mysql2 gem + mariadb + alpine linux.md

mysql2 gem + mariadb + Alpine Linux

tl;dr Use mariadb-dev. In case of Alpine Linux 3.8, 3.9, use mysql2 >= 0.4.10.

Starting with Alpine Linux 3.8 there are basically 2 options to install the mysql2 gem:

1.sh:

#!/bin/sh
set -eu
apk add build-base "$1"
gem install mysql2 -v "$2"

$ docker run --rm -v $PWD/1.sh:/1.sh ruby:2.6-alpine3.11 ./1.sh mariadb-dev 0.5.3
...
Gem 'mysql2' is not installed
Building native extensions. This could take a while...
Successfully installed mysql2-0.5.3
1 gem installed

$ docker run --rm -v $PWD/1.sh:/1.sh ruby:2.6-alpine3.11 ./1.sh mariadb-connector-c-dev 0.5.3
...
Gem 'mysql2' is not installed
Building native extensions. This could take a while...
Successfully installed mysql2-0.5.3
1 gem installed

But with mysql2 < 0.4.10 one of them doesn't work:

$ docker run --rm -v $PWD/1.sh:/1.sh ruby:2.6-alpine3.11 ./1.sh mariadb-dev 0.4.9
...
Gem 'mysql2' is not installed
Building native extensions. This could take a while...
Successfully installed mysql2-0.4.9
1 gem installed

$ docker run --rm -v $PWD/1.sh:/1.sh ruby:2.6-alpine3.11 ./1.sh mariadb-connector-c-dev 0.4.9
...
compiling client.c
In file included from client.c:1:
./mysql2_ext.h:14:10: fatal error: mysql_com.h: No such file or directory
   14 | #include <mysql_com.h>
      |          ^~~~~~~~~~~~~
...

$ docker run --rm -v $PWD/1.sh:/1.sh ruby:2.6-alpine3.11 ./1.sh mariadb-connector-c-dev 0.4.10
...
Gem 'mysql2' is not installed
Building native extensions. This could take a while...
Successfully installed mysql2-0.4.10
1 gem installed

That happens because mysql2 < 0.4.10 requires mysql_com.h for some reason (leftover #include?). But most of the time mysql_com.h comes with mariadb-dev, not with mariadb-connector-c-dev.

MariaDB Connector/C renamed mysql_com.h to mariadb_com.h in 3.0-cc-server-integ-0. MariaDB Connector/C 3.0.1-beta replaced libmysqlclient in MariaDB 10.2.2. But MariaDB itself (server) still had the mysql_com.h file, so nothing changed in this regard.

Before MariaDB 10.2.8 mysql_com.h was a part of the mariadb header files, that were used to build both clients, and server plugins. But in 10.2.8 those were split, server headers were moved to /usr/include/mysql/server. Then, in 10.2.9 there were added some client compatibility header files (with warnings), particularly mysql_com.h. That means mysql_com.h didn't exist in MariaDB 10.2.8.

So, either upgrade to mysql2 >= 0.4.10, or use mariadb-dev.

But that's not the only issue that mysql2-0.4.10 solves. MariaDB Connector/C doesn't define MYSQL_SERVER_VERSION until 3.0.9. That affects Alpine Linux 3.8 (3.0.4), 3.9 (3.0.8). mysql2 < 0.4.10 doesn't work on these releases.

So again, either upgrade mysql2 to >= 0.4.10, or use Alpine Linux >= 3.10.

$ docker run --rm -v $PWD/1.sh:/1.sh ruby:2.6-alpine3.8 ./1.sh mariadb-dev 0.4.9
...
compiling client.c
In file included from /usr/local/include/ruby-2.6.0/ruby/ruby.h:29:0,
                 from /usr/local/include/ruby-2.6.0/ruby.h:33,
                 from ./mysql2_ext.h:10,
                 from client.c:1:
client.c: In function 'rb_mysql_client_info':
client.c:59:30: error: 'MYSQL_SERVER_VERSION' undeclared (first use in this function)
   #define MYSQL_LINK_VERSION MYSQL_SERVER_VERSION
                              ^
...

$ docker run --rm -v $PWD/1.sh:/1.sh ruby:2.6-alpine3.8 ./1.sh mariadb-dev 0.4.10
...
Gem 'mysql2' is not installed
Building native extensions. This could take a while...
Successfully installed mysql2-0.4.10
1 gem installed

$ docker run --rm -v $PWD/1.sh:/1.sh ruby:2.6-alpine3.9 ./1.sh mariadb-dev 0.4.9
...
compiling client.c
In file included from /usr/local/include/ruby-2.6.0/ruby/ruby.h:29,
                 from /usr/local/include/ruby-2.6.0/ruby.h:33,
                 from ./mysql2_ext.h:10,
                 from client.c:1:
client.c: In function 'rb_mysql_client_info':
client.c:59:30: error: 'MYSQL_SERVER_VERSION' undeclared (first use in this function); did you mean 'MYSQL_LINK_VERSION'?
   #define MYSQL_LINK_VERSION MYSQL_SERVER_VERSION
                              ^~~~~~~~~~~~~~~~~~~~
...

$ docker run --rm -v $PWD/1.sh:/1.sh ruby:2.6-alpine3.9 ./1.sh mariadb-dev 0.4.10
...
Gem 'mysql2' is not installed
Building native extensions. This could take a while...
Successfully installed mysql2-0.4.10
1 gem installed

$ docker run --rm -v $PWD/1.sh:/1.sh ruby:2.6-alpine3.10 ./1.sh mariadb-dev 0.4.9
...
Gem 'mysql2' is not installed
Building native extensions. This could take a while...
Successfully installed mysql2-0.4.9
1 gem installed

MDEV-9055 replace libmysqlclient with Connector/C
MDEV-9293 change clients to use Connector/C
MDEV-9267 pull in Connector/C sources into the server tree on builds
56c4cfe0bea MDEV-9293 - Use MariaDB's Connector/C in server
ed0b84a0270 remove libmysql/
79fa256eb2e really add a submodule
main/mariadb: upgrade to 10.2.13, modernize
main/mariadb: split embedded, embedded-dev, static and server-utils

Judging from the following commit:

main/mariadb-connector-c: move from testing

Connector/C is needed for mariadb-10.2.x to work (at least for mariadb >= 10.2.2).