如何使用Docker覆盖配置文件

Question

I have a Docker project with the following structure:

.
├── config
└── Dockerfile

where the Dockerfile is

FROM alpine:latest
EXPOSE 8118
RUN apk --update add privoxy
COPY config /etc/privoxy/config
CMD ["privoxy", "--no-daemon"]

and the config contains the two lines

listen-address 0.0.0.0:8118
forward-socks5 / tor:9050 .

In the container, I would like to make the Privoxy configuration file, of which the default location is /etc/privoxy (cf. https://www.privoxy.org/user-manual/config.html ), into the 'local' config file, which is what I'm trying to achieve with the COPY directive.

However, if I docker build --tag my_privoxy . followed by docker run my_privoxy , I see the following error message:

2017-05-02 10:40:29.371 7f2ce5f00b48 Info: Privoxy version 3.0.24
2017-05-02 10:40:29.371 7f2ce5f00b48 Info: Program name: privoxy
2017-05-02 10:40:29.371 7f2ce5f00b48 Fatal error: can't check configuration file '//config':  Invalid argument

I don't see how the expected location of the configuration file ends up as '//config' in the container; the use of COPY seems to me consistent with https://docs.docker.com/engine/reference/builder/#copy . What is wrong with the above Dockerfile ?

Answer 1

is /etc/privoxy/config a directory? if no, then your command should be like

COPY config /etc/privoxy/

Answer 2

According to privoxy --help , the command accepts a [configfile] optional input. So I changed the last line to

CMD ["privoxy", "--no-daemon", "/etc/privoxy/config"]

and it works. (I still don't understand why it doesn't work without the configfile input though, as /etc/privoxy/config should be the default).

Answer 3

In the container, I would like to make the Privoxy configuration file

You could mount a volume into the folder with the configuration you want. This would be done with docker run -v hostFolder:containerFolder imagename . This however will not result in a new image with the configuration instead you will get a container with the configuration you want.