Compose: Docker Compose build fails: "Top level object in DockerFile needs to be an object not '<type 'str'>'"

[SunnyOswal]

docker version

Client:
    Version:      17.03.2-ee-5
    API version:  1.27
    Go version:   go1.7.5
    Git commit:   fa09039
    Built:        Wed Jul 19 23:56:45 2017
    OS/Arch:      windows/amd64
    Server:
    Version:      17.03.2-ee-5
    API version:  1.27 (minimum version 1.24)
    Go version:   go1.7.5
    Git commit:   fa09039
    Built:        Wed Jul 19 23:56:45 2017
    OS/Arch:      windows/amd64
    Experimental: false

docker-compose version

docker-compose version 1.14.0, build c7bdf9e3
docker-py version: 2.3.0
CPython version: 2.7.13
OpenSSL version: OpenSSL 1.0.2j  26 Sep 2016

docker-compose.yml

version: '2.1'

services:
  ucmvstsagent:
    volumes:
    - E:\DockerPoolCache:C:\_cache
    - E:\DockerPoolWork:C:\Agent\_work
    build:
     context: .
     dockerfile: DockerFile

DockerFile:

FROM microsoft/windowsservercore:latest

ENV chocolateyUseWindowsCompression=false
RUN @powershell -NoProfile -ExecutionPolicy Bypass -Command "iex ((New-Object System.Net.WebClient).DownloadString('https://chocolatey.org/install.ps1'))" && SET "PATH=%PATH%;%ALLUSERSPROFILE%\chocolatey\bin"
RUN choco install -y sql2016-dacframework

SHELL [ "powershell", "-Command", "$ErrorActionPreference = 'Stop'; $ProgressPreference = 'SilentlyContinue';" ]
RUN Install-PackageProvider Nuget -Force
RUN Install-Module Azure -Force
RUN Install-Module AzureRM -Force

RUN Import-Module Azure -Force
RUN Import-Module AzureRM -Force

RUN mkdir C:\Agent
RUN mkdir C:\Agent\Drop
RUN mkdir C:\shared\Deployment

WORKDIR C:/Agent

ENV Drop=C:\\Agent\\Drop
ENV WINDOWS_IMAGE_VERSION=latest

COPY ./Start.* ./

CMD ["Start.cmd"]

Error:
Top level object in 'd:\a\1\s\private\Docker\VstsAgent\DockerFile' needs to be an object not '<type 'str'>'.

Can someone please help me identify what is the issue with DockerFile or docker-compose file ?

[shin-]

What command are you running?

[SunnyOswal]

docker-compose build ucmvstsagent

[SunnyOswal]

Issue is resolved.
Root cause: Was passing docker-compose related files such as DockerFile as additional arguments file. But docker-compose vsts task can work fine even if we do not pass the DockerFile and it will look into related DockerFiles in respective working directory.

So I did not pass any dockerfile apart from docker-compose.yml to docker-compose vsts task and it passed.

[perguth]

That error is so cryptic 😨 For me it just meant "You must have a Dockerfile for you service."

[olisteadman]

That error is so cryptic 😨 For me it just meant _"You must have a Dockerfile for you service."_

Agreed... it could be made clearer for any n00bs trying (mistakenly) to run a Dockerfile as the -f argument in a docker-compose command.