pkg_npm should support stamping with arbitrary stable/volatile keys

[joeljeske]

🚀 feature request

Relevant Rules

pkg_npm

Description

I want to be able to stamp multiple pieces of version information in npm archive.

Describe the solution you'd like

pkg_npm (and probably pkg_web) should allow values to use make-style variable replacements in the substitutions dictionary. The keys would still refer to strings in the source files to find and replace.

pkg_npm(
  substitutions = {
    # normal substitution
    "blaze": "bazel",
    # Make-style substitutions (from both volatile-keys and stable-keys)
    "GIT_HASH": "$(BUILD_SCM_HASH)",
    "HOST": "$(BUILD_HOST)",
    "GIT_BRANCH": "$(STABLE_SCM_BRANCH)", 
  },
  stamp = 1 # or 0,
)

Describe alternatives you've considered

Writing a rule to manually copy the info from the version file into the relevant files.

[alexeagle]

Yeah that makes a lot of sense. Do you have time to contribute it?

[joeljeske]

Yea I can look into it hopefully. I would want to see your thoughts on #1693 and how it relates to this ticket. My needs would only be satisfied here if I could mark some targets as to never rely on stamping and some conditional on the stamp flag.

It seems like there might be place for a generic rule or task that makes the stamping easy for plain text interpolations as opposed to duplicating this functionality in multiple places.

[alexeagle]

Also I'd be curious why it's good to support both stable keys and volatile keys. In particular since contributing npm publishing to bazelisk I was wondering why they use the stable keys file, and whether we should be recommending users to do the same. @philwo if you have a minute to comment?

[philwo]

@meisterT told me he can help us out here. I'm not very knowledgeable about this particular feature of Bazel.

[joeljeske]

It would seem that the use of stable keys vs. volatile keys is up to the needs of the user/organization. Some orgs may want to re-use via cache as much as possible and only ever stamp an artifact the first time its contents are generated, and others may want to re-stamp it when certain criteria is met (branch change, user/host change, etc...)

It would seem to me that the stamping feature of Bazel is representative of the needs of Google but may not be very flexible for a wider variety of needs, especially when it comes to remote caching of stamped builds

[thesayyn]

I have opened up a PR for the stamping feature of pkg_web a long time ago. It works the way you've described. Which still waiting for a review BTW.

See #1621, #1664

[mattem]

@thesayyn, thanks for the contribution, apologies that we missed following up the on review. I'll take a look at the PR shortly and ping Alex too.

[thesayyn]

Thank you. Also, I can implement the same feature for pkg_npm too.

[alexeagle]

Okay I just did stamping at work with rules_go so it's super clear what to do (they did a nice job in rules_go docs of presenting it simply as well, so I'll borrow from them)

[alexeagle]

Fixed by #2157