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As I pointed out at https://news.ycombinator.com/item?id=14169188 https://news.ycombinator.com/item?id=14169188 , there's a discussion of MySQL on the systemd-d

by JdeBP 10y ago

As I pointed out at https://news.ycombinator.com/item?id=14169188 https://news.ycombinator.com/item?id=14169188 , there's a discussion of MySQL on the systemd-devel mailing list right now. Clearly some people in that discussion are not familiar with MySQL. Clearly some of the people in this discussion are not familiar with MySQL either. To help combat this ignorance, here are some actual systemd units: * https://github.com/MariaDB/server/blob/10.1/support-files/mariadb%40.service.in https://github.com/MariaDB/server/blob/10.1/support-files/ma... -- MariaDB's official systemd service unit, 173 lines long * https://github.com/mysql/mysql-server/blob/5.7/scripts/systemd/mysqld.service.in https://github.com/mysql/mysql-server/blob/5.7/scripts/syste... -- MySQL's official systemd service unit, 60 lines long * https://github.com/percona/percona-server/blob/5.7/scripts/systemd/mysqld.service.in https://github.com/percona/percona-server/blob/5.7/scripts/s... -- Percona's official systemd service unit, 61 lines long * https://sources.debian.net/src/apache2/2.4.25-3/debian/apache2.service/ https://sources.debian.net/src/apache2/2.4.25-3/debian/apach... -- Debian's third party systemd service unit for Apache2, 15 lines long So these figures that people are pulling out of thin air are erroneous by anywhere from half the actual length to an order of magnitude too small. And, ironically, the Apache systemd service unit is using a System 5 rc shell script under the covers to do all of the work. The apachectl program is in fact a System 5 rc script from 1997, complete with start/stop/restart/status verbs.

SwellJoe 10y ago
Yeah, legacy code is hard, sometimes, and sometimes complexity can't be hidden entirely. The initscripts for MySQL/MariaDB are still orders of magnitude larger than these (unusually large) systemd unit files. Managing complexity is hard. SystemD helps. More modern service design, and simpler services, helps (compare/contrast Apache startup vs nginx or caddy, or MySQL vs MongoDB; sure, the newer options do less, but they do "enough" for some use cases).
- JdeBP 10y ago
  You really should take the tack of learning about this subject rather than following rubbish numbers pulled out of thin air with more rubbish numbers pulled out of thin air. Here's the System 5 rc script for MariaDB. At 453 lines it is not even one order of magnitude larger than the systemd service unit, let alone orders of magnitude. * https://github.com/MariaDB/server/blob/10.1/support-files/mysql.server.sh https://github.com/MariaDB/server/blob/10.1/support-files/my... I recommend actually learning about the reality of MongoDB. For starters, the systemd service units supplied in the likes of Ubuntu and Debian do not set any of the settings recommended for MongoDB by its authors, so here (as in so many cases with systemd service units in the wild, alas) shortness actually equates to not doing things properly. * http://bazaar.launchpad.net/~ubuntu-branches/ubuntu/vivid/mongodb/vivid/view/head:/debian/mongodb-server.mongodb.service http://bazaar.launchpad.net/~ubuntu-branches/ubuntu/vivid/mo... * https://sources.debian.net/src/mongodb/1:3.2.11-2/debian/mongodb-server.mongodb.service/ https://sources.debian.net/src/mongodb/1:3.2.11-2/debian/mon... * https://docs.mongodb.com/manual/reference/ulimit/#linux-distributions-using-systemd https://docs.mongodb.com/manual/reference/ulimit/#linux-dist... Another example of such is WSO2 Carbon, with a 14-line system service unit from one source that gets things grossly wrong. * http://jdebp.eu./FGA/systemd-house-of-horror/wso2.html http://jdebp.eu./FGA/systemd-house-of-horror/wso2.html I recommend actually learning about Caddy, too. Ironically, the subject of its service unit came up here on Hacker News only a day ago. It is 43 lines long, some 6 times the length of the supposed 7-line systemd service unit being bandied about here, and not as far different from those for MySQL and Percona as you imply; and it does not attempt to be "more modern" as you claim, as it entirely lacks the socket unit that would make it more in line with the systemd way of doing things. * https://news.ycombinator.com/item?id=14167704 https://news.ycombinator.com/item?id=14167704 The idea that this is "modern service design" is borne of not knowing the subject, too. The sort of design changes recommended by the systemd people are in fact pretty much the same sort of design changes recommended by IBM in 1992 for services managed by the System Resource Controller and recommended by quite a lot of other people since, including Apple and ... well ... me for many years. Whilst this is good service design, it is not "modern", and not in any way unique or original to systemd. To further alleviate the ignorance of MySQL as well as demonstrate how this is far from "modern" and not something that one gets to claim for systemd service units, I point out that people were running mysqld without mysql_safe, in the very way that the systemd people are by all appearances just learning about in their mailing list discussion, under daemontools in 2002. I strongly suspect that that wasn't even the earliest occasion of that. * http://jdebp.eu./Softwares/nosh/mariadb-and-mysql.html#Prompt http://jdebp.eu./Softwares/nosh/mariadb-and-mysql.html#Promp...
vacri 10y ago
Counting empty lines and comments is hardly the way to make your point. The mariadb unit file you linked to is only 34 actual lines, the mysql unit file only 22, percona 23. And if you're writing your own unit files rather than ones for public consumption, you probably won't include lines like "Documentation=" and some other minor args.
- JdeBP 10y ago
  Actually, counting lines, whether empty, comment, or otherwise, very much is the way to make the point. The reality of actual service units that people write is not anything like the picture that was being painted. You erroneously think that the point is that short is good and long is bad, rather than what it actually is, which is learn the subject and don't make facile arguments based upon rubbish numbers plucked from thin air. Actually looking at reality and counting, rather than pulling the number 7 from a hat, is part of that point. I recommend reading the design of the Mewburn rc system, http://jdebp.eu./FGA/run-scripts-and-service-units-side-by-side.html http://jdebp.eu./FGA/run-scripts-and-service-units-side-by-s... , and some of the entries in the systemd House of Horror. This whole "It's just writing 7 lines and it's easy!" argument falls apart when one looks at the reality of short service units that are either grossly wrong or turn out to be underpinned by the very things that their lengths are being compared to (which also means that it is still those rc scripts that are being used and maintained by software authors -- from 1997 in the example of apachectl), real world service units that are not short, other systems of long standing that are equally concise, and -- yes -- the reality that people include commentary for maintainability. One of the amusing things about this argument that is of particular relevance to the Devuan release is that back when Devuan was announced someone put up a "fork Fedora" WWW page criticizing the Devuan people, with a systemd service unit side by side with a van Smoorenburg rc script. It is sad to note that few people observed that the systemd unit described just one service, whereas the van Smoorenburg rc script ran two. Since you are on the subject of commentary, I invite you to observe which of the twain included comments and which did not, as well, and determine what point the "fork Fedora" people were in fact demonstrating. (-:
  - mdekkers 10y ago
INTPenis 10y ago
To be fair, mariadb systemd unit is 173 lines of ini-style configuration. Not 173 lines of bash code. There's a massive difference. Also most of it is commented as examples.

by JdeBP 10y ago

SwellJoe 10y ago

Yeah, legacy code is hard, sometimes, and sometimes complexity can't be hidden entirely. The initscripts for MySQL/MariaDB are still orders of magnitude larger than these (unusually large) systemd unit files. Managing complexity is hard. SystemD helps. More modern service design, and simpler services, helps (compare/contrast Apache startup vs nginx or caddy, or MySQL vs MongoDB; sure, the newer options do less, but they do "enough" for some use cases).

JdeBP 10y ago
You really should take the tack of learning about this subject rather than following rubbish numbers pulled out of thin air with more rubbish numbers pulled out of thin air. Here's the System 5 rc script for MariaDB. At 453 lines it is not even one order of magnitude larger than the systemd service unit, let alone orders of magnitude. * https://github.com/MariaDB/server/blob/10.1/support-files/mysql.server.sh https://github.com/MariaDB/server/blob/10.1/support-files/my... I recommend actually learning about the reality of MongoDB. For starters, the systemd service units supplied in the likes of Ubuntu and Debian do not set any of the settings recommended for MongoDB by its authors, so here (as in so many cases with systemd service units in the wild, alas) shortness actually equates to not doing things properly. * http://bazaar.launchpad.net/~ubuntu-branches/ubuntu/vivid/mongodb/vivid/view/head:/debian/mongodb-server.mongodb.service http://bazaar.launchpad.net/~ubuntu-branches/ubuntu/vivid/mo... * https://sources.debian.net/src/mongodb/1:3.2.11-2/debian/mongodb-server.mongodb.service/ https://sources.debian.net/src/mongodb/1:3.2.11-2/debian/mon... * https://docs.mongodb.com/manual/reference/ulimit/#linux-distributions-using-systemd https://docs.mongodb.com/manual/reference/ulimit/#linux-dist... Another example of such is WSO2 Carbon, with a 14-line system service unit from one source that gets things grossly wrong. * http://jdebp.eu./FGA/systemd-house-of-horror/wso2.html http://jdebp.eu./FGA/systemd-house-of-horror/wso2.html I recommend actually learning about Caddy, too. Ironically, the subject of its service unit came up here on Hacker News only a day ago. It is 43 lines long, some 6 times the length of the supposed 7-line systemd service unit being bandied about here, and not as far different from those for MySQL and Percona as you imply; and it does not attempt to be "more modern" as you claim, as it entirely lacks the socket unit that would make it more in line with the systemd way of doing things. * https://news.ycombinator.com/item?id=14167704 https://news.ycombinator.com/item?id=14167704 The idea that this is "modern service design" is borne of not knowing the subject, too. The sort of design changes recommended by the systemd people are in fact pretty much the same sort of design changes recommended by IBM in 1992 for services managed by the System Resource Controller and recommended by quite a lot of other people since, including Apple and ... well ... me for many years. Whilst this is good service design, it is not "modern", and not in any way unique or original to systemd. To further alleviate the ignorance of MySQL as well as demonstrate how this is far from "modern" and not something that one gets to claim for systemd service units, I point out that people were running mysqld without mysql_safe, in the very way that the systemd people are by all appearances just learning about in their mailing list discussion, under daemontools in 2002. I strongly suspect that that wasn't even the earliest occasion of that. * http://jdebp.eu./Softwares/nosh/mariadb-and-mysql.html#Prompt http://jdebp.eu./Softwares/nosh/mariadb-and-mysql.html#Promp...

vacri 10y ago

Counting empty lines and comments is hardly the way to make your point. The mariadb unit file you linked to is only 34 actual lines, the mysql unit file only 22, percona 23. And if you're writing your own unit files rather than ones for public consumption, you probably won't include lines like "Documentation=" and some other minor args.

JdeBP 10y ago
Actually, counting lines, whether empty, comment, or otherwise, very much is the way to make the point. The reality of actual service units that people write is not anything like the picture that was being painted. You erroneously think that the point is that short is good and long is bad, rather than what it actually is, which is learn the subject and don't make facile arguments based upon rubbish numbers plucked from thin air. Actually looking at reality and counting, rather than pulling the number 7 from a hat, is part of that point. I recommend reading the design of the Mewburn rc system, http://jdebp.eu./FGA/run-scripts-and-service-units-side-by-side.html http://jdebp.eu./FGA/run-scripts-and-service-units-side-by-s... , and some of the entries in the systemd House of Horror. This whole "It's just writing 7 lines and it's easy!" argument falls apart when one looks at the reality of short service units that are either grossly wrong or turn out to be underpinned by the very things that their lengths are being compared to (which also means that it is still those rc scripts that are being used and maintained by software authors -- from 1997 in the example of apachectl), real world service units that are not short, other systems of long standing that are equally concise, and -- yes -- the reality that people include commentary for maintainability. One of the amusing things about this argument that is of particular relevance to the Devuan release is that back when Devuan was announced someone put up a "fork Fedora" WWW page criticizing the Devuan people, with a systemd service unit side by side with a van Smoorenburg rc script. It is sad to note that few people observed that the systemd unit described just one service, whereas the van Smoorenburg rc script ran two. Since you are on the subject of commentary, I invite you to observe which of the twain included comments and which did not, as well, and determine what point the "fork Fedora" people were in fact demonstrating. (-:
- mdekkers 10y ago

INTPenis 10y ago

To be fair, mariadb systemd unit is 173 lines of ini-style configuration. Not 173 lines of bash code. There's a massive difference. Also most of it is commented as examples.