Docker部署数据库如何初始化数据
大约 6 分钟
公司目前对外部署的应用基本上都是使用Docker和Docker-Compose，当然也包括数据库，例如：MySQL、Postgresql。如何减少频繁的拷贝SQL脚本到数据库容器中这种繁琐的操作，提高部署效率呢？
Docker其实提供docker-entrypoint-initdb.d这一个特殊的目录，专门用于MySQL或Postgresql等数据库用于初始化数据。
使用方式
我们以MySQL为例，提供docker-entrypoint-initdb.d的使用方式。
version: '3'
services:
mysql:
image: mysql:8.0
restart: always
ports:
- 3306:3306
volumes:
- ./config/mysql/initdb:/docker-entrypoint-initdb.d
- ./config/mysql/my.cnf:/etc/mysql/conf.d/my.cnf
- ./data/mysql:/var/lib/mysql
env_file:
- mysql.env
logging:
driver: "json-file"
options:
max-size: "100m"
max-file: "2"
在上面的使用示例中，我们将./config/mysql/initdb目录挂载进容器内：/docker-entrypoint-initdb.d目录，我们只需要在./config/mysql/initdb/目录下准备数据脚本，支持.sh和.sql两种数据脚本，也支持一些压缩的sql文件。
原理
那么为什么提供一个目录就可以初始化数据了呢？
这是由于Docker官方镜像启动时会执行entrypoint.sh脚本。我们可以访问一个MySQL容器，查看
cat /usr/local/bin/docker-entrypoint.sh
内容如下：
#!/bin/bash
set -eo pipefail
shopt -s nullglob
# logging functions
mysql_log() {
local type="$1"; shift
# accept argument string or stdin
local text="$*"; if [ "$#" -eq 0 ]; then text="$(cat)"; fi
local dt; dt="$(date --rfc-3339=seconds)"
printf '%s [%s] [Entrypoint]: %s\n' "$dt" "$type" "$text"
}
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.bz2) mysql_note "$0: running $f"; bunzip2 -c "$f" | docker_process_sql; 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 ;;
*.sql.zst) mysql_note "$0: running $f"; zstd -dc "$f" | docker_process_sql; echo ;;
*) mysql_warn "$0: ignoring $f" ;;
esac
echo
done
}
# arguments necessary to run "mysqld --verbose --help" successfully (used for testing configuration validity and for extracting default/configured values)
_verboseHelpArgs=(
--verbose --help
--log-bin-index="$(mktemp -u)" # https://github.com/docker-library/mysql/issues/136
)
mysql_check_config() {
local toRun=( "$@" "${_verboseHelpArgs[@]}" ) errors
if ! errors="$("${toRun[@]}" 2>&1 >/dev/null)"; then
mysql_error $'mysqld failed while attempting to check config\n\tcommand was: '"${toRun[*]}"$'\n\t'"$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="$1"; shift
"$@" "${_verboseHelpArgs[@]}" 2>/dev/null \
| awk -v conf="$conf" '$1 == conf && /^[^ \t]/ { sub(/^[^ \t]+[ \t]+/, ""); print; exit }'
# match "datadir /some/path with/spaces in/it here" but not "--xyz=abc\n datadir (xyz)"
}
# Ensure that the package default socket can also be used
# since rpm packages are compiled with a different socket location
# and "mysqlsh --mysql" doesn't read the [client] config
# related to https://github.com/docker-library/mysql/issues/829
mysql_socket_fix() {
local defaultSocket
defaultSocket="$(mysql_get_config 'socket' mysqld --no-defaults)"
if [ "$defaultSocket" != "$SOCKET" ]; then
ln -sfTv "$SOCKET" "$defaultSocket" || :
fi
}
# Do a temporary startup of the MySQL server, for init purposes
docker_temp_server_start() {
# For 5.7+ the server is ready for use as soon as startup command unblocks
if ! "$@" --daemonize --skip-networking --default-time-zone=SYSTEM --socket="${SOCKET}"; then
mysql_error "Unable to start server."
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 <<-'EOF'
Database is uninitialized and password option is not specified
You need to specify one of the following as an environment variable:
- MYSQL_ROOT_PASSWORD
- MYSQL_ALLOW_EMPTY_PASSWORD
- MYSQL_RANDOM_ROOT_PASSWORD
EOF
fi
# This will prevent the CREATE USER from failing (and thus exiting with a half-initialized database)
if [ "$MYSQL_USER" = 'root' ]; then
mysql_error <<-'EOF'
MYSQL_USER="root", MYSQL_USER and MYSQL_PASSWORD are for configuring a regular user and cannot be used for the root user
Remove MYSQL_USER="root" and use one of the following to control the root user password:
- MYSQL_ROOT_PASSWORD
- MYSQL_ALLOW_EMPTY_PASSWORD
- MYSQL_RANDOM_ROOT_PASSWORD
EOF
fi
# warn when missing one of MYSQL_USER or MYSQL_PASSWORD
if [ -n "$MYSQL_USER" ] && [ -z "$MYSQL_PASSWORD" ]; then
mysql_warn 'MYSQL_USER specified, but missing MYSQL_PASSWORD; MYSQL_USER will not be created'
elif [ -z "$MYSQL_USER" ] && [ -n "$MYSQL_PASSWORD" ]; then
mysql_warn 'MYSQL_PASSWORD specified, but missing MYSQL_USER; MYSQL_PASSWORD will be ignored'
fi
}
# creates folders for the database
# also ensures permission for user mysql of run as root
docker_create_db_directories() {
local user; user="$(id -u)"
local -A dirs=( ["$DATADIR"]=1 )
local dir
dir="$(dirname "$SOCKET")"
dirs["$dir"]=1
# "datadir" and "socket" are already handled above (since they were already queried previously)
local conf
for conf in \
general-log-file \
keyring_file_data \
pid-file \
secure-file-priv \
slow-query-log-file \
; do
dir="$(mysql_get_config "$conf" "$@")"
# skip empty values
if [ -z "$dir" ] || [ "$dir" = 'NULL' ]; then
continue
fi
case "$conf" in
secure-file-priv)
# already points at a directory
;;
*)
# other config options point at a file, but we need the directory
dir="$(dirname "$dir")"
;;
esac
dirs["$dir"]=1
done
mkdir -p "${!dirs[@]}"
if [ "$user" = "0" ]; then
# this will cause less disk access than `chown -R`
find "${!dirs[@]}" \! -user mysql -exec chown --no-dereference mysql '{}' +
fi
}
# initializes the database directory
docker_init_database_dir() {
mysql_note "Initializing database files"
"$@" --initialize-insecure --default-time-zone=SYSTEM
mysql_note "Database files initialized"
}
# Loads various settings that are used elsewhere in the script
# This should be called after mysql_check_config, but before any other functions
docker_setup_env() {
# Get config
declare -g DATADIR SOCKET
DATADIR="$(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 <my-file.sql
docker_process_sql() {
passfileArgs=()
if [ '--dont-use-mysql-root-password' = "$1" ]; then
passfileArgs+=( "$1" )
shift
fi
# args sent in can override this db, since they will be later in the command
if [ -n "$MYSQL_DATABASE" ]; then
set -- --database="$MYSQL_DATABASE" "$@"
fi
mysql --defaults-extra-file=<( _mysql_passfile "${passfileArgs[@]}") --protocol=socket -uroot -hlocalhost --socket="${SOCKET}" --comments "$@"
}
# Initializes database with timezone info and root password, plus optional extra db/user
docker_setup_db() {
# Load timezone info into database
if [ -z "$MYSQL_INITDB_SKIP_TZINFO" ]; then
# sed is for https://bugs.mysql.com/bug.php?id=20545
mysql_tzinfo_to_sql /usr/share/zoneinfo \
| sed 's/Local time zone must be set--see zic manual page/FCTY/' \
| docker_process_sql --dont-use-mysql-root-password --database=mysql
# tell docker_process_sql to not use MYSQL_ROOT_PASSWORD since it is not set yet
fi
# Generate random root password
if [ -n "$MYSQL_RANDOM_ROOT_PASSWORD" ]; then
MYSQL_ROOT_PASSWORD="$(openssl rand -base64 24)"; export MYSQL_ROOT_PASSWORD
mysql_note "GENERATED ROOT PASSWORD: $MYSQL_ROOT_PASSWORD"
fi
# Sets root password and creates root users for non-localhost hosts
local rootCreate=
# default root to listen for connections from anywhere
if [ -n "$MYSQL_ROOT_HOST" ] && [ "$MYSQL_ROOT_HOST" != 'localhost' ]; then
# no, we don't care if read finds a terminating character in this heredoc
# https://unix.stackexchange.com/questions/265149/why-is-set-o-errexit-breaking-this-read-heredoc-expression/265151#265151
read -r -d '' rootCreate <<-EOSQL || true
CREATE USER 'root'@'${MYSQL_ROOT_HOST}' IDENTIFIED BY '${MYSQL_ROOT_PASSWORD}' ;
GRANT ALL ON *.* TO 'root'@'${MYSQL_ROOT_HOST}' WITH GRANT OPTION ;
EOSQL
fi
local passwordSet=
# no, we don't care if read finds a terminating character in this heredoc (see above)
read -r -d '' passwordSet <<-EOSQL || true
ALTER USER 'root'@'localhost' IDENTIFIED BY '${MYSQL_ROOT_PASSWORD}' ;
EOSQL
# tell docker_process_sql to not use MYSQL_ROOT_PASSWORD since it is just now being set
docker_process_sql --dont-use-mysql-root-password --database=mysql <<-EOSQL
-- What's done in this file shouldn't be replicated
-- or products like mysql-fabric won't work
SET @@SESSION.SQL_LOG_BIN=0;
${passwordSet}
GRANT ALL ON *.* TO 'root'@'localhost' WITH GRANT OPTION ;
FLUSH PRIVILEGES ;
${rootCreate}
DROP DATABASE IF EXISTS test ;
EOSQL
# Creates a custom database and user if specified
if [ -n "$MYSQL_DATABASE" ]; then
mysql_note "Creating database ${MYSQL_DATABASE}"
docker_process_sql --database=mysql <<<"CREATE DATABASE IF NOT EXISTS \`$MYSQL_DATABASE\` ;"
fi
if [ -n "$MYSQL_USER" ] && [ -n "$MYSQL_PASSWORD" ]; then
mysql_note "Creating user ${MYSQL_USER}"
docker_process_sql --database=mysql <<<"CREATE USER '$MYSQL_USER'@'%' IDENTIFIED BY '$MYSQL_PASSWORD' ;"
if [ -n "$MYSQL_DATABASE" ]; then
mysql_note "Giving user ${MYSQL_USER} access to schema ${MYSQL_DATABASE}"
docker_process_sql --database=mysql <<<"GRANT ALL ON \`${MYSQL_DATABASE//_/\\_}\`.* TO '$MYSQL_USER'@'%' ;"
fi
fi
}
_mysql_passfile() {
# echo the password to the "file" the client uses
# the client command will use process substitution to create a file on the fly
# ie: --defaults-extra-file=<( _mysql_passfile )
if [ '--dont-use-mysql-root-password' != "$1" ] && [ -n "$MYSQL_ROOT_PASSWORD" ]; then
cat <<-EOF
[client]
password="${MYSQL_ROOT_PASSWORD}"
EOF
fi
}
# Mark root user as expired so the password must be changed before anything
# else can be done (only supported for 5.6+)
mysql_expire_root_user() {
if [ -n "$MYSQL_ONETIME_PASSWORD" ]; then
docker_process_sql --database=mysql <<-EOSQL
ALTER USER 'root'@'%' PASSWORD EXPIRE;
EOSQL
fi
}
# check arguments for an option that would cause mysqld to stop
# return true if there is one
_mysql_want_help() {
local arg
for arg; do
case "$arg" in
-'?'|--help|--print-defaults|-V|--version)
return 0
;;
esac
done
return 1
}
_main() {
# if command starts with an option, prepend mysqld
if [ "${1:0:1}" = '-' ]; then
set -- mysqld "$@"
fi
# skip setup if they aren't running mysqld or want an option that stops mysqld
if [ "$1" = 'mysqld' ] && ! _mysql_want_help "$@"; then
mysql_note "Entrypoint script for MySQL Server ${MYSQL_VERSION} started."
mysql_check_config "$@"
# Load various environment variables
docker_setup_env "$@"
docker_create_db_directories "$@"
# If container is started as root user, restart as dedicated mysql user
if [ "$(id -u)" = "0" ]; then
mysql_note "Switching to dedicated user 'mysql'"
exec gosu mysql "$BASH_SOURCE" "$@"
fi
# there's no database, so it needs to be initialized
if [ -z "$DATABASE_ALREADY_EXISTS" ]; then
docker_verify_minimum_env
# check dir permissions to reduce likelihood of half-initialized database
ls /docker-entrypoint-initdb.d/ > /dev/null
docker_init_database_dir "$@"
mysql_note "Starting temporary server"
docker_temp_server_start "$@"
mysql_note "Temporary server started."
mysql_socket_fix
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
else
mysql_socket_fix
fi
fi
exec "$@"
}
# If we are sourced from elsewhere, don't perform any further actions
if ! _is_sourced; then
_main "$@"
fi