feat: create action

Hopefully it works?

create-report.sh

@@ -0,0 +1,70 @@
+#!/bin/sh
+
+set -eu
+
+echo 'Retrieving Flake information' >&2
+flake_info=$(nix flake show --json 2>/dev/null)
+packages=$(
+	jq --raw-output '.packages."x86_64-linux" | keys[]' <<-EOF
+		$flake_info
+	EOF
+)
+echo "Packages:" >&2
+echo "$packages" >&2
+configurations=$(
+	jq --raw-output '.nixosConfigurations | keys[]' <<-EOF
+		$flake_info
+	EOF
+)
+echo "NixOS Configurations:" >&2
+echo "$configurations" >&2
+
+package_size_table() {
+	table='| Installable | NAR Size | Closure Size |
+|-------------|---------:|-------------:|
+'
+	for package in $packages; do
+		echo "Building $package" >&2
+		path=$(nix build --print-out-paths ".#$package" 2>/dev/null)
+		echo "Calculating size of $package" >&2
+		row=$(nix path-info --size --closure-size --human-readable "$path" 2>/dev/null |
+			sed "s/^\(\S\+\)\(\s\+\)\(\S\+\)\(\s\+\)\(\S\+\)$/| \`$package\` | \3 | \5 |/")
+		table="$table$row
+"
+	done
+
+	printf '%s' "$table"
+}
+
+configuration_size_table() {
+	table='| NixOS Configuration | NAR Size | Closure Size |
+|-------------|---------:|-------------:|
+'
+	for config in $configurations; do
+		echo "Building $config" >&2
+		path=$(nix build --print-out-paths ".#nixosConfigurations.$config.config.system.build.toplevel" 2>/dev/null)
+		echo "Calculating size of $config" >&2
+		row=$(nix path-info --size --closure-size --human-readable "$path" 2>/dev/null |
+			sed "s/^\(\S\+\)\(\s\+\)\(\S\+\)\(\s\+\)\(\S\+\)$/| \`$config\` | \3 | \5 |/")
+		table="$table$row
+"
+	done
+
+	printf '%s' "$table"
+}
+
+markdown() {
+	cat <<-EOF
+		## Outputs' size
+
+		### NixOS Configurations sizes
+
+		$(configuration_size_table)
+
+		### Package sizes
+
+		$(package_size_table)
+	EOF
+}
+
+markdown > size-report.md