docs: build_via_docker.sh

Author: lilith

README.md

@@ -107,12 +107,13 @@ All build scripts support `VALGRIND=True` to enable valgrind instrumentation of
 
 ## Docker (linux/macOS/WinUbuntu)
 
+This will create caches within `~/.docker_imageflow_caches` specific to the docker image used. Instances will be ephemeral; the only state will be in the caches.
+
 ```bash
-docker pull imazen/imageflow_build_ubuntu16
-cd ci
-./simulate_travis.sh imazen/imageflow_build_ubuntu16
+./build_via_docker.sh debug
 ```
 
+
 ## Linux
 
 We need quite a few packages in order to build all dependencies. You probably have most of these already.

build_via_docker.sh

@@ -4,6 +4,9 @@ set -e #Exit on failure.
 # Change directory to root (call this in a subshell if you have a problem with that)
 cd "$( dirname "${BASH_SOURCE[0]}" )"
 
+# To remove (the LARGE) caches this writes to your home directory 
+# rm -rf ~/.docker_imageflow_caches
+
 cd ci 
 
 export OVERRIDE="$1"