The last entrypoint is used, only the last one. 

You can check, put several lines with different `ENTRYPOINT` in your `Dockerfile`, and check what happens.

I&#39;m trying to replace my legacy job scheduler with Kubernetes job and wondering how to write sequential jobs as a Kubernetes job.

First, I wrote the following script to execute `job1` and `job2` in the written order but it didn&#39;t work as I expected.

    apiVersion: batch/v1
    kind: Job
    metadata:
      name: sequential
    spec:
      activeDeadlineSeconds: 100
      template:
        metadata:
          name: sequential_jobs
        spec:
          containers:
          - name: job1
            image: image1
          - name: job2
            image: image2
          restartPolicy: Never

The job described above seems to run `job1` and `job2` in parallel.
Is there any good way to run `job1` and `job2` in the written order?

Appended.

I recently found https://github.com/argoproj/argo very good for my usecase.

How to run containers sequentially as a Kubernetes job?

I have a route with two `canActivate` guards (`AuthGuard` and `RoleGuard`). The first (`AuthGuard`) checks to see if the user is logged in and, if not, redirects to the login page. The second checks to see if the user has a role defined that is allowed to view the page and, if not, redirects to the un-authorized page.

    canActivate: [ AuthGuard, RoleGuard ]
    ...
    export class AuthGuard implements CanActivate {
        canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): Promise&lt;boolean&gt; {
            ...
            this.router.navigate([&#39;/login&#39;]);
            resolve(false);
    }

    export class RoleGuard implements CanActivate {
        canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): Promise&lt;boolean&gt; {
            ...
            this.router.navigate([&#39;/unauthorized&#39;]);
            resolve(false);
    }

    
The problem is that when I access the route and I am not logged in I hit the `AuthGuard`, which fails and tells the router to navigate to `/login`. However, even though the `AuthGuard` failed, the `RoleGuard` runs anyway which then navigates to `/unauthorized`.

In my opinion it is pointless to run the next guard if the first fails. Is there any way to enforce this behavior? 

Multiple canActivate guards all run when first fails

Let&#39;s say I&#39;ve got the Docker image *parent* built by this Dockerfile:

    FROM ubuntu
    ENTRYPOINT [&quot;parent-entry&quot;]

Now I inherit from this *parent* image in my child image built with this code:

    FROM parent
    ENTRYPOINT [&quot;child-entry&quot;]

As far as I have tested it the entrypoint of the child image overwrites the one in the parent image.

But since I am new to Docker I am not sure about this. My research also hasn&#39;t yet resulted in a satisfying answer. So is the assumption above correct?



What happens to entrypoint of Docker parent image when child defines another one?

Let's say I've got the Docker image parent built by this Dockerfile:
<pre><code class="hljs language-css">FROM ubuntu
ENTRYPOINT ["parent-entry"]
</code></pre>
Now I inherit from this parent image in my child image built with this code:
<pre><code class="hljs language-css">FROM parent
ENTRYPOINT ["child-entry"]
</code></pre>
As far as I have tested it the entrypoint of the child image overwrites the one in the parent image.
But since I am new to Docker I am not sure about this. My research also hasn't yet resulted in a satisfying answer. So is the assumption above correct?

The following is an interview question. I came up with a solution, but I&#39;m not sure why it works.

---

**Question:**

Without modifying the `Sparta` class, write some code that makes `MakeItReturnFalse` return `false`.

    public class Sparta : Place
    {
        public bool MakeItReturnFalse()
        {
            return this is Sparta;
        }
    }


---

**My solution: (SPOILER)**

&gt;!`public class Place`  
&gt;!`{`  
&gt;!` ` ` ` ` ` `public interface Sparta { }`  
&gt;!`}`


But why does `Sparta` in `MakeItReturnFalse()` refer to `{namespace}.Place.Sparta` instead of `{namespace}.Sparta`?

This is Sparta, or is it?

Suppose I have a base class with unimplemented methods as follows:

    class Polygon():
        def __init__(self):
            pass

        def perimeter(self):
            pass

        def area(self):
            pass

Now, let&#39;s say one of my colleagues uses the Polygon class to create a subclass as follows:

    import math
    
    class Circle(Polygon):
        def __init__(self, radius):
            self.radius = radius

        def perimeter(self):
            return 2 * math.pi * self.radius
        
(H/Sh)e has forgotten to implement the area() method.

How can I force the subclass to implement the parent&#39;s area() method?

Force child class to override parent&#39;s methods

I have a basic inheritance situation with an overloaded method in the super class. 

    public class Person {
    	private String name;
    	private int dob;
    	private String gender;
    	
    	public Person(String theName, int birth, String sex){
    		name = theName;
    		dob = birth;
    		gender = sex;
    	}
    	
    	public void work(){
    		getWorkDetail(this);
    	}
    	
    	public void getWorkDetail(Employee e){
    		System.out.println(&quot;This person is an Employee&quot;);
    	}
    	
    	public void getWorkDetail(Person p){
    		System.out.println(&quot;This person is not an Employee&quot;);
    	}
    }

The following `Employee` class extends the `Person` class above:

    public class Employee extends Person {
    	
    	String department;
    	double salary;
    
    	public Employee(String theName, int birth, String sex){
    		super(theName, birth, sex);
    		department = &quot;Not assigned&quot;;
    		salary = 30000;
    	}
    }

The main method simply creates an `Employee` object (both static and dynamic type) and calls `.work()` on it:

    public static void main(String[] args){
    	Employee e1 = new Employee(&quot;Manager1&quot;, 1976, &quot;Female&quot;);
    	e1.work();
    }

This ends up printing

&gt; `This person is not an Employee` 

Looking through this I had thought that since both the static and dynamic type of the object `e1` is `Employee` it would call the overloaded method in Person that takes an `Employee` as a parameter. Since I am clearly wrong about this I opened a debugger assuming the reference to &quot;this&quot; at the line `getWorkDetail(this)` in the `Person` class must have morphed to it&#39;s super class. However this is not what I found.

[![screenshot][1]][1]


  [1]: https://i.stack.imgur.com/HzGoU.png


Clearly at this point in the code `this` is an `Employee` object, however it still chose to execute the overloaded method `getWorkDetail(Person p)`. Can anyone explain this behavior?

Which Overloaded Method is Called in Java

I understand that `&lt;? super T&gt;` represents any super class of `T` (parent class of `T` of any level). But I really struggle to imagine any real life example for this generic bound wildcard.

I understand what `&lt;? super T&gt;` means and I have seen this method:

    public class Collections {
      public static &lt;T&gt; void copy(List&lt;? super T&gt; dest, List&lt;? extends T&gt; src) {
          for (int i = 0; i &lt; src.size(); i++)
            dest.set(i, src.get(i));
      }
    }

I am looking for an example of *real life use case* where this construction can be used and not for an explanation of what it is.


What is a real life example of generic &lt;? super T&gt;?

I am not asking this -&gt; [Why is there no multiple inheritance in Java, but implementing multiple interfaces is allowed?][1]

In Java, multiple inheritance isn&#39;t allowed, but, after Java 8, Interfaces can have *default methods* (can implement methods itself), just like abstract classes. Within this context, it multiple inheritance should also be allowed.

    interface TestInterface 
    { 
        // abstract method 
        public void square(int a); 
      
        // default method 
        default void show() 
        { 
          System.out.println(&quot;Default Method Executed&quot;); 
        } 
    } 


  [1]: https://stackoverflow.com/questions/2515477/why-is-there-no-multiple-inheritance-in-java-but-implementing-multiple-interfac

Why does Java not allow multiple inheritance but does allow conforming to multiple interfaces with default implementations

I have downloaded the Ubuntu image inside Docker on Windows.

I can run Ubuntu by:

    docker run -it ubuntu

I only see `root`, but I don&#39;t see the Ubuntu GUI. How do I install or configure the GUI for that image and run applications on that GUI like we run in a VM?


How to open Ubuntu GUI inside a Docker image

I am aware there are a lot of questions about running Docker on windows, however this question is about running the brand new Docker for Windows, on Windows.  
In my case I am using Windows 10 Pro 64 bit. According to the site this version should be supported.  
I have been following a tutorial I found here:
https://prakhar.me/docker-curriculum/  
I also tried following the official guide of course: https://docs.docker.com/docker-for-windows/

In both tutorials I get the same error message when trying to assign a port using either the `-P` parameter or when trying to specify a port `-p 8080:5000`:

In the official guide I run `docker run -d -p 80:80 --name webserver nginx` and get:  

&gt;C:\Program Files\Docker\Docker\Resources\bin\docker.exe: Error response from daemon: driver failed programming external connectivity on endpoint webserver (f9946544e4c6ad2dd9cb8cbccd251e4d48254e86562bd8e6da75c3bd42c7e45a): Error starting userland proxy: mkdir /port/tcp:0.0.0.0:80:tcp:172.17.0.2:80: input/output error.

Following the unofficial guide i run `docker run -p 8888:5000 prakhar1989/catnip` and get basically the same error:  

&gt;C:\Program Files\Docker\Docker\Resources\bin\docker.exe: Error response from daemon: driver failed programming external connectivity on endpoint focused_swartz (48a0c005779c6e89bf525ead2ecff44a7f092495cd22ef7d19973002963cb232): Error starting userland proxy: mkdir /port/tcp:0.0.0.0:8888:tcp:172.17.0.2:5000: input/output error.

If I don&#39;t try to assign a port the container will run, but then I don&#39;t know how to access it.

The docker version I am running:  

 - Docker version 1.12.3, build 6b644ec`  
 - docker-compose version 1.8.1, build 004ddae`  
 - docker-machine.exe version 0.8.2, build e18a919`  

Any help would be very appreciated. Thank you.

Running Docker for Windows, Error when exposing Ports

I have a docker-compose file that deploys 8 different docker services in the same host. Is it possible to deploy it in different hosts?, I would like to deploy some service in one hosts and another ones in other host remotelly. Would I need to use docker-swarm? or is an easier way to do?

I have read that it could be done using DOCKER_HOST, but if I configure /etc/default/docker with this variable, all the services would be run on the remote host, and what I need is some services in one remote host, and other services in other remote host.

Docker-compose: deploying service in multiple hosts

At which IP address can a docker container connect to its host on Docker for Windows (on Windows 10)? How do you find this IP address?

Example: you have a service running at port 1234 on your Windows 10 machine. A program inside your container must access this service. What IP address should the program use to connect to the host?

How to connect to docker host from container on Windows 10 (Docker for Windows)

What is the difference between `ports` and `expose` options in `docker-compose.yml`?

Content Type	Original Author	Original Content on Stackoverflow
Question	Harold L. Brown	View Question on Stackoverflow
Solution 1 - Inheritance	user2915097	View Answer on Stackoverflow

What happens to entrypoint of Docker parent image when child defines another one?

Inheritance Problem Overview

Inheritance Solutions

Solution 1 - Inheritance

Multiple canActivate guards all run when first fails

How to run containers sequentially as a Kubernetes job?

Attributions