commit 2e13f1372ec1cad49ebbf40abbd03a63a6e0baa3
parent 5e573cef090cac8561688d01e0de8f8d07dbcdc9
Author: Daniel Barlow <dan@telent.net>
Date: Tue, 27 Sep 2022 22:07:18 +0100
add outputs.manifest for diagnosing image size problems
Diffstat:
3 files changed, 22 insertions(+), 3 deletions(-)
diff --git a/README.md b/README.md
@@ -114,6 +114,16 @@ Assuming you have nixpkgs checked out in a peer directory of this one,
NIX_PATH=nixpkgs=../nixpkgs:$NIX_PATH ./run-tests.sh
+## Diagnosing unexpectedly large images
+
+Sometimes you can add a package and it causes the image size to balloon
+because it has dependencies on other things you didn't know about. Build the
+`outputs.manifest` attribute, which is a json representation of the
+filesystem, and you can run `nix-store --query` on it:
+
+ NIX_PATH=nixpkgs=../nixpkgs:$NIX_PATH NIXPKGS_ALLOW_UNSUPPORTED_SYSTEM=1 nix-build -I liminix-config=path/to/your/configuration.nix --arg device "import ./devices/qemu.nix" -A outputs.manifest -o manifest
+ nix-store -q --tree manifest
+
## Articles of interest
diff --git a/THOUGHTS.txt b/THOUGHTS.txt
@@ -186,7 +186,7 @@ creates the interface instead of using an existing unconfigured one
5) write a test for udhcp
-6) squashfs size is ~ 14MB for a configuration with not much in it,
+DONE 6) squashfs size is ~ 14MB for a configuration with not much in it,
look for obvious wastes of space
7) some of the pppoe config should be moved into a ppp service
@@ -207,7 +207,13 @@ is that specified or fluke?
19) syslogd - use busybox or s6?
-20) The option currently called defaultPackages needs a better name as
+DONE 20) The option currently called defaultPackages needs a better name as
it doesn't have the same semantics as nixos
environment.defaultPackages. maybe call it packagesInProfile or
packagesOnPath. or defaultProfile.packages
+
+
+Tue Sep 27 22:00:36 BST 2022
+
+Found the cause of huge image size: rp-pppoe ships with scripts that
+reference build-time packages, so we have x86-64 glibc in there
diff --git a/default.nix b/default.nix
@@ -4,7 +4,7 @@
let
overlay = import ./overlay.nix;
nixpkgs = import <nixpkgs> ( device.system // {overlays = [overlay]; });
- inherit (nixpkgs.pkgs) callPackage liminix;
+ inherit (nixpkgs.pkgs) callPackage writeText liminix;
config = (import ./merge-modules.nix) [
./modules/base.nix
({ lib, ... } : { config = { inherit (device) kernel; }; })
@@ -24,6 +24,9 @@ in {
ln -s ${squashfs} squashfs
ln -s ${kernel.vmlinux} vmlinux
'';
+ # this exists so that you can run "nix-store -q --tree" on it and find
+ # out what's in the image, which is nice if it's unexpectedly huge
+ manifest = writeText "manifest.json" (builtins.toJSON config.filesystem.contents);
};
# this is just here as a convenience, so that we can get a
# cross-compiling nix-shell for any package we're customizing
