OCaml agent for Elastic APM

Dev setup

Clone

git clone git@github.com:elastic/apm-agent-ocaml.git
cd apm-agent-ocaml

Setup OCaml environment

opam switch create . 4.13.1
opam install ocamlformat ocamlformat-rpc ocaml-lsp-server

You can run a build in watch mode so new changes are automatically detected and rebuilt. In a terminal, in or outside of your editor:

dune build -w

Tests can also be run in watch mode with expectation tests automatically capturing changes in output! This gives an almost magical experience where test results update as new tests are written and as the library itself evolves.

dune test -w --auto-promote

If you don't have it installed already, watch mode needs fswatch which can be installed via brew on macOS:

brew install fswatch

If you're using vscode, install the OCaml Platform plugin by OCaml Labs. The OCaml plugin should automatically detect the local opam switch you just created. If you setup format on save in the editor it will automatically format new changes via the LSP server to conform to the project's standard formatting.

You should now be ready to work on the OCaml Elastic APM agent!

Running the examples locally

• Install docker + docker compose
• docker compose build ocaml-base
• docker compose build
• docker compose up -d

Once docker compose up finishes the following endpoints will be available:

• http://localhost:5601 -> Kibana
• http://localhost:4000 -> OCaml hello-world example
• http://localhost:4001 -> OCaml example that talks to a python service
• http://localhost:5000 -> Python flask application
• http://localhost:4003 -> OCaml example that talks to postgres