Bug #21692: Basic gems like `date` require a compiler

• Status: Open
• Assignee: -
• Target version: -
• ruby -v: 3.2.3
• Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN

[getajobmike (Mike Perham)]

I'm trying to use Ruby in a high security environment which does not allow a compiler to be installed. This was easy years ago when all of standard library was included with Ruby itself and I could use apt install ruby. But as the standard library has broken off into separate, optional gems it has become impossible to bundle a reasonable pure Ruby application without requiring basic gems like date which require a compiler to install.

Are there any plans to make native extensions optional for gems? With tools like ZJIT it can be better to use pure Ruby for performance; I would like to see Ruby encourage fewer native extensions and/or make them optional.

[mame (Yusuke Endoh)]

I think what you want is bundle install --prefer-local. (I wonder why this option is not the default.)

[getajobmike (Mike Perham)]

• ruby -v changed from 3.4.5 to 3.2.3

mame (Yusuke Endoh) wrote in #note-1:

I think what you want is bundle install --prefer-local. (I wonder why this option is not the default.)

Unfortunately this does not seem to work for me.

$ gem list | grep date
date (default: 3.3.3)

$ more Gemfile
source "https://rubygems.org"

gem "net-imap"
gem "date", "3.3.3"

$ bundle version
Bundler version 2.5.23 (2024-11-05 commit 35f4611265e)

$ ruby -v
ruby 3.2.3 (2024-01-18 revision 52bb2ac0a6) [x86_64-linux-gnu]

$ bundle install --prefer-local
Fetching gem metadata from https://rubygems.org/...
Resolving dependencies...
Installing date 3.3.3 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

    current directory: /var/lib/gems/3.2.0/gems/date-3.3.3/ext/date
/usr/bin/ruby3.2 -I/usr/lib/ruby/vendor_ruby extconf.rb
checking for rb_category_warn()... *** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.
[...]
/usr/lib/ruby/3.2.0/mkmf.rb:490:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.

[mame (Yusuke Endoh)]

Ah, it seems this happens on Ubuntu 24.04, without a Gemfile.lock, and when the Gemfile does not list the indirect dependencies.

I found three workarounds.

1. Add a Gemfile.lock

If a proper Gemfile.lock is present, --prefer-local seems to avoid the installation.

$ ls
Gemfile  Gemfile.lock

$ cat Gemfile
source "https://rubygems.org"

gem "net-imap"
gem "date", "3.3.3"

$ cat Gemfile.lock
GEM
  remote: https://rubygems.org/
  specs:
    date (3.3.3)
    net-imap (0.3.4.1)
      date
      net-protocol
    net-protocol (0.2.1)
      timeout
    timeout (0.3.1)

PLATFORMS
  x86_64-linux-gnu

DEPENDENCIES
  date (= 3.3.3)
  net-imap

BUNDLED WITH
   2.4.20

$ bundle install --prefer-local
Bundle complete! 2 Gemfile dependencies, 5 gems now installed.
Use `bundle info [gemname]` to see where a bundled gem is installed.

2. List all dependencies in the Gemfile

If the Gemfile lists all dependencies, including the indirect ones, --prefer-local also seems to avoid the installation.

$ ls
Gemfile

$ cat Gemfile
source "https://rubygems.org"

gem "timeout"
gem "net-protocol"
gem "net-imap"
gem "date", "3.3.3"

$ bundle install --prefer-local
Resolving dependencies...
Bundle complete! 4 Gemfile dependencies, 5 gems now installed.
Use `bundle info [gemname]` to see where a bundled gem is installed.

3. Use bundler from a newer Ubuntu release

I think this behavior is a bug in the older version of bundler. With Ubuntu 25.10, it works well as expected, as shown below:

$ ls
Gemfile

$ cat Gemfile
source "https://rubygems.org"

gem "net-imap"
gem "date", "3.3.4"

$ bundle install --prefer-local
Fetching gem metadata from https://rubygems.org/...
Resolving dependencies...
Bundle complete! 2 Gemfile dependencies, 5 gems now installed.
Use `bundle info [gemname]` to see where a bundled gem is installed.