kustomization.yaml
kind: Kustomization
bases:
- ../../base
patchesStrategicMerge:
- my-service.yaml
my-service.yaml
---
apiVersion: apps/v1
...
...
spec:
containers:
- name: myservice
image: myservice-dev-image:1.0.0
command: ['CompileDaemon', '--build=make build', '--command=./myservice']
volumeMounts:
- name: code
mountPath: /go/src/app
volumes:
- name: code
hostPath:
path: /source/mycodepath/github.com/myservice
What I'd like to do is make the path configurable via an environment variable, so that I don't have to check my specific path (/source/mycodepath/) into git, and so that other developers can easily use it in their own environment.
Is it possible to do this with kustomize ?

Answer 1

Create following directory structure
k8s
k8s/base
k8s/overlays
k8s/overlays/bob
k8s/overlays/sue
First we need to create the base. The base is the default template and it provide the bits that apply to both people. In k8s/base create a file called app.yaml and populate with the following (actually paste yours here. You can put other common bits in there too separated by a --- and new line).
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: myservice
namespace: default
spec:
strategy:
type: RollingUpdate
replicas: 1
template:
metadata:
labels:
name: myservice
app: myservice
spec:
containers:
- name: myservice
image: myservice-dev-image:1.0.0
command: ['CompileDaemon', '--build=make build', '--command=./myservice']
volumeMounts:
- name: code
mountPath: /go/src/app
volumes:
- name: code
hostPath:
path: /xxx
Next in the same directory (k8s/base) create another file called kustomization.yaml and populate with:
resources:
- app.yaml
Next we will create two overlays: one for Bob and one for Sue.
In k8s/overlays/bob let's create Bob's custom changes as app.yaml and populate with the following:
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: myservice
namespace: default
spec:
template:
spec:
volumes:
- name: code
hostPath:
path: /users/bob/code
Now also in k8s/overlays/bob create another file called kustomization.yaml with the following:
resources:
- ../../base
patchesStrategicMerge:
- app.yaml
We can copy the two files in k8s/overlays/bob into the k8s/overlays/sue directory and just change the path in the volumes: bit.
Next we need to do a kustomize build to generate the resulting versions - bob and sue.
If the k8s directory is in your code directory, open terminal (with Kustomize installed and run:
kustomize build k8s/overlays/bob
That should show you what Bob's kustomization will look like:
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: myservice
namespace: default
spec:
replicas: 1
strategy:
type: RollingUpdate
template:
metadata:
labels:
app: myservice
name: myservice
spec:
containers:
- command:
- CompileDaemon
- --build=make build
- --command=./myservice
image: myservice-dev-image:1.0.0
name: myservice
volumeMounts:
- mountPath: /go/src/app
name: code
volumes:
- hostPath:
path: /users/bob/code
name: code
To apply that you can run:
kustomize build k8s/overlays/bob | kubectl apply -f -
To apply Sue you can run:
kustomize build k8s/overlays/sue| kubectl apply -f -
Yaml is sensitive about spaces and I'm not sure this will sit well in a Stackoverflow answer so I've put on Github as well: https://github.com/just1689/kustomize-local-storage