Allow building without pushing

[mikebryant]

Context

When using tooling like Gitlab-CI, we want to be able to run the build process pre-merge, in order to validate changes

Problem

kaniko doesn't appear to allow you to run just the build without also needing credentials to push to a registry.

Solution

Allow for just the build process to run, without specifying a destination to push to.

[mikebryant]

m@hotppc17686:~/tmp/kaniko$ cat Dockerfile 
FROM library/busybox:latest
m@hotppc17686:~/tmp/kaniko$ docker run -it --rm -v ${PWD}:/workspace gcr.io/kaniko-project/executor:latest
INFO[0000] Unpacking filesystem of library/busybox:latest... 
INFO[0000] Whitelisted directories are [/kaniko /proc /dev /dev/pts /sys /sys/fs/cgroup /sys/fs/cgroup/systemd /sys/fs/cgroup/rdma /sys/fs/cgroup/net_cls,net_prio /sys/fs/cgroup/freezer /sys/fs/cgroup/memory /sys/fs/cgroup/cpu,cpuacct /sys/fs/cgroup/devices /sys/fs/cgroup/cpuset /sys/fs/cgroup/perf_event /sys/fs/cgroup/blkio /sys/fs/cgroup/hugetlb /sys/fs/cgroup/pids /dev/mqueue /workspace /etc/resolv.conf /etc/hostname /etc/hosts /dev/shm /dev/console /proc/asound /proc/bus /proc/fs /proc/irq /proc/sys /proc/sysrq-trigger /proc/kcore /proc/timer_list /proc/sched_debug /sys/firmware] 
INFO[0004] Initializing source image library/busybox:latest 
ERRO[0010] invalid reference format                     
m@hotppc17686:~/tmp/kaniko$ docker build .
Sending build context to Docker daemon 2.048 kB
Step 1/1 : FROM library/busybox:latest
 ---> 5b0d59026729
Successfully built 5b0d59026729
m@hotppc17686:~/tmp/kaniko$ 

[dlorenc]

This basically just drops the image after it's been built, as a way to validate the build "succeeds"?

[mikebryant]

@dlorenc yup. It validates that the Dockerfile syntax is correct and so on, prior to merge.

[mikebryant]

Alternatively if the build and push steps were separate commands that would be great too

[dlorenc]

We'll tackle this by adding a flag to output a tarball on disk, which is useful for other cases as well.

[dlorenc]

This should be fixed now. You can run with a --tar-path=/dev/null and it will skip the push.

[smrutimandal]

For the ones late to the party like me, add --no-push to the list of arguments.

docker run -it --rm -v ${PWD}:/workspace gcr.io/kaniko-project/executor:latest --no-push

[abdennour]

thank you @smrutimandal ! you saved my month

[DavidAntliff]

The --no-push option also requires the --cache-repo option, presumably as the --destination option is no longer required, and possibly even ignored if specified?

On the other hand, with the --tar-path option (which is now --tarPath), kaniko still makes use of the cache implied by --destination.