OpenTelemetry support

Both Buildx and BuildKit support OpenTelemetry.

To capture the trace to Jaeger, set JAEGER_TRACE environment variable to the collection address using a driver-opt.

First create a Jaeger container:

$ docker run -d --name jaeger -p "6831:6831/udp" -p "16686:16686" --restart unless-stopped jaegertracing/all-in-one

Then create a docker-container builder that will use the Jaeger instance via the JAEGER_TRACE env var:

$ docker buildx create --use \
  --name mybuilder \
  --driver docker-container \
  --driver-opt "network=host" \
  --driver-opt "env.JAEGER_TRACE=localhost:6831"

Boot and inspect mybuilder:

$ docker buildx inspect --bootstrap

Buildx commands should be traced at http://127.0.0.1:16686/: