PLEASE NOTE

THIS PROJECT MAY NOW BE OBSOLETE

docker's experimental buildkit seems to suffice with an unpatched ccache:

RUN --mount=type=cache,target=/tmp/ccache CCACHE_DIR=/tmp/ccache make

ccache-memcached-server

A docker container hosting a ccache over the memcached protocol to speed up builds

To use ccache persisted between docker builds, you need two things:

• a server (docker container) hosting the ccache server
• a patched ccache in your container to use this memcache

The ccache server

Setup a network and launch the server:

docker network create ci_network
docker run --rm --name ccache --network ci_network --network-alias ccache webhare/ccache-memcached-server:latest

We recommend mounting a data volume over /opt/memcache-data so that any cached compilations are persisted when the container is restarted, but this is not strictly necessary.

For more info about the container, see [server/]

The patched ccache

Your container needs to build this version of ccache: https://github.com/WebHare/ccache/tree/memcached-scopefix

(this part probably needs to be improved, either by setting up base containers with this ccache version preinstalled, or ideally, by getting the changes back into core and getting all distributions to ship them)

You will also need to make sure your build actually uses ccache, and invokes it with the proper parameters to connect to to the memcache, ie prefix all gcc, g++ etc invocations with ccache --SERVER=ccache

Finally, your docker build instructions will also need to add --network ci_network

See the [example/Dockerfile] for an example of how to build and configure it.

Example/test

# Run the example with ccache, forcing memcached, and ensuring the last few steps are always run
docker build --build-arg CCACHE_MEMCACHED_CONF=--SERVER=ccache \
             --build-arg CACHEBUST=$$ \
             --network ci_network \
             example