Jerod  Durgan

Jerod Durgan

1624621260

Understanding Kubernetes Maven Plugin Resource Fragments Configuration

In my previous blogpost, I talked about Eclipse JKube Kubernetes Maven Plugin XML configuration and how you can use it to configure Eclipse JKube’s output image/manifests. Today in this blog, we’ll be looking at Eclipse JKube Resource Fragments: a configuration option specific to Kubernetes manifests(JSON/YAML).

What are Resource fragments?

In Eclipse JKube terminology, resource fragments are complete/partial JSON/YAML snippets which user places in src/main/jkube directory of this project in order to tweak JKube’s opinionated manifest generation mechanism according to his needs. This use is usually for users who have decent knowledge of Kubernetes primitive types.

Let’s say a user wants to add an additional environment variable to his deployment. She can do it via XML configuration as well, but let’s say she adds a deployment.yml file in src/main/jkube directory of her project:

spec:
  template:
    spec:
      containers:
        - env:
            - name: FOO
              value: BAR

#maven #jkube #fragments #kubernetes

What is GEEK

Buddha Community

Understanding Kubernetes Maven Plugin Resource Fragments Configuration
Christa  Stehr

Christa Stehr

1602964260

50+ Useful Kubernetes Tools for 2020 - Part 2

Introduction

Last year, we provided a list of Kubernetes tools that proved so popular we have decided to curate another list of some useful additions for working with the platform—among which are many tools that we personally use here at Caylent. Check out the original tools list here in case you missed it.

According to a recent survey done by Stackrox, the dominance Kubernetes enjoys in the market continues to be reinforced, with 86% of respondents using it for container orchestration.

(State of Kubernetes and Container Security, 2020)

And as you can see below, more and more companies are jumping into containerization for their apps. If you’re among them, here are some tools to aid you going forward as Kubernetes continues its rapid growth.

(State of Kubernetes and Container Security, 2020)

#blog #tools #amazon elastic kubernetes service #application security #aws kms #botkube #caylent #cli #container monitoring #container orchestration tools #container security #containers #continuous delivery #continuous deployment #continuous integration #contour #developers #development #developments #draft #eksctl #firewall #gcp #github #harbor #helm #helm charts #helm-2to3 #helm-aws-secret-plugin #helm-docs #helm-operator-get-started #helm-secrets #iam #json #k-rail #k3s #k3sup #k8s #keel.sh #keycloak #kiali #kiam #klum #knative #krew #ksniff #kube #kube-prod-runtime #kube-ps1 #kube-scan #kube-state-metrics #kube2iam #kubeapps #kubebuilder #kubeconfig #kubectl #kubectl-aws-secrets #kubefwd #kubernetes #kubernetes command line tool #kubernetes configuration #kubernetes deployment #kubernetes in development #kubernetes in production #kubernetes ingress #kubernetes interfaces #kubernetes monitoring #kubernetes networking #kubernetes observability #kubernetes plugins #kubernetes secrets #kubernetes security #kubernetes security best practices #kubernetes security vendors #kubernetes service discovery #kubernetic #kubesec #kubeterminal #kubeval #kudo #kuma #microsoft azure key vault #mozilla sops #octant #octarine #open source #palo alto kubernetes security #permission-manager #pgp #rafay #rakess #rancher #rook #secrets operations #serverless function #service mesh #shell-operator #snyk #snyk container #sonobuoy #strongdm #tcpdump #tenkai #testing #tigera #tilt #vert.x #wireshark #yaml

Jerod  Durgan

Jerod Durgan

1624621260

Understanding Kubernetes Maven Plugin Resource Fragments Configuration

In my previous blogpost, I talked about Eclipse JKube Kubernetes Maven Plugin XML configuration and how you can use it to configure Eclipse JKube’s output image/manifests. Today in this blog, we’ll be looking at Eclipse JKube Resource Fragments: a configuration option specific to Kubernetes manifests(JSON/YAML).

What are Resource fragments?

In Eclipse JKube terminology, resource fragments are complete/partial JSON/YAML snippets which user places in src/main/jkube directory of this project in order to tweak JKube’s opinionated manifest generation mechanism according to his needs. This use is usually for users who have decent knowledge of Kubernetes primitive types.

Let’s say a user wants to add an additional environment variable to his deployment. She can do it via XML configuration as well, but let’s say she adds a deployment.yml file in src/main/jkube directory of her project:

spec:
  template:
    spec:
      containers:
        - env:
            - name: FOO
              value: BAR

#maven #jkube #fragments #kubernetes

Background Fetch for React Native Apps

react-native-background-fetch

Background Fetch is a very simple plugin which attempts to awaken an app in the background about every 15 minutes, providing a short period of background running-time. This plugin will execute your provided callbackFn whenever a background-fetch event occurs.

There is no way to increase the rate which a fetch-event occurs and this plugin sets the rate to the most frequent possible — you will never receive an event faster than 15 minutes. The operating-system will automatically throttle the rate the background-fetch events occur based upon usage patterns. Eg: if user hasn't turned on their phone for a long period of time, fetch events will occur less frequently or if an iOS user disables background refresh they may not happen at all.

:new: Background Fetch now provides a scheduleTask method for scheduling arbitrary "one-shot" or periodic tasks.

iOS

  • There is no way to increase the rate which a fetch-event occurs and this plugin sets the rate to the most frequent possible — you will never receive an event faster than 15 minutes. The operating-system will automatically throttle the rate the background-fetch events occur based upon usage patterns. Eg: if user hasn't turned on their phone for a long period of time, fetch events will occur less frequently.
  • scheduleTask seems only to fire when the device is plugged into power.
  • ⚠️ When your app is terminated, iOS no longer fires events — There is no such thing as stopOnTerminate: false for iOS.
  • iOS can take days before Apple's machine-learning algorithm settles in and begins regularly firing events. Do not sit staring at your logs waiting for an event to fire. If your simulated events work, that's all you need to know that everything is correctly configured.
  • If the user doesn't open your iOS app for long periods of time, iOS will stop firing events.

Android

Installing the plugin

⚠️ If you have a previous version of react-native-background-fetch < 2.7.0 installed into react-native >= 0.60, you should first unlink your previous version as react-native link is no longer required.

$ react-native unlink react-native-background-fetch

With yarn

$ yarn add react-native-background-fetch

With npm

$ npm install --save react-native-background-fetch

Setup Guides

iOS Setup

react-native >= 0.60

Android Setup

react-native >= 0.60

Example

ℹ️ This repo contains its own Example App. See /example

import React from 'react';
import {
  SafeAreaView,
  StyleSheet,
  ScrollView,
  View,
  Text,
  FlatList,
  StatusBar,
} from 'react-native';

import {
  Header,
  Colors
} from 'react-native/Libraries/NewAppScreen';

import BackgroundFetch from "react-native-background-fetch";

class App extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      events: []
    };
  }

  componentDidMount() {
    // Initialize BackgroundFetch ONLY ONCE when component mounts.
    this.initBackgroundFetch();
  }

  async initBackgroundFetch() {
    // BackgroundFetch event handler.
    const onEvent = async (taskId) => {
      console.log('[BackgroundFetch] task: ', taskId);
      // Do your background work...
      await this.addEvent(taskId);
      // IMPORTANT:  You must signal to the OS that your task is complete.
      BackgroundFetch.finish(taskId);
    }

    // Timeout callback is executed when your Task has exceeded its allowed running-time.
    // You must stop what you're doing immediately BackgroundFetch.finish(taskId)
    const onTimeout = async (taskId) => {
      console.warn('[BackgroundFetch] TIMEOUT task: ', taskId);
      BackgroundFetch.finish(taskId);
    }

    // Initialize BackgroundFetch only once when component mounts.
    let status = await BackgroundFetch.configure({minimumFetchInterval: 15}, onEvent, onTimeout);

    console.log('[BackgroundFetch] configure status: ', status);
  }

  // Add a BackgroundFetch event to <FlatList>
  addEvent(taskId) {
    // Simulate a possibly long-running asynchronous task with a Promise.
    return new Promise((resolve, reject) => {
      this.setState(state => ({
        events: [...state.events, {
          taskId: taskId,
          timestamp: (new Date()).toString()
        }]
      }));
      resolve();
    });
  }

  render() {
    return (
      <>
        <StatusBar barStyle="dark-content" />
        <SafeAreaView>
          <ScrollView
            contentInsetAdjustmentBehavior="automatic"
            style={styles.scrollView}>
            <Header />

            <View style={styles.body}>
              <View style={styles.sectionContainer}>
                <Text style={styles.sectionTitle}>BackgroundFetch Demo</Text>
              </View>
            </View>
          </ScrollView>
          <View style={styles.sectionContainer}>
            <FlatList
              data={this.state.events}
              renderItem={({item}) => (<Text>[{item.taskId}]: {item.timestamp}</Text>)}
              keyExtractor={item => item.timestamp}
            />
          </View>
        </SafeAreaView>
      </>
    );
  }
}

const styles = StyleSheet.create({
  scrollView: {
    backgroundColor: Colors.lighter,
  },
  body: {
    backgroundColor: Colors.white,
  },
  sectionContainer: {
    marginTop: 32,
    paddingHorizontal: 24,
  },
  sectionTitle: {
    fontSize: 24,
    fontWeight: '600',
    color: Colors.black,
  },
  sectionDescription: {
    marginTop: 8,
    fontSize: 18,
    fontWeight: '400',
    color: Colors.dark,
  },
});

export default App;

Executing Custom Tasks

In addition to the default background-fetch task defined by BackgroundFetch.configure, you may also execute your own arbitrary "oneshot" or periodic tasks (iOS requires additional Setup Instructions). However, all events will be fired into the Callback provided to BackgroundFetch#configure:

⚠️ iOS:

  • scheduleTask on iOS seems only to run when the device is plugged into power.
  • scheduleTask on iOS are designed for low-priority tasks, such as purging cache files — they tend to be unreliable for mission-critical tasks. scheduleTask will never run as frequently as you want.
  • The default fetch event is much more reliable and fires far more often.
  • scheduleTask on iOS stop when the user terminates the app. There is no such thing as stopOnTerminate: false for iOS.
// Step 1:  Configure BackgroundFetch as usual.
let status = await BackgroundFetch.configure({
  minimumFetchInterval: 15
}, async (taskId) => {  // <-- Event callback
  // This is the fetch-event callback.
  console.log("[BackgroundFetch] taskId: ", taskId);

  // Use a switch statement to route task-handling.
  switch (taskId) {
    case 'com.foo.customtask':
      print("Received custom task");
      break;
    default:
      print("Default fetch task");
  }
  // Finish, providing received taskId.
  BackgroundFetch.finish(taskId);
}, async (taskId) => {  // <-- Task timeout callback
  // This task has exceeded its allowed running-time.
  // You must stop what you're doing and immediately .finish(taskId)
  BackgroundFetch.finish(taskId);
});

// Step 2:  Schedule a custom "oneshot" task "com.foo.customtask" to execute 5000ms from now.
BackgroundFetch.scheduleTask({
  taskId: "com.foo.customtask",
  forceAlarmManager: true,
  delay: 5000  // <-- milliseconds
});

API Documentation

Config

Common Options

@param {Integer} minimumFetchInterval [15]

The minimum interval in minutes to execute background fetch events. Defaults to 15 minutes. Note: Background-fetch events will never occur at a frequency higher than every 15 minutes. Apple uses a secret algorithm to adjust the frequency of fetch events, presumably based upon usage patterns of the app. Fetch events can occur less often than your configured minimumFetchInterval.

@param {Integer} delay (milliseconds)

ℹ️ Valid only for BackgroundFetch.scheduleTask. The minimum number of milliseconds in future that task should execute.

@param {Boolean} periodic [false]

ℹ️ Valid only for BackgroundFetch.scheduleTask. Defaults to false. Set true to execute the task repeatedly. When false, the task will execute just once.

Android Options

@config {Boolean} stopOnTerminate [true]

Set false to continue background-fetch events after user terminates the app. Default to true.

@config {Boolean} startOnBoot [false]

Set true to initiate background-fetch events when the device is rebooted. Defaults to false.

NOTE: startOnBoot requires stopOnTerminate: false.

@config {Boolean} forceAlarmManager [false]

By default, the plugin will use Android's JobScheduler when possible. The JobScheduler API prioritizes for battery-life, throttling task-execution based upon device usage and battery level.

Configuring forceAlarmManager: true will bypass JobScheduler to use Android's older AlarmManager API, resulting in more accurate task-execution at the cost of higher battery usage.

let status = await BackgroundFetch.configure({
  minimumFetchInterval: 15,
  forceAlarmManager: true
}, async (taskId) => {  // <-- Event callback
  console.log("[BackgroundFetch] taskId: ", taskId);
  BackgroundFetch.finish(taskId);
}, async (taskId) => {  // <-- Task timeout callback
  // This task has exceeded its allowed running-time.
  // You must stop what you're doing and immediately .finish(taskId)
  BackgroundFetch.finish(taskId);
});
.
.
.
// And with with #scheduleTask
BackgroundFetch.scheduleTask({
  taskId: 'com.foo.customtask',
  delay: 5000,       // milliseconds
  forceAlarmManager: true,
  periodic: false
});

@config {Boolean} enableHeadless [false]

Set true to enable React Native's Headless JS mechanism, for handling fetch events after app termination.

  • 📂 index.js (MUST BE IN index.js):
import BackgroundFetch from "react-native-background-fetch";

let MyHeadlessTask = async (event) => {
  // Get task id from event {}:
  let taskId = event.taskId;
  let isTimeout = event.timeout;  // <-- true when your background-time has expired.
  if (isTimeout) {
    // This task has exceeded its allowed running-time.
    // You must stop what you're doing immediately finish(taskId)
    console.log('[BackgroundFetch] Headless TIMEOUT:', taskId);
    BackgroundFetch.finish(taskId);
    return;
  }
  console.log('[BackgroundFetch HeadlessTask] start: ', taskId);

  // Perform an example HTTP request.
  // Important:  await asychronous tasks when using HeadlessJS.
  let response = await fetch('https://reactnative.dev/movies.json');
  let responseJson = await response.json();
  console.log('[BackgroundFetch HeadlessTask] response: ', responseJson);

  // Required:  Signal to native code that your task is complete.
  // If you don't do this, your app could be terminated and/or assigned
  // battery-blame for consuming too much time in background.
  BackgroundFetch.finish(taskId);
}

// Register your BackgroundFetch HeadlessTask
BackgroundFetch.registerHeadlessTask(MyHeadlessTask);

@config {integer} requiredNetworkType [BackgroundFetch.NETWORK_TYPE_NONE]

Set basic description of the kind of network your job requires.

If your job doesn't need a network connection, you don't need to use this option as the default value is BackgroundFetch.NETWORK_TYPE_NONE.

NetworkTypeDescription
BackgroundFetch.NETWORK_TYPE_NONEThis job doesn't care about network constraints, either any or none.
BackgroundFetch.NETWORK_TYPE_ANYThis job requires network connectivity.
BackgroundFetch.NETWORK_TYPE_CELLULARThis job requires network connectivity that is a cellular network.
BackgroundFetch.NETWORK_TYPE_UNMETEREDThis job requires network connectivity that is unmetered. Most WiFi networks are unmetered, as in "you can upload as much as you like".
BackgroundFetch.NETWORK_TYPE_NOT_ROAMINGThis job requires network connectivity that is not roaming (being outside the country of origin)

@config {Boolean} requiresBatteryNotLow [false]

Specify that to run this job, the device's battery level must not be low.

This defaults to false. If true, the job will only run when the battery level is not low, which is generally the point where the user is given a "low battery" warning.

@config {Boolean} requiresStorageNotLow [false]

Specify that to run this job, the device's available storage must not be low.

This defaults to false. If true, the job will only run when the device is not in a low storage state, which is generally the point where the user is given a "low storage" warning.

@config {Boolean} requiresCharging [false]

Specify that to run this job, the device must be charging (or be a non-battery-powered device connected to permanent power, such as Android TV devices). This defaults to false.

@config {Boolean} requiresDeviceIdle [false]

When set true, ensure that this job will not run if the device is in active use.

The default state is false: that is, the for the job to be runnable even when someone is interacting with the device.

This state is a loose definition provided by the system. In general, it means that the device is not currently being used interactively, and has not been in use for some time. As such, it is a good time to perform resource heavy jobs. Bear in mind that battery usage will still be attributed to your application, and shown to the user in battery stats.


Methods

Method NameArgumentsReturnsNotes
configure{FetchConfig}, callbackFn, timeoutFnPromise<BackgroundFetchStatus>Configures the plugin's callbackFn and timeoutFn. This callback will fire each time a background-fetch event occurs in addition to events from #scheduleTask. The timeoutFn will be called when the OS reports your task is nearing the end of its allowed background-time.
scheduleTask{TaskConfig}Promise<boolean>Executes a custom task. The task will be executed in the same Callback function provided to #configure.
statuscallbackFnPromise<BackgroundFetchStatus>Your callback will be executed with the current status (Integer) 0: Restricted, 1: Denied, 2: Available. These constants are defined as BackgroundFetch.STATUS_RESTRICTED, BackgroundFetch.STATUS_DENIED, BackgroundFetch.STATUS_AVAILABLE (NOTE: Android will always return STATUS_AVAILABLE)
finishString taskIdVoidYou MUST call this method in your callbackFn provided to #configure in order to signal to the OS that your task is complete. iOS provides only 30s of background-time for a fetch-event -- if you exceed this 30s, iOS will kill your app.
startnonePromise<BackgroundFetchStatus>Start the background-fetch API. Your callbackFn provided to #configure will be executed each time a background-fetch event occurs. NOTE the #configure method automatically calls #start. You do not have to call this method after you #configure the plugin
stop[taskId:String]Promise<boolean>Stop the background-fetch API and all #scheduleTask from firing events. Your callbackFn provided to #configure will no longer be executed. If you provide an optional taskId, only that #scheduleTask will be stopped.

Debugging

iOS

🆕 BGTaskScheduler API for iOS 13+

  • ⚠️ At the time of writing, the new task simulator does not yet work in Simulator; Only real devices.
  • See Apple docs Starting and Terminating Tasks During Development
  • After running your app in XCode, Click the [||] button to initiate a Breakpoint.
  • In the console (lldb), paste the following command (Note: use cursor up/down keys to cycle through previously run commands):
e -l objc -- (void)[[BGTaskScheduler sharedScheduler] _simulateLaunchForTaskWithIdentifier:@"com.transistorsoft.fetch"]
  • Click the [ > ] button to continue. The task will execute and the Callback function provided to BackgroundFetch.configure will receive the event.

Simulating task-timeout events

  • Only the new BGTaskScheduler api supports simulated task-timeout events. To simulate a task-timeout, your fetchCallback must not call BackgroundFetch.finish(taskId):
let status = await BackgroundFetch.configure({
  minimumFetchInterval: 15
}, async (taskId) => {  // <-- Event callback.
  // This is the task callback.
  console.log("[BackgroundFetch] taskId", taskId);
  //BackgroundFetch.finish(taskId); // <-- Disable .finish(taskId) when simulating an iOS task timeout
}, async (taskId) => {  // <-- Event timeout callback
  // This task has exceeded its allowed running-time.
  // You must stop what you're doing and immediately .finish(taskId)
  print("[BackgroundFetch] TIMEOUT taskId:", taskId);
  BackgroundFetch.finish(taskId);
});
  • Now simulate an iOS task timeout as follows, in the same manner as simulating an event above:
e -l objc -- (void)[[BGTaskScheduler sharedScheduler] _simulateExpirationForTaskWithIdentifier:@"com.transistorsoft.fetch"]

Old BackgroundFetch API

  • Simulate background fetch events in XCode using Debug->Simulate Background Fetch
  • iOS can take some hours or even days to start a consistently scheduling background-fetch events since iOS schedules fetch events based upon the user's patterns of activity. If Simulate Background Fetch works, your can be sure that everything is working fine. You just need to wait.

Android

  • Observe plugin logs in $ adb logcat:
$ adb logcat *:S ReactNative:V ReactNativeJS:V TSBackgroundFetch:V
  • Simulate a background-fetch event on a device (insert <your.application.id>) (only works for sdk 21+:
$ adb shell cmd jobscheduler run -f <your.application.id> 999
  • For devices with sdk <21, simulate a "Headless JS" event with (insert <your.application.id>)
$ adb shell am broadcast -a <your.application.id>.event.BACKGROUND_FETCH

Download Details:
Author: transistorsoft
Source Code: https://github.com/transistorsoft/react-native-background-fetch
License: MIT license

#react  #reactnative  #mobileapp  #javascript 

Maud  Rosenbaum

Maud Rosenbaum

1601051854

Kubernetes in the Cloud: Strategies for Effective Multi Cloud Implementations

Kubernetes is a highly popular container orchestration platform. Multi cloud is a strategy that leverages cloud resources from multiple vendors. Multi cloud strategies have become popular because they help prevent vendor lock-in and enable you to leverage a wide variety of cloud resources. However, multi cloud ecosystems are notoriously difficult to configure and maintain.

This article explains how you can leverage Kubernetes to reduce multi cloud complexities and improve stability, scalability, and velocity.

Kubernetes: Your Multi Cloud Strategy

Maintaining standardized application deployments becomes more challenging as your number of applications and the technologies they are based on increase. As environments, operating systems, and dependencies differ, management and operations require more effort and extensive documentation.

In the past, teams tried to get around these difficulties by creating isolated projects in the data center. Each project, including its configurations and requirements were managed independently. This required accurately predicting performance and the number of users before deployment and taking down applications to update operating systems or applications. There were many chances for error.

Kubernetes can provide an alternative to the old method, enabling teams to deploy applications independent of the environment in containers. This eliminates the need to create resource partitions and enables teams to operate infrastructure as a unified whole.

In particular, Kubernetes makes it easier to deploy a multi cloud strategy since it enables you to abstract away service differences. With Kubernetes deployments you can work from a consistent platform and optimize services and applications according to your business needs.

The Compelling Attributes of Multi Cloud Kubernetes

Multi cloud Kubernetes can provide multiple benefits beyond a single cloud deployment. Below are some of the most notable advantages.

Stability

In addition to the built-in scalability, fault tolerance, and auto-healing features of Kubernetes, multi cloud deployments can provide service redundancy. For example, you can mirror applications or split microservices across vendors. This reduces the risk of a vendor-related outage and enables you to create failovers.

#kubernetes #multicloud-strategy #kubernetes-cluster #kubernetes-top-story #kubernetes-cluster-install #kubernetes-explained #kubernetes-infrastructure #cloud

Understanding Kubernetes Operators

Automation is one of the fundamental components that makes Kubernetes so robust as a containerization engine. Even complex cloud infrastructure creation can be automated in order to simplify the process of managing cloud deployments. Despite the capability of leveraging so many resources and components to support an application, your cloud environment can still be fairly manageable.

Despite the many tools available on Kubernetes, the effort to make cloud infrastructure management more scalable and automated is ongoing. Kubernetes operator is one of the tools designed to push automation past its limits. You can do so much more without having to rely on manual inputs every time.

Getting to Know Kubernetes Operators

A Kubernetes operator, by definition, is an orchestration framework. It is a tool that lets you orchestrate and maintain cloud infrastructures with little to no human input. Kubernetes define operators as software extensions designed to utilize custom resources to manage applications and their components.

Kubernetes operators are not complex at all. Operators use controllers and the Kubernetes API to handle packaging, deployment, management, and maintenance of applications and the custom resources that they need. The whole process is fully automated, plus you can still rely on _kubectl _tooling for commands and operations.

In other words, an operator is basically a custom Kubernetes controller that integrates custom resources for management purposes. You can define parameters and configurations inside the custom resources directly, and then let the operators translate those parameters and run autonomously. Kubernetes operators’ continuous nature is their defining factor.

#blog #kubernetes #automation #kubernetes api #kubernetes deployment #kubernetes operators