[test] improve docker scripts README file

1 files changed, 28 insertions, 12 deletions

diff --git a/scripts/docker/README.md b/scripts/docker/README.md
index 101db837..c4d7ac94 100644
--- a/scripts/docker/README.md
+++ b/scripts/docker/README.md
@@ -7,17 +7,18 @@ especially useful for testing purposes as you can limit/reserve a certain
 amount of resources for the soledad process, and thus provide a baseline for
 comparison of time and resource consumption between distinct runs.
 
-Check the `Dockerfile` for the rules for building the docker image.
+Check the `Dockerfile` for the steps for creating the docker image.
 
-Check the `Makefile` for example usage of the files in this directory.
+Check the `Makefile` for the rules for running containers.
 
+Check the `helper/` directory for scripts that help running tests.
 
-Environment variables for server script
----------------------------------------
 
-If you want to run the image for testing you may pass the following
-environment variables for the `files/start-server.sh` script for checking out
-a specific branch on the soledad repository:
+Environment variables for docker containers
+-------------------------------------------
+
+Different environment variables can be set for docker containers and will
+cause the scripts to behave differently:
 
   SOLEDAD_REMOTE - a git url for a remote repository that is added at run time
                    to the local soledad git repository.
@@ -25,9 +26,24 @@ a specific branch on the soledad repository:
   SOLEDAD_BRANCH - the name of a branch to be checked out from the configured
                    remote repository.
 
-Example:
+  SOLEDAD_PRELOAD_NUM - The number of documents to be preloaded in the
+                        container database (either client or server).
+
+  SOLEDAD_PRELOAD_SIZE - The size of the payload of the documents to be
+                         prelaoded in the container database (either client or
+                         server).
+
+  SOLEDAD_SERVER_URL - The URL of the soledad server to be used during the
+                       test.
+
+Check the Makefile for examples on how to use these and maybe even other
+variables not documented here.
+
+
+Communication between client and server containers
+--------------------------------------------------
 
-  docker run \
-    --env="SOLEDAD_REMOTE=https://0xacab.org/leap/soledad.git" \
-    --env="SOLEDAD_BRANCH=develop" \
-    leap/soledad:1.0 /usr/local/soledad/start-server.sh
+A CONTAINER_ID_FILE variable can be passed to the Makefile target so that the
+container id is recorded in a file for further use. This makes it possible to
+extract a container's IP and pass it to another container so they can
+communicate.