docker-container: Remove /etc symlink

The system output usually contains a symlink from /etc to the static
configuration for the benefit of the stage-1 script in the initrd. The stage-2
script is usually started in the real root without such a symlink. In a
container, there is no stage-1 and the system output is used directly as a real
root. If the symlink is present, setup-etc.pl will create a symlink cycle and
the system cannot boot. There is no reason for the /etc link to exist in a
container because setup-etc.pl will create the necessary files. The container
module will now remove the /etc symlink and create an empty directory. The empty
/etc is for container managers to populate it with site-specific settings; for
example, to set the hostname. This is required to boot NixOS in an LXC container
on another host.

See also: #9735
This commit is contained in:
Thomas Tuegel 2019-11-27 15:44:32 -06:00
parent 0ee0489d42
commit 757c7f3773
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@ -2,6 +2,8 @@
with lib;
let inherit (pkgs) writeScript; in
let
pkgs2storeContents = l : map (x: { object = x; symlink = "none"; }) l;
@ -30,7 +32,12 @@ in {
];
# Some container managers like lxc need these
extraCommands = "mkdir -p proc sys dev";
extraCommands =
let script = writeScript "extra-commands.sh" ''
rm etc
mkdir -p proc sys dev etc
'';
in script;
};
boot.isContainer = true;