create configmap from a file

 kubectl create configmap database-config --from-file=database.properties

Once it is created, you can use it in a deployment to point to a file inside it using below sample.

Reference(mode details about configmaps)

Reference 2

Reference 3

apiVersion: v1
kind: Service
metadata:
  name: Shit-service
spec:
  selector:
    app: Shit
  ports:
    - protocol: TCP
      port: 80
      targetPort: Shit-port
  type: LoadBalancer

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: Shit-deployment
  labels:
    app: Shit
spec:
  replicas: 1
  selector:
    matchLabels:
      app: Shit
  template:
    metadata:
      labels:
        app: Shit
      annotations:
        consul.hashicorp.com/connect-inject: "true"
        consul.hashicorp.com/enable-metrics-merging: "false"
    spec:
      imagePullSecrets:
      - name: acr-mindset
      containers:
        - name: Shit
          image: Shitserverlinux.azurecr.io/Shit:4.0
          ports:
            - containerPort: 50345
              name: Shit-port
          volumeMounts:
            - name: config
              mountPath: /darwin/Shit Server
            - name: config
              mountPath: /home/spring/darwin/Shit Server
      volumes:
      - name: config
        configMap:
          name: nginx-configmap
          items:
          - key: ShitConfiguration.properties
            path: ShitConfiguration.properties

Or you can copy paste contents of the file after |.

You can replace the key value above volumes section with "ShitConfiguration.properties" with "config"   

Sample:

---
apiVersion: v1
kind: ConfigMap
metadata:
  name: database-configmap
data:
  config: |
   dbport=5432
   dcname=
   dbssl=false
   locktime=300
   domainuser=
   dbserver=420.420.420.420
   domainpwd=