Configuration properties can be passed to the Data Flow Server using Kubernetes ConfigMap and Secrets. The server uses the Fabric8 spring-cloud-kubernetes module to process both ConfigMap and Secrets settings. You just need to enable the ConfigMap support by passing in an environment variable of SPRING_CLOUD_KUBERNETES_CONFIG_NAME and setting that to the name of the ConfigMap. Same is true for the Secrets where the environment variable is SPRING_CLOUD_KUBERNETES_SECRETS_NAME. To use the Secrets you also need to set SPRING_CLOUD_KUBERNETES_SECRETS_ENABLE_API to true.

An example configuration could look like the following where we configure Kafka, MySQL and Redis for the server:

apiVersion: v1
kind: ConfigMap
metadata:
  name: scdf-config
data:
  application.yaml: |-
    spring:
      cloud:
        deployer:
          kubernetes:
            environmentVariables: 'SPRING_CLOUD_STREAM_KAFKA_BINDER_BROKERS=${KAFKA_SERVICE_HOST}:${KAFKA_SERVICE_PORT},SPRING_CLOUD_STREAM_KAFKA_BINDER_ZK_NODES=${KAFKA_ZK_SERVICE_HOST}:${KAFKA_ZK_SERVICE_PORT},SPRING_REDIS_HOST=${REDIS_SERVICE_HOST},SPRING_REDIS_PORT=${REDIS_SERVICE_PORT}'
      datasource:
        url: jdbc:mysql://${MYSQL_SERVICE_HOST}:${MYSQL_SERVICE_PORT}/test
        driverClassName: org.mariadb.jdbc.Driver
        testOnBorrow: true
        validationQuery: "SELECT 1"
      redis:
        host: ${REDIS_SERVICE_HOST}
        port: ${REDIS_SERVICE_PORT}

We assume here that Kafka is deployed using kafka and kafka_zk as the service names. For the MySQL we assume the service name is mysql and for Redis we assume it is redis. Kubernetes will publish these services host and port values as environment variables that we can use when configuring any deployed apps.

We prefer to provide the MySQL connection secrets in a Secrets file:

apiVersion: v1
kind: Secret
metadata:
  name: scdf-secrets
data:
  spring.datasource.username: cm9vdA==
  spring.datasource.password: eW91cnBhc3N3b3Jk

The username and password are provided as base64 encoded values.