Registry

This is the central registry of applications we build. The main use cases:

• assign unique ports to each application

• manage port numbers so there is some logic to their assignment to minimize human friction long term and help humans understand what type of application is running based on port number

• support docker for development environments

The design of the system includes:

• services which have names (e.g. postgresql) and default ports (e.g. 5432). This enables identifying consistently the internal ports an application users.

• applications which are services w/ a list of assigned ports. These ports map the internal port numbers to a globally unique external port number.

• declared dependencies on other applications. This can be used to, for example, generate the appropriate sequence in which to start the applications so that they their dependencies are started in order. Note that we enforce that there can be no cyclical dependencies.

CLI

See https://github.com/flowcommerce/workstation/blob/main/bin/registry

API

Create the application and allocates a single port for it. Note that the implementation leaves room adjacent to the allocated port so that if you need another port in the future it is likely to be sequential.

curl -d id=splashpage -d service=play http://registry.api.flow.io/applications

curl -d id=www -d service=nodejs http://registry.api.flow.io/applications

curl -d id=splashpage-postgresql -d service=nodejs http://registry.api.flow.io/applications

or you can use PUT which will upsert the application, as well as allocate a port for this service if not already allocated.

curl -X PUT -d service=play http://registry.api.flow.io/applications/splashpage

Notes:

We also provide consistent external port allocations based on the service name:

• nodejs: 0
• play: 1
• postgresql: 9

Example allocations:

splashpage:
  www: 7000
  api: 7001
  psql: 7009

user
  www: 7010
  api: 7011
  psql: 7019