build: opentelemetry support

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

_data/toc.yaml

@@ -1561,6 +1561,8 @@ manuals:
           title: Multi-stage builds
         - path: /build/building/multi-platform/
           title: Multi-platform images
+        - path: /build/building/opentelemetry/
+          title: OpenTelemetry support
         - path: /build/building/base-images/
           title: Create your own base image
     - sectiontitle: Drivers

build/building/opentelemetry.md

@@ -0,0 +1,37 @@
+---
+title: OpenTelemetry support
+keywords: build, buildx buildkit, opentelemetry
+---
+
+Both Buildx and BuildKit support [OpenTelemetry](https://opentelemetry.io/){:target="blank" rel="noopener" class=""}.
+
+To capture the trace to [Jaeger](https://github.com/jaegertracing/jaeger){:target="blank" rel="noopener" class=""},
+set `JAEGER_TRACE` environment variable to the collection address using a
+`driver-opt`.
+
+First create a Jaeger container:
+
+```console
+$ docker run -d --name jaeger -p "6831:6831/udp" -p "16686:16686" jaegertracing/all-in-one
+```
+
+Then [create a `docker-container` builder](../drivers/docker-container.md)
+that will use the Jaeger instance via the `JAEGER_TRACE` env var:
+
+```console
+$ docker buildx create --use \
+  --name mybuilder \
+  --driver docker-container \
+  --driver-opt "network=host" \
+  --driver-opt "env.JAEGER_TRACE=localhost:6831"
+```
+
+Boot and [inspect `mybuilder`](../../engine/reference/commandline/buildx_inspect.md):
+
+```console
+$ docker buildx inspect --bootstrap
+```
+
+Buildx commands should be traced at `http://127.0.0.1:16686/`:
+
+![OpenTelemetry Buildx Bake](../images/opentelemetry.png)