ERROR: invalid not-modified ETag:

[howardjohn]

This seems similar to #905 although I think its slightly different. In that issue, there is an ETag, but in this there is no ETag at all

When using buildx, I get this error:

#77 https://storage.googleapis.com/shellcheck/shellcheck-v0.7.0.linux.x86_64...
#77 ERROR: invalid not-modified ETag: 

Full log: https://prow.istio.io/view/gcs/istio-prow/pr-logs/pull/istio_tools/575/containers-test_tools/48 from PR istio/tools#575 which starts using buildx

Our build runs in Kubernetes, running from image gcr.io/istio-testing/build-tools:master-2019-12-15T16-17-48. This image has docker version:

Client: Docker Engine - Community
 Version:           19.03.2
 API version:       1.40
 Go version:        go1.12.8
 Git commit:        6a30dfc
 Built:             Thu Aug 29 05:29:11 2019
 OS/Arch:           linux/amd64
 Experimental:      false

Server: Docker Engine - Community
 Engine:
  Version:          19.03.2
  API version:      1.40 (minimum version 1.12)
  Go version:       go1.12.8
  Git commit:       6a30dfc
  Built:            Thu Aug 29 05:27:45 2019
  OS/Arch:          linux/amd64
  Experimental:     false
 containerd:
  Version:          1.2.6
  GitCommit:        894b81a4b802e4eb2a91d1ce216b8817763c29fb
 runc:
  Version:          1.0.0-rc8
  GitCommit:        425e105d5a03fabd737a126ad93d62a9eeede87f
 docker-init:
  Version:          0.18.0
  GitCommit:        fec368

This happens 100% of the time in our CI, but if I run locally it seems to work fine. This includes both running directly, and running DinD (docker run --privileged -v $PWD:$PWD -e DRY_RUN=1 -w $PWD gcr.io/istio-testing/build-tools:master-2019-12-15T16-17-48 entrypoint ./build-and-push.sh), so it seems like its some fairly obscure issue possibly.

Let me know if any more info is useful

[tonistiigi]

This was mitigated in #1159 (docker v19.03.3)