LGTM

LGTM

<3

Trying to understand how caching works in general in docker. I understand -no-cache will disable caching for the entire Dockerfile. But how can I disable cache for a specific RUN command? For example updating repos or downloading a remote file .. etc. From my understanding that right now RUN apt-get update if cached wouldn't actually update the repo? This will cause the results to be different than from a VM?

If it is possible to disable caching for specific commands in the Dockerfile, would the subsequent commands in the file then not use the cache? Or would they do something a bit more intelligent - e.g. use cache if the previous command result did not change even if didn't use the cache etc ?

Can someone please explain? @crosbymichael ?

Thanks,

It's not possible to disable caching selectively atm. This is mostly because I can't think of a good way to select the layer to invalidate. Suggestions are welcome :)

​

One thing you can do is remove the intermediary image used for caching - if you run "docker history" on your most recently built image, you'll see the image IDs corresponding to each build step.

—
@solomonstre
@getdocker

On Mon, Sep 23, 2013 at 11:09 AM, Mohan Raj Rajamanickam
notifications@github.com wrote:

Trying to understand how caching works in general in docker. I understand -no-cache will disable caching for the entire Dockerfile. But how can I disable cache for a specific RUN command? For example updating repos or downloading a remote file .. etc. From my understanding that right now RUN apt-get update if cached wouldn't actually update the repo? This will cause the results to be different than from a VM?
If it is possible to disable caching for specific commands in the Dockerfile, would the subsequent commands in the file then not use the cache? Or would they do something a bit more intelligent - e.g. use cache if the previous command result did not change even if didn't use the cache etc ?
Can someone please explain? @crosbymichael ?

Thanks,

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#1384 (comment)

Thanks @shykes