?Docker Volume 是 docker的数据卷，用于保持数据持久化。MySQL运行在Docker容器中时，一般将数据通过Docker Volume保存在主机上，即使删除MySQL容器，数据不会丢失。
找到docker hub上的mysql 5.7官方dockerfile
https://github.com/docker-library/mysql/blob/e0d43b2a29867c5b7d5c01a8fea30a086861df2b/5.7/Dockerfile.debian
#
# NOTE: THIS DOCKERFILE IS GENERATED VIA "apply-templates.sh"
#
# PLEASE DO NOT EDIT IT DIRECTLY.
#
FROM debian:buster-slim
# add our user and group first to make sure their IDs get assigned consistently, regardless of whatever dependencies get added
RUN groupadd -r mysql && useradd -r -g mysql mysql
RUN apt-get update && apt-get install -y --no-install-recommends gnupg dirmngr && rm -rf /var/lib/apt/lists/*
# add gosu for easy step-down from root
# https://github.com/tianon/gosu/releases
ENV GOSU_VERSION 1.14
RUN set -eux; \
savedAptMark="$(apt-mark showmanual)"; \
apt-get update; \
apt-get install -y --no-install-recommends ca-certificates wget; \
rm -rf /var/lib/apt/lists/*; \
dpkgArch="$(dpkg --print-architecture | awk -F- '{ print $NF }')"; \
wget -O /usr/local/bin/gosu "https://github.com/tianon/gosu/releases/download/$GOSU_VERSION/gosu-$dpkgArch"; \
wget -O /usr/local/bin/gosu.asc "https://github.com/tianon/gosu/releases/download/$GOSU_VERSION/gosu-$dpkgArch.asc"; \
export GNUPGHOME="$(mktemp -d)"; \
gpg --batch --keyserver hkps://keys.openpgp.org --recv-keys B42F6819007F00F88E364FD4036A9C25BF357DD4; \
gpg --batch --verify /usr/local/bin/gosu.asc /usr/local/bin/gosu; \
gpgconf --kill all; \
rm -rf "$GNUPGHOME" /usr/local/bin/gosu.asc; \
apt-mark auto '.*' > /dev/null; \
[ -z "$savedAptMark" ] || apt-mark manual $savedAptMark > /dev/null; \
apt-get purge -y --auto-remove -o APT::AutoRemove::RecommendsImportant=false; \
chmod +x /usr/local/bin/gosu; \
gosu --version; \
gosu nobody true
RUN mkdir /docker-entrypoint-initdb.d
RUN set -eux; \
apt-get update; \
apt-get install -y --no-install-recommends \
bzip2 \
openssl \
# FATAL ERROR: please install the following Perl modules before executing /usr/local/mysql/scripts/mysql_install_db:
# File::Basename
# File::Copy
# Sys::Hostname
# Data::Dumper
perl \
xz-utils \
zstd \
; \
rm -rf /var/lib/apt/lists/*
RUN set -eux; \
# gpg: key 3A79BD29: public key "MySQL Release Engineering <mysql-build@oss.oracle.com>" imported
key='859BE8D7C586F538430B19C2467B942D3A79BD29'; \
export GNUPGHOME="$(mktemp -d)"; \
gpg --batch --keyserver keyserver.ubuntu.com --recv-keys "$key"; \
mkdir -p /etc/apt/keyrings; \
gpg --batch --export "$key" > /etc/apt/keyrings/mysql.gpg; \
gpgconf --kill all; \
rm -rf "$GNUPGHOME"
ENV MYSQL_MAJOR 5.7
ENV MYSQL_VERSION 5.7.40-1debian10
RUN echo 'deb [ signed-by=/etc/apt/keyrings/mysql.gpg ] http://repo.mysql.com/apt/debian/ buster mysql-5.7' > /etc/apt/sources.list.d/mysql.list
# the "/var/lib/mysql" stuff here is because the mysql-server postinst doesn't have an explicit way to disable the mysql_install_db codepath besides having a database already "configured" (ie, stuff in /var/lib/mysql/mysql)
# also, we set debconf keys to make APT a little quieter
RUN { \
echo mysql-community-server mysql-community-server/data-dir select ''; \
echo mysql-community-server mysql-community-server/root-pass password ''; \
echo mysql-community-server mysql-community-server/re-root-pass password ''; \
echo mysql-community-server mysql-community-server/remove-test-db select false; \
} | debconf-set-selections \
&& apt-get update \
&& apt-get install -y \
mysql-server="${MYSQL_VERSION}" \
# comment out a few problematic configuration values
&& find /etc/mysql/ -name '*.cnf' -print0 \
| xargs -0 grep -lZE '^(bind-address|log)' \
| xargs -rt -0 sed -Ei 's/^(bind-address|log)/#&/' \
# don't reverse lookup hostnames, they are usually another container
&& echo '[mysqld]\nskip-host-cache\nskip-name-resolve' > /etc/mysql/conf.d/docker.cnf \
&& rm -rf /var/lib/apt/lists/* \
&& rm -rf /var/lib/mysql && mkdir -p /var/lib/mysql /var/run/mysqld \
&& chown -R mysql:mysql /var/lib/mysql /var/run/mysqld \
# ensure that /var/run/mysqld (used for socket and lock files) is writable regardless of the UID our mysqld instance ends up having at runtime
&& chmod 1777 /var/run/mysqld /var/lib/mysql
VOLUME /var/lib/mysql
COPY docker-entrypoint.sh /usr/local/bin/
RUN ln -s usr/local/bin/docker-entrypoint.sh /entrypoint.sh # backwards compat
ENTRYPOINT ["docker-entrypoint.sh"]
EXPOSE 3306 33060
CMD ["mysqld"]
注意VOLUME /var/lib/mysql
docker volume prune
docker image pull mysql
docker image inspect mysql
# "Volumes": {
# "/var/lib/mysql": {}
# }
# docker image inspect mysql --format '{{ .Config.Volumes }}'
启动mysql
docker container run -d --name mysql -e MYSQL_ALLOW_EMPTY_PASSWORD=True mysql
docker container ls
docker container inspect mysql
# "Mounts": [
# {
# "Type": "volume",
# "Name": "766475a93e0f1e4583f3d6067377451e444c14b15d2450ca349bbe36899f1806",
# "Source": "/var/lib/docker/volumes/766475a93e0f1e4583f3d6067377451e444c14b15d2450ca349bbe36899f1806/_data",
# "Destination": "/var/lib/mysql",
# "Driver": "local",
# "Mode": "",
# "RW": true,
# "Propagation": ""
# }
# ],
# docker container inspect mysql --format '{{ .Mounts }}'
ls /var/lib/docker/volumes/
mounts显示了source和destination
docker volume ls
# DRIVER VOLUME NAME
# local 766475a93e0f1e4583f3d6067377451e444c14b15d2450ca349bbe36899f1806
docker volume inspect 766475a93e0f1e4583f3d6067377451e444c14b15d2450ca349bbe36899f1806
#[
# {
# "CreatedAt": "2023-01-15T23:52:38Z",
# "Driver": "local",
# "Labels": null,
# "Mountpoint": "/var/lib/docker/volumes/766475a93e0f1e4583f3d6067377451e444c14b15d2450ca349bbe36899f1806/_data",
# "Name": "766475a93e0f1e4583f3d6067377451e444c14b15d2450ca349bbe36899f1806",
# "Options": null,
# "Scope": "local"
# }
#]
从volume视角，我们只能看到哪个数据卷挂载在主机上，但是不能得知该数据卷属于哪个容器
比如我们启动第二个mysql容器，再停止所有mysql
docker container run -d --name mysql2 -e MYSQL_ALLOW_EMPTY_PASSWORD=True mysql
docker volume ls
docker container rm -f mysql mysql2
docker volume ls
volume并不会消失，但是很难直观判断属于哪个容器
docker container run -d --name mysql -e MYSQL_ALLOW_EMPTY_PASSWORD=True -v mysql-db:/var/lib/mysql mysql
docker volume ls
# DRIVER VOLUME NAME
# local 766475a93e0f1e4583f3d6067377451e444c14b15d2450ca349bbe36899f1806
# local b3b2ab7a9557160a9066bef15c61af2cfc3d7d05dd5323fc51a80cb414ef6799
# local mysql-db
显示指定数据卷
docker volume inspect mysql-db
# [
# {
# "CreatedAt": "2023-01-16T00:13:34Z",
# "Driver": "local",
# "Labels": null,
# "Mountpoint": "/var/lib/docker/volumes/mysql-db/_data",
# "Name": "mysql-db",
# "Options": null,
# "Scope": "local"
# }
# ]
甚至可以创建新的容器，使用已有的数据卷
docker container run -d --name mysql3 -e MYSQL_ALLOW_EMPTY_PASSWORD=True -v mysql-db:/var/lib/mysql mysql
Volume的绑定只能使用container run，不能使用Dockerfile
挂载之后主机上的文件会覆盖掉容器内对应位置的文件
mkdir nginx
cd nginx
echo "Nginx Docker" > index.html
docker container run -d --name nginx -p 80:80 -v $(pwd):/usr/share/nginx/html nginx
echo "test" > test.txt
利用这个方式可以将数据库的数据存储在指定位置，然后通过docker更新数据库的版本。