Generate backup manifests for base backups, and validate them.

A manifest is a JSON document which includes (1) the file name, size,
last modification time, and an optional checksum for each file backed
up, (2) timelines and LSNs for whatever WAL will need to be replayed
to make the backup consistent, and (3) a checksum for the manifest
itself. By default, we use CRC-32C when checksumming data files,
because we are trying to detect corruption and user error, not foil an
adversary. However, pg_basebackup and the server-side BASE_BACKUP
command now have options to select a different algorithm, so users
wanting a cryptographic hash function can select SHA-224, SHA-256,
SHA-384, or SHA-512. Users not wanting file checksums at all can
disable them, or disable generating of the backup manifest altogether.
Using a cryptographic hash function in place of CRC-32C consumes
significantly more CPU cycles, which may slow down backups in some
cases.

A new tool called pg_validatebackup can validate a backup against the
manifest. If no checksums are present, it can still check that the
right files exist and that they have the expected sizes. If checksums
are present, it can also verify that each file has the expected
checksum. Additionally, it calls pg_waldump to verify that the
expected WAL files are present and parseable. Only plain format
backups can be validated directly, but tar format backups can be
validated after extracting them.

Robert Haas, with help, ideas, review, and testing from David Steele,
Stephen Frost, Andrew Dunstan, Rushabh Lathia, Suraj Kharage, Tushar
Ahuja, Rajkumar Raghuwanshi, Mark Dilger, Davinder Singh, Jeevan
Chalke, Amit Kapila, Andres Freund, and Noah Misch.

Discussion: http://postgr.es/m/CA+TgmoZV8dw1H2bzZ9xkKwdrk8+XYa+DC9H=F7heO2zna5T6qg@mail.gmail.com

1 files changed, 58 insertions, 0 deletions

diff --git a/src/bin/pg_validatebackup/t/002_algorithm.pl b/src/bin/pg_validatebackup/t/002_algorithm.pl
new file mode 100644
index 00000000000..98871e12a5e
--- /dev/null
+++ b/src/bin/pg_validatebackup/t/002_algorithm.pl
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+# Verify that we can take and validate backups with various checksum types.
+
+use strict;
+use warnings;
+use Cwd;
+use Config;
+use File::Path qw(rmtree);
+use PostgresNode;
+use TestLib;
+use Test::More tests => 19;
+
+my $master = get_new_node('master');
+$master->init(allows_streaming => 1);
+$master->start;
+
+for my $algorithm (qw(bogus none crc32c sha224 sha256 sha384 sha512))
+{
+	my $backup_path = $master->backup_dir . '/' . $algorithm;
+	my @backup = ('pg_basebackup', '-D', $backup_path,
+				  '--manifest-checksums', $algorithm,
+				  '--no-sync');
+	my @validate = ('pg_validatebackup', '-e', $backup_path);
+
+	# A backup with a bogus algorithm should fail.
+	if ($algorithm eq 'bogus')
+	{
+		$master->command_fails(\@backup,
+							   "backup fails with algorithm \"$algorithm\"");
+		next;
+	}
+
+	# A backup with a valid algorithm should work.
+	$master->command_ok(\@backup, "backup ok with algorithm \"$algorithm\"");
+
+	# We expect each real checksum algorithm to be mentioned on every line of
+	# the backup manifest file except the first and last; for simplicity, we
+	# just check that it shows up lots of times. When the checksum algorithm
+	# is none, we just check that the manifest exists.
+	if ($algorithm eq 'none')
+	{
+		ok(-f "$backup_path/backup_manifest", "backup manifest exists");
+	}
+	else
+	{
+		my $manifest = slurp_file("$backup_path/backup_manifest");
+		my $count_of_algorithm_in_manifest =
+			(() = $manifest =~ /$algorithm/mig);
+		cmp_ok($count_of_algorithm_in_manifest, '>', 100,
+			   "$algorithm is mentioned many times in the manifest");
+	}
+
+	# Make sure that it validates OK.
+	$master->command_ok(\@validate,
+						"validate backup with algorithm \"$algorithm\"");
+
+	# Remove backup immediately to save disk space.
+	rmtree($backup_path);
+}