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Silver Fabric Docker Enabler How Tos

(1) How do I map a public host port(ex.9090) to an internal Docker container port(ex.8080)?


  First, create an auto-increment "Numeric" runtime context variable of type "String" for host port like  so:

  "MY_PORT=9090"
  
  Next, create a port mapping runtime context variable with name prefixed by "!PORT_MAP_" like so:

  "!PORT_MAP_my_http=${MY_PORT}:8080"
  
  Note: The internal port 8080 will be publically exposed as port 9090,9091, 9092,...depending on the engine     instances the Docker container is managed from.

(2) How do I mount a host directory(ex. "/logs") to an internal Docker container directory(ex. "/my_logs")?

  
  First, make sure the host directory is created first or exists first.
  Next, create a runtime context variable of type "String" with name prefixed by "!VOL_MAP_" like so:
  
  "!VOL_MAP_logs=/logs:/my_logs:rw"
  where 'rw' can be replaced by 'ro'

(3) How do I add one or more environmental variables to the Docker container?

  There are 2 ways that you can do that:
  
  (a) Create a runtime context variable of type "String" with a name prefixed by "!ENV_VAR_"
  
  Example : "!ENV_VAR_myvar1=Hello"

  
  (b) Create a runtime context variable of type "String" with a name prefixed by "!ENV_FILE_"
  
  Example: "!ENV_FILE_env1=/env_config/env1.properties" where "env1.properties" holds each line of environment variable in key-value pair format.
  
  Note: There is a already a preconfigured "!ENV_FILE_default" environment files that you can used. Use this
  unless there is a need to add another environment file

(4) How do I build and run a Docker file?

  Upload your Dockerfile as a content file using relative content   "docker/docker_context" directory as the     target directory for the Dockerfile.
  Then set runtime context variable "BUILD_ALWAYS=true" and "DOCKER_IMAGE_NAME=<namespace>/<app name>:[tag]"
  
  Example: "DOCKER_IMAGE_NAME=bbrets/tomcat:6.0.36"

Note: If you are using `COPY` or `ADD` commands in the Dockerfile, you can add the files to be copied/added in those commands as content files in the same relative content dir above.

(5) How do I collect JMX stats from a J2EE Docker container?

Basically, you have 2 main choices:

  • work with JMX directly This is harder since you may need take into account RMI idiosyncrasies and scripting in raw JMX API.
  • work with a JMX-HTTP Bridge This is easier and this enabler bundles Jolokia JMX-HTTP Bridge version 1.2.2 Java client which allows you to script in an easier API, especially if you need to deal with complex JMX data types.

Assume that you have a Jolokia-enabled J2EE image,you need to supply a statistic script in Jython, JRuby or ECMAScript and implement a getStatistic method and runtime context variable JOLOKIA_URL that binds to the Tomcat8-Jolokia url:

from org.jolokia.client import J4pClient;
from org.jolokia.client.request import J4pReadRequest;
from org.jolokia.client.request import J4pReadResponse;
from javax.management import ObjectName;

client = None;

def getRcv(varName):
    rcv = runtimeContext.getVariable(varName)
    if rcv == None:
        return None;
    else:
        return rcv.getValue();
    
def getClient():
    global client
    if client == None :
        url=getRcv("JOLOKIA_URL");
        client =J4pClient(url);
    return client;
        
    
    
def usedMemory():
    obj_name= ObjectName("java.lang:type=Memory");
    request = J4pReadRequest(obj_name,["HeapMemoryUsage"]);
    request.setPath("used");
    response = getClient().execute(request);
    return str(response.get(0).getValue());

def peakThreadCount():
    obj_name=ObjectName("java.lang:type=Threading");
    request = J4pReadRequest(obj_name,["PeakThreadCount"]);
    response = getClient().execute(request);
    return str(response.get(0).getValue());

def uptime():
    obj_name = ObjectName("java.lang:type=Runtime");
    request = J4pReadRequest(obj_name,["Uptime"]);
    response = getClient().execute(request);
    return str(response.get(0).getValue());
    
def getStatistic(statName):
    statValue = 0.0;
    if statName == "USED_MEMORY" :
        statValue=usedMemory();
    elif statName == "PEAK_THREAD_COUNT":
        statValue = peakThreadCount();
    elif statName == "UPTIME":
        statValue = uptime();
    else:
        logger.warning('Unknown statistic: ' + statName);
        
    return statValue;

(6) How do I script a component notification when one or more dependent components is down?

First, you need to register one or more dependent components from the view point of the listening component, using ComponentNotificationFeature. Then add a script implementing the componentNotification method like so:

from com.datasynapse.fabric.admin.info import NotificationEngineInfo;
from com.datasynapse.fabric.admin import AdminManager;

def componentNotification(componentName, notificationEngineInfoList):
  logger.info("Notification from component '" + componentName + "'.");
  logger.info("Component engines located at :" + notificationEngineInfoList.toString());
  engineAdmin=AdminManager.getEngineAdmin();
  n= NotificationEngineInfo();
  for n in notificationEngineInfoList:
      engine_id=n.getEngineId();
      instance=n.getInstance();
      info=engineAdmin.getEngineInfo(engine_id,instance);
      alloc=info.getAllocationInfo();
      props=alloc.getProperties();
      logger.info("--------------properties are -----------------------");
      for p in props:
         logger.info(p.getName() + "=" + p.getValue())
      logger.info("-----------------------------------------------------");

Note: You may use the class AdminManager to query for any additional information from the Silver Fabric broker.

(7) How can I manage the lifecycle of an J2EE archive(.WAR,.EAR) for a J2EE Docker container?

First make sure that you configure your component with ArchiveManagementFeature enabled and as a J2EE component. Next, since a Docker container is a blackbox, you need to implement 1 set of mandatory and 1 optional set of scripting "hooks" methods from the interface ArchiveManagement from the TIBCO Silver Fabric SDK API, version 5.7:

  • Archive lifecycle set(mandatory):

    • archiveDeploy
    • archiveStart
    • archiveStop
    • archiveUndeploy
    • archiveDetect
    • urlDetect

  • Archive microscaling set(optional):

    • archiveScaleUp
    • archiveScaleDown

Note: In addition, if you are doing Archive microscaling, you may need also to implement the interface ArchiveProvider if you are using certain J2EE platform, so that the Silver Fabric Broker can cached your archives as an "archive truth source" for scaling across engines. Each of above scripting hook set of methods can be implemented in separate scripting files.