From 8c8ecd8da1b81809876105aba2dd48b10e6ba63a Mon Sep 17 00:00:00 2001 From: Abhishek Kumar Date: Mon, 20 Jul 2015 16:37:50 -0700 Subject: Initial draft of a naming proposal. First draft for public review and comments. Some code formatting is still broken. --- doc/naming.md | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) create mode 100644 doc/naming.md (limited to 'doc/naming.md') diff --git a/doc/naming.md b/doc/naming.md new file mode 100644 index 0000000000..e9101db991 --- /dev/null +++ b/doc/naming.md @@ -0,0 +1,51 @@ +gRPC Naming and Discovery Support + +Hongwei Yang, Craig Tiller, Eric Anderson, Abhishek Kumar + +# Overview + +gRPC supports DNS as the default name-system. A number of alternative name-systems are used in various deployments. We propose an API that is general enough to support a range of name-systems and the corresponding syntax for names. The gRPC client library in various languages will provide a plugin mechanism so resolvers for different name-systems can be plugged in. + +# Detailed Proposal + + A fully qualified, self contained name used for gRPC channel construction uses the syntax: + +scheme://authority/endpoint_name + +Here, scheme indicates the name-system to be used. Example schemes to be supported include: + +* dns + +* zookeeper + +* etcd + +Authority indicates some scheme-specific bootstrap information, e.g., for DNS, the authority may include the IP[:port] of the DNS server to use. Often, a DNS name may used as the authority, since the ability to resolve DNS names is already built into all gRPC client libraries. + +Finally, the endpoint_name indicates a concrete name to be looked up in a given name-system identified by the scheme and the authority. The syntax of endpoint name is dictated by the scheme in use. + +## Plugins + +The gRPC client library will switch on the scheme to pick the right resolver plugin and pass it the fully qualified name string. + +Resolvers should be able to contact the authority and get a resolution that they return back to the gRPC client library. The returned contents include a list of IP:port, an optional config and optional auth config data to be used for channel authentication. The plugin API allows the resolvers to continuously watch an endpoint_name and return updated resolutions as needed. + +# Zookeeper + +Apache [ZooKeeper](https://zookeeper.apache.org/) is a popular solution for building name-systems. Curator is a service discovery system built on to of ZooKeeper. We propose to organize names hierarchically as /path/service/instance similar to Apache Curator. + +A fully-qualified ZooKeeper name used to construct a gRPC channel will look as follows: + +zookeeper://host:port/path/service/instance + +Here zookeeper is the scheme identifying the name-system. host:port identifies an authoritative name-server for this scheme (i.e., a Zookeeper server). The host can be an IP address or a DNS name. +Finally /path/service/instance is the Zookeeper name to be resolved. + +## Service Registration + + +Service providers can register their services in Zookeeper by using a Zookeeper client. + +Each service is a zookeeper node, and each instance is a child node of the corresponding service. For example, a MySQL service may have multiple instances, /mysql/1, /mysql/2, /mysql/3. The name of the service or instance, as well as an optional path is specified by the service provider. + +The data in service nodes is empty. Each instance node stores its address in the format of host:port, where host can be either hostname or IP address. -- cgit v1.2.3