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a1ef920e27
This affects mostly code comments, some documentation, and tests. Official APIs already used "standby".
257 lines
6.9 KiB
Perl
257 lines
6.9 KiB
Perl
package RewindTest;
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# Test driver for pg_rewind. Each test consists of a cycle where a new cluster
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# is first created with initdb, and a streaming replication standby is set up
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# to follow the master. Then the master is shut down and the standby is
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# promoted, and finally pg_rewind is used to rewind the old master, using the
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# standby as the source.
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#
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# To run a test, the test script (in t/ subdirectory) calls the functions
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# in this module. These functions should be called in this sequence:
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#
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# 1. setup_cluster - creates a PostgreSQL cluster that runs as the master
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#
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# 2. start_master - starts the master server
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#
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# 3. create_standby - runs pg_basebackup to initialize a standby server, and
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# sets it up to follow the master.
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#
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# 4. promote_standby - runs "pg_ctl promote" to promote the standby server.
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# The old master keeps running.
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#
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# 5. run_pg_rewind - stops the old master (if it's still running) and runs
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# pg_rewind to synchronize it with the now-promoted standby server.
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#
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# 6. clean_rewind_test - stops both servers used in the test, if they're
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# still running.
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#
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# The test script can use the helper functions master_psql and standby_psql
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# to run psql against the master and standby servers, respectively. The
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# test script can also use the $connstr_master and $connstr_standby global
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# variables, which contain libpq connection strings for connecting to the
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# master and standby servers. The data directories are also available
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# in paths $test_master_datadir and $test_standby_datadir
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use strict;
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use warnings;
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use Config;
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use Exporter 'import';
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use File::Copy;
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use File::Path qw(rmtree);
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use IPC::Run qw(run);
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use PostgresNode;
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use TestLib;
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use Test::More;
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our @EXPORT = qw(
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$node_master
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$node_standby
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master_psql
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standby_psql
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check_query
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setup_cluster
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start_master
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create_standby
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promote_standby
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run_pg_rewind
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clean_rewind_test
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);
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# Our nodes.
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our $node_master;
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our $node_standby;
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sub master_psql
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{
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my $cmd = shift;
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system_or_bail 'psql', '-q', '--no-psqlrc', '-d',
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$node_master->connstr('postgres'), '-c', "$cmd";
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}
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sub standby_psql
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{
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my $cmd = shift;
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system_or_bail 'psql', '-q', '--no-psqlrc', '-d',
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$node_standby->connstr('postgres'), '-c', "$cmd";
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}
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# Run a query against the master, and check that the output matches what's
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# expected
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sub check_query
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{
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my ($query, $expected_stdout, $test_name) = @_;
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my ($stdout, $stderr);
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# we want just the output, no formatting
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my $result = run [
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'psql', '-q', '-A', '-t', '--no-psqlrc', '-d',
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$node_master->connstr('postgres'),
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'-c', $query ],
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'>', \$stdout, '2>', \$stderr;
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# We don't use ok() for the exit code and stderr, because we want this
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# check to be just a single test.
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if (!$result)
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{
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fail("$test_name: psql exit code");
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}
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elsif ($stderr ne '')
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{
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diag $stderr;
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fail("$test_name: psql no stderr");
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}
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else
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{
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$stdout =~ s/\r//g if $Config{osname} eq 'msys';
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is($stdout, $expected_stdout, "$test_name: query result matches");
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}
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}
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sub setup_cluster
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{
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# Initialize master, data checksums are mandatory
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$node_master = get_new_node('master');
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$node_master->init(allows_streaming => 1);
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}
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sub start_master
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{
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$node_master->start;
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#### Now run the test-specific parts to initialize the master before setting
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# up standby
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}
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sub create_standby
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{
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$node_standby = get_new_node('standby');
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$node_master->backup('my_backup');
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$node_standby->init_from_backup($node_master, 'my_backup');
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my $connstr_master = $node_master->connstr();
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$node_standby->append_conf(
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"recovery.conf", qq(
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primary_conninfo='$connstr_master application_name=rewind_standby'
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standby_mode=on
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recovery_target_timeline='latest'
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));
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# Start standby
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$node_standby->start;
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# The standby may have WAL to apply before it matches the primary. That
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# is fine, because no test examines the standby before promotion.
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}
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sub promote_standby
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{
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#### Now run the test-specific parts to run after standby has been started
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# up standby
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# Wait for the standby to receive and write all WAL.
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my $wal_received_query =
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"SELECT pg_current_wal_lsn() = write_lsn FROM pg_stat_replication WHERE application_name = 'rewind_standby';";
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$node_master->poll_query_until('postgres', $wal_received_query)
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or die "Timed out while waiting for standby to receive and write WAL";
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# Now promote standby and insert some new data on master, this will put
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# the master out-of-sync with the standby.
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$node_standby->promote;
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# Force a checkpoint after the promotion. pg_rewind looks at the control
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# file to determine what timeline the server is on, and that isn't updated
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# immediately at promotion, but only at the next checkpoint. When running
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# pg_rewind in remote mode, it's possible that we complete the test steps
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# after promotion so quickly that when pg_rewind runs, the standby has not
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# performed a checkpoint after promotion yet.
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standby_psql("checkpoint");
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}
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sub run_pg_rewind
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{
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my $test_mode = shift;
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my $master_pgdata = $node_master->data_dir;
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my $standby_pgdata = $node_standby->data_dir;
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my $standby_connstr = $node_standby->connstr('postgres');
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my $tmp_folder = TestLib::tempdir;
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# Stop the master and be ready to perform the rewind
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$node_master->stop;
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# At this point, the rewind processing is ready to run.
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# We now have a very simple scenario with a few diverged WAL record.
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# The real testing begins really now with a bifurcation of the possible
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# scenarios that pg_rewind supports.
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# Keep a temporary postgresql.conf for master node or it would be
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# overwritten during the rewind.
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copy(
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"$master_pgdata/postgresql.conf",
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"$tmp_folder/master-postgresql.conf.tmp");
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# Now run pg_rewind
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if ($test_mode eq "local")
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{
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# Do rewind using a local pgdata as source
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# Stop the master and be ready to perform the rewind
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$node_standby->stop;
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command_ok(
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[ 'pg_rewind',
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"--debug",
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"--source-pgdata=$standby_pgdata",
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"--target-pgdata=$master_pgdata" ],
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'pg_rewind local');
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}
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elsif ($test_mode eq "remote")
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{
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# Do rewind using a remote connection as source
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command_ok(
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[ 'pg_rewind', "--debug",
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"--source-server", $standby_connstr,
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"--target-pgdata=$master_pgdata" ],
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'pg_rewind remote');
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}
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else
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{
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# Cannot come here normally
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die("Incorrect test mode specified");
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}
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# Now move back postgresql.conf with old settings
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move(
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"$tmp_folder/master-postgresql.conf.tmp",
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"$master_pgdata/postgresql.conf");
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# Plug-in rewound node to the now-promoted standby node
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my $port_standby = $node_standby->port;
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$node_master->append_conf(
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'recovery.conf', qq(
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primary_conninfo='port=$port_standby'
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standby_mode=on
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recovery_target_timeline='latest'
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));
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# Restart the master to check that rewind went correctly
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$node_master->start;
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#### Now run the test-specific parts to check the result
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}
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# Clean up after the test. Stop both servers, if they're still running.
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sub clean_rewind_test
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{
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$node_master->teardown_node if defined $node_master;
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$node_standby->teardown_node if defined $node_standby;
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}
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1;
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