FR: Provide override flag for terminal check

[jhillyerd]

My cook stage in failing inside a Kaniko automated builder running inside a docker container, it seems to have fooled atty::is(atty::Stream::Stdout)

It would be helpful to have a flag to force it to continue.

Output:

INFO[0102] Taking snapshot of full filesystem...        
INFO[0108] cmd: /bin/sh                                 
INFO[0108] args: [-c cargo chef cook --recipe-path recipe.json] 
INFO[0108] Running: [/bin/sh -c cargo chef cook --recipe-path recipe.json] 
WARNING stdout appears to be a terminal.
cargo-chef is not meant to be run in an interactive environment and will overwrite some existing files (namely any `lib.rs`, `main.rs` and `Cargo.toml` it finds).

To continue anyway, type `yes`: error building image: error building stage: failed to execute command: waiting for process to exit: exit status 1
exit status 1

If you have a preferred name for the flag, I can make a PR.

[jhillyerd]

It seems tee can be used as a workaround for now:

cargo chef cook --recipe-path recipe.json | tee /tmp/cook.txt

[LukeMathWalker]

This feels like an issue upstream - either in atty (false negative) or kaniko.

[jhillyerd]

I think that assuming the presence of a TTY means it is always an interactive session is a mistake, the build shouldn't break because of it.

[LukeMathWalker]

It's true that it can break down in some edge cases, but I do wonder if this is intentional for kaniko.

[jhillyerd]

In my case, I'm using (testing really) Hashicorp Waypoint, which starts up a build runner as a docker container within a Nomad cluster. That runner apparently uses kaniko to build the docker image, but I don't have direct control over the kaniko config, or a way to introspect it.

I do see this random blog post intentionally enabling tty for kaniko+Jenkins, but I don't know why, perhaps related to the debug executor: https://support.cloudbees.com/hc/en-us/articles/360031223512-What-you-need-to-know-when-using-Kaniko-from-Kubernetes-Jenkins-Agents

I don't think I will be continuing with this kaniko-on-a-cluster build system, as it doesn't actually benefit from any of the layer caching that chef gives me when building locally, so the builds are incredibly slow. It was an experiment.