10 Yarn Interview Questions and Answers in 2023
1. How do you debug an application running on Yarn?
Debugging an application running on Yarn requires a few steps.
First, you need to identify the source of the issue. This can be done by examining the application logs, which can be accessed through the Yarn Resource Manager UI. You can also use the Yarn CLI to view the application logs.
Once you have identified the source of the issue, you can use the Yarn CLI to debug the application. You can use the ‘yarn logs’ command to view the application logs, and the ‘yarn application -list’ command to view the list of running applications.
You can also use the ‘yarn application -status’ command to view the status of the application. This will provide you with information such as the application’s start time, the number of containers running, and the application’s memory usage.
If the issue is related to a specific container, you can use the ‘yarn container -list’ command to view the list of containers running on the cluster. You can then use the ‘yarn container -logs’ command to view the logs of the specific container.
Finally, you can use the ‘yarn application -kill’ command to kill the application if necessary. This will stop the application and all of its containers.
By following these steps, you should be able to debug an application running on Yarn.
2. What is the difference between Yarn and NPM?
Yarn and NPM are both package managers for JavaScript, but they have some key differences.
Yarn was created by Facebook in 2016 as an improvement over NPM. It was designed to be faster, more secure, and more reliable than NPM. Yarn uses a lockfile to ensure that all packages are installed in the same versions across different machines, and it also uses checksums to verify the integrity of packages. It also has an offline mode, which allows you to install packages without an internet connection.
In contrast, NPM is the original package manager for JavaScript, and it is still widely used. It does not have a lockfile, so the versions of packages installed on different machines may vary. It also does not have an offline mode, so you must have an internet connection to install packages.
Overall, Yarn is a more reliable and secure package manager than NPM, and it is the preferred choice for many developers.
3. How do you optimize the performance of a Yarn application?
Optimizing the performance of a Yarn application requires a multi-faceted approach.
First, it is important to ensure that the application is configured correctly. This includes setting the correct number of containers, memory, and CPU cores for the application. It is also important to ensure that the application is using the most efficient scheduling algorithm for the job.
Second, it is important to ensure that the application is using the most efficient data structures and algorithms. This includes using data structures that are optimized for the task at hand, as well as using algorithms that are optimized for the data set.
Third, it is important to ensure that the application is using the most efficient communication protocols. This includes using the most efficient network protocols, such as TCP/IP, as well as using the most efficient messaging protocols, such as Apache Kafka.
Finally, it is important to ensure that the application is using the most efficient storage solutions. This includes using the most efficient databases, such as Apache HBase, as well as using the most efficient file systems, such as HDFS.
By following these steps, it is possible to optimize the performance of a Yarn application.
4. What is the purpose of the Yarn lock file?
The Yarn lock file, also known as yarn.lock, is a file used by Yarn to ensure that the dependencies installed in a project are consistent across all machines. It stores exact versions of each dependency that was installed, so that when another developer or machine installs the same project, the same versions of the dependencies will be installed. This helps to ensure that the project will work the same way on all machines, and that any changes to the dependencies will be tracked and managed.
5. How do you handle versioning of packages in Yarn?
Versioning of packages in Yarn is handled through the use of the yarn version command. This command allows developers to specify the version of a package that they want to install or upgrade to. The command also allows developers to specify the exact version of a package that they want to install or upgrade to.
When using the yarn version command, developers can specify the exact version of a package that they want to install or upgrade to. This is done by using the --tag flag. For example, if a developer wanted to install version 1.2.3 of a package, they would use the command yarn version --tag 1.2.3.
The yarn version command also allows developers to specify the range of versions of a package that they want to install or upgrade to. This is done by using the --range flag. For example, if a developer wanted to install any version of a package between 1.2.3 and 1.2.5, they would use the command yarn version --range 1.2.3-1.2.5.
Finally, the yarn version command also allows developers to specify the latest version of a package that they want to install or upgrade to. This is done by using the --latest flag. For example, if a developer wanted to install the latest version of a package, they would use the command yarn version --latest.
Overall, the yarn version command is a powerful tool for managing the versioning of packages in Yarn. It allows developers to specify the exact version, range of versions, or latest version of a package that they want to install or upgrade to.
6. What is the purpose of the Yarn cache?
The purpose of the Yarn cache is to store packages that have been downloaded from the Yarn registry so that they can be reused in future installations. This helps to reduce the amount of time and bandwidth required to install packages, as the packages can be retrieved from the cache instead of being downloaded again. Additionally, the cache helps to ensure that the same version of a package is used across multiple installations, as the cached version is always used if available. This helps to ensure that the same version of a package is used in all environments, which helps to reduce the risk of unexpected behavior due to version differences.
7. How do you configure Yarn to use a private registry?
Configuring Yarn to use a private registry is a straightforward process.
First, you need to create a .npmrc file in the root of your project. This file should contain the registry URL and authentication credentials. For example:
registry=https://my.private.registry/
_auth=username:password
Next, you need to configure Yarn to use the .npmrc file. This can be done by setting the registry-config option in the .yarnrc file. For example:
registry-config .npmrc
Finally, you need to install the packages from the private registry. This can be done by running the yarn install command. Yarn will automatically use the registry specified in the .npmrc file.
Once the packages have been installed, you can use them in your project as normal.
8. What is the difference between Yarn and Webpack?
Yarn and Webpack are both popular tools used in web development. Yarn is a package manager for JavaScript, while Webpack is a module bundler.
Yarn is used to manage and install packages from the npm registry. It helps developers to easily install, update, and remove packages from their projects. It also helps to ensure that all packages are installed in the correct version and that all dependencies are satisfied.
Webpack, on the other hand, is a module bundler. It takes all of the individual JavaScript files in a project and bundles them into a single file. This helps to reduce the number of requests that need to be made to the server, which can improve the performance of the application. Webpack also provides a number of features such as code splitting, tree shaking, and minification.
In summary, Yarn is a package manager for JavaScript, while Webpack is a module bundler. Yarn helps developers to easily install, update, and remove packages from their projects, while Webpack bundles all of the individual JavaScript files into a single file.
9. How do you handle security vulnerabilities in Yarn packages?
When it comes to handling security vulnerabilities in Yarn packages, the first step is to identify the vulnerability. This can be done by regularly scanning the packages for known vulnerabilities and using tools such as the Yarn Security Audit. Once the vulnerability has been identified, the next step is to determine the severity of the vulnerability and the potential impact it could have on the application. Depending on the severity, the package may need to be updated or removed. If the package needs to be updated, the developer should use the latest version of the package available and ensure that all dependencies are up to date. If the package needs to be removed, the developer should replace it with an alternative package or use a different package manager. Finally, the developer should ensure that the application is tested thoroughly to ensure that the vulnerability has been addressed.
10. How do you set up a continuous integration pipeline for a Yarn application?
Setting up a continuous integration pipeline for a Yarn application requires several steps.
First, you need to create a repository for your application. This can be done using a version control system such as Git or Subversion. Once the repository is created, you need to add the source code for your application to the repository.
Next, you need to set up a continuous integration server. This can be done using a tool such as Jenkins or Travis CI. The server will be responsible for running tests and building the application.
Once the server is set up, you need to configure the build process. This includes setting up the build environment, configuring the build scripts, and setting up the build triggers.
Finally, you need to configure the deployment process. This includes setting up the deployment environment, configuring the deployment scripts, and setting up the deployment triggers.
Once all of these steps are complete, your continuous integration pipeline for a Yarn application will be ready to use.