No longer see Docker build output properly!

Question

I am using the latest version of Docker Desktop on Windows (Docker Engine version v19.03.13).

After the last update, the output of docker build . has changed! It is now harder to debug what is going on.

Here is my Dockerfile:

# set base image as the dotnet 3.1 SDK.
FROM mcr.microsoft.com/dotnet/core/sdk:3.1 AS build-env
set the working directory for any RUN, CMD, ENTRYPOINT, COPY and ADD
instructions that follows the WORKDIR instruction.
WORKDIR /app
debug purposes - see where we are
RUN pwd
our current working directory within the container is /app
we now copy all the files (from local machine) to /app (in the container).
COPY . ./
debug purposes - list files in current folder
RUN ls -la
run unit tests within the solution.
RUN dotnet test Phoneden.sln
again, on the container (we are in /app folder)
we now publish the project into a folder called 'out'.
RUN dotnet publish Phoneden.Web/Phoneden.Web.csproj -c Release -o out
debug purposes - list files in current folder
RUN ls -la
set base image as the dotnet 3.1 runtime.
FROM mcr.microsoft.com/dotnet/core/aspnet:3.1 AS runtime
telling the application what port to run on.
ENV ASPNETCORE_URLS=http://*:5005
set the working directory for any RUN, CMD, ENTRYPOINT, COPY and ADD
instructions that follows the WORKDIR instruction.
WORKDIR /app
copy the contents of /app/out in the build-env and paste it in the
/app directory of the new runtime container.
COPY --from=build-env /app/Phoneden.Web/out .
set the entry point into the application.
ENTRYPOINT ["dotnet", "Phoneden.Web.dll", "-seed"]

When I run docker build --no-cache . I get the following:

jwan@home-desktop MSYS /c/code/phoneden (upgrade/net-3.1)
$ docker build --no-cache .
[+] Building 38.9s (16/16) FINISHED
 => [internal] load .dockerignore                                                                                                                                                                                                                                                  0.1s
 => => transferring context: 35B                                                                                                                                                                                                                                                   0.0s
 => [internal] load build definition from Dockerfile                                                                                                                                                                                                                               0.0s
 => => transferring dockerfile: 32B                                                                                                                                                                                                                                                0.0s
 => [internal] load metadata for mcr.microsoft.com/dotnet/core/aspnet:3.1                                                                                                                                                                                                          0.0s
 => [internal] load metadata for mcr.microsoft.com/dotnet/core/sdk:3.1                                                                                                                                                                                                             0.0s
 => [internal] load build context                                                                                                                                                                                                                                                  0.3s
 => => transferring context: 96.50kB                                                                                                                                                                                                                                               0.2s
 => [build-env 1/8] FROM mcr.microsoft.com/dotnet/core/sdk:3.1@sha256:1d96e460ac4af00ffc41c5d4a27b503f2589098c84b6ca10d09e0f7ef6e31689                                                                                                                                             0.0s
 => [runtime 1/3] FROM mcr.microsoft.com/dotnet/core/aspnet:3.1@sha256:41ece4e6218d5f2c66191c4bd8b8dda060ea3b1512353fe1185e239121458ab5                                                                                                                                            0.0s
 => CACHED [build-env 2/8] WORKDIR /app                                                                                                                                                                                                                                            0.0s
 => CACHED [runtime 2/3] WORKDIR /app                                                                                                                                                                                                                                              0.0s
 => [build-env 3/8] RUN pwd                                                                                                                                                                                                                                                        0.3s
 => [build-env 4/8] COPY . ./                                                                                                                                                                                                                                                      0.3s
 => [build-env 5/8] RUN ls -la                                                                                                                                                                                                                                                     0.3s
 => [build-env 6/8] RUN dotnet test Phoneden.sln                                                                                                                                                                                                                                  17.7s
 => [build-env 7/8] RUN dotnet publish Phoneden.Web/Phoneden.Web.csproj -c Release -o out                                                                                                                                                                                         19.5s
 => [build-env 8/8] RUN ls -la                                                                                                                                                                                                                                                     0.6s
 => ERROR [runtime 3/3] COPY --from=build-env /app/Phoneden.Web/out .                                                                                                                                                                                                              0.0s
------
 > [runtime 3/3] COPY --from=build-env /app/Phoneden.Web/out .:
------
failed to solve with frontend dockerfile.v0: failed to build LLB: failed to compute cache key: "/app/Phoneden.Web/out" not found: not found

As you can see, it is not listing the result of the debug commands I added.

How can I get the output to be verbose like it was before the update?

Answer 1

This is the output from buildkit. You can run buildkit based builds with a different output syntax:

$ docker build --help
...
  --progress string         Set type of progress output (auto, plain, tty). Use plain to show container output
                            (default "auto")

In your command, that would be:

docker build --progress=plain .

Or you can disable buildkit by setting DOCKER_BUILDKIT=0 in your shell:

DOCKER_BUILDKIT=0 docker build .