How to mount volumes on kubernetes using emptyDir - docker

Question

I am trying to create a deployment out of my kompose file, but whenever I try:
kompose convert -f docker-compose.yaml
I get the error:
Volume mount on the host "[file directory]" isn't supported - ignoring path on the host
I have tried a few different solutions to my issue, firstly trying to add hostPath to my kompose convert as well as using persistent volumes, however both do not work.
my kompose files looks like this:
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
annotations:
kompose.cmd: kompose convert -f docker-compose.yaml --volumes emptyDir
kompose.version: 1.7.0 (HEAD)
creationTimestamp: null
labels:
io.kompose.service: es01
name: es01
spec:
replicas: 1
strategy:
type: Recreate
template:
metadata:
creationTimestamp: null
labels:
io.kompose.service: es01
spec:
containers:
- env:
- name: COMPOSE_CONVERT_WINDOWS_PATHS
value: "1"
- name: COMPOSE_PROJECT_NAME
value: elastic_search_container
- name: ES_JAVA_OPTS
value: -Xms7g -Xmx7g
- name: discovery.type
value: single-node
- name: node.name
value: es01
image: docker.elastic.co/elasticsearch/elasticsearch:7.2.1
name: es01
ports:
- containerPort: 9200
resources: {}
volumeMounts:
- mountPath: /usr/share/elasticsearch/data
name: es01-empty0
restartPolicy: Always
volumes:
- emptyDir: {}
name: es01-empty0
status: {}
I am using kompose version 1.7.0
My Docker Compose version:
version: '3'
services:
es01:
image: docker.elastic.co/elasticsearch/elasticsearch:7.2.1
container_name: es01
environment:
- node.name=es01
- COMPOSE_PROJECT_NAME=elastic_search_container
- discovery.type=single-node
- "ES_JAVA_OPTS=-Xms7g -Xmx7g"
- COMPOSE_CONVERT_WINDOWS_PATHS=1
ulimits:
nproc: 3000
nofile: 65536
memlock: -1
volumes:
- /home/centos/Sprint0Demo/Servers/elasticsearch:/usr/share/elasticsearch/data
ports:
- 9200:9200
networks:
- kafka_demo

Answer 1

You need to take a look on warning you get:
Volume mount on the host "[file directory]" isn't supported - ignoring path on the host
It happens when volume in docker-compose.yaml is configured with direct path.
Example below:
version: '3'
services:
web:
build: .
ports:
- "5000:5000"
volumes:
- "./storage1:/test1"
- "./storage2:/test2"
redis:
image: "redis:alpine"
volumes:
storage1:
storage2:
Persistent Volume Claim
Take a look on this link: Conversion matrix.
It describes how kompose converts Docker's volumes to Kubernetes ones.
Executing the conversion command without --volumes parameter:
$ kompose convert -f docker-compose.yml
With kompose 1.19 output will yield:
WARN Volume mount on the host "SOME_PATH" isn't supported - ignoring path on the host
WARN Volume mount on the host "SOME_PATH" isn't supported - ignoring path on the host
INFO Kubernetes file "web-service.yaml" created
INFO Kubernetes file "redis-deployment.yaml" created
INFO Kubernetes file "web-deployment.yaml" created
INFO Kubernetes file "web-claim0-persistentvolumeclaim.yaml" created
INFO Kubernetes file "web-claim1-persistentvolumeclaim.yaml" created
Warning message means that you are explicitly telling docker-compose to create volumes with direct path. By default kompose will convert Docker's volume to Persistent Volume Claim.
emptyDir
Executing the conversion command with --volumes emptyDir parameter:
$ kompose convert -f docker-compose.yml --volumes emptyDir
Will yield effect:
WARN Volume mount on the host "SOME_PATH" isn't supported - ignoring path on the host
WARN Volume mount on the host "SOME_PATH" isn't supported - ignoring path on the host
INFO Kubernetes file "web-service.yaml" created
INFO Kubernetes file "redis-deployment.yaml" created
INFO Kubernetes file "web-deployment.yaml" created
kompose will create emptyDir declaration inside web-deployment.yaml instead of creating separate definitions of PVC as it has in default.
hostPath
Executing the conversion command with --volumes hostPath parameter:
$ kompose convert -f docker-compose.yml --volumes hostPath
Will yield effect:
INFO Kubernetes file "web-service.yaml" created
INFO Kubernetes file "redis-deployment.yaml" created
INFO Kubernetes file "web-deployment.yaml" created
As you can see there is no warning about not supported path. There is no warning because it created hostPath explicitly using your own provided paths from docker-compose.yml.
Take a look on web-deployment.yaml volume section:
volumes:
- hostPath:
path: /LOCAL_PATH-/POD_PATH/storage1
name: web-hostpath0
- hostPath:
path: /LOCAL_PATH-/POD_PATH/storage2
name: web-hostpath1