Emerald - a service registry

This is a simple service registry compatible with pymicroservice based services which uses JSON RPC protocol for communication and sqlalchemy for data persistance.

What is this?

This service registry tracks microservices and helps them to identify each other with little knowledge (just the location of the service registry.

This service is implemented using te pymicroservice library and exposes the following methods:

• ping(name, host, port) - registers the fact that at http://host:port/api is a service running with the name name. A service must call ping at least once every 60 seconds in order to be considered active.
• locate_service(name) - locates a service based on a given pattern (glob-like pattern). returns a list of ``{host: ..., port: ...}` (multiple instances of the same service can run at the same time).

Installation

    git clone https://github.com/vladcalin/emerald.git
    python emerald/setup.py install

To run the tests, use the command

    python emerald/setup.py test

Start the service

In order to start the service at http://0.0.0.0:5000/api, use the command

    emerald --host=0.0.0.0 --port=0.0.0.0 --dburl=sqlite:///:memory: --accesslog=access.log

The following parameters can be specified:

• --host = the address to bind

• --port = the port to bind

• --dburl = a database url (as in the sqlalchemy specifications). Here are some quick examples:

  • using SQLite: sqlite:///mydatabase.db, sqlite:////etc/run/servreg/servreg.db, sqlite://:memory:
  • using MySQL: mysql+mysqldb://<user>:<password>@<host>:<port>/<dbname> (requires mysql-python), mysql+pymysql://<user>:<password>@<host>:<port>/<dbname> (requires pymysql)
  • using Oracle with cx_oracle: oracle+cx_oracle://user:pass@host:port/dbname
  • using PostgreSQL with psycopg2: postgresql+psycopg2://user:password@host:port/dbname
  • using PostgreSQL with pg8000: postgresql+pg8000://user:password@host:port/dbname

  Note : you must install the database driver separately (except for sqlite).

• --accesslog = the file where the access log will be stored