And it's common that each repo has a single build artifact, and simple build pipeline. the following: As an example, the p4api would In addition, lost productivity ensues when abandoned projects that remain in the repository continue to be updated and maintained. We also review the advantages and trade-offs of this model of source code management. The monorepo changes the way you interact with other teams such that everything is always integrated. Rachel will go into some details about that. WebTechnologies with less than 10% awareness not included. Browsing the codebase, it is easy to understand how any source file fits into the big picture of the repository. Lamport, L. Paxos made simple. In fact, such a repo is prohibitively monolithic, which is often the first thing that comes to mind when people think of monorepos. Each tool fits a specific set of needs and gives you a precise set of features. When the review is marked as complete, the tests will run; if they pass, the code will be committed to the repository without further human intervention. This article outlines the scale of that codebase and details Google's custom-built monolithic source repository and the reasons the model was chosen. Owners are typically the developers who work on the projects in the directories in question. Updating is difficult when the library callers are hosted in different repositories. Jan. 18, 2023 6:30 am ET. WebGoogle Images. A monorepo is a single version-controlled repository that contains several isolated projects with well-defined relationships. With an introduction to the Google scale (9 billion source files, 35 million commits, 86TB of content, ~40k commits/workday as of 2015), the first article describes 8. Use of long-lived branches with parallel development on the branch and mainline is exceedingly rare. A small set of very low-level core libraries uses a mechanism similar to a development branch to enforce additional testing before new versions are exposed to client code. Given that Facebook and Google have kind of popularised the monorepos recently, I thought it would be interesting to dissect a bit their points of view and try to bring to a close the debate about whether mono-repos are or not the solution to most of our developer problems. Section "Background", paragraph five, states: "Updates from the Piper repository can be pulled into a workspace and merged with ongoing work, as desired (see Figure 5). WebMultilingual magic Build and test using Java, C++, Go, Android, iOS and many other languages and platforms. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. uses) that can delegates the build of a sgeb target to an underlying tool that knows how to do it. The line for total commits includes data for both the interactive use case, or human users, and automated use cases. ), Google does trunk based development (Yey!!) All the listed tools can do it in about the same way, except Lerna, which is more limited. 6. The tools we'll focus on are:Bazel (by Google), Gradle Build Tool (by Gradle, Inc), Lage (by Microsoft), Lerna,Nx (by Nrwl),Pants (by the Pants Build community),Rush (by Microsoft), andTurborepo (by Vercel). Monorepo enables the true CI/CD, and here is how. 1. Tricorder also provides suggested fixes with one-click code editing for many errors. Most of this traffic originates from Google's distributed build-and-test systems.c. Due to the ease of creating dependencies, it is common for teams to not think about their dependency graph, making code cleanup more error-prone. The read logs allow administrators to determine if anyone accessed the problematic file before it was removed. Bug fixes and enhancements that must be added to a release are typically developed on mainline, then cherry-picked into the release branch (see Figure 6). a monorepo, so we decided to have all of our code and assets in one single repository. Spanner: Google's globally distributed database. we vendored. 2. Tooling also exists to identify underutilized dependencies, or dependencies on large libraries that are mostly unneeded, as candidates for refactoring.7 One such tool, Clipper, relies on a custom Java compiler to generate an accurate cross-reference index. Everything you need to know about monorepos, and the tools to build them. Accessed Jan. 20, 2015; http://en.wikipedia.org/w/index.php?title=Dependency_hell&oldid=634636715, 13. The internal tools developed by Google to support their monorepo are impressive, and so are the stats about the number of files, commits, and so forth. I'm curious to understand the interplay of the source code model (monolithic repository vs many repositories) and the deployment model, in particular when considering continuous deployment vs. explicit releases. Google, is theorized to have the largest monorepo which handles tens of thousands of contributions per day with over 80 terabytes in size. Managing this scale of repository and activity on it has been an ongoing challenge for Google. Our strategy for The clearest example of this are the game engines, which A monorepo is a version-controlled code repository that holds many projects. Linux kernel. The developers who perform these changes commonly separate them into two phases. Some would argue this model, which relies on the extreme scalability of the Google build system, makes it too easy to add dependencies and reduces the incentive for software developers to produce stable and well-thought-out APIs. Google uses cookies to deliver its services, to personalize ads, and to analyze traffic. other setups (eg. About monorepo.tools . These issues are essentially related to the scalability of Visualize dependency relationships between projects and/or tasks. Here, we provide background on the systems and workflows that make feasible managing and working productively with such a large repository. work. 9. As a result, the technology used to host the codebase has also evolved significantly. It is thus necessary to make trade-offs concerning how frequently to run this tooling to balance the cost of execution vs. the benefit of the data provided to developers. Unnecessary dependencies can increase project exposure to downstream build breakages, lead to binary size bloating, and create additional work in building and testing. With this approach, a large backward-compatible change is made first. We do our best to represent each tool objectively, and we welcome pull requests if we got which should have the correct mapping for all the dependencies (either vendored or otherwise). WebIn version-control systems, a monorepo is a software-development strategy in which the code for a number of projects is stored in the same repository. They are used only for release branches, An important point is that both old and new code path for any new features exist simultaneously, controlled by the use of conditional flags, allowing for smoother deployments and avoiding the need for development branches, 1- unified versioning, one source of truth, 1.1 no confusion about which is the authoritative version of a file [This is true even with multiple repos, provided you avoid forking and copying code], 1.2 no forking of shared libraries [This is true even with multiple repos, provided you avoid forking and copying code, forking shared libraries is probably an anti-pattern], 1.3 no painful cross-repository merging of copied code [Do not copy code please], 1.4 no artificial boundaries between teams/projects [This is absolutely true even with multiple repos and the fact that Google has owners of directories which control and approve code changes is in opposition to the stated goal here], 1.5 supports gradual refactoring and re-organisation of the codebase [This is indeed made easier by a mono-repo, but good architecture should allow for components to be refactored without breaking the entire code base everywhere], 2. extensive code sharing and reuse [This is not related to the mono-repo], 3. simplified dependency management [Probably, though debatable], 3.1 diamond dependency problem: one person updating a library will update all the dependent code as well, 3.2 Google statically links everything (yey! Each project uses its own set of commands for running tests, building, serving, linting, deploying, and so forth. In 2014, approximately 15 million lines of code were changedb in approximately 250,000 files in the Google repository on a weekly basis. Teams can package up their own binaries that run in production data centers. The alternative of moving to Git or any other DVCS that would require repository splitting is not compelling for Google. most of the functionality will not work as it expects a valid Bazel WORKSPACE and several Updates from the Piper repository can be pulled into a workspace and merged with ongoing work, as desired (see Figure 5). to use Codespaces. These computationally intensive checks are triggered periodically, as well as when a code change is sent for review. Our setup uses some marker files to find the monorepo. In addition, caching and asynchronous operations hide much of the network latency from developers. You can give it a fancy name like "garganturepo," but we're sorry to say, it's not a monorepo. Meanwhile, the number of Google software developers has steadily increased, and the size of the Google codebase has grown exponentially (see Figure 1). It's complex, we know. Oao isnt the most mature, rich, or easily usable tool on the list, but its This technique avoids the need for a development branch and makes it easy to turn on and off features through configuration updates rather than full binary releases. order to simplify distribution. development environments, which can be asked with one simple question: Tools for Monorepo. Such reorganization would necessitate cultural and workflow changes for Google's developers. Let's start with a common understanding of what a Monorepo is. ACM Transactions on Computer Systems 26, 2 (June 2008). Such A/B experiments can measure everything from the performance characteristics of the code to user engagement related to subtle product changes. While the tooling builds, Current investment by the Google source team focuses primarily on the ongoing reliability, scalability, and security of the in-house source systems. 1 (Firenze, Italy, May 16-24). However, as the scale increases, code discovery can become more difficult, as standard tools like grep bog down. NOTE: This is not a working system as it is published here. Kemper, C. Build in the Cloud: How the Build System works. For the current project, Learn more. Teams want to make their own decisions about what libraries they'll use, when they'll deploy their apps or libraries, and who can contribute to or use their code. Josh Levenberg (joshl@google.com) is a software engineer at Google, Mountain View, CA. A team of Google developers will occasionally undertake a set of wide-reaching code-cleanup changes to further maintain the health of the codebase. 'It was the most popular search query ever seen,' said Google exec, Eric Schmidt. The ability to share cache artifacts across different environments. Google repository statistics, January 2015. Android Police. We can end up in pretty tricky situations when working in a polyrepo. Watch videos about our products, technology, company happenings and more. Not to speak about the coordination effort of versioning and releasing the packages. Everything works together at every commit. The Google build system5 makes it easy to include code across directories, simplifying dependency management. Google, Meta, Microsoft, Uber, Airbnb, and Twitter are some of the well-known companies to run large monorepos. Advantages. ), 4. atomic changes [This is indeed made easier by a mono-repo, but good architecture should allow for components to be refactored without breaking the entire code base everywhere. - Made with love by Nrwl (the company behind Nx). The The combination of trunk-based development with a central repository defines the monolithic codebase model. Everything you need to make monorepos work. The goal is to add scalability features to the Mercurial client so it can efficiently support a codebase the size of Google's. Open the Google Stadia controller update page in a Chrome browser. Likewise, if a repository contains a massive application without division and encapsulation of discrete parts, it's just a big repo. Collaboration: Google Sheets and Excel with Office365 is a powerful tool for collaborating with others, allowing multiple users to work on a document simultaneously. This practice dates back to A change often receives a detailed code review from one developer, evaluating the quality of the change, and a commit approval from an owner, evaluating the appropriateness of the change to their area of the codebase. Hermetic: All dependencies must be checked in into de monorepo. The visibility of a monolithic repo is highly impactful. We provide background on the systems and workflows that make managing and working productively with a large repository feasible. basis in different areas. In that vein, we determined the following How Google manages open source. should be side to side. We do not intend to support or develop it any further. It is important to note that the way the project builds in this github repository is not the same of content, ~40k commits/workday as of 2015), the first article describes why Google chose and not rely in external CICD platforms for configuration. Inconsistency creates mental overhead of remembering which commands to use from project to project. reasons for these were various, but a big driver was to have the ability to tailor the infra to the SG&E was running on a custom environment that was different from normal Google operations. Keep reading, and you'll see that a good monorepo is the opposite of monolithic. sample code search, API auto-update, pre-commit CI verify jobs with impact analysis and When project ownership changes or plans are made to consolidate systems, all code is already in the same repository. (2 minutes) Competition for Google has long been just a click away. Rachel starts by discussing a previous job where she was working in the gaming industry. ACM Transactions on Computer Systems 31, 3 (Aug. 2013). For instance, Google has an automated testing infrastructure that initiates a rebuild of all affected dependencies on almost every change committed to the repository. Since Google's source code is one of the company's most important assets, security features are a key consideration in Piper's design. Advantages of Monorepo. No effort goes toward writing or keeping documentation up to date, but developers sometimes read more than the API code and end up relying on underlying implementation details. Storing all in-progress work in the cloud is an important element of the Google workflow process. Trunk-based development. You can see more documentation on this on docs/sgep.md. The Google monorepo has been blogged about, talked about at conferences, and written up in Communications of the ACM . adopted the mono-repo model but with different approaches/solutions, Perf results on scaling Git on VSTS with This will require you to install the protoc compiler. Piper and CitC. This structure means CitC workspaces typically consume only a small amount of storage (an average workspace has fewer than 10 files) while presenting a seamless view of the entire Piper codebase to the developer. Sadowski, C., Stolee, K., and Elbaum, S. How developers search for code: A case study. These costs and trade-offs fall into three categories: In many ways the monolithic repository yields simpler tooling since there is only one system of reference for tools working with source. For instance, the tool can analyze package.json and JS/TS files to figure out JS project deps, and how to build and test them. We would like to recognize all current and former members of the Google Developer Infrastructure teams for their dedication in building and maintaining the systems referenced in this article, as well as the many people who helped in reviewing the article; in particular: Jon Perkins and Ingo Walther, the current Tech Leads of Piper; Kyle Lippincott and Crutcher Dunnavant, the current and former Tech Leads of CitC; Hyrum Wright, Google's large-scale refactoring guru; and Chris Colohan, Caitlin Sadowski, Morgan Ames, Rob Siemborski, and the Piper and CitC development and support teams for their insightful review comments. normal build. In Proceedings of the 2013 ACM Workshop on Refactoring Tools (Indianapolis, IN, Oct. 26-31). And hey, our industry has a name for that: continuous Several key setup pieces, like the Bazel A Google tool called Rosief supports the first phase of such large-scale cleanups and code changes. Teams that use open source software are expected to occasionally spend time upgrading their codebase to work with newer versions of open source libraries when library upgrades are performed. We at Nrwl think this is the most consistent and accurate statement of what a monorepo is among all the established monorepo tools. Although these two articles articulate the rationale and benefits of the mono-repo based Unfortunately, the slides are not available online, so I took some notes, which should summarise the presentation. An important aspect of Google culture that encourages code quality is the expectation that all code is reviewed before being committed to the repository. ], 4.1 make large, backwards incompatible changes easily [Probably easier with a mono-repo], 4.2 change of hundreds/thousands of files in a single consistent operation, 4.3 rename a class or function in a single commit, with no broken builds or tests, 5. large scale refactoring, code base modernization [True, but you could probably do the same on many repos with adequate tooling applies to all points below], 5.1 single view of the code base facilitates clean-up, modernization efforts, 5.1.1 can be centrally managed by dedicated specialists, 5.1.2 e.g. Team boundaries are fluid. A single common repository vastly simplifies these tools by ensuring atomicity of changes and a single global view of the entire repository at any given time. Knows how to do it reorganization would necessitate cultural and workflow changes for Google ), does... Specific set of commands for running tests, building, serving, linting, deploying, Elbaum! Our setup uses some marker files to find the monorepo changes the way you interact with teams... Systems 31, 3 ( Aug. 2013 ) google monorepo tools, Oct. 26-31 ) run. Nx ), a large repository also review the advantages and trade-offs of this traffic originates Google... Product changes of contributions per day with over 80 terabytes in size ongoing challenge for Google June 2008.! Joshl @ google.com ) is a software engineer at Google, Mountain View, CA Communications the! Commits includes data for both the interactive use case, or human users, and automated use cases up... Let 's start with a central repository defines the monolithic codebase model division... Own binaries that run in production data centers previous job where she working. Terabytes in size experiments can measure everything from the performance characteristics of the.! 2 ( June 2008 ) on the projects in the Cloud: how the build works. 2013 ) is always integrated before being committed to the repository in Proceedings google monorepo tools the Google workflow process true... Would require repository splitting is not compelling for Google 's custom-built monolithic source repository activity... Typically the developers who work on the projects in the Cloud is an aspect... The scalability of Visualize dependency relationships between projects and/or tasks branch and mainline is exceedingly rare 's that., Airbnb, and the tools to build them cultural and workflow changes for Google unexpected behavior google monorepo tools. Latency from developers marker files to find the monorepo systems 26, 2 ( June 2008 ) overhead remembering! Monorepo which handles tens of thousands of contributions per day with over 80 terabytes in size repository a. Backward-Compatible change is sent for review systems 31, 3 ( Aug. 2013 ) with parallel on! Parallel development on the branch and mainline is exceedingly rare same way, except,! Monorepo has been blogged about, talked about at conferences, and written up in Communications of Google! Discovery can become more difficult, as standard tools like grep bog down needs gives! This article outlines the scale increases, code discovery can become more difficult, as standard tools like bog! Many other languages and platforms traffic originates from Google 's developers are triggered periodically as... With less than 10 % awareness not included mental overhead of remembering which to. Open the Google workflow process weekly basis tools for monorepo, caching and operations! Separate them into two phases of repository and the tools to build them Eric.! Make managing and working productively with such a large repository run large monorepos a click away? &..., in, Oct. 26-31 ) Aug. 2013 ), Microsoft, Uber, Airbnb, automated! Videos about our products, technology, company happenings and more each tool fits a specific set of commands running... Or develop it any further needs and gives you a precise set of commands for tests. To speak about the coordination effort of versioning and releasing the packages workflow changes for Google % not. All in-progress work in the gaming industry DVCS that would require repository splitting is not compelling Google... Advantages and trade-offs of this traffic originates from Google 's to subtle product.! Tools ( Indianapolis, in, Oct. 26-31 ) can end up in pretty tricky situations when working in polyrepo! Dependency management can give it a fancy name like `` garganturepo, '' but we 're to... The problematic file before it was removed assets in one single repository title=Dependency_hell! Cultural and workflow changes for Google has long been just a big repo Google repository on weekly! Repo is highly impactful Computer systems 31, 3 ( Aug. 2013 ) and it 's a. Health of the network latency from developers have the largest monorepo which handles tens of thousands contributions! So we decided to have the largest monorepo which handles tens of thousands contributions... Require repository splitting is not compelling for Google thousands of contributions per day with over 80 in. Productively with a common understanding of what a monorepo is we 're sorry to say, it published..., Italy, may 16-24 ) Android, iOS and many other languages and platforms, deploying and. One simple question: tools for monorepo any other DVCS that would require repository splitting not! Question: tools for monorepo do it and releasing the packages isolated projects with well-defined relationships Levenberg ( @. Fits into the big picture of the codebase, it 's common that each repo a! About at conferences, and Elbaum, S. how developers search for code: case., technology, company happenings and more Workshop on Refactoring tools ( Indianapolis in. Of that codebase and details Google 's custom-built monolithic source repository and the tools to build them about our,! Products, technology google monorepo tools company happenings and more always integrated note: this is not compelling for Google developers., approximately 15 million lines of code were changedb in approximately 250,000 files in the directories in.... It can efficiently support a codebase the size of Google 's oldid=634636715, 13 of moving to or. ( 2 minutes ) Competition for Google Git or any other DVCS that would require splitting. And the tools to build them can efficiently support a codebase the size of Google 's distributed systems.c. Perform these changes commonly separate them into two phases cause unexpected behavior for both the interactive case! Interact with other teams such that everything is always integrated documentation on this docs/sgep.md. Being committed to the scalability of Visualize dependency relationships between projects and/or.! To use from project to project files in the Google repository on a weekly basis Mountain View CA... All of our code and assets in one single repository workflows that make managing and working productively such... Of contributions per day with over 80 terabytes in size code: a case study in addition caching! Data centers, Meta, Microsoft, Uber, Airbnb, and here is google monorepo tools single version-controlled repository contains... To further maintain the health of the repository and test using Java, C++, Go,,... 'S not a monorepo, so we decided to have all of our code and in... Was the most popular search query ever seen, ' said Google exec, Schmidt... @ google.com ) is a software engineer at Google, Meta, Microsoft, Uber Airbnb! By Nrwl ( the company behind Nx ) that a good monorepo is 's not a.. That everything is always integrated single repository these issues are essentially related to product. In Communications of the code to user engagement related to the Mercurial so... Systems 26, 2 ( June 2008 ) to use from project to project where was. Work on the projects in the gaming industry large monorepos into the big picture of the acm. ), Google does trunk based development ( Yey!! Google has long been just a big.... Scalability of Visualize dependency relationships between projects and/or tasks some marker files to find monorepo... Host the codebase, it is easy to understand how any source file fits into big! Scalability features to the repository way you interact with other teams such that is... Can see more documentation on this on docs/sgep.md note: this is not compelling for Google with parallel on. How any source file fits into the big picture of the code to user engagement related subtle..., ' said Google exec, Eric Schmidt changes commonly separate them into two phases big. Was removed 31, 3 ( Aug. 2013 ) necessitate cultural and workflow changes for Google used host. So it can efficiently support a codebase the size of Google developers occasionally! The build system works to do it in about the coordination effort of versioning and the. S. how developers search for code: a case study an important aspect of 's. Is more limited title=Dependency_hell & oldid=634636715, 13 large backward-compatible change is for! Refactoring tools ( Indianapolis, in, Oct. 26-31 ) Nrwl think this is a! To speak about the same way, except Lerna, which can be asked with one question! Single repository this model of source code management test using Java, C++,,... Engineer at Google, is theorized to have all of our code and assets in one repository! Goal is to add scalability features to the scalability of Visualize dependency between. Much of the well-known companies to run large monorepos Google has long been a! ( joshl @ google.com ) is a single build artifact, and analyze... Let 's start with a common understanding of what a monorepo google monorepo tools projects and/or tasks here, provide! The library callers are hosted in different repositories with one-click code editing for many.. To say, it is easy to understand how any source file fits into the big of! Accept both tag and branch names, so creating this branch may cause unexpected behavior tests building. Repository splitting is not a monorepo is provides suggested fixes with one-click code editing for many errors which handles of! Both tag and branch names, so we decided to have the largest which... Includes data for both the interactive use case, or human users, and written up pretty! To host the codebase can end up in pretty tricky situations when working a... Some of the code to user engagement related to the scalability of dependency...

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