It is quite easy to run Ceptor inside a Docker image, but there are some caveats that you need to know of.

Caveats You Need to Know About

First, Docker behaves differently regarding memory, and by default, the JVM reads the memory size of the machine that docker runs inside, not the amount of memory that is reserved to the individual docker image.
If a docker containers memory limit is hit, the Linux kernel simply kills the process with no easily identifiable messages, so troubleshooting can be difficult.

Second, many container engines (e.g. OpenShift) have by default very low amount of CPU reserved for an image, causing starvation where the processes are starved of CPU for dozens of seconds, and even minutes. If this occurs, internal diagnostics within Ceptor will start complaining that something is wrong, connections between component might be considered timed out and closed, and for extreme delays, components might be killed and restarted.

Memory-related command-line arguments in Java 8

To work around the memory issues, the JVM you start must have the options -XX:+UnlockExperimentalVMOptions -XX:+UseCGroupMemoryLimitForHeap defined on the java command line - this enables the JVM to recognize the limits imposed by the docker container and adjust accordingly.

When using Java 11, no such options are needed - it will figure it out by default.

CPU Settings

You should in general reserve at least 2 cores to Ceptor - the amount needed depends heavily upon load, and the number of services started up in the same container. If you start seeing errors in the logs, such as "It took more than 5 seconds (38256 msecs) to...." - then it is a sign that the processes are starved of CPU.

Ceptor Docker Images

Ceptor provides 5 docker images;

ceptor-base
ceptor-base-gateway
ceptor-base-microgateway
ceptor-demo
ceptor-demo-gateway

These images reside on Docker Hub - to get read access to the repositories, please register your docker hub account at sales@ceptor.io and we will ensure that your docker account is allowed to access our repositories.

Once you have access, you can go to https://hub.docker.com/u/ceptor to view the list of available repositories and images.

ceptor-base

This is the base/core image - it contains all the code needed, but little or no configuration - all the remaining ceptor images build upon this one.

ceptor-base-gateway

This image is based upon ceptor-base but it removes everything not needed by the gateway itself - this is a useful image to base a single Gateway (or API Gateway) upon, since it has all non-essential files removed so it is suitable to use in e.g. DMZ zones.

ceptor-base-microgateway

This image is like ceptor-base-gateway based upon ceptor-base, but keeps full ceptor functionality providing a scaled down configuration with very low resource requirements - this is an excellent choice for basing a microgateway upon.

ceptor-demo

This image can be used as a demonstration for Ceptor - it contains a single instance of both Ceptor Server and Gateway, along with example configuration - starting everything up in the same, single instance.

ceptor-demo-gateway

The ceptor-demo-gateway image contains a demonstration version of a standalone gateway, based upon the ceptor-base-gateway image. It starts only a single instance of the gateway.

Dockerfile

This is an example of a Dockerfile for the Ceptor Demonstration image, which runs all components in a single docker image, and only exposes port 4243 to the console, port 8443 to the gateway and port 9443 to the internal gateway (used for admin REST APIs)

FROM ceptor-base
MAINTAINER Ceptor ApS <support@ceptor.io>

LABEL description="Ceptor Demonstration"

EXPOSE 4243 8443 9443

COPY pp/testdatabase /ceptor/template/testdatabase
COPY pp/config /ceptor/template/config
COPY docker/cfg /ceptor/template/config

COPY docker/ceptor_demo.sh /ceptor/ceptor.sh

RUN tr -d '\r' < /ceptor/ceptor.sh > /usr/local/bin/ceptor-entrypoint.sh \
 && chmod +x /usr/local/bin/ceptor-entrypoint.sh \
 && rm /ceptor/ceptor.sh \
 && mkdir /ceptor/testdatabase \
#Allow it to be run by non-root users
 && chgrp -R 0 /ceptor/template/testdatabase \
 && chmod -R g=u /ceptor/template/testdatabase \
 && chgrp -R 0 /ceptor/template/config \
 && chmod -R g=u /ceptor/template/config

ENV elasticsearch_server=elasticsearch
ENV elasticsearch_enabled=false

VOLUME ["/ceptor/logs", "/ceptor/statistics", "/ceptor/config", "/ceptor/testdatabase"]

Note the elasticsearch_server and elasticsearch_enabled environment variables - to use Elasticsearch for API Usage information, simply set elasticsearch_enabled to true and elasticsearch_server to the elasticsearch hostname.

Docker Docker ENTRYPOINT

As you can see from the Dockerfile, it sets an entrypoint copied from ceptor.sh - that files is below, its purpose it to check if the config and testdatabase directories are empty on startup, and if they are - it will populate them with default values - this makes it easier to use persistent volumes on e.g. OpenShift without needing to copy files around manually before starting.

ceptor.sh - docker entrypoint

#!/bin/bash

#
# Check if config and database directories are empty.
# They might be if volume is mounted to an empty dir - if so,
# copy from template so we can startup - then run the program
# supplied in the parameters
#

#if nothing in config, copy from template
if [ "$(ls -A /ceptor/config)" ]; then
	echo "Files are already in /ceptor/config - reusing them"
else
     cp -R /ceptor/template/config/* /ceptor/config
fi

#if nothing in testdatabase, copy from template
if [ "$(ls -A /ceptor/testdatabase)" ]; then
	echo "Files are already in /ceptor/testdatabase - reusing them"
else
     cp -R /ceptor/template/testdatabase/* /ceptor/testdatabase
fi

exec "$@"

Which Ports to Expose

See Deployment Firewall Settings which contains a list of ports different components use by default.

Persistent volumes

By default, in the Demo image, Ceptor needs 5 persistent volumes or directories;

/ceptor/config
The configuration is persisted here - any changes made will be saved to the config folder - this should contain a separate persistent image for each config server.
/ceptor/logs
Logfiles are by default written to this directory by all Ceptor components.
/ceptor/statistics
The statistics server stores its files in this directory.
/ceptor/work
If using Apache Ignite, it stores its file in the work directory, so each Ignite instance should have its own.
/ceptor/testdatabase
When using the default test derby database for useradmin, or as datastore for APIs, it persists its files in this directory.

Different Approaches

Running Using the Service Launcher

Normally outside Docker, Ceptor is started using the service launcher / bootstrapper, which is a process that starts up and reads ceptor-launch.xml from the contents of this file, it then starts several sub-processes, and monitors and restarts them if any failures occur.

This approach can be used in docker, but beware that the total memory requirement is the sum of the maximum heap + non-heap memory and container overhead for all processes.

Telling Service Launcher to Run in Standalone Mode

The Service Launcher is capable of running in standalone mode - this means it loads the JVM definitions within ceptor-launch.xml but does not spawn separate child JVMs processes - instead it loads it all in the current process. This is often easier if running just a single JVM.

Below is an example of changed startup options which runs in standalone mode.

CMD ["java", "-XX:+HeapDumpOnOutOfMemoryError", "-Dorg.jboss.logging.provider=slf4j", "--add-opens", "jdk.management/com.sun.management.internal=ALL-UNNAMED", "-jar", "/ceptor/bin/boot.jar", "-standalone", "/ceptor/config/ceptor_launch.xml"]

Splitting into Multiple Containers

It is also possible to split into multiple containers, and start each component in its own - this is easily enough accomplished using parameters for the launcher, which can tell it to start just a single JVM, and even not to start any client-process, but instead load the services in the parent process.

This approach is preferred by many, since it allows scaling each individual component up and down depending on load.

It has a significant downside though, and that is increased complexity in the setup - it complicates configuration, load balancing etc. and since there are significant differences between different container engines and their configuration / capabilities, there is no one good guide that covers them all.

A tradeoff can be a good idea, where e.g. the gateway and session controller are kept as separate containers and able to scale up and down depending on load - then configuration servers, console, logserver etc. can be kept together

JVMs and Services

The default docker command to start looks like this:

CMD ["java", "-jar", "/ceptor/bin/boot.jar", "/ceptor/config/ceptor_launch.xml"]

You can add more arguments to control which modules/jvms to startup - see more information here: Ceptor Getting Started

The default ceptor_launch.xml file in the docker image contains these JVMs (note that this differs slightly from default distribution to save memory within the docker container).

Here is an appreviated list with most of the settings removed for clarity.

<jvm name="cfg" ...>	 
  <service name="configserver1" launcherclass="dk.itp.managed.service.ConfigServerLauncher">
  <service name="logserver1" serviceclass="dk.itp.peer2peer.log.server.LogServer" />
  <service name="statisticsserver1" serviceclass="dk.itp.managed.service.StatisticsService" />


<jvm name="ignite" ...>
  <service name="ignite1" launcherclass="io.ceptor.ignite.IgniteLauncher">


<jvm name="console" ...>
  <service name="ceptorconsole" launcherclass="io.ceptor.console.ConsoleLauncher">


<jvm name="session_user" ...>
  <service name="derby" launcherclass="io.ceptor.datastore.db.DerbyLauncher">
  <service name="sessionctrl1" serviceclass="dk.itp.security.passticket.server.PTSServer" />
  <service name="useradmin1" launcherclass="dk.itp.pp.useradmin.server.UserAdminServerLauncher" />
  <service name="useradminapp" launcherclass="dk.asseco.pp.ua.UserAdminAppLauncher">


<jvm name="gateway" ...>
  <service name="gateway1" launcherclass="io.ceptor.gateway.GatewayLauncher">


<jvm name="apideveloperportal" ...>
  <service name="apideveloperportal" launcherclass="io.ceptor.apimanager.developerportal.DeveloperPortalLauncher">


<jvm name="demoapp" ...>
  <service name="webserver1" launcherclass="dk.itp.managed.service.GenericWarLauncher">

If you e.g only want to start a gateway within a particular docker container (or pod if using Kubernetes terminology), add a few extra command-line arguments like this:

CMD ["java", "-jar", "/ceptor/bin/boot.jar", "/ceptor/config/ceptor_launch.xml", "-jvms", "gateway"]

or if you want to start only the sessionctrl1 and useradmin1 within the session_user jvm, add these arguments instead:

CMD ["java", "-jar", "/ceptor/bin/boot.jar", "/ceptor/config/ceptor_launch.xml", "-jvms", "session_user", "-services", "sessionctrl1;useradmin1"]

Note that when starting the configuration server, you should only have one instance of the statisticsserver and one instance of the master config server - you can have as many slave configserver instances as you want, but there can only be a single master running at a time and only a single statisticsserver.

When you only start a single JVM, there is no reason to use the launcher and let it start a client process - in this case, add -standalone to the command-line arguments, and also add any JVM options, e.g.

java -Djava.awt.headless=true -Xnoclassgc -XX:+UnlockExperimentalVMOptions -XX:+UseCGroupMemoryLimitForHeap-jar \
  ceptor/bin/boot.jar \
  /ceptor/config/ceptor_launch.xml \
  -jvms session_user \
  -services sessionctrl1;useradmin1

When you run it this way, only a single process will run within the docker container, using the least amount of resources.

Autoscaling

Autoscaling does not make sense for all components - there is no reason for instance to autoscale the configuration server, logserver or the console - but autoscaling the gateway or even the session controller might be a good idea.

OpenShift Notes...

OpenShift has a known bug which we have run into about pulling from private repositories.... info and workaround here: https://access.redhat.com/solutions/3568231

Note that the workaround is NOT (at the time of writing) implemented in the Online version of OpenShift.

Using Docker Compose

The following file is an example that configures docker compose to start an Elasticsearch, as well as a single demonstration Ceptor container which uses Elasticsearch for API Usage information.

Example docker-compose.yml

version: '2.2'
services:
  elasticsearch:
    image: docker.elastic.co/elasticsearch/elasticsearch:6.5.4
    container_name: elasticsearch
    environment:
      - cluster.name=docker-cluster
      - bootstrap.memory_lock=true
      - "ES_JAVA_OPTS=-Xms512m -Xmx512m"
      - discovery.type=single-node
    ulimits:
      memlock:
        soft: -1
        hard: -1
    volumes:
      - esdata1:/usr/share/elasticsearch/data
    ports:
      - 9200:9200
    networks:
      - net1
  ceptor1:
    image: ceptor/ceptor-demo:latest
    container_name: ceptor1
    environment:
      - cluster.name=docker-cluster
      - elasticsearch_server=elasticsearch
      - elasticsearch_enabled=true
    ulimits:
      memlock:
        soft: -1
        hard: -1
    volumes:
      - ceptor1_log:/ceptor/logs
      - ceptor1_stat:/ceptor/statistics
      - ceptor1_config:/ceptor/config
      - ceptor1_db:/ceptor/testdatabase
    ports:
      - 4243:4243
      - 8443:8443
      - 9443:9443
    depends_on:
      - elasticsearch
    networks:
      - net1

volumes:
  esdata1:
    driver: local
  ceptor1_log:
    driver: local
  ceptor1_stat:
    driver: local
  ceptor1_config:
    driver: local
  ceptor1_db:
    driver: local
  
networks:
  net1:

Sample OpenShift template

Below, is an example template for deployment to OpenShift - it sets up a demonstration project with one Postgres database, and one Ceptor instance.

To use it, you should modify the default datastore within Ceptor to:

{"datastore": {
  "name": "API Postgres datastore",
  "description": "Datastore implementation using a postgres database",
  "factoryclass": "io.ceptor.datastore.db.JDBCDataStoreFactory",
  "configuration": {
    "databasetype": "postgres",
    "pool": {
      "db.checkexecuteupdate": true,
      "db.connectionurl": "jdbc:postgresql://${environment:POSTGRESQL_SERVICE_HOST}:${environment:POSTGRESQL_SERVICE_PORT}/ceptordb",
      "db.credentials": "${environment:POSTGRESQL_PASSWORD}",
      "db.debug": false,
      "db.drivername": "org.postgresql.Driver",
      "db.delaygetconnection": "0",
      "db.getconnectiontimeout": 60000,
      "db.initialpoolsize": 5,
      "db.maxconnectionlife": 600,
      "db.maxconnectionusage": 5000,
      "db.searchstartwithwildcard": false,
      "db.testonreserve": false,
      "db.username": "${environment:POSTGRESQL_USER}"
    }
  },
  "id": "datastore-postgres"
}}

and use this YAML file with OpenShift:

base_env: &base_env
- name: TENANT_NAME
  value: "${TENANT_NAME}"

apiVersion: v1  
kind: Template
metadata:
  name: Ceptor
  description: Ceptor - more info at https://ceptor.io
objects:
- apiVersion: v1
  kind: ImageStream
  metadata:
    annotations:
      openshift.io/generated-by: Ceptor ApS
    labels:
      app: ceptor-demo
    name: ceptor-demo
  spec:
    lookupPolicy:
      local: false
    tags:
    - annotations:
        openshift.io/imported-from: ceptor/ceptor_docker
      from:
        kind: DockerImage
        name: ${CEPTOR_IMAGE}
      generation: 2
      importPolicy: {}
      name: latest
      referencePolicy:
        type: Source
        
- apiVersion: v1
  kind: Service
  metadata:
    annotations:
      openshift.io/generated-by: Ceptor ApS
    labels:
      app: ceptor-demo
    name: ceptor-demo
  spec:
    ports:
    - name: 4243-tcp
      port: 4243
      protocol: TCP
      targetPort: 4243
    - name: 8443-tcp
      port: 8443
      protocol: TCP
      targetPort: 8443
    selector:
      app: ceptor-demo
      deploymentconfig: ceptor-demo
    sessionAffinity: None
    type: ClusterIP
  status:
    loadBalancer: {}

- apiVersion: "v1"
  kind: "PersistentVolumeClaim"
  metadata:
    name: "ceptor-persistent"
  spec:
    accessModes:
      - "ReadWriteOnce"
    resources:
      requests:
        storage: "1Gi"

- apiVersion: v1
  kind: DeploymentConfig
  metadata:
    annotations:
      openshift.io/generated-by: Ceptor ApS
    labels:
      app: ceptor-demo
    name: ceptor-demo
  spec:
    replicas: 1
    revisionHistoryLimit: 10
    selector:
      app: ceptor-demo
      deploymentconfig: ceptor-demo
    strategy:
      activeDeadlineSeconds: 21600
      resources: {}
      rollingParams:
        intervalSeconds: 1
        maxSurge: 25%
        maxUnavailable: 25%
        timeoutSeconds: 600
        updatePeriodSeconds: 1
      type: Rolling
    template:
      metadata:
        annotations:
          openshift.io/generated-by: OpenShiftNewApp
        creationTimestamp: null
        labels:
          app: ceptor-demo
          deploymentconfig: ceptor-demo
      spec:
        containers:
        - image: ${CEPTOR_IMAGE}
          imagePullPolicy: IfNotPresent
          name: ceptor-demo
          ports:
          - containerPort: 4243
            protocol: TCP
          - containerPort: 8443
            protocol: TCP
          resources:
            requests:
              cpu: 2000m
              memory: 2000Mi
            limits:
              cpu: 4000m
              memory: 3000Mi
#          livenessProbe:
#            initialDelaySeconds: 30
#            periodSeconds: 10
#            tcpSocket:
#              port: 8443
#          readinessProbe:
#            tcpSocket:
#              port: 8443
#            initialDelaySeconds: 30
#            timeoutSeconds: 5
          volumeMounts:
          - mountPath: /ceptor/config
            name: ceptor-volume
            subPath: config
          - mountPath: /ceptor/logs
            name: ceptor-volume
            subPath: logs
          - mountPath: /ceptor/statistics
            name: ceptor-volume
            subPath: statistics
          - mountPath: /ceptor/testdatabase
            name: ceptor-volume
            subPath: testdatabase
          - mountPath: /ceptor/work
            name: ceptor-volume
            subPath: work
          env:
          - name: POSTGRESQL_USER
            valueFrom:
              secretKeyRef:
                key: database-user
                name: "${DATABASE_SERVICE_NAME}"
          - name: POSTGRESQL_PASSWORD
            valueFrom:
              secretKeyRef:
                key: database-password
                name: "${DATABASE_SERVICE_NAME}"
        dnsPolicy: ClusterFirst
        restartPolicy: Always
        terminationGracePeriodSeconds: 30
        volumes:
        - name: ceptor-volume
          persistentVolumeClaim:
            claimName: ceptor-persistent
    test: false
    triggers:
    - type: ConfigChange
    - imageChangeParams:
        automatic: true
        containerNames:
        - ceptor-demo
        from:
          kind: ImageStreamTag
          name: ceptor-demo:latest
      type: ImageChange

- apiVersion: v1
  kind: Route
  metadata:
    labels:
      app: ceptor-demo
    name: console
  spec:
    host: console-${TENANT_NAME}.${WILDCARD_DOMAIN}
    port:
      targetPort: 4243-tcp
    tls:
      termination: passthrough
    to:
      kind: Service
      name: ceptor-demo
      weight: 100
    wildcardPolicy: None

- apiVersion: v1
  kind: Route
  metadata:
    labels:
      app: ceptor-demo
    name: gateway
  spec:
    host: gateway-${TENANT_NAME}.${WILDCARD_DOMAIN}
    port:
      targetPort: 8443-tcp
    tls:
      termination: passthrough
    to:
      kind: Service
      name: ceptor-demo
      weight: 100
    wildcardPolicy: None

- apiVersion: v1
  kind: Secret
  metadata:
    annotations:
      template.openshift.io/expose-database_name: "{.data['database-name']}"
      template.openshift.io/expose-password: "{.data['database-password']}"
      template.openshift.io/expose-username: "{.data['database-user']}"
    name: "${DATABASE_SERVICE_NAME}"
  stringData:
    database-name: "${POSTGRESQL_DATABASE}"
    database-password: "${POSTGRESQL_PASSWORD}"
    database-user: "${POSTGRESQL_USER}"
- apiVersion: v1
  kind: Service
  metadata:
    annotations:
      template.openshift.io/expose-uri: postgres://{.spec.clusterIP}:{.spec.ports[?(.name=="postgresql")].port}
    name: "${DATABASE_SERVICE_NAME}"
  spec:
    ports:
    - name: postgresql
      nodePort: 0
      port: 5432
      protocol: TCP
      targetPort: 5432
    selector:
      name: "${DATABASE_SERVICE_NAME}"
    sessionAffinity: None
    type: ClusterIP
  status:
    loadBalancer: {}
- apiVersion: v1
  kind: PersistentVolumeClaim
  metadata:
    name: "${DATABASE_SERVICE_NAME}"
  spec:
    accessModes:
    - ReadWriteOnce
    resources:
      requests:
        storage: "${VOLUME_CAPACITY}"
- apiVersion: v1
  kind: DeploymentConfig
  metadata:
    annotations:
      template.alpha.openshift.io/wait-for-ready: 'true'
    name: "${DATABASE_SERVICE_NAME}"
  spec:
    replicas: 1
    selector:
      name: "${DATABASE_SERVICE_NAME}"
    strategy:
      type: Recreate
    template:
      metadata:
        labels:
          name: "${DATABASE_SERVICE_NAME}"
      spec:
        containers:
        - capabilities: {}
          env:
          - name: POSTGRESQL_USER
            valueFrom:
              secretKeyRef:
                key: database-user
                name: "${DATABASE_SERVICE_NAME}"
          - name: POSTGRESQL_PASSWORD
            valueFrom:
              secretKeyRef:
                key: database-password
                name: "${DATABASE_SERVICE_NAME}"
          - name: POSTGRESQL_DATABASE
            valueFrom:
              secretKeyRef:
                key: database-name
                name: "${DATABASE_SERVICE_NAME}"
          image: " "
          imagePullPolicy: IfNotPresent
          livenessProbe:
            exec:
              command:
              - "/usr/libexec/check-container"
              - "--live"
            initialDelaySeconds: 120
            timeoutSeconds: 10
          name: postgresql
          ports:
          - containerPort: 5432
            protocol: TCP
          readinessProbe:
            exec:
              command:
              - "/usr/libexec/check-container"
            initialDelaySeconds: 5
            timeoutSeconds: 1
          resources:
            limits:
              memory: "${MEMORY_LIMIT}"
          securityContext:
            capabilities: {}
            privileged: false
          terminationMessagePath: "/dev/termination-log"
          volumeMounts:
          - mountPath: "/var/lib/pgsql/data"
            name: "${DATABASE_SERVICE_NAME}-data"
        dnsPolicy: ClusterFirst
        restartPolicy: Always
        volumes:
        - name: "${DATABASE_SERVICE_NAME}-data"
          persistentVolumeClaim:
            claimName: "${DATABASE_SERVICE_NAME}"
    triggers:
    - imageChangeParams:
        automatic: true
        containerNames:
        - postgresql
        from:
          kind: ImageStreamTag
          name: postgresql:${POSTGRESQL_VERSION}
          namespace: "${NAMESPACE}"
        lastTriggeredImage: ''
      type: ImageChange
    - type: ConfigChange
  status: {}
  
parameters:
- description: Maximum amount of memory the container can use.
  displayName: Memory Limit
  name: MEMORY_LIMIT
  required: true
  value: 512Mi
- description: The OpenShift Namespace where the ImageStream resides.
  displayName: Namespace
  name: NAMESPACE
  value: openshift
- description: The name of the OpenShift Service exposed for the database.
  displayName: Database Service Name
  name: DATABASE_SERVICE_NAME
  required: true
  value: postgresql
- description: Username for PostgreSQL user that will be used for accessing the database.
  displayName: PostgreSQL Connection Username
  from: user[A-Z0-9]{3}
  generate: expression
  name: POSTGRESQL_USER
  required: true
- description: Password for the PostgreSQL connection user.
  displayName: PostgreSQL Connection Password
  from: "[a-zA-Z0-9]{16}"
  generate: expression
  name: POSTGRESQL_PASSWORD
  required: true
- description: Name of the PostgreSQL database accessed.
  displayName: PostgreSQL Database Name
  name: POSTGRESQL_DATABASE
  required: true
  value: ceptordb
- description: Volume space available for data, e.g. 512Mi, 2Gi.
  displayName: Volume Capacity
  name: VOLUME_CAPACITY
  required: true
  value: 1Gi
- description: Version of PostgreSQL image to be used (9.4, 9.5, 9.6 or latest).
  displayName: Version of PostgreSQL Image
  name: POSTGRESQL_VERSION
  required: true
  value: '9.6'

- name: WILDCARD_DOMAIN
  description: Root domain for the wildcard routes. Eg. example.com will generate xxxxx.example.com.
  displayName: Domain name
  required: true
- name: TENANT_NAME
  description: "Tenant name under the root"
  displayName: Hostname
  required: true
  value: "ceptor"
- name: CEPTOR_IMAGE
  displayName: Ceptor docker image name
  description: Ceptor image to use
  required: true
  value: "ceptor/ceptor-demo:latest"

To build your own custom configurations using ceptor-demo image as a base, you can use a Dockerfile similar to this:

FROM ceptor/ceptor-base:latest

EXPOSE 4243 8443 9443

# Place any configuration files you want to override the default settings in the cfg directory - e.g. your own ceptor_launch.xml and ceptor-configuration.xml

# Copy from cfg, overwriting the default configuration.
ADD cfg /ceptor/template/config

Running Ceptor in Docker