Injection

Injection is Datadog's strategy to instrument application without touching application code. Currently, This strategy is implemented by adding ddtrace to your application's Gemfile to instrument your application).

• Supports Ruby on Rails and Hanami application
• Requires bundler version 2.3 or above
• Does not support frozen Gemfile or vendoring gems (Bundler's Deployment Mode or setting BUNDLE_PATH)

Examples:

Bundler vendors gems from a specific location, instead of system default.

bundle config path vendor/cache
# or
BUNDLE_PATH=vendor/cache bundle install
# or
bundle install --path=vendor/cache

Bundler freezes the Gemfile to prevent the Gemfile.lock to be updated after this install.

bundle config set frozen true
# or
bundle install --frozen

Bundler's Deployment Mode would freeze the Gemfile and vendor gems from vendor/cache.

bundle config set deployment true
# or
bundle install --deployment

Packaging

There's an internal gitlab build pipeline ships pre-installed ddtrace deb and rpm packages.

Currently, we support

Environment	version
Ruby	2.7, 3.0, 3.1, 3.2
Arch	amd64
glibc	2.28+

In order to ship ddtrace and its dependencies as a pre-install package, we need a few tweaks in our build pipeline.

• Use multiple custom built Ruby images to build native extensions. Those images are based on Debian buster to support older distribution and Ruby is compiled as a static library with --disable-shared option which disables the creation of shared libraries (also known as dynamic libraries or DLLs).
• Install ffi gem with its built-in libffi native extension instead of using system's libffi.
• After gem installation, the native extensions would be store in extensions/x86_64-linux/3.2.0-static/(see Gem.extension_api_version). We symlink those directories to remove the -static suffix so user’s ruby can detect those .so files and make sure files have read permission.