Ever wonder why docker pauses when you do docker build
, and what you can do
about it? You know, when it says Sending build context to Docker daemon
?
This program shows where time and bytes are spent when building a docker context.
It is based directly on the same logic that Docker itself uses to build the context.
docker build -t docker-show-context https://github.com/pwaller/docker-show-context.git
docker run --rm -v $PWD:/data docker-show-context
Binaries are available on the
releases page.
Just grab the binary and put it in your path, then invoke it as
docker-show-context
. Use at your own risk.
You will need go 1.11 or more recent, which can be obtained from the go website.
Then run:
git clone https://github.com/pwaller/docker-show-context
cd docker-show-context
GO111MODULE=on go install -v
The output looks something like this. It's easy to see now that I accidentally
included some large binary content (*.deb
and *.pdf
files in particular),
so I can now go and add those to my .dockerignore
or delete them.
$ cd ~/path/to/project/using/docker
$ docker-show-context
Scanning local directory (in tar / on disk):
24 / 1057 (62 / 216 MiB) (0.0s elapsed) .. completed
Excluded by .dockerignore: 1033 files totalling 153.98 MiB
Final .tar:
24 files totalling 61.83 MiB (+ 0.02 MiB tar overhead)
Took 0.04 seconds to build
Top 10 directories by time spent:
40 ms: .
1 ms: example
Top 10 directories by storage:
61.83 MiB: .
0.00 MiB: example
Top 10 directories by file count:
23: .
1: example
Top 10 file extensions by storage:
57.10 MiB:
4.71 MiB: .exe
0.01 MiB: .pprof
0.01 MiB: .md
0.01 MiB: .go
0.00 MiB: .sum
0.00 MiB: .mod
0.00 MiB: .sh
0.00 MiB: .gitignore
0.00 MiB: .dockerignore
This documents the current behaviour, which may not be ideal, but it is what it is for now. Pull requests welcome.
-
The amounts shown don't show recursive usage, they just show a single level of the directory. (Otherwise, the root would always be the biggest thing).
-
Time records the amount of time between
tarFile.Next()
calls. I assume that this approximates the amount of timedocker/pkg/archive
spent constructing one tar entry. It might not be precise. -
"Total content" shows the uncompressed bytes inside files inside the tar. The total amount sent to the docker daemon is this amount plus the tar overhead.
-
At this moment, only running with the build context root as the current working directory is supported, with a dockerfile named
Dockerfile
. Pull requests welcome to add parameters, so long as the existing default behaviour is preserved.
Frequently, I find that docker build
suddenly takes longer than I expect. It
is often the case that I have accidentally included some binaries or something
which I did not intend to include. This the purpose of this tool is to give
visibility into this, taking into account your existing .dockerignore
,
so that you can improve your .dockerfile
or delete assets you don't need.
It scratches an itch.
The MIT License (MIT)
Copyright (c) 2016-2018 Peter Waller [email protected]
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
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