Unable to use COPY --from , docker build trying to pull image

[UltWolf]

Description
I have a Dockerfile like this:

FROM mcr.microsoft.com/dotnet/core/sdk:3.0-buster AS build-env
WORKDIR /app 

COPY CostsAnalyse/*.csproj ./
RUN dotnet restore

COPY . ./
RUN dotnet publish -c Release -o out
 
WORKDIR /app
COPY --from=build-env /app/out/ .
CMD dotnet CostsAnalyse.dll 

and when i`m run COPY --from=build-env /app/out/ . i have been get the error:
invalid from flag value build-env: pull access denied for build-env, repository does not exist or may require 'docker login'

Steps to reproduce the issue:

1. Run docker version 18.09.2
2. Create docker file with above contents
3. Run docker build .

Describe the results you received:

i get the error: invalid from flag value build-env: pull access denied for build-env, repository does not exist or may require 'docker login', after running COPY --from=build-env /app/out/ .

Describe the results you expected:
I am expecting that the build will work with the syntax --from=build .

Additional information you deem important (e.g. issue happens only occasionally):

Output of docker version:

Client: Docker Engine - Community
 Version:           18.09.2
 API version:       1.39
 Go version:        go1.10.8
 Git commit:        6247962
 Built:             Sun Feb 10 04:12:31 2019
 OS/Arch:           windows/amd64
 Experimental:      false

Server: Docker Engine - Community
 Engine:
  Version:          18.09.2
  API version:      1.39 (minimum version 1.12)
  Go version:       go1.10.6
  Git commit:       6247962
  Built:            Sun Feb 10 04:13:06 2019
  OS/Arch:          linux/amd64
  Experimental:     false

Output of docker info:

Containers: 1
 Running: 0
 Paused: 0
 Stopped: 1
Images: 45
Server Version: 18.09.2
Storage Driver: overlay2
 Backing Filesystem: extfs
 Supports d_type: true
 Native Overlay Diff: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
 Volume: local
 Network: bridge host macvlan null overlay
 Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog
Swarm: inactive
Runtimes: runc
Default Runtime: runc
Init Binary: docker-init
containerd version: 9754871865f7fe2f4e74d43e2fc7ccd237edcbce
runc version: 09c8266bf2fcf9519a651b04ae54c967b9ab86ec
init version: fec3683
Security Options:
 seccomp
  Profile: default
Kernel Version: 4.9.125-linuxkit
Operating System: Docker for Windows
OSType: linux
Architecture: x86_64
CPUs: 1
Total Memory: 1.442GiB
Name: linuxkit-00155daca30a
ID: DHFO:KJHS:JNS7:MFZL:ZCSB:REFE:XSV6:S6HC:OVGA:F3VT:4PA3:K6RS
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): true
 File Descriptors: 22
 Goroutines: 47
 System Time: 2019-07-03T12:41:07.6438807Z
 EventsListeners: 1
Registry: https://index.docker.io/v1/
Labels:
Experimental: false
Insecure Registries:
 127.0.0.0/8
Live Restore Enabled: false
Product License: Community Engine

Additional environment details (AWS, VirtualBox, physical, etc.):
Running on Windows 10.
Circle CLI build that assemble without any error.

[thaJeztah]

Looks like your COPY --from is in the same build stage; it's still inside the build-dev stage

[thaJeztah]

You probably want to add a new FROM above the second WORKDIR to start a new buildstage for the final image.

I'll close this issue, because I don't think there's a bug here, but feel free to continue the conversation

[UltWolf]

But why then build on the https://circleci.com is okay?

Info docker:

Containers: 0
 Running: 0
 Paused: 0
 Stopped: 0
Images: 0
Server Version: 17.09.0-ce
Storage Driver: overlay2
 Backing Filesystem: extfs
 Supports d_type: true
 Native Overlay Diff: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
 Volume: local
 Network: bridge host macvlan null overlay
 Log: awslogs fluentd gcplogs gelf journald json-file logentries splunk syslog
Swarm: inactive
Runtimes: runc
Default Runtime: runc
Init Binary: docker-init
containerd version: 06b9cb35161009dcb7123345749fef02f7cea8e0
runc version: 3f2f8b84a77f73d38244dd690525642a72156c64
init version: 949e6fa
Security Options:
 apparmor
Kernel Version: 4.4.0-96-generic
Operating System: Ubuntu 14.04.5 LTS
OSType: linux
Architecture: x86_64
CPUs: 2
Total Memory: 7.305GiB
Name: default-d664688d-0647-4a33-ada8-f31a7d35c347
ID: H4I5:ZTAM:GNQK:AM3G:HF4X:RFAK:U67G:GHDB:L4S3:EBKB:Y7Z2:QPXP
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): false
Registry: https://index.docker.io/v1/
Experimental: false
Insecure Registries:
 127.0.0.0/8
Live Restore Enabled: false

It`s can be problem in machine or windows?

[thaJeztah]

Hm interesting; I can confirm it worked on Docker 17.09, but that's not by design: the build-env stage is not finished yet at that point, so cannot be referenced, in which case --from=build-env should be looking for an image reference by that name.

Older versions of Docker failed to detect this situation, and just went ahead. Docker 17.09 seems to use build-env as "everything we did so far in the build-env stage", and copy from that;

docker build -t myimage -<<'EOF'
FROM busybox AS build-env
WORKDIR /app
RUN mkdir -p out && echo foo > out/CostsAnalyse.dll


WORKDIR /app
COPY --from=build-env /app/out/ .
EOF

Which copies the file from the current stage (or "build-env");

docker run --rm myimage ls -la /app
total 16
drwxr-xr-x    1 root     root          4096 Jul  4 13:06 .
drwxr-xr-x    1 root     root          4096 Jul  4 13:18 ..
-rw-r--r--    1 root     root             4 Jul  4 13:06 CostsAnalyse.dll
drwxr-xr-x    2 root     root          4096 Jul  4 13:06 out

Given that we're still inside the build-env stage, that Dockerfile would be roughly the
equivalent of:

FROM busybox AS build-env
WORKDIR /app
RUN mkdir -p out && echo foo > out/CostsAnalyse.dll
RUN cp -r /app/out/* .

Note that current versions of Docker with buildkit enabled will produce a more useful error message;

DOCKER_BUILDKIT=1 docker build -t myimage -<<'EOF'
FROM busybox AS build-env
WORKDIR /app
RUN mkdir -p out && echo foo > out/CostsAnalyse.dll


WORKDIR /app
COPY --from=build-env /app/out/ .
EOF

Running the above produces:

[+] Building 0.2s (2/2) FINISHED                                                                                                                                                             
 => [internal] load build definition from Dockerfile                                                                                                                                    0.1s
 => => transferring dockerfile: 184B                                                                                                                                                    0.0s
 => [internal] load .dockerignore                                                                                                                                                       0.2s
 => => transferring context: 2B                                                                                                                                                         0.0s
failed to create LLB definition: circular dependency detected on stage: build-env

[UltWolf]

Oh, but Windows doesn't support this function yet.
And it's very sad.
Thanks for your help, and detailed answers.

[thaJeztah]

Correct, BuildKit is unfortunately not yet supported on Windows, but for this Dockerfile to work, it's not needed; if you intended to make a multi-stage build, you need to add aFROM line

[thaJeztah]

Well, BuildKit is not supported for Windows containers/images; I see you're running docker desktop with Linux images;

Kernel Version: 4.9.125-linuxkit

So buildkit should work