I'm trying to simply create a dockerfile that installs wget and unzip on a centOS image. This is the file:
FROM centos:latest
EXPOSE 9000
RUN echo "proxy=http://xxx.xxx.xxx.xxx:x" >> /etc/yum.conf \
&& echo "proxy_username=username" >> /etc/yum.conf \
&& echo "proxy_password=password" >> /etc/yum.conf \
&& yum update \
&& yum -y install wget unzip
...
When I run the build it resolves the dependencies just fine but it doesn't seem to be honoring the -y flag and assuming yes for any prompts:
Total download size: 61 M
Is this ok [y/d/N]: Exiting on user command
Your transaction was saved, rerun it with:
yum load-transaction /tmp/yum_save_tx.2018-08-08.21-22.Q7f8LW.yumtx
The command '/bin/sh -c yum update && yum -y install wget unzip' returned
a non-zero code: 1
I've used the -y flag in this situation many times and have never had any trouble. It doesn't seem like this could be a caching issue but I have no idea what's going on. I also tried yum install -y wget unzip just for good measure but still no luck (as expected). I've searched stackoverflow but it seems like anyone with the same issue just wasn't using the -y flag. Any guidance would be appreciated because I don't know what could be going wrong with such a simple file.
It looks like you're missing the -y on the yum update.
Also, you should split those commands out to separate RUN commands. In this case, it doesn't make too much difference, but splitting the echos onto different lines will make it clearer.
You should keep the update and installs in the same command though
https://docs.docker.com/develop/develop-images/dockerfile_best-practices/#run
Related
I use the following Dockerfile to build an image and start a container. But once I am in the container, I still can not find manpages. Does anybody know how to solve this problem?
$ cat Dockerfile
FROM ubuntu
RUN apt -y update && apt -y upgrade
RUN apt-get -y install build-essential
RUN apt-get -y install vim
RUN apt-get -y install man
RUN apt-get -y install gawk
RUN apt-get -y install mawk
$ man man
No manual entry for man
See 'man 7 undocumented' for help when manual pages are not available.
$ find /usr/share/man /usr/local/share/man -type f
You need to make a change to your /etc/dpkg/dpkg.cfg.d/excludes within the container. You can do this in your Dockerfile with the following command:
RUN sed -i 's:^path-exclude=/usr/share/man:#path-exclude=/usr/share/man:' \
/etc/dpkg/dpkg.cfg.d/excludes
Then make another update to your Dockerfile to install the man pages
RUN apt-get update && \
apt-get install -y \
man \
manpages-posix
There is a easier way to enable the MAN command.
In terminal, just execute the command below:
unminimize
It will ask if you like to continue [Y/n]
Just press:
Y
It will take a while to finish all the processing.
After that, test this:
man man
Simple as that
Thanks to #kazushi
I have a Dockerfile that looks like this:
FROM debian:stable-slim
RUN apt-get update && \
apt-get install -y --no-install-recommends fp-compiler fp-units-fcl fp-units-net libc6-dev
COPY src /whatwg/wattsi/src
WORKDIR /whatwg/wattsi/src
RUN ./build.sh
RUN rm -rf /whatwg/wattsi/src && \
apt-get purge -y fp-compiler fp-units-fcl fp-units-net libc6-dev && \
apt-get autoremove -y
ENTRYPOINT ["/whatwg/wattsi/bin/wattsi"]
As you can see, there are three separate RUN steps: one to install dependencies, one to build, and one to cleanup after building.
I've been poking around to try to figure out why the resulting image is relatively large, and it seems like it's because, even though I do a cleanup step, a layer is retained containing all the installed dependencies.
Should I restructure my Dockerfile like so?
FROM debian:stable-slim
COPY src /whatwg/wattsi/src
WORKDIR /whatwg/wattsi/src
RUN apt-get update && \
apt-get install -y --no-install-recommends fp-compiler fp-units-fcl fp-units-net libc6-dev && \
./build.sh && \
rm -rf /whatwg/wattsi/src && \
apt-get purge -y fp-compiler fp-units-fcl fp-units-net libc6-dev && \
apt-get autoremove -y
ENTRYPOINT ["/whatwg/wattsi/bin/wattsi"]
This feels a bit "squashed", and I can't find any documentation explicitly recommending it. All the documentation that says "minimize RUN commands" seems to focus on not doing multiple apt-get steps; it doesn't talk about squashing everything into one. But maybe it's the right thing to do?
Each layer in a Docker image is like a commit in version control, in can't change previous layers just like deleting a file in Git won't remove it from from history. So deleting a file from a previous layer doesn't make the image smaller.
Since layers are created at the end of RUN, doing what you're doing is indeed one way to make smaller images. The other, as someone mentioned, is multi-stage builds.
The downside of the single RUN variant is that you have to rerun the whole thing every time source code changes. So you need to apt-get all those packages each time instead of relying on Docker's build caching (I wrote a thing explaining the caching here: https://pythonspeed.com/articles/docker-caching-model/).
So multi-stage lets you have both faster builds via caching, and small images. But it's complicated to get right, what you did is simpler and easier.
I use the following Dockerfile to build an image and start a container. But once I am in the container, I still can not find manpages. Does anybody know how to solve this problem?
$ cat Dockerfile
FROM ubuntu
RUN apt -y update && apt -y upgrade
RUN apt-get -y install build-essential
RUN apt-get -y install vim
RUN apt-get -y install man
RUN apt-get -y install gawk
RUN apt-get -y install mawk
$ man man
No manual entry for man
See 'man 7 undocumented' for help when manual pages are not available.
$ find /usr/share/man /usr/local/share/man -type f
You need to make a change to your /etc/dpkg/dpkg.cfg.d/excludes within the container. You can do this in your Dockerfile with the following command:
RUN sed -i 's:^path-exclude=/usr/share/man:#path-exclude=/usr/share/man:' \
/etc/dpkg/dpkg.cfg.d/excludes
Then make another update to your Dockerfile to install the man pages
RUN apt-get update && \
apt-get install -y \
man \
manpages-posix
There is a easier way to enable the MAN command.
In terminal, just execute the command below:
unminimize
It will ask if you like to continue [Y/n]
Just press:
Y
It will take a while to finish all the processing.
After that, test this:
man man
Simple as that
Thanks to #kazushi
I'm trying to create a Docker image for ripping CDs (using abcde).
Here's the relevant portion of the Dockerfile:
FROM ubuntu:17.10
MAINTAINER Graham Nicholls <graham#rockcons.co.uk>
RUN apt update && apt -y install eject vim ruby abcde
...
Unfortunately, the package "abcde" pulls in a mail client (not sure which), and apt tries to configure that by asking what type of mail connection to configure (smarthost/relay etc).
When docker runs, it's not appearing to read from stdin, so I can't redirect into the docker process.
I've tried using --nodeps with apt (and replacing apt with apt-get); unfortunately --nodeps seems no-longer to be a supported option and returns:
E: Command line option --nodeps is not understood in combination with the other options
Someone has suggested using expect in response to a similar question, which I'd rather avoid. This seems to be a "difficult to google" problem - I can't find anything.
So, is there a way of passing in the answer to the config in apt, or of preventing apt from pulling in a mail client, which would be better - I'm not planning in sending updates to cddb.
The typical template to install apt packages in a docker container looks like:
RUN apt-get update \
&& DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
eject \
vim \
ruby \
abcde \
&& apt-get clean \
&& rm -rf /var/lib/apt/lists/*
Running it with the "noninteractive" value removes any prompts. You don't want to set that as an ENV since that would also impact any interactive commands you run inside the container.
You also want to cleanup the package database when finished to reduce the layer size and avoid reusing a stale cached package database in a later step.
The no-install-recommends option will reduce the number of packages installed by only installing the required dependencies, not the additional recommended packages. This cuts the size of the root filesystem down by half for me.
If you need to pass a non-default configuration to a package, then use debconf. First run you install somewhere interactively and enter the options you want to save. Install debconf-utils. Then run:
debconf-get-selections | grep "${package_name}"
to view all the options you configured for that package. You can then pipe these options to debconf-set-selections in your container before running your install, e.g.:
RUN echo "postfix postfix/main_mailer_type select No configuration" \
| debconf-set-selections \
&& apt-get update \
&& DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
....
or save your selections to a file that you copy in:
COPY debconf-selections /
RUN debconf-set-selections </debconf-selections \
&& apt-get update \
&& DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
....
I have a Dockerfile that works, but if I add any new dependencies to the apt-get install command, it fails. For example, this works:
FROM debian:stable
RUN apt-get update
RUN apt-get install -y \
python \
...
apache2
But if I try this, it fails:
FROM debian:stable
RUN apt-get update
RUN apt-get install -y \
python \
...
apache2
python-mysqldb
I can replace python-mysqldb with anything else, git-core, for example, and it will still fail with the same error message:
Unable to correct missing packages.
E: Failed to fetch http://security.debian.org/pool/updates/main/l/linux/linux-libc-dev_3.16.7-ckt11-1+deb8u5_amd64.deb 404 Not Found [IP: 149.20.20.6 80]
E: Aborting install.
Any thoughts on why adding a new dependency causes the failure and how to fix it?
I've found that you need to join the update & install command into the same RUN block.
eg:
RUN apt-get update \
&& apt-get install -y \
python \
...
apache2 \
python-mysqldb
According to this post describing the issue
By default, Docker cache your commands to reduce time spent building
images. Unless there was any change before such commands (or at the
same line).
Meanwhile, I notice that the AWS examples separate them, as you have them. So I dunno if it works different there. Maybe they disable the cache by default.