建议使用最小化的image.

RUN

有依赖的指令, 最好使用&&写在一条指令中, 例如
RUN apt-get update && apt-get install -y package-bar package-foo package-baz比较长的指令, 最好分行, 并排序
RUN apt-get update && apt-get install -y \aufs-tools \automake \btrfs-tools \build-essential \curl \dpkg-sig \git \iptables \libapparmor-dev \libcap-dev \libsqlite3-dev \lxc=1.0* \mercurial \parallel \reprepro \ruby1.9.1 \ruby1.9.1-dev \s3cmd=1.1.0*

ENV

可用于设置路径, 软件需要的特殊环境变量, 或者便于管理的环境变量等.
使用docker inspect可查.
For example, ENV PATH /usr/local/nginx/bin:$PATH will ensure that CMD [“nginx”] just works.
The ENV instruction is also useful for providing required environment variables specific to services you wish to containerize, such as Postgres’s PGDATA.
Lastly, ENV can also be used to set commonly used version numbers so that version bumps are easier to maintain, as seen in the following example:ENV PG_MAJOR 9.3
ENV PG_VERSION 9.3.4
RUN curl -SL http://example.com/postgres-$PG_VERSION.tar.xz | tar -xJC /usr/src/postgress && …
ENV PATH /usr/local/postgres-$PG_MAJOR/bin:$PATH

ADD & COPY

一般建议使用COPY, 如果要下载URL到image, 建议使用wget或curl ,然后解压.
For example, you should avoid doing things like:
ADD http://example.com/big.tar.xz /usr/src/things/
RUN tar -xJf /usr/src/things/big.tar.xz -C /usr/src/things
RUN make -C /usr/src/things allAnd instead, do something like:
RUN mdkir -p /usr/src/things \&& curl -SL http://example.com/big.tar.gz \| tar -xJC /usr/src/things \&& make -C /usr/src/things all不需要帮忙自动解压的地方, 建议使用COPY.

#!/bin/bash
set -eif [ "$1" = 'postgres' ]; thenchown -R postgres "$PGDATA"if [ -z "$(ls -A "$PGDATA")" ]; thengosu postgres initdbfiexec gosu postgres "$@"
fiexec "$@"

另一个例子 :

(for example, docker run -it mysql mysqld --some --flags will transparently run mysqld --some --flags after ENTRYPOINT runs initdb).

mysql的ENTRYPOINT脚本 :

#!/bin/bash
set -eif [ -z "$(ls -A /var/lib/mysql)" -a "${1%_safe}" = 'mysqld' ]; thenif [ -z "$MYSQL_ROOT_PASSWORD" ]; thenecho >&2 'error: database is uninitialized and MYSQL_ROOT_PASSWORD not set'echo >&2 '  Did you forget to add -e MYSQL_ROOT_PASSWORD=... ?'exit 1fimysql_install_db --user=mysql --datadir=/var/lib/mysql# These statements _must_ be on individual lines, and _must_ end with# semicolons (no line breaks or comments are permitted).# TODO proper SQL escaping on ALL the things D:TEMP_FILE='/tmp/mysql-first-time.sql'cat > "$TEMP_FILE" <<-EOSQLDELETE FROM mysql.user ;CREATE USER 'root'@'%' IDENTIFIED BY '${MYSQL_ROOT_PASSWORD}' ;GRANT ALL ON *.* TO 'root'@'%' WITH GRANT OPTION ;DROP DATABASE IF EXISTS test ;EOSQLif [ "$MYSQL_DATABASE" ]; thenecho "CREATE DATABASE IF NOT EXISTS $MYSQL_DATABASE ;" >> "$TEMP_FILE"fiif [ "$MYSQL_USER" -a "$MYSQL_PASSWORD" ]; thenecho "CREATE USER '$MYSQL_USER'@'%' IDENTIFIED BY '$MYSQL_PASSWORD' ;" >> "$TEMP_FILE"if [ "$MYSQL_DATABASE" ]; thenecho "GRANT ALL ON $MYSQL_DATABASE.* TO '$MYSQL_USER'@'%' ;" >> "$TEMP_FILE"fifiecho 'FLUSH PRIVILEGES ;' >> "$TEMP_FILE"set -- "$@" --init-file="$TEMP_FILE"
fichown -R mysql:mysql /var/lib/mysql
exec "$@"

使用例子 :

COPY ./docker-entrypoint.sh /
ENTRYPOINT ["/docker-entrypoint.sh"]

[参考]