Added a pgbouncer container to allow more then 100 simultaneous processes

The docker-compose environment:

• zookernel: the zoo-kernel container built with python, javascript, postgresql, OAS
• pg: the postgresql container with defaut configuration (max_connections=100)
• pgbouncer: the pgbouncer container with max_client_conn=1000

include a python script to test the max_client_conn setting:

` python docker/test_long_process.py 900 `

Patch generated with:

` diff -ruN ../ZOO-Project.orig/ . > ../docker-clean.patch `

This patch adds:

• a Dockerfile for building the zoo-kernel with some modules
• a docker-compose.yml file with zoo-kernel and postgresql
• a docker folder containing various configuration files

Hi,

We used zooproject in a clustered mode. So we have a database backend to share ongoing informations of running services between 2 ZOO-Kernel instances. When the load on the cluster increases, some requests fails due to databases errors :

ERROR 1: ERROR: duplicate key value violates unique constraint "services_osid_key" DÉTAIL : Key (osid)=(1593003150) already exists. ERROR 1: ERROR: insert or update on table "responses" violates foreign key constraint "responses_uuid_fkey" DÉTAIL : Key (uuid)=(519e1ea2-b481-11ea-917c-005056b8dc20) is not present in table "services".

• The osid value calculated by the kernel is not unique

The osid is calculated by the script zoo-project/zoo-kernel/zoo_service_loader.c (line 830) : sprintf (tmpBuff, "%i", (cpid + ((int) tp.tv_sec + (int) tp.tv_usec)));

• In some cases, the PID variation is cancelled by the timestamp variation