MDEV-39061 mariadb-backup compatible wrappers for BACKUP SERVER - #5140
Thirunarayanan wants to merge 1 commit into
Conversation
|
|
![gemini-code-assist[bot]](https://avatars.githubusercontent.com/in/956858?s=60&v=4){kind=small}
There was a problem hiding this comment.
Code Review
This pull request introduces server-side backup support (BACKUP SERVER) for MariaDB, implementing backup and log archiving mechanisms for both the InnoDB and Aria storage engines. It also includes a compatibility wrapper script (mariabackup.sh) to map legacy mariabackup CLI commands to the new server-side SQL interface. The code review identified several critical issues, including a potential server crash in backup_innodb.cc due to invalid format arguments in error reporting, null pointer dereferences and assertion failures in both engines when backup steps are executed out of order or fail to initialize, and security vulnerabilities (command injection) and argument parsing bugs in the shell wrapper script.
| if [[ -n "$FINAL_INCLUDE" ]]; then | ||
| echo "Setting backup_include='$FINAL_INCLUDE'" >&2 | ||
| mariadb $MARIADB_OPTS -e "SET GLOBAL backup_include='$FINAL_INCLUDE'" | ||
| fi | ||
|
|
||
| if [[ -n "$FINAL_EXCLUDE" ]]; then | ||
| echo "Setting backup_exclude='$FINAL_EXCLUDE'" >&2 | ||
| mariadb $MARIADB_OPTS -e "SET GLOBAL backup_exclude='$FINAL_EXCLUDE'" | ||
| fi | ||
|
|
||
| # Execute BACKUP SERVER | ||
| SQL="BACKUP SERVER TO '$TARGET_DIR'" | ||
| echo "Executing: $SQL" >&2 | ||
| mariadb $MARIADB_OPTS -e "$SQL" |
There was a problem hiding this comment.
The parameters FINAL_INCLUDE, FINAL_EXCLUDE, and TARGET_DIR are interpolated into shell commands. To effectively prevent command injection, we should validate these inputs using a strict whitelist of allowed characters (such as alphanumeric characters and a limited set of safe symbols like '-', '_', '.') instead of relying on a blacklist or simple escaping.
| if [[ -n "$FINAL_INCLUDE" ]]; then | |
| echo "Setting backup_include='$FINAL_INCLUDE'" >&2 | |
| mariadb $MARIADB_OPTS -e "SET GLOBAL backup_include='$FINAL_INCLUDE'" | |
| fi | |
| if [[ -n "$FINAL_EXCLUDE" ]]; then | |
| echo "Setting backup_exclude='$FINAL_EXCLUDE'" >&2 | |
| mariadb $MARIADB_OPTS -e "SET GLOBAL backup_exclude='$FINAL_EXCLUDE'" | |
| fi | |
| # Execute BACKUP SERVER | |
| SQL="BACKUP SERVER TO '$TARGET_DIR'" | |
| echo "Executing: $SQL" >&2 | |
| mariadb $MARIADB_OPTS -e "$SQL" | |
| if [[ -n "$FINAL_INCLUDE" && ! "$FINAL_INCLUDE" =~ ^[a-zA-Z0-9_.-]+$ ]]; then | |
| echo "Error: Invalid characters in FINAL_INCLUDE" >&2 | |
| exit 1 | |
| fi |
References
- When validating input that will be interpolated into shell commands, use a strict whitelist of allowed characters (e.g., alphanumeric and a limited set of safe symbols like '-', '_', '.') instead of a blacklist to effectively prevent command injection.
| TABLES_PATTERN="" | ||
| TABLES_EXCLUDE_PATTERN="" | ||
| TABLES_FILE="" | ||
| MARIADB_OPTS="" |
There was a problem hiding this comment.
Handling MARIADB_OPTS as a flat string will break if any option contains spaces or special characters (e.g., --password="my secret pass"). We should use a bash array instead.
| MARIADB_OPTS="" | |
| MARIADB_OPTS=() |
| --user=*|--password=*|--host=*|--port=*|--socket=*) | ||
| # Connection options (long form) - pass through to mariadb client | ||
| MARIADB_OPTS="$MARIADB_OPTS $1" | ||
| shift | ||
| ;; | ||
| -u|-p|-h|-P|-S) | ||
| # Short form. If the next argv looks like a value (not another | ||
| # flag), consume it as well — supports both `-u USER` and bare | ||
| # `-p` (which mariadb client treats as a password prompt). | ||
| if [[ -n "${2-}" && "$2" != -* ]]; then | ||
| MARIADB_OPTS="$MARIADB_OPTS $1 $2" | ||
| shift 2 | ||
| else | ||
| MARIADB_OPTS="$MARIADB_OPTS $1" | ||
| shift | ||
| fi | ||
| ;; | ||
| -u*|-p*|-h*|-P*|-S*) | ||
| # Bundled short form: -uUSER, -pSECRET, -hHOST, ... | ||
| MARIADB_OPTS="$MARIADB_OPTS $1" | ||
| shift | ||
| ;; | ||
| --defaults-file=*|--defaults-extra-file=*) | ||
| # Config file options - pass through to mariadb client | ||
| MARIADB_OPTS="$MARIADB_OPTS $1" | ||
| shift | ||
| ;; |
There was a problem hiding this comment.
We should append connection options to the MARIADB_OPTS array instead of concatenating them into a flat string to correctly handle arguments with spaces or special characters.
--user=*|--password=*|--host=*|--port=*|--socket=*)
# Connection options (long form) - pass through to mariadb client
MARIADB_OPTS+=("$1")
shift
;;
-u|-p|-h|-P|-S)
# Short form. If the next argv looks like a value (not another
# flag), consume it as well — supports both `-u USER` and bare
# `-p` (which mariadb client treats as a password prompt).
if [[ -n "${2-}" && "$2" != -* ]]; then
MARIADB_OPTS+=("$1" "$2")
shift 2
else
MARIADB_OPTS+=("$1")
shift
fi
;;
-u*|-p*|-h*|-P*|-S*)
# Bundled short form: -uUSER, -pSECRET, -hHOST, ...
MARIADB_OPTS+=("$1")
shift
;;
--defaults-file=*|--defaults-extra-file=*)
# Config file options - pass through to mariadb client
MARIADB_OPTS+=("$1")
shift
;;| } | ||
|
|
||
| #ifndef _WIN32 | ||
| int dir= open(target.str, O_DIRECTORY); |
There was a problem hiding this comment.
To be fully standard and portable, open with O_DIRECTORY should explicitly include the access mode O_RDONLY.
| int dir= open(target.str, O_DIRECTORY); | |
| int dir= open(target.str, O_RDONLY | O_DIRECTORY); |
| explicit Aria_backup(THD *thd, Target target) noexcept | ||
| : target(target) | ||
| #ifndef _WIN32 | ||
| , datadir_fd(open(maria_data_root, O_DIRECTORY)) |
There was a problem hiding this comment.
To be fully standard and portable, open with O_DIRECTORY should explicitly include the access mode O_RDONLY.
, datadir_fd(open(maria_data_root, O_RDONLY | O_DIRECTORY))
|
Hey @Thirunarayanan , have you thought of how this is going to end up in packaging? It is replacing the original mariadb-backup? It needs some INSTALL/INSTALL_SCRIPT cmake directives around this to give it a install location and a cmake component. debian installation/packaging would need the relevant debian/{package}.install to include te script. |
8d0dc79 to
051f681
Compare
dr-m
left a comment
dr-m
left a comment
There was a problem hiding this comment.
Please rebase this on the current branch.
| @@ -0,0 +1,82 @@ | |||
| --source include/have_mariabackup_wrapper.inc | |||
There was a problem hiding this comment.
Can this be implemented in a way that is compatible with the .combinations logic?
I would like most of --suite=mariabackup to be run both with the genuine mariadb-backup and with the BACKUP SERVER based wrapper scripts. Currently, this is the only test that exercises the wrappers, and it fails to test the original executables to demonstrate compatibility between them and the wrappers.
| --echo # | ||
| --echo # --stream=mbstream emits a valid tar archive to stdout | ||
| --echo # | ||
| --let $targetdir=$MYSQLTEST_VARDIR/tmp/bk_stream | ||
| --let $streamfile=$MYSQLTEST_VARDIR/tmp/bk_stream.tar | ||
| --exec $XTRABACKUP $defaults --backup --target-dir=$targetdir --stream=mbstream > $streamfile 2>$logfile | ||
| --exec tar -tf $streamfile > /dev/null | ||
| --let SEARCH_PATTERN=Creating tar stream | ||
| --source include/search_pattern_in_file.inc | ||
| --rmdir $targetdir | ||
| --remove_file $streamfile |
There was a problem hiding this comment.
I’m not sure if this should be in the current scope. We don’t have any MDEV-38362 streaming backup yet. What should be more in the scope is demonstrating that the mbstream wrapper script is syntactically compatible with its namesake utility.
| @@ -0,0 +1,19 @@ | |||
| #!/bin/bash | |||
There was a problem hiding this comment.
Can we write this for the POSIX shell? Bourne Again Shell (bash) is not available in all environments, for good reasons: reduced resource usage as well as attack surface; remember https://en.wikipedia.org/wiki/Shellshock_(software_bug)
| -p|--parallel) | ||
| SKIP_NEXT=1 | ||
| ;; | ||
| -p*) | ||
| ;; | ||
| --parallel=*) | ||
| ;; |
There was a problem hiding this comment.
These are necessary but not sufficient rules. mbstream -xp4 would be a valid invocation of the original utility (equivalent to -x -p4), but not of GNU tar.
I did test that mbstream indeed treats anything after -p as a single argument. For example, -p4t and -p4x would report the following, respectively:
Warning: option 'parallel': signed value 4398046511104 adjusted to 2147483647
Unknown suffix 'x' used for variable 'parallel' (value '4x'). Legal suffix characters are: K, M, G, T, P, E
mbstream: Error while setting value '4x' to 'parallel'
Please add a test file that covers both the real mbstream and this wrapper. Both with some invalid and valid invocation. For example, mbstream -t is not allowed, while tar -t is.
051f681 to
6e37d3a
Compare
| --parallel=*|--throttle=*|--no-lock|--safe-slave-backup) | ||
| # Handled server-side by BACKUP SERVER. | ||
| shift ;; |
There was a problem hiding this comment.
The --parallel option will have to be passed through to non-streaming backup.
8077134 in #4817 implements multi-threaded backup to a mounted file system. By default, only 1 thread will be used.
For streaming backup (which is not implemented yet except as stubs), I think that we must limit the backup to a single thread, because unlike the old xbstream or mbstream format, BACKUP SERVER will generate one stream per thread. So, the only way to end up with one backup stream is to use a single thread.
6e37d3a to
3427e04
Compare
9ce9751 to
1fcb44e
Compare
dr-m
left a comment
dr-m
left a comment
There was a problem hiding this comment.
Now that #4817 includes support for streaming (see the test backup.backup_stream, which passes on Linux, FreeBSD, Microsoft Windows and Apple macOS), it would be good to add support for streaming backup.
When I tested the merge of this to the current #4817, I got one test failure:
CURRENT_TEST: mariabackup.wrapper_basic
NOT FOUND /Executing: BACKUP SERVER TO/ in wrapper.log
mysqltest: In included file "./include/search_pattern_in_file.inc":
included from /mariadb/main/mysql-test/suite/mariabackup/wrapper_basic.test at line 19:
At line 65: command "perl" failed with error: 255 my_errno: 0 errno: 0
I couldn’t figure this out. At the very end of scripts/mariabackup/mariabackup.sh we are writing a configuration file, and that is what happens. I even added set -eux or set -eu to the start of the script, and it did not complain about any uninitialized variables. I think that set -eu would be a good safety measure.
Note: I am going to squash #4817 shortly.
| if ($errno) | ||
| { | ||
| --skip mariabackup.sh wrapper unavailable (script or sh missing) | ||
| } |
There was a problem hiding this comment.
/bin/sh can’t possibly be missing on a POSIX system; it is what system(3), popen(3) and friends will invoke.
| # | ||
| # $XTRABACKUP — now points at mariabackup.sh | ||
|
|
||
| --source include/linux.inc |
There was a problem hiding this comment.
I think we only want to exclude non-POSIX environments, more specifically, Microsoft Windows. For that, I would suggest the following:
--source include/not_windows.incor if it cannot be used for some reason:
if ($MARIADB_UPGRADE_EXE) {
--skip Need POSIX
}
87036f8 to
4769a43
Compare
86c9bc3 to
b99a766
Compare
b99a766 to
cee7cfc
Compare
dr-m
left a comment
dr-m
left a comment
There was a problem hiding this comment.
Here are some initial comments. I did not check the mariabackup.sh in detail, but I think that this is a very good start.
| ######################################################################## | ||
| # mariadb-backup-server: BACKUP SERVER-compatible shell wrapper | ||
| ######################################################################## | ||
| # A drop-in mariadb-backup-compatible POSIX-sh wrapper that translates the | ||
| # CLI into server-side BACKUP SERVER SQL. Experimental; OFF by default | ||
| # Installed as a mariadb-backup-server; clients opt in via symlink/alias | ||
| # (see scripts/mariabackup/README.md). | ||
| OPTION(WITH_MARIABACKUP_WRAPPER | ||
| "Install the BACKUP SERVER shell wrapper (mariadb-backup-server)" OFF) |
There was a problem hiding this comment.
scripts/mariabackup/CMakeLists.txt would be a less surprising place for this. Would it work? If not, then I would suggest moving scripts/mariabackup to extra/mariabackup/scripts.
| -v|--verbose) ;; | ||
|
|
||
| --) shift; break ;; | ||
| -*) ;; |
There was a problem hiding this comment.
Shouldn’t we throw an error for any unknown option? For example, -b 1 works in GNU tar, but certainly not in mbstream.
| # The wrapper streams several tar archives | ||
| # back to back (one per stream, plus backup-prepare.cnf), | ||
| # so --ignore-zeros is required to extract them all rather | ||
| # than stopping at the first archive's end-of-file marker. | ||
| x) exec tar --ignore-zeros -x -f - -C "$dir" ;; |
There was a problem hiding this comment.
We are not currently adding any NUL block at the end of each stream, so the GNU tar specific option --ignore-zeros should not be needed. If you install libarchive-tools, you should get a bsdtar that is compatible with the tar.exe that is shipped with Microsoft Windows. That executable does not recognize an --ignore-zeros option.
I think that we should try to make this script compatible also with BSD tar.
| if [ -n "$_enc" ]; then | ||
| echo "plugin-load-add=$_enc" |
There was a problem hiding this comment.
Two tests would fail unless we extend this with a patch that you shared with me:
_plugin_dir=$(ask "SELECT @@global.plugin_dir")
[ -n "$_plugin_dir" ] && echo "plugin-dir=$_plugin_dir"| esac | ||
| # Where "rr record" stores traces, so we can point at it on a crash. | ||
| rr_trace_dir=${_RR_TRACE_DIR:-${XDG_DATA_HOME:-$HOME/.local/share}/rr} | ||
|
|
There was a problem hiding this comment.
Do we really want it this complicated, or could we do the following:
: ${MARIADBD=mariadbd}Then, to have the invoked server run under rr record, one would execute (for example)
_RR_TRACE_DIR=/dev/shm/rr MARIADBD='rr record -h` mariabackup.shAlso, should we rather call this script mariadb-backup-server? The name mariabackup was deprecated and replaced with mariadb-backup some years ago.
fee9458 to
ac4c513
Compare
| # Write more than 2MiB of FILE_MODIFY mini-transactions to exercise the parser. | ||
| my $extra = pack("CCxa*", 0xb9, 127, "a/b.ibd"); | ||
| $extra .= pack("CN", 0, mycrc32($extra, 0, $polynomial)); |
There was a problem hiding this comment.
As you can see here, the mariabackup.huge_lsn,strict_full_crc32 combinations are writing some normally impossible log records. The SERVER variant (having the wrapper script invoke BACKUP SERVER) would hang on many targets because log_t::set_archive() is waiting for a checkpoint, but apparently the buf_flush_page_cleaner() thread has nothing to do because the buf_pool.flush_list is apparently empty; the log buffer is filled solely with FILE_ records and no page-level records, like it normally would be the case.
I am unable to reproduce this hang locally, but it does occur on many platforms. I will apply the following patch to #4817, which I think should fix this hang:
diff --git a/storage/innobase/log/log0log.cc b/storage/innobase/log/log0log.cc
index aa2063719d8..c313b3d9b51 100644
--- a/storage/innobase/log/log0log.cc
+++ b/storage/innobase/log/log0log.cc
@@ -810,7 +810,7 @@ bool log_t::set_archive(my_bool archive, THD *thd, bool backup) noexcept
if (wait_lsn)
{
mysql_mutex_lock(&buf_pool.flush_list_mutex);
- buf_flush_wait(wait_lsn, false);
+ buf_flush_wait(wait_lsn, !UT_LIST_GET_LEN(buf_pool.flush_list));
mysql_mutex_unlock(&buf_pool.flush_list_mutex);
}
latch.wr_unlock();There was a problem hiding this comment.
This was applied to 9e27d73, which you should rebase on.
There was a problem hiding this comment.
The test is still hanging, with log_t::set_archive() apparently stuck in an infinite loop. I think that you must find an environment where it can be reproduced and check the content of log_sys and buf_pool.flush_list during the hang.
9e27d73 to
5235e7a
Compare
dr-m
left a comment
dr-m
left a comment
There was a problem hiding this comment.
I think that this is good enough for a first step. I only have some minor commments. More may be found by testing.
| # To run the prepare bootstrap under rr, include it in MARIADBD | ||
| # (rr's own _RR_TRACE_DIR controls where the trace is written). | ||
| # e.g. _RR_TRACE_DIR=/dev/shm/rr MARIADBD='rr record mariadbd' ... | ||
| : "${MARIADB:=mariadb}" | ||
| : "${TAR:=tar}" |
There was a problem hiding this comment.
Do we need to mention a tool here that is not likely to work for end users, at least until the instrumentation of the copy_file_range system call has been fixed?
Why is the mariadbd executable not wrapped in the same way?
| # The wrapped commands can be overridden for testing, e.g. | ||
| # MARIADB='mariadb --protocol=tcp', TAR=bsdtar. |
There was a problem hiding this comment.
I’d suggest to omit the , after MARIADB= and the . after TAR= because literally copying the line to the start of a shell command should result in --protocol=tcp, which I assume is not going to work. Maybe, in a preceding line, say that the environment variables can be overridden at the start of a shell command, or give more complete examples:
# MARIADB='mariadb --protocol=tcp' TAR=bsdtar mariadb-backup-server.sh --backup ...
# TAR=bsdtar mariadb-backup-server.sh --prepare ...| # In stream mode --target-dir is optional: | ||
| # it is only a scratch directory for the per-stream tar parts | ||
| # (a mktemp dir is used when it is omitted). | ||
| [ -n "$STREAM" ] || [ -n "$TARGET_DIR" ] || die "--target-dir required" |
There was a problem hiding this comment.
Here and elsewhere, we are invoking the external command [ a.k.a. test multiple times. That command does support logical -a and -o. We should use them. man 1 test to learn the syntax.
| @@ -1,3 +1,4 @@ | |||
| --source include/have_mariabackup_combination.inc | |||
There was a problem hiding this comment.
We have the SERVER variant of this test failing on FreeBSD:
mariabackup.full_backup '32k,SERVER' w6 [ fail ]
Test ended at 2026-06-30 01:54:32
CURRENT_TEST: mariabackup.full_backup
mysqltest: At line 39: exec of '/data/buildbot/workers/prod/amd64-freebsd-14/build/mysql-test/../extra/mariabackup/scripts/mariadb-backup-server.sh --prepare --target-dir=/data/buildbot/workers/prod/amd64-freebsd-14/build/mysql-test/var/6/tmp/backup 2>&1' failed, error: 256, status: 1, errno: 22
Output from before failure:
/data/buildbot/workers/prod/amd64-freebsd-14/build/mysql-test/../extra/mariabackup/scripts/mariadb-backup-server.sh: mariadbd: not found
ac4c513 to
45b94b3
Compare
e5a9d2d to
b625be2
Compare
| sql="BACKUP SERVER WITH" | ||
| case $PARALLEL in # --parallel=N -> "N CONCURRENT" (1 is default) | ||
| ''|*[!0-9]*) ;; | ||
| *) [ "$PARALLEL" -gt 1 ] && sql="$sql $PARALLEL CONCURRENT" ;; | ||
| esac |
There was a problem hiding this comment.
This is off by one. In mariadb-backup --backup, there is a dedicated log_copying_thread() that runs concurrently with any other copying threads. The number of CONCURRENT must be 1 more than the number specified by --parallel, always at least 2.
For supporting the --stream variant (which I suppose could be supported via a named pipe), I believe that we would have to stick to 1 thread so that a single stream will be produced.
There was a problem hiding this comment.
I can see two ways of supporting a genuine streamed operation. One is via named pipes (created with mkfifo, possibly the "server" or "sink" could be cat started in the background.) Another is via sockaddr_un(3type), served by Netcat (nc) which some Galera scripts already depend on: https://stackoverflow.com/questions/25256320/best-way-to-use-unix-domain-socket-in-bash-script
In both cases, I assume that the file name may have to be created with mktemp(1).
| # The server appends the stream index as $1 and writes that stream's tar | ||
| # to our stdin; we drop each one into the scratch dir under <index>.tar. | ||
| helper=$scratch/.mariabackup-stream.sh | ||
| cat > "$helper" <<EOF | ||
| #!/bin/sh | ||
| exec cat > "$scratch/\$1.tar" | ||
| EOF |
There was a problem hiding this comment.
This does not look like streaming operation to me. We appear to write the entire uncompressed stream to a local file, and maybe subsequently copy that tile to an output stream. Proper streaming operation could be possible by writing the output to a named pipe, which would be relayed to the standard output.
9fac1f8 to
b0944c9
Compare
1370d5a to
0a23ebb
Compare
| --source include/have_mariabackup_combination.inc | ||
| let $basedir=$MYSQLTEST_VARDIR/tmp/mdev-18438; | ||
| mkdir $basedir; | ||
| exec $XTRABACKUP --defaults-file=$MYSQLTEST_VARDIR/my.cnf --backup --extra-lsndir=$basedir/extra_lsndir --stream=xbstream > $basedir/stream.xb; |
There was a problem hiding this comment.
This test is failing when applied to the current #4817 branch, as follows:
CURRENT_TEST: mariabackup.mdev-18438
--------------
BACKUP SERVER WITH '/bin/sh /tmp/mariabackup-stream.2weSev/.mariabackup-stream.sh'
--------------
ERROR 1210 (HY000) at line 1: Incorrect arguments to BACKUP SERVER WITH
Since the time you rebased the branch on #4817, the way how BACKUP SERVER WITH works was changed. The user-specified script name must not contain any path separators or quotes, and the server will prepend mariadb-backup- to the name. The script must be located in the $PATH of the mariadbd process so that it can be found.
We probably must distribute a script that gets the rest of its parameters via environment variables. Or it simply assumes that a named pipe exists in the server data directory:
#!/bin/sh
set -e
test -p ".mariadb-backup-pipe-$1.tar"
exec cat > ".mariadb-backup-pipe-$1.tar"It would be the job of the mariadb-backup wrapper script to run mkfifo in the server @@datadir (which is the current directory of the mariadbd process) and to set up a listener for it, and finally remove the named pipe. Even though the wrapper script would only use one named pipe, I would make the utility script work with multiple streams so that a different wrapper could run it on multiple streams. The name of the script could be mariadb-backup-pipe so that the invocation would be as follows:
BACKUP SERVER WITH 'pipe';
This adds a shell script that lets users keep using their existing
mariadb-backup commands while the real work is done by the new
server-side BACKUP SERVER command. The goal is "drop-in": users
should not have to change their backup scripts.
mariadb-backup-server.sh : Understands the usual mariadb-backup
modes and translates each one.
mbstream-server.sh : lets streamed backups be unpacked by
pipelines that expect the mbstream CLI
mariadb-backup-pipe.sh is the stream sink that
BACKUP SERVER itself runs.
All three are documented in README.md.
--backup
========
Connects with the mariadb client and runs
"BACKUP SERVER TO '<dir>'".
Connection options (--user, --host, --port, --socket,
--defaults-file, ssl, ...) are passed through to the client.
--parallel=N becomes "<N+1> CONCURRENT": mariadb-backup
runs a dedicated log_copying_thread() besides its N data-copy
threads, while CONCURRENT counts every BACKUP SERVER worker.
The result is clamped to the 1..256 the parser accepts,
and to a minimum of 2.
After the backup it writes backup-prepare.cnf into the backup
directory, recording what --prepare needs later:
- where mariadbd lives
- InnoDB parameters (page size, data file path, undo tablespaces,
checksum algorithm, log file size)
- If the server is encrypted then how to reload the
encryption key plugin (the file_key_management variables),
so an encrypted backup can be prepared without extra input.
--backup --stream
=================
Runs "BACKUP SERVER WITH 'pipe'".
The server only accepts a bare command name, which it resolves
n the PATH of the mariadbd process after prepending mariadb-backup-,
so uses the installed mariadb-backup-pipe instead.
mariadb-backup-pipe writes the tar into
.mariadb-backup-pipe-<stream>.tar, a named pipe the wrapper
created in the server @@datadir and is already draining to
its own stdout.
The backup therefore reaches the consumer as it is produced and
never lands on local disk. The wrapper appends backup-prepare.cnf
as a final tar afterwards; the server's tar carries no
end-of-archive marker, so that trailing archive supplies the
only one and the whole stream extracts with a plain "tar -x".
--parallel is ignored here, with a warning.
Four properties follow from how BACKUP SERVER streams,
all differing from mariadb-backup:
- local: the stream command runs inside the server,
so the wrapper must share its filesystem;
- fifo lives in @@datadir, because mariadb-backup-pipe resolves it
relative to the working directory of mariadbd, so --stream needs
write access there;
- tar only: any --stream=<format> yields tar;
- single-threaded: one worker, so no parallel read either.
--target-dir is optional in stream mode;
mbstream-server.sh maps the mbstream CLI onto a plain
"tar -x"/"tar -c", so existing "mbstream -x"/"-c" pipelines
keep working on the wrapper's stream.
mbstream-only flags (-p/--parallel, ...) are accepted and
ignored; any other unknown option is rejected.
Environment overrides:
MARIADB (client),
MARIADBD (the --prepare bootstrap server) and
TAR (the tar implementation, e.g. TAR=bsdtar) can each be overridden.
To run the bootstrap under rr, put it in MARIADBD and
let rr's own _RR_TRACE_DIR choose the trace location, e.g.
_RR_TRACE_DIR=/dev/shm/rr MARIADBD='rr record mariadbd'
--prepare
=========
Starts "mariadbd --bootstrap" on the backup directory using
backup-prepare.cnf as its defaults file, replays the archived redo
log between the start and target LSN read from backup.cnf,
then builds a fresh ib_logfile0 so a normal server can start
on the directory.
mariadbd is taken from the path recorded in backup-prepare.cnf
if that binary exists, otherwise by searching
/libexec, /sbin, /bin and the configured install directories.
PATH is not searched; set MARIADBD to point elsewhere.
User --defaults-file/-extra-file and encryption options are
layered onto the bootstrap.
--copy-back / --move-back
=========================
Copy or move a prepared backup into the datadir. The datadir
is created if missing, a non-empty datadir is refused unless
--force-non-empty-directories is given, and a chown
reminder is printed.
If --aria-log-dir-path is given, the Aria logs (aria_log_control,
aria_log.*) are relocated into that directory.
Packaging
=========
The wrapper is not installed by default and never replaces the
real mariadb-backup / mbstream binaries.
1. cmake -DWITH_MARIABACKUP_WRAPPER=ON (default OFF) controls it.
2. When ON, the scripts install as /usr/bin/mariadb-backup-server,
/usr/bin/mbstream-server and /usr/bin/mariadb-backup-pipe, tagged
COMPONENT Backup so they ship in the mariadb-backup package.
mariadb-backup-pipe must end up in the PATH of the mariadbd
process, not merely in the PATH of whoever runs the wrapper.
3. RPM: nothing extra to do. the component handles it.
4. DEB: not wired. debian/rules uses --fail-missing and does not
enable the option, so the -server binaries are not listed.
To ship via DEB, make a paired change: add
-DWITH_MARIABACKUP_WRAPPER=ON in debian/rules and list all three of
usr/bin/mariadb-backup-server, usr/bin/mbstream-server and
usr/bin/mariadb-backup-pipe in debian/mariadb-backup.install together.
5. The real mariadb-backup/mbstream binaries and the
mariabackup symlink are left untouched; opt in via an alias or a
symlink early in PATH.
Limitations (not supported yet)
===============================
1) Incremental backup & prepare (--incremental-basedir,
--incremental-dir, --apply-log-only)
2) --rollback-xa
3) Partial backup (--databases, --tables, --tables-file)
4) Output compression and encryption (--compress, --encrypt)
5) --export is accepted but only warns and runs a plain recovery
6) --extra-lsndir is ignored
7) --parallel is ignored with --stream
8) Windows: POSIX sh only, not installed on Windows
Behaviour differences from native mariadb-backup
================================================
- The wrapper needs the mariadb client on PATH for --backup;
--prepare needs mariadbd recorded in backup-prepare.cnf, in a
standard install directory, or named by MARIADBD
- BACKUP SERVER refuses an already-existing target directory
- BACKUP SERVER does copy the data file as raw pages without
checksum validation, so a corrupted table is not detected
at backup time
- --prepare only works on a wrapper-made backup: it
needs backup-prepare.cnf
- --stream is tar, not xbstream, local-only and single-threaded,
and needs write access to @@datadir for the fifo
Tests
=====
include/have_mariabackup_wrapper.inc redirects $XTRABACKUP to
mariadb-backup-server.sh and $XBSTREAM to mbstream-server.sh,
skipping when a wrapper or the mariadb client is unavailable.
include/have_mariabackup_combination.inc runs a test under both the
[CLIENT] mariadb-backup binary and the [SERVER] wrapper.
0a23ebb to
243058f
Compare
4 participants
This adds a shell script that lets users keep using their existing
mariadb-backup commands while the real work is done by the new
server-side BACKUP SERVER command. The goal is "drop-in": users should
not have to change their backup scripts.
extra/mariabackup/scripts/mariadb-backup-server.sh (plain POSIX sh)
understands the usual mariadb-backup modes and translates each one.
A companion helper, extra/mariabackup/scripts/mbstream-server.sh,
lets streamed backups be unpacked by pipelines that expect the
mbstream CLI. Both are documented in extra/mariabackup/scripts/README.md.
--backup --stream
=================
Runs "BACKUP SERVER WITH ''", where writes the
tar into a fifo that the wrapper drains to its own stdout, so the
backup reaches the consumer as it is produced and never lands on
local disk.
bootstrap under rr, put it in MARIADBD and let rr's own _RR_TRACE_DIR
choose the trace location, e.g.
_RR_TRACE_DIR=/dev/shm/rr MARIADBD='rr record mariadbd'
enable the option, so the -server binaries are not listed.
To ship via DEB, make a paired change: add
-DWITH_MARIABACKUP_WRAPPER=ON in debian/rules and list both
usr/bin/mariadb-backup-server and
usr/bin/mbstream-server in debian/mariadb-backup.install together.
5. The real mariadb-backup/mbstream binaries and the
mariabackup symlink are left untouched; opt in via an alias or a
symlink early in PATH.
Tests