How to mount jar file to tomcat container - kubernetes

Question

I have a folder in my project, which contains 1 properties file and 1 jar file(db-driver) file.
I need to copy both of these files to /usr/local/tomcat/lib directory on my pod. I am not sure how to achieve this in kubernetes yaml file. Below is my yaml file where I am trying to achieve this using configMap, but pod creation fails with error "configmap references non-existent config key: app.properties"
Target /usr/local/tomcat/lib already has other jar files so I am trying to use configMap to not override entire directory and just add 2 files which are specific to my application.
apiVersion: apps/v1
kind: Deployment
metadata:
name: tomcatdeployment
labels:
app: tomcat
spec:
replicas: 1
selector:
matchLabels:
app: tomcat
template:
metadata:
labels:
app: tomcat
spec:
containers:
- name: tomcat
image: tomcat:latest
imagePullPolicy: IfNotPresent
volumeMounts:
- name: appvolume
mountPath: /usr/local/data
- name: config
mountPath: /usr/local/tomcat/lib
subPath: ./configuration
ports:
- name: http
containerPort: 8080
protocol: TCP
volumes:
- name: appvolume
- name: config
configMap:
name: config-map
items:
- key: app.properties
path: app.properties
---
apiVersion: v1
kind: ConfigMap
metadata:
name: config-map
data:
key: app.properties
Current Directory structure...
.
├── configuration
│   ├── app.properties
│   └── mysql-connector-java-5.1.21.jar
├── deployment.yaml
└── service.yaml
Please share your valuable feedback on how to achieve this.
Regards.

Answer 1

Please try this:
kubectl create configmap config-map --from-file=app.properties --from-file=mysql-connector-java-5.1.21.jar
apiVersion: apps/v1
kind: Deployment
metadata:
name: tomcatdeployment
labels:
app: tomcat
spec:
replicas: 1
selector:
matchLabels:
app: tomcat
template:
metadata:
labels:
app: tomcat
spec:
containers:
- name: tomcat
image: tomcat:latest
imagePullPolicy: IfNotPresent
volumeMounts:
- name: config
mountPath: /usr/local/tomcat/lib/conf
ports:
- name: http
containerPort: 8080
protocol: TCP
volumes:
- name: config
configMap:
name: config-map
or
apiVersion: apps/v1
kind: Deployment
metadata:
name: tomcatdeployment
labels:
app: tomcat
spec:
replicas: 1
selector:
matchLabels:
app: tomcat
template:
metadata:
labels:
app: tomcat
spec:
containers:
- name: tomcat3
image: tomcat:latest
imagePullPolicy: IfNotPresent
volumeMounts:
- name: config
mountPath: /usr/local/tomcat/lib/app.properties
subPath: app.properties
- name: config
mountPath: /usr/local/tomcat/lib/mysql-connector-java-5.1.21.jar
subPath: mysql-connector-java-5.1.21.jar
ports:
- name: http
containerPort: 8080
protocol: TCP
volumes:
- name: config
configMap:
name: config-map
items:
- key: app.properties
path: app.properties
- key: mysql-connector-java-5.1.21.jar
path: mysql-connector-java-5.1.21.jar

Answer 2

it's normal to have this error because in this volume declaration you mentioned that key: app.properties otherwise in the configmap key: app.properties so here the key is key and the value is app.properties so you must in the volume declaration change :
volumes:
- name: appvolume
- name: config
configMap:
name: config-map
items:
- key: app.properties
path: app.properties
to :
volumes:
- name: appvolume
- name: config
configMap:
name: config-map
items:
- key: key
path: app.properties
for more you can refer here : add-configmap-data-to-a-volume