Rules should use `/usr/bin/env bash` instead of `/bin/bash`

[AleksanderGondek]

Description of the problem:

Gitops rules should not assume /bin/bash is present on the host machine, as it breaks the compatibility for Linux OS'es which do not place bash executable in such location. It should use more portable /usr/bin/env bash.

Bugs: what's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

1. Use NixOS operating system (for example, in version 20.09)
2. Clone the example repository: Link
3. Remove patch fixing the issue (WORKSPACE line 33)
4. Run bazel build //kubeview:kustomize-dev

Alternatively:

1. Use NixOS operating system (for example, in version 20.09)
2. Clone any bazel project using rules_gitops
3. Run bazel target utilizing k8s_deploy

What operating system are you running Bazel on?

NixOS 20.09

What's the output of bazel info release?

release 3.3.1- (@non-git)

If bazel info release returns "development version" or "(@Non-Git)", tell us how you built Bazel.

It was installed by nix package manager (link).

Snippet of the WORKSPACE file that includes rules_gitops rules.

...

load("@bazel_tools//tools/build_defs/repo:git.bzl", "git_repository")
load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")

git_repository(
  name="com_adobe_rules_gitops",
  commit="354e7d3341f05e076f286663731f18caf1e62340",
  remote="https://github.com/adobe/rules_gitops.git",
  shallow_since="1611050644 +0000",
)
load("@com_adobe_rules_gitops//gitops:deps.bzl", "rules_gitops_dependencies")
rules_gitops_dependencies()

...
load("@com_adobe_rules_gitops//gitops:repositories.bzl", "rules_gitops_repositories")
rules_gitops_repositories()

Have you found anything relevant by searching the web?

No.

Any other information, logs, or outputs that you want to share?

Fixing this issue will not make adobe/rules_gitops work on NixOS, as downloaded golang binaries are using wrong ELF (which, imho, should be a separate issue).