Why is docker build not showing any output from commands?
DockerDocker BuildDocker Problem Overview
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 worl" 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.
Docker Solutions
Solution 1 - Docker
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 no loaded from the 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 ...
Solution 2 - Docker
Just use this flag --progress=plain
after build
.
For example:
docker-compose build --progress=plain <container_name>
OR
docker build --progress=plain .
If you don't want to use this flag every time, then permanently tell docker to use this flag by doing:
export BUILDKIT_PROGRESS=plain
Here is the official documentation when you type docker build --help
.
--progress string Set type of progress output (auto, plain, tty). Use plain to show container output (default "auto")
Solution 3 - Docker
In Docker 20.10 i had to use the --no-cache flag, too. Otherwise cached output is not shown.
docker build --progress=plain --no-cache .
Solution 4 - Docker
As an alternative to specifying the --progress=plain
option, you can also permanently disable the "pretty" output by setting this env variable in your shell config:
export BUILDKIT_PROGRESS=plain