Docker error during connect: Post http://docker:2375/v1.40/build? - docker

Question

I am using docker+machine to run my gitlab ci/cd jobs.
So my .gitlab-ci.yml looks like below:
stages:
- RUN_TESTS
image:
name: docker:stable
services:
- name: docker:dind
variables:
DOCKER_HOST: tcp://docker:2375/
DOCKER_DRIVER: overlay2
DOCKER_TLS_CERTDIR: ""
build-docker:
stage: RUN_TESTS
script:
- echo "Running the tests..."
- docker build -t run-tests .
This works totally fine with docker:dind image set as the service block as shown above.
Now here comes the fun part, I need some other packages inside the docker:dind image. So I wrote the Dockerfile as below:
FROM docker:dind
RUN apk update
ENV PYTHONUNBUFFERED=1
RUN apk add --update --no-cache python3 && ln -sf python3 /usr/bin/python
RUN python3 -m ensurepip
RUN pip3 install --no-cache --upgrade pip setuptools
RUN apk add groff
RUN pip3 install awscli
RUN apk --purge -v del py-pip
RUN rm /var/cache/apk/*
So, I built the above image and pushed it into my dockerhub.
As of now, everything is cool. Image built successfully and pushed successfully.
And then I changed the services in the .gitlab-ci.yml to my new images as below:
services:
- name: 199508/dind-new:latest
And I ran the pipeline and I get the error below.
This error I am getting below is strange:
error during connect: Post http://docker:2375/v1.40/build?buildargs=%7B%7D&cachefrom=%5B%5D&cgroupparent=&cpuperiod=0&cpuquota=0&cpusetcpus=&cpusetmems=&cpushares=0&dockerfile=Dockerfile&labels=%7B%7D&memory=0&memswap=0&networkmode=default&rm=1&session=n6fvaaoisom3ny2cfozrlom50&shmsize=0&t=run-tests&target=&ulimits=null&version=1: dial tcp: lookup docker on : no such host
The only change I did was installing some applications/dependencies in the above Dockerfile but why it is not working? How come when I use docker:dind it is working and when I created a new Dockerfile with the same docker:dind base image and it doesn't work?
Can someone please help me?

Answer 1

Actually I just run into this problem yesterday
The main thing is to switch to docker image version
In Your case in the Dockerfile not like here
FROM docker:18.09
And change the port:
The lines commented out are the once the didn't work for me.
image: 199508/dind-new:v5
services:
# - docker:19.03.12-dind
- docker:18.09-dind
variables:
# Use TLS https://docs.gitlab.com/ee/ci/docker/using_docker_build.html#tls-enabled
DOCKER_HOST: tcp://docker:2375/
# DOCKER_HOST: tcp://docker:2376
# DOCKER_TLS_CERTDIR: "/certs"
DOCKER_TLS_CERTDIR: ""
CONTAINER_TEST_IMAGE: $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_SLUG
CONTAINER_RELEASE_IMAGE: $CI_REGISTRY_IMAGE:latest
DOCKER_DRIVER: overlay2