nix-otel

This program shims the Nix logger with a Nix plugin to extract precise timing for builds from Nix. It has only been tested against Honeycomb with OTLP/gRPC.

Setup

Installation

To install nix-otel, it needs to be passed to Nix in the option plugin-files. Currently nix-otel can only run on the Nix client, so my recommendation is to just use the flake from this repository and --option plugin-files, for now. In the future, it will be able to run on the daemon so it will be easier to install system wide.

Important note

You need to ensure that the version of Nix that nix-otel is loaded in is exactly the same as the one it's built against. We found a strange macOS-only bug where nix-otel built against a different copy of Nix 2.11.0 than it was run against would not get any data.

In practice, this means running with the nix binary provided by the nix develop shell from this project rather than the system Nix.

Honeycomb

Set env vars like so in .envrc.local:

export OTEL_EXPORTER_OTLP_ENDPOINT=https://api.honeycomb.io
export OTEL_EXPORTER_OTLP_HEADERS=x-honeycomb-team=YOUR_APIKEY

Then set the Nix configuration option plugin-files to include the plugin .so or .dylib file.

Other services

No idea. Sorry. They probably work but might need some minor patches since rust-opentelemetry-otlp doesn't support all environment variables yet.

Development

I use nix-direnv and direnv to make this project work across C++ and Rust.

To make rust-analyzer work for you and pick up the right compiler and so on, you will need to create a wrapper script direnv-ra somewhere in your $PATH, like so:

#!/bin/sh

direnv exec . rust-analyzer "$@"

then set the "rust-analyzer.server.path" variable in your editor settings to point to it.

Making the C++ IDE work

This is unnecessarily silly because C++ is bad. Anyway, you can get clangd working on this project by doing the following:

[nix-shell]$ cargo clean -p nix-otel-plugin
[nix-shell]$ bear -- cargo build

which will create a compile_commands.json with the appropriate contents.

Running in development

Run in development like so:

nix-otel/plugin » cargo b && nix --option plugin-files ../target/debug/libnix_otel_plugin.so build ..#

Project information

Everyone is expected to follow the code of conduct while participating in this project.