d-c build fails when URL has capital letters - misleading error message

[xkortex]

Description of the issue

docker-compose build fails when image name contains capital letters (maybe related to #1416). However, the error message returned is

ERROR: Couldn't connect to Docker daemon - you might need to run `docker-machine start default`.

when running locally or

Couldn't connect to Docker daemon at http+docker://localhost - is it running?
If it's at a non-standard location, specify the URL with the DOCKER_HOST environment variable.

if running on a drone server.

I only figured this out once I tried running

docker build -t url.com/proj/REPO_WITH_CAPS/img:latest

and got the useful message:

invalid reference format: repository name must be lowercase

Context information (for bug reports)

Output of docker-compose version

docker-compose version 1.24.0, build 0aa5906

Output of docker version

9 | Client:
10 | Version: 18.09.1-ce
11 | API version: 1.39
12 | Go version: go1.11.4
13 | Git commit: 4c52b901c6cb019f7552cd93055f9688c6538be4
14 | Built: Fri Jan 11 15:41:33 2019
15 | OS/Arch: linux/amd64
16 | Experimental: false
17 |  
18 | Server: Docker Engine - Community
19 | Engine:
20 | Version: 18.09.5
21 | API version: 1.39 (minimum version 1.12)
22 | Go version: go1.10.8
23 | Git commit: e8ff056
24 | Built: Thu Apr 11 04:10:53 2019
25 | OS/Arch: linux/amd64
26 | Experimental: false

Output of docker-compose config
(Make sure to add the relevant -f and other flags)

services:
  redacted:
    build:
      context: /home/$USER/code/REDACTED
      dockerfile: docker/redacted.docker
    container_name: redacted
    entrypoint:
    - bash
    image: url.com:1234/project/REDACTED/redacted:latest
    runtime: nvidia
    tty: true
version: '2.4'

Steps to reproduce the issue

1. Make a compose file with capital letters in image name
2. docker-compose build
3. Profit

Observed result

Couldn't connect to Docker daemon at http+docker://localhost - is it running?
If it's at a non-standard location, specify the URL with the DOCKER_HOST environment variable.

Expected result

invalid reference format: repository name must be lowercase

Additional information

• ubuntu 18.04 desktop
• drone/dind/linux/amd64

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[ndeloof]

I tried to reproduce this issue with docker-compose 1.24 and got expected behaviour:
ERROR: invalid reference format: repository name must be lowercase