nix-push: create a manifest-less binary cache

Manifests are a huge pain, since users need to run nix-pull directly
or indirectly to obtain them.  They tend to be large and lag behind
the available binaries; also, the downloaded manifests in
/nix/var/nix/manifest need to be in sync with the Nixpkgs sources.  So
we want to get rid of them.

The idea of manifest-free operation works as follows.  Nix is
configured with a set of URIs of binary caches, e.g.

  http://nixos.org/binary-cache

Whenever Nix needs a store path X, it checks each binary cache for the
existence of a file <CACHE-URI>/<SHA-256 hash of X>.narinfo, e.g.

  http://nixos.org/binary-cache/bi1gh9...ia17.narinfo

The .narinfo file contains the necessary information about the store
path that was formerly kept in the manifest, i.e., (relative) URI of
the compressed NAR, references, size, hash, etc.  For example:

  StorePath: /nix/store/xqp4l88cr9bxv01jinkz861mnc9p7qfi-neon-0.29.6
  URL: 1bjxbg52l32wj8ww47sw9f4qz0r8n5vs71l93lcbgk2506v3cpfd.nar.bz2
  CompressedHash: sha256:1bjxbg52l32wj8ww47sw9f4qz0r8n5vs71l93lcbgk2506v3cpfd
  CompressedSize: 202542
  NarHash: sha256:1af26536781e6134ab84201b33408759fc59b36cc5530f57c0663f67b588e15f
  NarSize: 700440
  References: 043zrsanirjh8nbc5vqpjn93hhrf107f-bash-4.2-p24 cj7a81wsm1ijwwpkks3725661h3263p5-glibc-2.13 ...
  Deriver: 4idz1bgi58h3pazxr3akrw4fsr6zrf3r-neon-0.29.6.drv
  System: x86_64-linux

Nix then knows that it needs to download

  http://nixos.org/binary-cache/1bjxbg52l32wj8ww47sw9f4qz0r8n5vs71l93lcbgk2506v3cpfd.nar.bz2

to substitute the store path.

Note that the store directory is omitted from the References and
Deriver fields to save space, and that the URL can be relative to the
binary cache prefix.

This patch just makes nix-push create binary caches in this format.
The next step is to make a substituter that supports them.

1 files changed, 93 insertions, 159 deletions

diff --git a/scripts/nix-push.in b/scripts/nix-push.in
index a1c02190b..db94b51fd 100755
--- a/scripts/nix-push.in
+++ b/scripts/nix-push.in
@@ -1,10 +1,13 @@
 #! @perl@ -w @perlFlags@
 
 use strict;
+use File::Basename;
 use File::Temp qw(tempdir);
+use File::Path qw(mkpath);
 use File::stat;
+use File::Copy;
 use Nix::Config;
-use Nix::Manifest;
+use Nix::Store;
 
 my $hashAlgo = "sha256";
 
@@ -12,7 +15,6 @@ my $tmpDir = tempdir("nix-push.XXXXXX", CLEANUP => 1, TMPDIR => 1)
     or die "cannot create a temporary directory";
 
 my $nixExpr = "$tmpDir/create-nars.nix";
-my $manifest = "$tmpDir/MANIFEST";
 
 my $curl = "$Nix::Config::curl --fail --silent";
 my $extraCurlFlags = ${ENV{'CURL_FLAGS'}};
@@ -22,18 +24,14 @@ $curl = "$curl $extraCurlFlags" if defined $extraCurlFlags;
 # Parse the command line.
 my $localCopy;
 my $localArchivesDir;
-my $localManifestFile;
-
-my $targetArchivesUrl;
 
 my $archivesPutURL;
 my $archivesGetURL;
-my $manifestPutURL;
 
 sub showSyntax {
     print STDERR <<EOF
-Usage: nix-push --copy ARCHIVES_DIR MANIFEST_FILE PATHS...
-   or: nix-push ARCHIVES_PUT_URL ARCHIVES_GET_URL MANIFEST_PUT_URL PATHS...
+Usage: nix-push --copy ARCHIVES_DIR PATHS...
+   or: nix-push ARCHIVES_PUT_URL ARCHIVES_GET_URL PATHS...
 
 `nix-push' copies or uploads the closure of PATHS to the given
 destination.
@@ -45,25 +43,16 @@ EOF
 showSyntax if scalar @ARGV < 1;
 
 if ($ARGV[0] eq "--copy") {
-    showSyntax if scalar @ARGV < 3;
+    showSyntax if scalar @ARGV < 2;
     $localCopy = 1;
     shift @ARGV;
     $localArchivesDir = shift @ARGV;
-    $localManifestFile = shift @ARGV;
-    if ($ARGV[0] eq "--target") {
-       shift @ARGV;
-       $targetArchivesUrl = shift @ARGV;
-    }
-    else {
-       $targetArchivesUrl = "file://$localArchivesDir";
-    }
-}
-else {
-    showSyntax if scalar @ARGV < 3;
+    mkpath($localArchivesDir, 0, 0755);
+} else {
+    showSyntax if scalar @ARGV < 2;
     $localCopy = 0;
     $archivesPutURL = shift @ARGV;
     $archivesGetURL = shift @ARGV;
-    $manifestPutURL = shift @ARGV;
 }
 
 
@@ -92,8 +81,8 @@ foreach my $path (@ARGV) {
 my @storePaths = keys %storePaths;
 
 
-# For each path, create a Nix expression that turns the path into
-# a Nix archive.
+# Create a list of Nix derivations that turn each path into a Nix
+# archive.
 open NIX, ">$nixExpr";
 print NIX "[";
 
@@ -112,172 +101,117 @@ print NIX "]";
 close NIX;
 
 
-# Instantiate store derivations from the Nix expression.
-my @storeExprs;
-print STDERR "instantiating store derivations...\n";
-my $pid = open(READ, "$Nix::Config::binDir/nix-instantiate $nixExpr|")
-    or die "cannot run nix-instantiate";
+# Build the Nix expression.
+print STDERR "building compressed archives...\n";
+my @narPaths;
+my $pid = open(READ, "$Nix::Config::binDir/nix-build $nixExpr|")
+    or die "cannot run nix-build";
 while (<READ>) {
     chomp;
     die unless /^\//;
-    push @storeExprs, $_;
-}
-close READ or die "nix-instantiate failed: $?";
-
-
-# Build the derivations.
-print STDERR "creating archives...\n";
-
-my @narPaths;
-
-my @tmp = @storeExprs;
-while (scalar @tmp > 0) {
-    my $n = scalar @tmp;
-    if ($n > 256) { $n = 256 };
-    my @tmp2 = @tmp[0..$n - 1];
-    @tmp = @tmp[$n..scalar @tmp - 1];
-
-    my $pid = open(READ, "$Nix::Config::binDir/nix-store --realise @tmp2|")
-        or die "cannot run nix-store";
-    while (<READ>) {
-        chomp;
-        die unless (/^\//);
-        push @narPaths, "$_";
-    }
-    close READ or die "nix-store failed: $?";
+    push @narPaths, $_;
 }
+close READ or die "nix-build failed: $?";
 
 
-# Create the manifest.
-print STDERR "creating manifest...\n";
+# Upload the archives and the corresponding info files.
+print STDERR "uploading/copying archives...\n";
 
-my %narFiles;
-my %patches;
+my $totalNarSize = 0;
+my $totalNarBz2Size = 0;
 
-my @narArchives;
 for (my $n = 0; $n < scalar @storePaths; $n++) {
     my $storePath = $storePaths[$n];
     my $narDir = $narPaths[$n];
-    
-    $storePath =~ /\/([^\/]*)$/;
-    my $basename = $1;
-    defined $basename or die;
-
-    open HASH, "$narDir/narbz2-hash" or die "cannot open narbz2-hash";
-    my $narbz2Hash = <HASH>;
-    chomp $narbz2Hash;
-    $narbz2Hash =~ /^[0-9a-z]+$/ or die "invalid hash";
-    close HASH;
-
-    my $narName = "$narbz2Hash.nar.bz2";
-
-    my $narFile = "$narDir/$narName";
-    (-f $narFile) or die "narfile for $storePath not found";
-    push @narArchives, $narFile;
-
-    my $narbz2Size = stat($narFile)->size;
-
-    my $references = `$Nix::Config::binDir/nix-store --query --references '$storePath'`;
-    die "cannot query references for `$storePath'" if $? != 0;
-    $references = join(" ", split(" ", $references));
-
-    my $deriver = `$Nix::Config::binDir/nix-store --query --deriver '$storePath'`;
-    die "cannot query deriver for `$storePath'" if $? != 0;
-    chomp $deriver;
-    $deriver = "" if $deriver eq "unknown-deriver";
+    my $baseName = basename $storePath;
 
-    my $narHash = `$Nix::Config::binDir/nix-store --query --hash '$storePath'`;
-    die "cannot query hash for `$storePath'" if $? != 0;
-    chomp $narHash;
+    # Get info about the store path.
+    my ($deriver, $narHash, $time, $narSize, $refs) = queryPathInfo($storePath);
 
     # In some exceptional cases (such as VM tests that use the Nix
     # store of the host), the database doesn't contain the hash.  So
     # compute it.
     if ($narHash =~ /^sha256:0*$/) {
-        $narHash = `$Nix::Config::binDir/nix-hash --type sha256 --base32 '$storePath'`;
-        die "cannot hash `$storePath'" if $? != 0;
+        my $nar = "$tmpDir/nar";
+        system("$Nix::Config::binDir/nix-store --dump $storePath > $nar") == 0
+            or die "cannot dump $storePath\n";
+        $narHash = `$Nix::Config::binDir/nix-hash --type sha256 --flat $nar`;
+        die "cannot hash `$nar'" if $? != 0;
         chomp $narHash;
         $narHash = "sha256:$narHash";
+        $narSize = stat("$nar")->size;
+        unlink $nar or die;
     }
 
-    my $narSize = `$Nix::Config::binDir/nix-store --query --size '$storePath'`;
-    die "cannot query size for `$storePath'" if $? != 0;
-    chomp $narSize;
-
-    my $url;
-    if ($localCopy) {
-        $url = "$targetArchivesUrl/$narName";
-    } else {
-        $url = "$archivesGetURL/$narName";
-    }
-    $narFiles{$storePath} = [
-        { url => $url
-        , hash => "$hashAlgo:$narbz2Hash"
-        , size => $narbz2Size
-        , narHash => "$narHash"
-        , narSize => $narSize
-        , references => $references
-        , deriver => $deriver
-        }
-    ];
-}
-
-writeManifest $manifest, \%narFiles, \%patches;
-
-
-sub copyFile {
-    my $src = shift;
-    my $dst = shift;
-    my $tmp = "$dst.tmp.$$";
-    system("@coreutils@/cp", $src, $tmp) == 0 or die "cannot copy file";
-    rename($tmp, $dst) or die "cannot rename file: $!";
-}
-
+    $totalNarSize += $narSize;
+    
+    # Get info about the compressed NAR.
+    open HASH, "$narDir/narbz2-hash" or die "cannot open narbz2-hash";
+    my $narBz2Hash = <HASH>;
+    chomp $narBz2Hash;
+    $narBz2Hash =~ /^[0-9a-z]+$/ or die "invalid hash";
+    close HASH;
 
-# Upload/copy the archives.
-print STDERR "uploading/copying archives...\n";
+    my $narName = "$narBz2Hash.nar.bz2";
 
-sub archiveExists {
-    my $name = shift;
-    print STDERR "  HEAD on $archivesGetURL/$name\n";
-    return system("$curl --head $archivesGetURL/$name > /dev/null") == 0;
-}
+    my $narFile = "$narDir/$narName";
+    (-f $narFile) or die "NAR file for $storePath not found";
 
-foreach my $narArchive (@narArchives) {
+    my $narBz2Size = stat($narFile)->size;    
+    $totalNarBz2Size += $narBz2Size;
 
-    $narArchive =~ /\/([^\/]*)$/;
-    my $basename = $1;
+    printf STDERR "%s [%.2f MiB, %.1f%%]\n", $storePath,
+        $narBz2Size / (1024 * 1024), $narBz2Size / $narSize * 100;
 
+    # Upload the compressed NAR.
     if ($localCopy) {
-        # Since nix-push creates $dst atomically, if it exists we
-        # don't have to copy again.
-        my $dst = "$localArchivesDir/$basename";
-        if (! -f "$localArchivesDir/$basename") {
-            print STDERR "  $narArchive\n";
-            copyFile $narArchive, $dst;
+        my $dst = "$localArchivesDir/$narName";
+        if (! -f $dst) {
+            my $tmp = "$localArchivesDir/.tmp.$$.$narName";
+            copy($narFile, $tmp) or die "cannot copy $narFile to $tmp: $!\n";
+            rename($tmp, $dst) or die "cannot rename $tmp to $dst: $!\n";
         }
+    } else {
+        die "unimplemented";
+        #if (!archiveExists("$basename")) {
+        #    system("$curl --show-error --upload-file " .
+        #           "'$narArchive' '$archivesPutURL/$basename' > /dev/null") == 0 or
+        #           die "curl failed on $narArchive: $?";
+        #}
     }
-    else {
-        if (!archiveExists("$basename")) {
-            print STDERR "  $narArchive\n";
-            system("$curl --show-error --upload-file " .
-                   "'$narArchive' '$archivesPutURL/$basename' > /dev/null") == 0 or
-                   die "curl failed on $narArchive: $?";
+
+    # Upload the info file.
+    my $info;
+    $info .= "StorePath: $storePath\n";
+    $info .= "URL: $narName\n";
+    $info .= "CompressedHash: sha256:$narBz2Hash\n";
+    $info .= "CompressedSize: $narBz2Size\n";
+    $info .= "NarHash: $narHash\n";
+    $info .= "NarSize: $narSize\n";
+    $info .= "References: " . join(" ", map { basename $_ } @{$refs}) . "\n";
+    if (defined $deriver) {
+        $info .= "Deriver: " . basename $deriver, "\n";
+        if (isValidPath($deriver)) {
+            my $drv = derivationFromPath($deriver);
+            $info .= "System: $drv->{platform}\n";
         }
     }
-}
-
 
-# Upload the manifest.
-print STDERR "uploading manifest...\n";
-if ($localCopy) {
-    copyFile $manifest, $localManifestFile;
-    copyFile "$manifest.bz2", "$localManifestFile.bz2";
-} else {
-    system("$curl --show-error --upload-file " .
-           "'$manifest' '$manifestPutURL' > /dev/null") == 0 or
-           die "curl failed on $manifest: $?";
-    system("$curl --show-error --upload-file " .
-           "'$manifest'.bz2 '$manifestPutURL'.bz2 > /dev/null") == 0 or
-           die "curl failed on $manifest: $?";
+    my $infoName = hashString("sha256", 1, $storePath);
+    
+    if ($localCopy) {
+        my $dst = "$localArchivesDir/$infoName.narinfo";
+        if (! -f $dst) {
+            my $tmp = "$localArchivesDir/.tmp.$$.$infoName";
+            open INFO, ">$tmp" or die;
+            print INFO "$info" or die;
+            close INFO or die;
+            rename($tmp, $dst) or die "cannot rename $tmp to $dst: $!\n";
+        }
+    } else {
+        die "unimplemented";
+    }
 }
+
+printf STDERR "total compressed size %.2f MiB, %.1f%%\n",
+    $totalNarBz2Size / (1024 * 1024), $totalNarBz2Size / $totalNarSize * 100;