Jon and Kevin talk to Gary Ewan Park and Mattias Karlsson about Cake, a cross platform build automation system with a C# DSL to do things like compiling code, copy files/folders, running unit tests, compress files and build NuGet packages.
Download / Listen: Herding Code 219: Cake with Gary Park and Mattias Karlsson
- Hello and Intro to Cake
- (01:48) Jon asks about the integrations and CI support. Gary says that’s a key feature: the build you run on your development machine is going to be as close as possible, if not identical to, the build you’re going to run on your CI server. Right now, Cake is set up with at least 10 online CI servers, which has the added benefit of providing them with a ton of badges for their GitHub readme.
- (03:15) Jon says that he cloned the getting started repo and ran a script and some magic happened… but what exactly was that magic doing? Mattias explains that the bootstrapper (either build.ps1 or build.sh) fetches Cake from NuGet, then it launches the build.cake file.
- (04:07) Jon asks if PowerShell on Linux will have an impact on Cake, or if the build.sh is simple enough that they’ll just stay with that. Gary says that the bootstrappers are very lightweight and normally don’t need to be changed (although you can if you want), so there’s no real advantage to moving to PowerShell since people who are building on Mac and Linux will probably prefer to just run a shell script.
- (05:17) Kevin flips it around and asks if it matters for Bash on Windows. Gary says they’ve got this one covered, too, as they’ve already tested out Cake on Bash on Windows. Mattias says the hard part is the platform specific dependencies, and Gary agrees, saying that Cake is just a wrapper around the tools – there’s an expectation that the tools are either installed or available as a NuGet package.
- (06:55) Jon asks if tools are well segmented per-project. Mattias confirms that everything is project specific – you can share if you want, but the default is that you can just clone a repository and build without thinking about dependencies.
- (07:50) Jon asks how Cake works with Docker. Mattias talks about the preconfigured Docker images for Cake, which make it easy to easily test builds, handle integration tests, etc. He’s currently testing against Nano Server. Nano Server is very stripped down requires you to install a lot of prerequisites for Cake, so it’s nice to have a preconfigured Docker image for testing. Mattias talks about how versioning with tagged containers help them with integration testing. Gary talk about how they’re using Docker with Bitbucket Pipelines to really speed up their Travis build tests.
- Cake Script
- (10:25) Jon asks what a Cake script is – is it just C# code? Gary describes some of the additional build DSL features they’ve added, but other than that it’s just standard C# code.
- (13:30) Jon said that he opened the Cake file in Visual Studio code and saw there was an extension for syntax highlighting, and asks if there’s additional tools for IntelliSense. Gary talks about the current status of OmniSharp when running against Cake. Note that since this podcast was recorded, this has improved as explained in this blog post: How to debug a Cake file using Visual Studio Code.
- (15:28) Jon asks about debugging a Cake script. Mattias says they’ve added a debug switch to the Cake exe, which waits for you to attach so you can debug. Jon says it sounds great to have debugging support for a build script. Mattias says it’s nice, but since your build scripts are often running on build server it’s also important to have good logging support.
- (17:02) Jon asks what the logging support is. Mattias says there’s a built-in abstraction for logging as well as an exception handler, so to break the build you can just throw an exception. Gary say that the default is just to log to the build server like AppVeyor, but if you want to log to something like logstash you can. Mattias says that they log to standard output and standard error, and every build system integrates well with that.
- .NET Core support, DI and Modules, Cross-platform Support
- (18:06) Jon asks more about the .NET Core port. Mattias says they’re just about done, just working with integration tests. For the most part it’s pretty straightforward, but you can run into things like differences between kernel versions on Linux. The biggest issue has been waiting for dependencies to be available on .NET Core. In the past they’ve relied on Mono for Linux and Mac, and there are slight differences compared to the .NET Framework, so it will be good to be on Core CLR everywhere. (note: the port to .NET Core has since been completed).
- (19:52) Jon says he notices they’re using Autofac. Mattias says they use it for dependency injection throughout the codebase, but they’ve replaced it in some places for things like their module system.
- (20:33) Jon asks how the module system works. Mattias says you just add a module folder in your tools and implement some attributes on your interfaces that indicate what your module should replace. (22:17) Jon asks about any issues they ran into with the .NET Core cross-platform port. Mattias says there are a lot of dependencies you don’t think about – for instance nuget.exe isn’t available cross-platform or on Nano Server, since it only has the Core CLR. Gary says they made a conscious decision not to implement .NET Core early, so they avoided some of the early adopter pain that some other projects ran into.
- (23:47) Jon asks if they’re doing anything specific to handle platform differences. Mattias says that there are a few IFDEFs, but for the most part issues are around tools support, in which case it just won’t launch at all. Gary talks about platform specific criteria you can use in your build scripts to make platform specific decisions.
- Cake Tasks, Parallel Tasks, Build System Integration, Unit Tests
- (26:36) Jon asks how task names are used in a script. Mattias says that those labels are used to determine task dependencies. Gary says you can also use the labels as entry points which are specific to the build server.
- (28:22) Jon asks if tasks are run in parallel. Mattias says it’s not currently multithreaded because logs would be difficult to follow. When you define a task, it’s just added to the graph, and nothing’s actually executed until you call RunTarget. Gary said there is an open issue to allow parallel execution of tasks, but they’re still working on a good story around debugging and logging. Mattias says it’s standard C# so there’s noting stopping you from running async tasks using the standard C# async methods.
- (31:46) Jon says he sees support for several build systems and asks about how you integrate with them. Mattias explains how CI systems can call commandline options, and Gary says that all build systems have provisions for environment variables, and Cake provides a typed wrapper around that, so you get a strongly typed object from the build-specific provider to make informed decisions. For instance, when running on AppVeyor their script pushes the NuGet packages to the prerelease MyGet feed from the development branch and the official NuGet feed when running on release.
- (34:09) Jon asks about assembly info patching and versions. Cake can update based on version info. It’s got file hash support, which is important for pushing to Homebrew.
- (34:55) Jon asks about unit test integration. Gary says they have method aliases for calling common unit test frameworks, and you can easily extend for other frameworks. Unit test harnesses have published return values, so you can make informed decisions based on specific unit test results.
- Publishing, Installers, Release Notes
- (36:46) Jon asks about publishing options. Cake can build the nuspec for you, you can use your own if you want, or on Core CLR you can use dotnet pack. Jon asks about some of the different ways NuGet is used as a deployment package. (38:42) Jon asks about other installers like WiX, NSIS, etc. Gary says that Cake is really just wrapping tools with strongly typed classes, which makes it easier to pass in property values to tools. There’s no real magic, it’s just bringing it up an abstraction layer, so you don’t have to remember the command semantics of each tool. Jon asks if, in addition to simplifying how you interact with tools, the abstraction makes it a little easier to switch between tools. Gary says that’s true, and describes how this works in practice.
- (41:44) Jon asks about the release note parsing feature. Gary says there’s an included release notes parser, which can extract version numbers and bulleted release features from a markdown file assuming it’s in a known format. This allows you to stamp your assembly with the version number, and use the bulleted release notes in your NuGet or Chocolatey release notes. There are also Git Release Notes and Git Release Manager which can be used to generate release notes from issues in a milestone based release on GitHub. Gary says they use this with Cake releases, so just tagging a release gives them an end to end publish process which sets version numbers and writes release notes for all their release endpoints (NuGet, Chocolatey, GitHub release, etc.).
- (44:54) Jon asks about the social network support. Gary and Mattias explain how the different addins can announce builds to Twitter, Slack, Gitter, Hipchat, etc. They describe how things like this that are useful but not essential are available as addins.
- (46:28) Kevin asks if there are any addins that they see as missing. Gary says there aren’t at the moment. He’s got a generic build script for all of his addins, so adding to the script rolls out to all of his addins.
- (48:08) Jon asks about the discussion in their repo: How do we prevent Addin’s becoming stale? Gary talks about the problem (a community member creates a useful addin, then stops maintaining the addin). Their plan is to set up a cake-contrib organization which can help with long-term ownership and support for community addins, allowing them to push NuGet updates as required if the original creator is no longer available or involved. The plan is to ask users to move their addins into the new cake-contrib organization and make the cake contrib user a co-maintainer. Note: Since this was recorded, they’ve set up this organization, as discussed in the wrap-up after the show.
- Open Source Project Case Studies: NancyFx and IdentityServer
- (53:14) Jon asks about some of the open source project build conversions to Cake, starting with NancyFx. Mattias explains some of the challenges, as well as the clear payoff: build script pull requests very soon after the conversion. Jon asks some nitpicky details about why the NancyFx build script script is spawning a process instead of using a Cake wrapper. Mattias explains the process by which build scripts are refined, and Gary points out the advantage of always being able to spawn a process if you need to do something Cake doesn’t yet support.
- (57:43) Jon asks about the IdentityServer migration. Gary said the IdentityServer team had already done the .NET Core port running under PSake and just wanted to migrate to Cake to get cross-platform builds going. It’s also a lot simple of a build process because it’s doing less.
- Assembly Merging
- (58:50) Jon asks about ilmerge suport. Mattias says it’s pretty popular for tools, to allow you to distribute the tool as a single exe. Gary says he uses Fody Costura instead to handle assembly merging. Jon says he doesn’t think any assembly merging support is available yet for .NET Core. Gary agrees, and Mattias says that .NET Native support will be helpful when it arrives.
- Future Plans and Getting In Touch
- (1:00:08) Jon asks about future milestones and what’s on the horizon after the .NET Core release. Gary hints at some upcoming releases, which are covered in the post-show wrap-up.
- (1:01:20) Gary talks about some upcoming speaking engagements, and Mattias mentions the Gitter chat, Twitter and GitHub issues as ways for users to ask any questions.
- Post-Show Update
- (1:03:10) Cake Contributions organization
The Cake Contributions organization (cake-contrib on GitHub) is now in full motion. It’s a common place where people can put their Cake addins & modules, if they want. They still maintain and for all purposes “own” the code, but they get access to resources like CI services, common build scripts, better exposure and the Cake core team can assist with merging pull requests, fixing issues and pushing to NuGet if addin grows stale or the author just too busy with life in general. It’s been well received and quite a few projects has moved over.
- (1:03:52) 0.16 Release with .NET Core support
So in addition to full .net Framework support, Cake now supports .NET Core (netstandard 1.6). There have been a few patch releases following this, so as of Oct 11 they’re up to 0.16.2. Also, due to adding .NET Core support, it’s now possible to debug a Cake file with Visual Studio Code. That’s cool, because there’s now cross platform debugging support for Cake. There’s a blog post showing how to do that.
- (1:04:25) Frosting
Frosting is a stand-alone .NET Core runner and host for cake. Cake uses the Roslyn scripting API and provides a DSL for fetching dependencies like tools and addins. Frosting uses the .NET core SDK to handle dependencies, and your cake build script is really just a .NET Core console app. Both are running against the same Cake.Core and Cake.Common packages, they’re just being hosted differently. This gives you some advantages – you’ve got full Visual Studio IntelliSense and tooling support, use the standard methods to package your build as a NuGet package, etc. Frosting also includes a dotnet CLI tool, so you can call dotnet cake.
- (1:05:46) Cake for Yeoman support
This adds a cake generator which makes it easy to bootstrap Cake, including a build script, bootstrapper scripts and config files in the current directory just by typing yo cake. There’s also scaffolding support to create a new .NET Core project using Frosting with yeoman.
- (1:06:18) Cake for Visual Studio
This is the first release of the Cake for Visual Studio extension. It includes syntax highlighting, Task Runner Explorer integration, bootstrapper commands in the Build menu, project templates for Cake addins, Cake Addin unit test projects, and Cake Modules