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Docker Image tags are simple labels or aliases given to a docker image before or after building an image to describe that particular image. It can be the version of the project or the container, features of the image, technologies used in the image or pretty much anything you want. It plays a key role in the overall software development life cycle because it helps you keep track of the different parts of your project as well as help you in version management of the product.While pulling an image, you can specify the tag of the image you want or ... Read More
The official Docker registry contains a lot of pre-built images and publicly available customized images that are very useful and can be easily pulled by the users in their local machine and used as base images for their projects. In fact, you can also build your own customized docker image using one of those publicly available docker images and push it back either in a public or private mode.In this article, we will discuss how to search for a docker image using the search command through the command line interface. We will also see how to filter the search results ... Read More
Dockerhub or the official docker registry consists of numerous pre-built Docker Images as well as customized images by other users that you can pull to your system if they have been made public. In order to pull or push images to the docker registry, you need to first have an account in Dockerhub.To create an account and a repository in dockerhub, you can follow these steps −Visit the docker hub (Link − https://hub.docker.com/).Create an account or if you already have one, sign in with your account details.After signing in, click on create repository on the welcome page.Fill in the details ... Read More
We all know the importance of dockerfile in creating an efficient and flexible Docker Image. A dockerfile contains a set of instructions that are executed step by step when you use the docker build command to build the docker image. It contains certain instructions and commands that decides the structure of your image, the amount of time taken to build the image, contains instructions related to docker build context, contains information related to the packages and libraries to be installed in the container and many more. Hence, it becomes very important to create an efficient, reusable, clean dockerfile as it ... Read More
To define Docker Volumes, they are file systems that can be mounted on Docker containers. They help in preserving the data and are independent of the container life cycle. One of the major advantages of Docker Volumes is that it allows the developers to backup their data and also allows easy sharing of file systems among Docker containers. We can easily mount a volume when we launch a Docker container. It is also possible to mount the same volume to different containers and this allows easy sharing of data between them and this can be easily achieved with the use ... Read More
Docker allows us to automate the process of building and deploying an application. It also allows us to create a packaged environment to run the application which makes it easily portable and lightweight while also allowing us to keep track of the versions. All of these are possible through Docker Containers. It helps in making the applications platform independent.Let’s say we have a docker container running in our machine and we want to take a snapshot or keep a backup of that container so that in case of any emergency, if we want to roll back changes or execute a ... Read More
We all know that we can run our application in a packaged environment called container using Docker. When you want containers to talk to each other, the network they create can be assumed to be a bridge network. Run the following command to get a list of networks.sudo docker network lsEach network of containers has a subnet mask and can be used to distribute IP addresses to its containers. This also means that each container in the docker network is assigned an IP address. The default subnet for a docker network is 172.17.0.0/16.Knowing these, we will now see the different ... Read More
To get the number of true/ false values in an array, the code is as follows −var obj = [ { isMarried: true }, { isMarried: false }, { isMarried: true }, { isMarried: true }, { isMarried: false } ] function numberOfTrueValues(obj) { var counter = 0; for (var index = 0; index < obj.length; index++) { if (obj[index].isMarried === true) { counter++; ... Read More
To fetch a specific record, use find() with some condition.ExampleFollowing is the code −var obj=[ { studentId:101, studentName:"John" }, { studentId:102, studentName:"Bob" }, { studentId:103, studentName:"David" } ] const result = obj.find( (o) => { return o.studentId === 102 } ); console.log(result);To run the above program, you need to use the below command −node fileName.js.Here, my file name is demo315.js.OutputThis will produce the following output −PS C:\Users\Amit\javascript-code> node demo315.js { studentId: 102, studentName: 'Bob' }
To fix this, you can use map() in JavaScript.The syntax is as follows −var anyVariableName= new Array(yourSize).fill().map(Object);ExampleFollowing is the code −var arrayOfObject = new Array(5).fill().map(Object); console.log(arrayOfObject);To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo311.js.OutputThis will produce the following output −PS C:\Users\Amit\javascript-code> node demo311.js [ {}, {}, {}, {}, {} ]