编写Dockerfiles

指令

docker build通过Dockerfile制作镜像

docker build [PATH] [-f Dockerfile]

其中PATH不写，默认执行指令的当前目录，不要用 /,这样将导致整个操作系统复制到镜像中

ENV

定义环境变量

ENV abc=hello
ENV abc=bye def=$abc
ENV ghi=$ab

使用环境变量

WORKDIR ${foo}   # WORKDIR /bar
ADD . $foo       # ADD . /bar
COPY \$foo /quux # COPY $foo /quux

.dockerignore

# comment
*/temp*
*/*/temp*
temp?

RULE	Behavior

comment| Ignored.

/temp | Exclude files and directories whose names start with temp in any immediate subdirectory of the root. For example, the plain file /somedir/temporary.txt is excluded, as is the directory /somedir/temp.
//temp* | Exclude files and directories starting with temp from any subdirectory that is two levels below the root. For example, /somedir/subdir/temporary.txt is excluded.
temp? | Exclude files and directories in the root directory whose names are a one-character extension of temp. For example, /tempa and /tempb are excluded.

FROM 母镜像

FROM <image>[:<tag>] [AS <name>]

Dockerfile通过ARG设置编译变量,通过${xxxx}在编译过程中调用

ARG  CODE_VERSION=latest
FROM base:${CODE_VERSION}
CMD  /code/run-app

FROM extras:${CODE_VERSION}
CMD  /code/run-extras

RUN 镜像制作指令

用于制作镜像过程之中，执行指令，比如拷贝文件，删除文件。

RUN [/bin/sh -c | cmd /S /C ]

linux下，默认采用 /bin/sh -c

window下，默认采用 cmd /S /C

RUN ["executable", "param1", "param2"]

不像shell form ,exec form 不用直接通过shell命令运行，比如 RUN [ "echo", "$HOME" ]就不会运行，如果希望exce from像shell form那样运行，必须写成RUN [ "sh", "-c", "echo $HOME" ]

CMD 容器启动默认执行脚本

• CMD ["executable","param1","param2"] (exec form, this is the preferred form)
• CMD ["param1","param2"] (as default parameters to ENTRYPOINT)
• CMD command param1 param2 (shell form)

CMD 节点在Dockerfile只能有一个，如果有多个CMD的话，最后出现的CMD生效，其他的忽略
CMD节点目的是给容器提供一个默认的运行指令。

LABEL 镜像标签

示例

LABEL "com.example.vendor"="ACME Incorporated"
LABEL com.example.label-with-value="foo"
LABEL version="1.0"
LABEL description="This text illustrates \
that label-values can span multiple lines."

EXPOSE 监听端口

EXPOSE <port> [<port>/<protocol>...]

EXPOSE 80/tcp
EXPOSE 80/udp

容器中定义好监听端口后，在docker run中如果不用 -p 重新指定监听端口，将直接默认端口映射出去

docker run -p 80:80/tcp -p 80:80/udp

ENV 镜像环境变量

ENV <key> <value>
ENV <key>=<value> ...

示例：

ENV myName="John Doe" myDog=Rex\ The\ Dog \
    myCat=fluffy
ENV myName John Doe
ENV myDog Rex The Dog
ENV myCat fluffy    

在docker run中可以通过 --env 重写参数

docker run --env <key>=<value>

ADD

• ADD [--chown=:] ...
• ADD [--chown=:] ["",... ""] (this form is required for paths containing whitespace)

ADD hom* /mydir/        # adds all files starting with "hom"
ADD hom?.txt /mydir/    # ? is replaced with any single character, e.g., "home.txt"

COPY

• COPY [--chown=:] ...
• COPY [--chown=:] ["",... ""] (this form is required for paths containing whitespace)

COPY hom* /mydir/ # adds all files starting with "hom"

COPY hom?.txt /mydir/ # ? is replaced with any single character, e.g., "home.txt"

ENTRYPOINT

• ENTRYPOINT ["executable", "param1", "param2"] (exec form, preferred)
• ENTRYPOINT command param1 param2 (shell form)

WORKDIR

ENV DIRPATH /path
WORKDIR $DIRPATH/$DIRNAME
RUN pwd