Shipit breaks with Bundler v4, `--frozen` was option removed

[amomchilov]

$ bundle install --frozen --jobs 4 --path /app/data/bundler --retry 2
pid: 3395254
[DEPRECATED] The `--frozen` flag is deprecated because it relies on being remembered across bundler invocations, which bundler will no longer do in future versions. Instead please use `bundle config set frozen true`, and stop using this flag
[DEPRECATED] The `--path` flag is deprecated because it relies on being remembered across bundler invocations, which bundler will no longer do in future versions. Instead please use `bundle config set path '/app/data/bundler'`, and stop using this flag
Bundler 2.7.2 is running, but your lockfile was generated with 4.0.2. Installing Bundler 4.0.2 and restarting using that version.
Fetching gem metadata from https://rubygems.org/.
Fetching bundler 4.0.2
Installing bundler 4.0.2
The `--frozen` flag has been removed because it relied on being remembered
across bundler invocations, which bundler no longer does. Instead please use
`bundle config set frozen true`, and stop using this flag
bundle install --frozen --jobs 4 --path /app/data/bundler --retry 2 terminated with exit status 15

https://blog.rubygems.org/2025/12/03/upgrade-to-rubygems-bundler-4.html

Looks like we have two options:

1. Freeze via config by running bundle config set --local frozen true before running bundle install ...
2. Freeze via an environment: BUNDLE_FROZEN=true

Likewise for replacing --path

[timothysmith0609]

I think my vote would be for environment variable, and we can just default to BUNDlE_FROZEN=true and BUNDLE_PATH=/app/data/bundler so gem users can overwrite should they wish. What do you think?

[amomchilov]

Makes sense to me. What would be the best place to set the default env vars, in this repo?