Why is docker build not showing any output from commands?
Nov 12
Snippet from my Dockerfile:
FROM node:12.18.0
RUN echo "hello world"
RUN psql --version
When I run docker build . I don't see any output from these two commands even if they are not cached. The documentation says that docker build is verbose by default. Why am I not seeing the output from commands? I used to see them before.
The output while building:
=> [7/18] RUN echo "hello world" 0.9s
The output I am seeing after building finishes:
=> CACHED [6/18] RUN apt-get install postgresql -y 0.0s
=> [7/18] RUN echo "hello world" 6.4s
=> [8/18] RUN psql --version 17.1s
The Dockerfile is created from node:12.18.0 which is based on Debian 9.
Docker version 19.03.13, build 4484c46d9d.
docker1 answer
Accepted answer · original discussion
Nov 12
The output you are showing is from buildkit, which is a replacement for the classic build engine that docker ships with. You can adjust output from this with the --progress option:
--progress string Set type of progress output (auto, plain, tty). Use plain to show container output
(default "auto")
Adding --progress=plain will show the output of the run commands that were not loaded from the cache. This can also be done by setting the BUILDKIT_PROGRESS variable:
export BUILDKIT_PROGRESS=plain
If you are debugging a build, and the steps have already been cached, add --no-cache to your build to rerun the steps and redisplay the output:
docker build --progress=plain --no-cache ...
If you don't want to use buildkit, you can revert to the older build engine by exporting DOCKER_BUILDKIT=0 in your shell, e.g.:
DOCKER_BUILDKIT=0 docker build ...
or
export DOCKER_BUILDKIT=0
docker build ...
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