kubernetes volumes for nestjs app for hot reloading data - docker

Question

I'm having an issue with volumes on Kubernetes when I'm trying to mount hostPath volumes. (i also tried with PVC, but no success)
Dockerfile:
FROM node:16
WORKDIR /usr/src/app
COPY package.json /usr/src/app
RUN yarn install
COPY . /usr/src/app
EXPOSE 3000
ENTRYPOINT ["yarn", "start:dev"]
docker-compose.yml:
version: '3.8'
services:
api:
container_name: api
build:
context: .
dockerfile: Dockerfile
volumes:
- .:/usr/src/app
- /usr/src/app/node_modules
ports:
- 3000:3000
restart: always
labels:
kompose.volume.type: 'hostPath'
database:
container_name: database
image: postgres:latest
ports:
- 5432:5432
environment:
POSTGRES_USER: postgres
POSTGRES_PASSWORD: postgres
POSTGRES_DB: task-management
api-development.yml
apiVersion: apps/v1
kind: Deployment
metadata:
annotations:
kompose.cmd: kompose -f docker-compose.yml convert
kompose.version: 1.26.1 (HEAD)
kompose.volume.type: hostPath
creationTimestamp: null
labels:
io.kompose.service: api
name: api
spec:
replicas: 1
selector:
matchLabels:
io.kompose.service: api
strategy:
type: Recreate
template:
metadata:
annotations:
kompose.cmd: kompose -f docker-compose.yml convert
kompose.version: 1.26.1 (HEAD)
kompose.volume.type: hostPath
creationTimestamp: null
labels:
io.kompose.service: api
spec:
containers:
- image: task-management_api
name: api
imagePullPolicy: Never
ports:
- containerPort: 3000
resources: {}
volumeMounts:
- mountPath: /usr/src/app
name: api-hostpath0
- mountPath: /usr/src/app/node_modules
name: api-hostpath1
restartPolicy: Always
volumes:
- hostPath:
path: /Users/handrei/workspace/devs/nest-ws/task-management
name: api-hostpath0
- hostPath:
name: api-hostpath1
status: {}
the error I received from the pod is the next one:
kubectl logs api-84b56776c5-v86c7
yarn run v1.22.17
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
error Couldn't find a package.json file in "/usr/src/app"
I assume that's something wrong with volumes because applying the deployment and service without volumes it's working

Answer 1

A hostPath volume mounts a file or directory from the host node's filesystem into your Pod.
To the required path property, you can also specify a type for a hostPath volume.
NOTE: HostPath volumes present many security risks, and it is a best practice to avoid the use of HostPaths when possible. When a HostPath volume must be used, it should be scoped to only the required file or directory, and mounted as ReadOnly.
As #David Maze mentioned before, It's better idea to
use Node locally for day-to-day development and use a self-contained image (without any volume mounts at all) in Kubernetes. (...)
The node_modules directory is empty and nothing in Kubernetes will every copy data there. You'll need to delete all of the volume declarations from your Deployment spec for this to run.
This quide will help you to translate a Docker Compose File to Kubernetes Resources.
See also this questions on StackOverflow:
Why node_modules is empty after docker build?
Kubernetes volume for node_modules