Why does Docker build take long time in "Sending context to daemon" step?

Question

I am pretty new to the Docker world. I am running this command:

docker build -t worker -f worker-Dockerfile-local .

This is the content of the Docker file:

FROM centos
MAINTAINER MyTeam

RUN /usr/bin/getent group worker || /usr/sbin/groupadd -r worker
RUN /usr/bin/getent passwd worker || /usr/sbin/useradd -r -g worker -s /sbin/nologin worker

# INSTALL PIP
RUN curl "https://bootstrap.pypa.io/get-pip.py" -o "get-pip.py"
RUN python get-pip.py


ADD . /code
RUN pip install ./code

I get this message after starting this command:

Sending build context to Docker daemon 2.942 GB

My other builds take only a few seconds and the "Sending context to daemon" stage send only a few KB of data. I am not sure what's going on. Can someone help me out please?

What else is in your current working directory? (`ls -lah` if you're on Linux / OS). — johnharris85, Jul 06 '16 at 23:47
@JHarris: There was a test data file, I accidentally put in the working dir. That was causing problems. — Bhushan, Jul 06 '16 at 23:49

score 33 · Accepted Answer · answered Jul 06 '16 at 23:47

33

I solved it, silly mistake.

Seems like Docker build tars up the current working directory (i.e. the folder containing the dockerfile). And it then uploads it to the Docker Daemon for the build steps. I had accidently put a big test data file (2.9 GB) in the working directory. And that was getting included in the build context. After removing it things are back to normal.

answered Jul 06 '16 at 23:47

Bhushan

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You can also add this file to `.dockerignore`. – Opal Jul 07 '16 at 07:42
@Opal: Yes, that's a nice option as well. Will keep in mind. – Bhushan Jul 07 '16 at 16:52
1

also try using DOCKER_BUILDKIT=1 for docker ver >=18.09, for more info see: https://stackoverflow.com/questions/58592259/how-do-you-enable-buildkit-with-docker-compose – pangyuteng Jun 16 '21 at 18:52
It is not clear what "uploads to the docker deamon for build steps" means. Uploading is used for network connectoins, but the docker deamon is on the same machine. What build steps? – problemofficer - n.f. Monica Jul 16 '22 at 13:46

Why does Docker build take long time in "Sending context to daemon" step?

1 Answers1