BuildXL VS act

Seems they came up with a way to scale up build toolchains with BuildXL[0]

Doesn't seem fully baked yet though

[0]: https://github.com/microsoft/BuildXL

> With regards to chroot, I stand corrected. I knew it was a tree of symlinks, but I thought it was also more than that because symlinks alone don't seem like a sandbox. Honestly, Cosmopolitan's system appears to be more of a sandbox than that.

To be totally clear: the tree of symlinks thing is a fallback, used only when lacking platform support or when sandboxing is explicitly turned off [0]. On Linux, the normal sandboxing strategy is to use namespaces, like most container runtimes. On Mac it apparently uses sandbox-exec (some opaque Apple tool), as was mentioned above. Chroot, being both non-POSIX, requiring root access on many systems, and not providing the necessary facilities is not really a great fit -- which I assume is why it's not used.

There was experimental Windows sandbox support at one point [1] based on how MS does it for BuildXL (their own build tool for giant monorepos) [2]. Unfortunately it doesn't seem to be maintained, and under the hood it's kinda ugly -- it actively rewrites code in-memory to intercept calls to the Win32 APIs [3], which was apparently the cleanest/best way MS could come up with. However, from Bazel's POV it works in a roughly similar way -- you spawn subprocesses under a supervisor, which is in charge of spinning up whatever the target process is with restrictions on time/memory usage/file access.

On the "sandbox in the interpreter" thing: what kind of checks are you envisioning? It seems like putting checks at that level would end up leaving a lot out -- the goal of any build system is to eventually spawn an arbitrary process (Python, gcc, javac, some shell script, etc.) and so even with extensive checks in starlark you'd end up with accidental sandbox breaks all over the place. For pure starlark rules you could e.g. check that there are no inputs from /usr, but even then if gcc does it implicitly, you're SOL. Or am I thinking of the wrong kind of checks?

[0] https://bazel.build/docs/sandboxing#sandboxing-strategies

[1] https://github.com/bazelbuild/bazel/issues/5136#issuecomment...

[2] https://github.com/microsoft/BuildXL/blob/master/Documentati...

[3] https://github.com/microsoft/Detours/wiki

To speed up your development cycle, install and use the act tool to test-run your action directly in your development environment. This tool lets you invoke a GitHub workflow right on your local machine and will save you the round-trips of pushing each change to GitHub to see if it works.

When it comes to the alternatives to tmate, there is another great debugging tool that you could check out. It is called act and it allows you to run GitHub Actions code on your local machine making debugging even easier. It has its own limitations and some learning curve but overall it is another tool you should use if you can’t fix the CI bugs by connecting directly into the running action with the tmate.

Link: https://github.com/nektos/act

Could you upload your build of GitHub's runner image to Docker Hub?

This would be quite useful for users of other GitHub Actions clones like act [0].

[0]: https://github.com/nektos/act

> These kinds of commit messages are typically an indicator of a broken process where somebody needs to commit to see something happen, like a deployment or build process, and aren't able to assert that stuff works locally.

This is one of my biggest pet peeves with services like github actions. Something running locally like "act" [1] isn't sufficient because it doesn't have everything github has and is extra friction anyway to get everyone to use it for testing.

[1] https://github.com/nektos/act

View on GitHub

If you use Github actions, act is incredibly useful. It can be used to test your GH actions, but also serves as an interface for running tasks locally.

That's something that often is difficult or basically impossible. Except for maybe GitHub actions through Act (https://github.com/nektos/act). I'd still lean to something in the yaml sphere if it eventually would be used in deployment pipelines and such. For example a solution incorporating ansible.

It also seems to me that the argument you make is mostly focused on the building step? Earthly certainly seems focused on that aspect.

I feel I'm being trolled, but I'll bite and accept the resulting downvotes

I don't think treating every mention of act as an opportunity for airing of personal grievances is helpful in a discussion when there's already ample reports of people's concrete issues with it, had one looked at the 800 issues in its repo https://github.com/nektos/act/issues?q=is%3Aissue or the 239 from gitea's for https://gitea.com/gitea/act_runner/issues or whatever is going on with Forgejo's fork https://code.forgejo.org/forgejo/act .

But, as for me specifically, there are two and a half answers: I wanted to run VSCodium's build locally, which act for sure puked about. Then, while trying to troubleshoot that, I thought I'd try something simpler and have it run the lint job from act's own repo <https://github.com/nektos/act/blob/1252e551b8672b1e16dc8835d...> to rule out "you're holding it wrong" type junk. It died with

  [checks/lint]     Failure - Main actions/setup-go@v3

https://twitter.com/mitsuhiko/status/1720410479141487099 :

> GitHub Actions currently charges $0.16 per minute* for the macOS M1 Runners. That comes out to $84,096 for 1 machine year*

GitHub Runner is written in Go; it fetches tasks from GitHub Actions and posts the results back to the Pull Request that spawned the build.

nektos/act is how Gitea Actions builds GitHub Actions workflow YAML build definition documents. https://github.com/nektos/act

https://twitter.com/MatthewCroughan/status/17200423527675700... :

> This is the macOS Ventura installer running in 30 VMs, in 30 #nix derivations at once. It gets the installer from Apple, automates the installation using Tesseract OCR and TCL Expect scripts. This is to test the repeatability. A single function call `makeDarwinImage`.

With a Multi-Stage Dockerfile/Containerfild, you can have a dev environment like xcode or gcc+make in the first stage that builds the package, and then the second stage the package is installed and tested, and then the package is signed and published to a package repo / app store / OCI container image repository.

SLSA now specifies builders for signing things correctly in CI builds with keys in RAM on the build workers.

"Build your own SLSA 3+ provenance builder on GitHub Actions" https://slsa.dev/blog/2023/08/bring-your-own-builder-github