cURL does not work (anymore)

[sameersbn]

cURL installed in docker:17.06.0-ce-git release does not seem to work.

# docker run -it --rm docker:17.06.0-ce-git sh -c 'apk add --no-cache curl && curl -vL https://www.google.com'
Unable to find image 'docker:17.06.0-ce-git' locally
17.06.0-ce-git: Pulling from library/docker
88286f41530e: Pull complete 
61bf6059e353: Pull complete 
0b539e28e9a6: Pull complete 
ad3af5fe81b0: Pull complete 
ec33fee374b5: Pull complete 
Digest: sha256:b5ff49006c6d5f6a4962953c6cafe3949c43f342c1eea84c12b76a9f5f4a1777
Status: Downloaded newer image for docker:17.06.0-ce-git
fetch http://dl-cdn.alpinelinux.org/alpine/v3.6/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.6/community/x86_64/APKINDEX.tar.gz
(1/1) Installing curl (7.55.0-r0)
Executing busybox-1.26.2-r5.trigger
OK: 28 MiB in 20 packages
curl: (48) An unknown option was passed in to libcurl

The issue seems to be due to the mismatch between libcurl and curl package versions, Upgrading libcurl fixes the issue (something that apk should automatically do).

# docker run -it --rm docker:17.06.0-ce-git sh -c 'apk upgrade --no-cache libcurl && apk add --no-cache curl && curl -vL https://www.google.com'

Since libcurl is not required by Docker itself, you should probably remove it and any other unused dependencies.

[tianon]

Sorry for the delay!

We only explicit install curl (or libcurl) in one place:

docker/18.06/Dockerfile

Lines 19 to 26 in 4782798

	# why we use "curl" instead of "wget":
	# + wget -O docker.tgz https://download.docker.com/linux/static/stable/x86_64/docker-17.03.1-ce.tgz
	# Connecting to download.docker.com (54.230.87.253:443)
	# wget: error getting response: Connection reset by peer
	apk add --no-cache --virtual .fetch-deps \
	curl \
	tar \
	; \

It is then subsequently removed: (and I've just gone and verified that both curl and libcurl are removed by this line)

docker/18.06/Dockerfile

Line 51 in 4782798

apk del .fetch-deps; \

So, all I can figure is that one of git or openssh-client is pulling in libcurl:

docker/18.06/git/Dockerfile

Lines 3 to 5 in 4782798

	RUN apk add --no-cache \
	git \
	openssh-client

I'm not sure what to do from here. Part of me wants to simply deprecate the git variant entirely, given that the value it provides is pretty minimal (as you can see, its only addition is two packages above the base).

Given that it works on the latest 18.06 release, I'm also inclined to close this as a fluke.