Editing Files from dockerfile

DockerDockerfile

Docker Problem Overview

I need to add several lines to /etc/sysctl.conf in a Docker image.

Is there an idempotent way to do this via a Dockerfile rather than editing manually and using the docker commit approach?

Docker Solutions

Solution 1 - Docker

I would use the following approach in the Dockerfile

RUN   echo "Some line to add to a file" >> /etc/sysctl.conf

That should do the trick. If you wish to replace some characters or similar you can work this out with sed by using e.g. the following:

RUN   sed -i "s|some-original-string|the-new-string |g" /etc/sysctl.conf

However, if your problem lies in simply getting the settings to "bite" this question might be of help.

Solution 2 - Docker

sed work pretty well to replace stuff, if you need to append, you can user double redirect

sed -i 's/origin text/new text/g' /etc/sysctl.conf
bash -c 'echo hello world' >> /etc/sysctl.conf

-i is a non-standard option of GNU sed for inline editing (alleviating the need for dealing with temporary files).

The s is the substitute command of sed for find and replace

The g means global replace i.e. find all occurrences of origin text and replace with new text using sed

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Content TypeOriginal AuthorOriginal Content on Stackoverflow
QuestionMyles McDonnellView Question on Stackoverflow
Solution 1 - DockerwassgrenView Answer on Stackoverflow
Solution 2 - DockercreackView Answer on Stackoverflow