This component will automatically adapt to different service discovery
frameworks, such as nacos, consul, zookeeper, etc？
Zexuan Luo <spacewan...@apache.org> 于2021年7月6日周二 下午6:07写道：
> Currently, we do service discovery on the DP side. Each APISIX
> instance talks with the service discovery service directly, asks for
> new nodes.
>
> This service discovery framework has been in use for over a year and
> has identified a number of issues.
> 1. each APISIX instance needs to pull data from inside the service
> discovery system, which complicates the network topology.
> 2. each service discovery data has to store a list of services on each
> APISIX worker
> 3. Service discovery configuration needs to be configured once per
> APISIX instance. For example, if you want to change a password, you
> need to modify the configuration file and then publish it to each
> APISIX.
>
> That's why we design the v2 service discovery framework. This version
> is similar to the previous one, but there are two differences:
> 1. Service discovery is placed at the CP side. We will introduce a new
> component to do this.
> 2. The updated data is written to etcd if there are changes, which are
> synchronized to each APISIX instance. Each instance sees the latest
> node information, and no longer needs to do service discovery itself.
>
> We don't need to do any modifications to APISIX itself. APISIX writes
> data like this:
>
> ```
> "upstream": {
> "type": "roundrobin",
> "service_name": "APISIX-NACOS",
> "discovery_type": "nacos",
> "discovery_args": {
> "namespace_id": "test_ns"
> }
> }
> ```
>
> Then a separate component rewrites this data to:
>
> ```
> "upstream": {
> "nodes": {
> "1.2.3.4:80":1
> },
> "type": "roundrobin",
> "_service_name": "APISIX-NACOS",
> "_discovery_type": "nacos",
> "discovery_args": {
> "namespace_id": "test_ns"
> }
> }
> ```
>
> The component will watch upstream with "discovery_type" and
> "_discovery_type", and make sure they are up-to-date.
>
> Service discovery was localized, but now it is centralized. New nodes
> are discovered top-down from the center.
>
> This solves the above problems:
> 1. the network topology becomes simpler
> 2. the total data volume becomes smaller
> 3. it is easier to manage
>
> But it also has some drawbacks.
> 1. if the component is not available, the latest node information will
> not be available for each instance
> 2. the pressure on etcd will increase
>
