Styjun

I have build a Docker image from a Docker file using the below command.

$ docker build -t u12_core -f u12_core .

When I am trying to rebuild it with the same command, it's using the build cache like:

Step 1 : FROM ubuntu:12.04
 ---> eb965dfb09d2
Step 2 : MAINTAINER Pavan Gupta <pavan.gupta@gmail.com>
 ---> Using cache
 ---> 4354ccf9dcd8
Step 3 : RUN apt-get update
 ---> Using cache
 ---> bcbca2fcf204
Step 4 : RUN apt-get install -y openjdk-7-jdk
 ---> Using cache
 ---> 103f1a261d44
Step 5 : RUN apt-get install -y openssh-server
 ---> Using cache
 ---> dde41f8d0904
Step 6 : RUN apt-get install -y git-core
 ---> Using cache
 ---> 9be002f08b6a
Step 7 : RUN apt-get install -y build-essential
 ---> Using cache
 ---> a752fd73a698
Step 8 : RUN apt-get install -y logrotate
 ---> Using cache
 ---> 93bca09b509d
Step 9 : RUN apt-get install -y lsb-release
 ---> Using cache
 ---> fd4d10cf18bc
Step 10 : RUN mkdir /var/run/sshd
 ---> Using cache
 ---> 63b4ecc39ff0
Step 11 : RUN echo 'root:root' | chpasswd
 ---> Using cache
 ---> 9532e31518a6
Step 12 : RUN sed -i 's/PermitRootLogin without-password/PermitRootLogin yes/' /etc/ssh/sshd_config
 ---> Using cache
 ---> 47d1660bd544
Step 13 : RUN sed 's@sessions*requireds*pam_loginuid.so@session optional pam_loginuid.so@g' -i /etc/pam.d/sshd
 ---> Using cache
 ---> d1f97f1c52f7
Step 14 : RUN wget -O aerospike.tgz 'http://aerospike.com/download/server/latest/artifact/ubuntu12'
 ---> Using cache
 ---> bd7dde7a98b9
Step 15 : RUN tar -xvf aerospike.tgz
 ---> Using cache
 ---> 54adaa09921f
Step 16 : RUN dpkg -i aerospike-server-community-*/*.deb
 ---> Using cache
 ---> 11aba013eea5
Step 17 : EXPOSE 22 3000 3001 3002 3003
 ---> Using cache
 ---> e33aaa78a931
Step 18 : CMD /usr/sbin/sshd -D
 ---> Using cache
 ---> 25f5fe70fa84
Successfully built 25f5fe70fa84

The cache shows that aerospike is installed. However, I don't find it inside containers spawn from this image, so I want to rebuild this image without using the cache. How can I force Docker to rebuild a clean image without the cache?

There's a --no-cache option:

docker build --no-cache -t u12_core -f u12_core .

In older versions of Docker you needed to pass --no-cache=true, but this is no longer the case.

In some extreme cases, your only way around recurring build failures is by running:

docker system prune

The command will ask you for your confirmation:

WARNING! This will remove:
 - all stopped containers
 - all volumes not used by at least one container
 - all networks not used by at least one container
 - all images without at least one container associated to them
Are you sure you want to continue? [y/N]

This is of course not a direct answer to the question, but might save some lives... It did save mine.

The command docker build --no-cache . solved our similar problem.

Our Dockerfile was:

RUN apt-get update
RUN apt-get -y install php5-fpm

But should have been:

RUN apt-get update && apt-get -y install php5-fpm

To prevent caching the update and install separately.

See: Best practices for writing Dockerfiles

I would not recommend using --no-cache in your case.

You are running a couple of installations from step 3 to 9 (I would, by the way, prefer using a one liner) and if you don't want the overhead of re-running these steps each time you are building your image you can modify your Dockerfile with a temporary step prior to your wget instruction.

I use to do something like RUN ls . and change it to RUN ls ./ then RUN ls ./. and so on for each modification done on the tarball retrieved by wget

You can of course do something like RUN echo 'test1' > test && rm test increasing the number in 'test1 for each iteration.

It looks dirty, but as far as I know it's the most efficient way to continue benefiting from the cache system of Docker, which saves time when you have many layers...

You can manage the builder cache with docker builder