Add truststore merger description in readme

Issue-ID: DCAEGEN2-2253
Signed-off-by: Piotr Marcinkiewicz <piotr.marcinkiewicz@nokia.com>
Change-Id: I522f40f86fd7433c9b3d3578cd819a294ea078e8

2 files changed, 79 insertions, 1 deletions

diff --git a/README.md b/README.md
index 90da14f1..c214973f 100644
--- a/README.md
+++ b/README.md
@@ -7,9 +7,10 @@ More information about the project and all its functionalities you can find unde
     https://wiki.onap.org/display/DW/OOM+Certification+Service
     ``` 
   
-Project consists of two submodules:
+Project consists of three submodules:
 1. oom-certservice-api
 2. oom-certservice-client
+3. oom-truststore-merger
 
 Detailed information about submodules can be found in ```README.md``` in their directories.
 
diff --git a/trustStoreMerger/README.md b/trustStoreMerger/README.md
new file mode 100644
index 00000000..dff8a145
--- /dev/null
+++ b/trustStoreMerger/README.md
@@ -0,0 +1,77 @@
+# Truststore merger
+
+### Project building
+```
+mvn clean package
+```
+
+### Install the package into the local repository
+```
+mvn clean install
+```
+
+### Building Docker image and  install the package into the local repository
+```
+mvn clean install -P docker
+```
+
+### Nexus container image
+```
+nexus3.onap.org:10001/onap/org.onap.oom.platform.cert-service.oom-truststore-merger:latest
+```
+
+### Running application as standalone docker container
+
+Exemplary config.env file with necessary envs
+```
+TRUSTSTORES_PATHS=/var/certs/truststore.jks:/var/certs/truststore.pem
+TRUSTSTORES_PASSWORDS_PATHS=/var/certs/truststoreJks.pass:
+```
+TRUSTSTORES_PATHS env indicates paths (separated by ":") where truststores files are located.
+
+TRUSTSTORES_PASSWORDS_PATHS env indicates paths (separated by ":") where files with passwords to truststores are located.
+PEM is not protected by password so its value should be empty
+
+Execute below command in order to run app as docker container
+```
+docker run \
+    --name oom-truststore-merger \
+    --env-file ./config.env \
+    --mount type=bind,src=<src_path>,dst=/var/certs \
+onap/org.onap.oom.platform.cert-service.oom-truststore-merger:latest
+```
+Before run replace <src_path> with absolute path where you located truststores to merge (eg. /certs/resources/)
+
+Output from merger (when pointed more than one truststore to merge in TRUSTSTORES_PATHS env) success execution should be:
+1. Created backup file (with .bak ext) of first truststore pointed in TRUSTSTORES_PATHS env
+2. First truststore pointed in TRUSTSTORES_PATHS env contains merged certificates from all truststores mentioned in TRUSTSTORES_PATHS env
+
+Remove docker container:
+```
+docker rm oom-truststore-merger
+```
+
+### Logs locally
+
+path:
+```
+var/log/onap/oom/truststore-merger/truststore-merger.log
+```
+### Logs in Docker container
+```
+docker logs oom-merger
+```
+###Exit codes
+```
+0   Success
+1   Invalid paths in environment variables
+2   Invalid merger configuration
+3   Invalid truststore file-password pair
+4   Cannot read password from file
+5   Cannot create backup file
+6   Cannot initialize keystore instance
+7   Cannot load truststore file
+8   Cannot operate on truststore data
+9   Missing truststore certificates in provided file
+10  Alias conflict detected
+11  Cannot save truststore file