Problems with build output

Some CI tools do not support updating rows in logs. This feature makes the output very nice and dynamic in most terminals, but terrible in CI tools. For example:

#2 [internal] load Dockerfile
#2       digest: sha256:2c6f8b4480264b5726c0d71b15eabc3fcc89c57ff9726fcb7423900978eb2011
#2         name: "[internal] load Dockerfile"
#2      started: 2018-08-08 20:20:55.499773549 +0000 UTC
#2    completed: 2018-08-08 20:20:55.508116402 +0000 UTC
#2     duration: 8.342853ms
#2      started: 2018-08-08 20:20:55.55401781 +0000 UTC
#2 transferring dockerfile:
#2 transferring dockerfile: 8.36kB 0.1s done
#2    completed: 2018-08-08 20:20:56.02282162 +0000 UTC
#2     duration: 468.80381ms


#1 [internal] load .dockerignore
#1       digest: sha256:cd79e09d00ab98ba8a18ffae0192aae97f5141509285d80a1e57f853d3219db7
#1         name: "[internal] load .dockerignore"
#1      started: 2018-08-08 20:20:55.499686297 +0000 UTC
#1    completed: 2018-08-08 20:20:55.50802369 +0000 UTC
#1     duration: 8.337393ms
#1      started: 2018-08-08 20:20:55.553973005 +0000 UTC
#1 transferring context: 182B 0.1s done
#1    completed: 2018-08-08 20:20:56.222713362 +0000 UTC
#1     duration: 668.740357ms


#3 [internal] load metadata for docker.io/library/buildpack-deps:stretch-sc...
#3       digest: sha256:041cad18349bb3a69a06b0e8e8309e12a1c508911575a32a13ab199c6d7ecad8
#3         name: "[internal] load metadata for docker.io/library/buildpack-deps:stretch-scm"
#3      started: 2018-08-08 20:20:56.403116254 +0000 UTC
#3    completed: 2018-08-08 20:20:57.870701656 +0000 UTC
#3     duration: 1.467585402s

The same issue sometimes happens if you are ssh-ed through multiple layers of servers. Would it be possible to add a flag that disables outputting all the metadata for dynamic log updates?

Start by tracing BuildKit's dynamic log output and CLI flag handling, then reproduce the behavior in a CI tool or through multiple SSH layers. Add a way to disable metadata intended for dynamic terminal updates while preserving a readable build log, and verify the resulting output in both interactive and non-interactive environments.