docker官方镜像Mysql构建脚本
概述
解读官方脚本，为了模仿官方格式，提升自己的Shell脚本的编写能力和规范编写方式。如下是原版脚本内容：
#!/bin/bash
set -eo pipefail
shopt -s nullglob
mysql_log() {
local type="$1"; shift
printf '%s [%s] [Entrypoint]: %s
' "$(date --rfc-3339=seconds)" "$type" "$*"
}
mysql_note() {
mysql_log Note "$@"
}
mysql_warn() {
mysql_log Warn "$@" >&2
}
mysql_error() {
mysql_log ERROR "$@" >&2
exit 1
}
# usage: file_env VAR [DEFAULT]
# ie: file_env 'XYZ_DB_PASSWORD' 'example'
# (will allow for "$XYZ_DB_PASSWORD_FILE" to fill in the value of
# "$XYZ_DB_PASSWORD" from a file, especially for Docker's secrets feature)
file_env() {
local var="$1"
local fileVar="${var}_FILE"
local def="${2:-}"
if [ "${!var:-}" ] && [ "${!fileVar:-}" ]; then
mysql_error "Both $var and $fileVar are set (but are exclusive)"
fi
local val="$def"
if [ "${!var:-}" ]; then
val="${!var}"
elif [ "${!fileVar:-}" ]; then
val="$(< "${!fileVar}")"
fi
export "$var"="$val"
unset "$fileVar"
}
# check to see if this file is being run or sourced from another script
_is_sourced() {
# https://unix.stackexchange.com/a/215279
[ "${#FUNCNAME[@]}" -ge 2 ]
&& [ "${FUNCNAME[0]}" = '_is_sourced' ]
&& [ "${FUNCNAME[1]}" = 'source' ]
}
# usage: docker_process_init_files [file [file [...]]]
# ie: docker_process_init_files /always-initdb.d/*
# process initializer files, based on file extensions
docker_process_init_files() {
# mysql here for backwards compatibility "${mysql[@]}"
mysql=( docker_process_sql )
echo
local f
for f; do
case "$f" in
*.sh)
# https://github.com/docker-library/postgres/issues/450#issuecomment-393167936
# https://github.com/docker-library/postgres/pull/452
if [ -x "$f" ]; then
mysql_note "$0: running $f"
"$f"
else
mysql_note "$0: sourcing $f"
. "$f"
fi
;;
*.sql) mysql_note "$0: running $f"; docker_process_sql < "$f"; echo ;;
*.sql.gz) mysql_note "$0: running $f"; gunzip -c "$f" | docker_process_sql; echo ;;
*.sql.xz) mysql_note "$0: running $f"; xzcat "$f" | docker_process_sql; echo ;;
*) mysql_warn "$0: ignoring $f" ;;
esac
echo
done
}
mysql_check_config() {
local toRun=( "$@" --verbose --help ) errors
if ! errors="$("${toRun[@]}" 2>&1 >/dev/null)"; then
mysql_error $'mysqld failed while attempting to check config
command was: '"${toRun[*]}"$'
'"$errors"
fi
}
# Fetch value from server config
# We use mysqld --verbose --help instead of my_print_defaults because the
# latter only show values present in config files, and not server defaults
mysql_get_config() {
local conf="$1"; shift
"$@" --verbose --help --log-bin-index="$(mktemp -u)" 2>/dev/null
| awk -v conf="$conf" '$1 == conf && /^[^ ]/ { sub(/^[^ ]+[ ]+/, ""); print; exit }'
# match "datadir /some/path with/spaces in/it here" but not "--xyz=abc
datadir (xyz)"
}
# Do a temporary startup of the MySQL server, for init purposes
docker_temp_server_start() {
if [ "${MYSQL_MAJOR}" = '5.6' ] || [ "${MYSQL_MAJOR}" = '5.7' ]; then
"$@" --skip-networking --socket="${SOCKET}" &
mysql_note "Waiting for server startup"
local i
for i in {30..0}; do
# only use the root password if the database has already been initializaed
# so that it won't try to fill in a password file when it hasn't been set yet
extraArgs=()
if [ -z "$DATABASE_ALREADY_EXISTS" ]; then
extraArgs+=( '--dont-use-mysql-root-password' )
fi
if docker_process_sql "${extraArgs[@]}" --database=mysql <<<'SELECT 1' &> /dev/null; then
break
fi
sleep 1
done
if [ "$i" = 0 ]; then
mysql_error "Unable to start server."
fi
else
# For 5.7+ the server is ready for use as soon as startup command unblocks
if ! "$@" --daemonize --skip-networking --socket="${SOCKET}"; then
mysql_error "Unable to start server."
fi
fi
}
# Stop the server. When using a local socket file mysqladmin will block until
# the shutdown is complete.
docker_temp_server_stop() {
if ! mysqladmin --defaults-extra-file=<( _mysql_passfile ) shutdown -uroot --socket="${SOCKET}"; then
mysql_error "Unable to shut down server."
fi
}
# Verify that the minimally required password settings are set for new databases.
docker_verify_minimum_env() {
if [ -z "$MYSQL_ROOT_PASSWORD" -a -z "$MYSQL_ALLOW_EMPTY_PASSWORD" -a -z "$MYSQL_RANDOM_ROOT_PASSWORD" ]; then
mysql_error $'Database is uninitialized and password option is not specified
You need to specify one of MYSQL_ROOT_PASSWORD, MYSQL_ALLOW_EMPTY_PASSWORD and MYSQL_RANDOM_ROOT_PASSWORD'
fi
}
# creates folders for the database
# also ensures permission for user mysql of run as root
docker_create_db_directories() {
local user; user="$(id -u)"
# TODO other directories that are used by default? like /var/lib/mysql-files
# see https://github.com/docker-library/mysql/issues/562
mkdir -p "$DATADIR"
if [ "$user" = "0" ]; then
# this will cause less disk access than `chown -R`
find "$DATADIR" ! -user mysql -exec chown mysql '{}' +
fi
}
# initializes the database directory
docker_init_database_dir() {
mysql_note "Initializing database files"
if [ "$MYSQL_MAJOR" = '5.6' ]; then
mysql_install_db --datadir="$DATADIR" --rpm --keep-my-cnf "${@:2}"
else
"$@" --initialize-insecure
fi
mysql_note "Database files initialized"
if command -v mysql_ssl_rsa_setup > /dev/null && [ ! -e "$DATADIR/server-key.pem" ]; then
# https://github.com/mysql/mysql-server/blob/23032807537d8dd8ee4ec1c4d40f0633cd4e12f9/packaging/deb-in/extra/mysql-systemd-start#L81-L84
mysql_note "Initializing certificates"
mysql_ssl_rsa_setup --datadir="$DATADIR"
mysql_note "Certificates initialized"
fi
}
# Loads various settings that are used elsewhere in the script
# This should be called after mysql_check_config, but before any other functions
docker_setup_env() {
# Get config
declare -g DATADIR SOCKET
DATADIR="$(mysql_get_config 'datadir' "$@")"
SOCKET="$(mysql_get_config 'socket' "$@")"
# Initialize values that might be stored in a file
file_env 'MYSQL_ROOT_HOST' '%'
file_env 'MYSQL_DATABASE'
file_env 'MYSQL_USER'
file_env 'MYSQL_PASSWORD'
file_env 'MYSQL_ROOT_PASSWORD'
declare -g DATABASE_ALREADY_EXISTS
if [ -d "$DATADIR/mysql" ]; then
DATABASE_ALREADY_EXISTS='true'
fi
}
# Execute sql script, passed via stdin
# usage: docker_process_sql [--dont-use-mysql-root-password] [mysql-cli-args]
# ie: docker_process_sql --database=mydb <<<'INSERT ...'
# ie: docker_process_sql --dont-use-mysql-root-password --database=mydb /dev/null
docker_init_database_dir "$@"
mysql_note "Starting temporary server"
docker_temp_server_start "$@"
mysql_note "Temporary server started."
docker_setup_db
docker_process_init_files /docker-entrypoint-initdb.d/*
mysql_expire_root_user
mysql_note "Stopping temporary server"
docker_temp_server_stop
mysql_note "Temporary server stopped"
echo
mysql_note "MySQL init process done. Ready for start up."
echo
fi
fi
exec "$@"
}
# If we are sourced from elsewhere, don't perform any further actions
if ! _is_sourced; then
_main "$@"
fi
脚本内容
定义错误捕获
#!/bin/bash set -eo pipefail # 包括管道符，只要出现错误，脚本中断 shopt -s nullglob # 开启nullglob，确保不会将*号错误解析
定义日志输出函数
定义日志输出内容函数，并调用日志函数
mysql_log() {
# 定义type为本地变量，根据 shift 来动态获取函数后面的参数 type="$1"
local type="$1"; shift
# 将内容通过格式化输出 $type 为等级，$*为后面的其他内容
printf '%s [%s] [Entrypoint]: %s
' "$(date --rfc-3339=seconds)" "$type" "$*"
}
mysql_note() {
# 将第一个参数传入mysql_log函数，并通过$@捕获所有尾部参数
mysql_log Note "$@"
}
mysql_warn() {
mysql_log Warn "$@" >&2
}
mysql_error() {
mysql_log ERROR "$@" >&2
exit 1
}
获取传入的ENV变量信息
该功能是将变量和值绑定到一起
# file_env 'MYSQL_ROOT_HOST' '%'
# file_env 'MYSQL_DATABASE'
file_env() {
# 获取函数变量的第一位参数 例如：file_env 'MYSQL_DATABASE'
local var="$1" // 1. var=MYSQL_DATABASE
# 将var变量拼接成fileVar变量：MYSQL_DATABASE_FILE
local fileVar="${var}_FILE" // 2. fileVar=MYSQL_DATABASE_FILE
# $2存在值，则赋值为def变量，没有则def为空
local def="${2:-}" // 3. 为空
# 判断如果${!var} 和${!fileVar},也就是MYSQL_DATABASE和MYSQL_DATABASE_FILE 不为空则进入if，mysql_error输出错误日志
if [ "${!var:-}" ] && [ "${!fileVar:-}" ]; then
mysql_error "Both $var and $fileVar are set (but are exclusive)" // 4. 进入if输出日志
fi
# 将def变量传入到局部val变量
local val="$def" // 5. val=''
# 如果${!var}也就是有值则进入函数体
if [ "${!var:-}" ]; then // var=$MYSQL_DATABASE
val="${!var}" // val=$MYSQL_DATABASE
elif [ "${!fileVar:-}" ]; then
val="$(< "${!fileVar}")"
fi
# 导入环境变量
export "$var"="$val" //也就是将MYSQL_DATABASE=xxx绑定
# 删除$fileVar变量
unset "$fileVar"
}
执行方式判断
# 如果是./执行则函数为假执行_main函数，如果是source则为真不执行_main
_is_sourced() {
# https://unix.stackexchange.com/a/215279
[ "${#FUNCNAME[@]}" -ge 2 ]
&& [ "${FUNCNAME[0]}" = '_is_sourced' ]
&& [ "${FUNCNAME[1]}" = 'source' ]
}
if ! _is_sourced; then
_main "$@"
fi
$FUNCNAME —— Bash 内部环境变量，它是一个包含了当前在执行调用堆栈中的所有 Shell 函数名称的数组变量。${FUNCNAME[0]} 代表当前正在执行的 Shell 函数的名称，${FUNCNAME[1]} 则代表调用函数
测试代码
1.sh
#!/bin/bash
_is_sourced() {
[ "${#FUNCNAME[@]}" -ge 2 ] && [ "${FUNCNAME[0]}" = '_is_sourced' ] && [ "${FUNCNAME[1]}" = 'source' ]
}
wsl(){
echo 1
}
if ! _is_sourced; then
wsl
fi
2.sh
#!/bin/bash source ./1.sh