dockerTools.buildImage: support impure dates #47005
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Because dates are an impurity, by default buildImage will use a static
date of one second past the UNIX Epoch. This can be a bit frustrating
when listing docker images in the CLI:
$ docker image list
REPOSITORY TAG IMAGE ID CREATED SIZE
hello latest 08c791c7846e 48 years ago 25.2MB
If you want to trade the purity for a better user experience, you can
set created to now.
pkgs.dockerTools.buildImage {
name = "hello";
tag = "latest";
created = "now";
contents = pkgs.hello;
config.Cmd = [ "/bin/hello" ];
}
and now the Docker CLI will display a reasonable date and sort the
images as expected:
$ docker image list
REPOSITORY TAG IMAGE ID CREATED SIZE
hello latest de2bf4786de6 About a minute ago 25.2MB
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amazing nerdsnipe! Thank you so much, @graham-at-target !! |
grahamc
requested review from
nlewo and
aszlig
and removed request for
nlewo
| '' | ||
| jq ".created = \"$(TZ=utc date --iso-8601="seconds")\"" ${pure} > $out | ||
| ''; | ||
| in if created == "now" then impure else pure; |
There was a problem hiding this comment.
there was some question about why not just use builtins.currentTime.
builtins.currentTime will never be a cache hit, whereas this method will cache while still achieving the intended effect.
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I like it! |
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This seems like a bad idea because it breaks binary reproducibility. |
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@edolstra do you think it is bad to have the ability to break binary reproducibility? This change keeps the reproducibility by default, and but does allow users to make a trade-off. |
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It doesn't just provide the ability, but advertises it in the manual as "providing better user experience" (so nudges the user in that direction). BTW, apart from the minor cosmetic aspect of improving the "CREATED" column, how does this improve user experience? |
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Well it does provide a better user experience if you're looking at the output of |
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what if the docs said:
edit: changed and to but |
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This isn't enabled by default right? I don't see a big problem with providing an option that has a small (cosmetic) impurity. |
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My impression is the biggest concern is in the too-positive nudge for users to turn it on without understanding the cost. |
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@grahamc Yeah something like that sounds good. |
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Great! Improved in
7736337
…On Thu, Sep 20, 2018 at 5:05 PM Eelco Dolstra ***@***.***> wrote:
@grahamc <https://github.com/grahamc> Yeah something like that sounds
good.
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Sounds good! As long as we keep binary reproducibility by default and set up big warning signs, I don’t see why that shouldn’t be an option. |
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That's nice. |
Because dates are an impurity, by default buildImage will use a static
date of one second past the UNIX Epoch. This can be a bit frustrating
when listing docker images in the CLI:
If you want to trade the purity for a better user experience, you can
set created to now.
and now the Docker CLI will display a reasonable date and sort the
images as expected:
Motivation for this change
-- https://twitter.com/StewOConnor/status/1042671588447936512
cc @stew
Things done
sandboxinnix.confon non-NixOS)nix-shell -p nox --run "nox-review wip"./result/bin/)nix path-info -Sbefore and after)