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README.md

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+# HyperNet.Nexus
+
+Nexus is the core component of HyperNet,
+which managed the resources allocation (such as the database allocate and more)
+and the service gateway.
+
+## Features
+
+### Gateway
+
+Gateway is one of the core features in Nexus, every HyperNet services will establish a connection to the Nexus
+when they start. And it is required, if Nexus is died or it did not connected it successfully, the service will exit.
+
+During the registration, the service will provide follow details:
+
+1. An unique service ID - `id`
+2. The human readable name of the service - `label`
+3. The code for accessing the service - `type`
+4. The grpc outbound address of the service - `grpc_addr`
+5. The http outbound address of the service - `http_addr`
+
+There is two kind of the gateway, the grpc one and the http one.
+
+When the user requested the `/cgi/<type>`, the request was forwarded to the `http_addr`
+of the service with load balancer included.
+
+And when the internal service call `GetServiceGrpcConn(type)`, the Nexus will run a health check to ensure the
+target service is alive and respond with a `grpc_addr`, the rest of the connection will be handled by the SDK.
+It is also load balancer included.
+
+### Allocation
+
+The allocation is the additional service which make our developer experience better.
+For simple, the allocation is basically a improved version of the shared configuration.
+With some part of the configuration will be re-configured according to the service's demand.
+
+Like the database allocation, service request with the database name they want,
+and the Nexus will respond a configured connection string to the service, then the SDK will handle
+the establishment of the connection.
+
+At the same time, the allocated database will be added into the watchtower for auto maintenance
+(auto remove the soft-deleted records, backup and more).
+
+### Authorization
+
+All the request forwarded by the Nexus will handle the authorization automatically.
+The Authorization header field will be replaced by the internal one with full user data.
+
+To implement the authorization, you must have at least one [Passport](https://github.com/Solsynth/HyperNet.Passport) instance alive.
+
+For further usage, checkout the `hypernet/nexus/pkg/nex/sec` package.
+
+## Installation
+
+To run the Nexus, you need to have an etcd server and a nats server running.
+The best way to run the Nexus is using docker compose. Here is an example with the required dependencies added
+and health check configured:
+
+```yaml
+services:
+  nexus:
+    image: xsheep2010/nexus:nightly
+    network_mode: "host"
+    restart: unless-stopped
+    depends_on:
+      - nats
+      - etcd
+    volumes:
+      - "/srv/hypernet/nexus.settings.toml:/settings.toml"
+      - "/srv/hypernet/keys:/keys"
+    healthcheck:
+      test: ["CMD", "nc", "-z", "localhost", "7001"]
+      interval: 30s
+      timeout: 5s
+      retries: 5
+      start_period: 15s
+
+  nats:
+    image: nats:latest
+    network_mode: "host"
+    restart: unless-stopped
+
+  etcd:
+    image: bitnami/etcd:latest
+    network_mode: "host"
+    restart: unless-stopped
+    environment:
+      - ALLOW_NONE_AUTHENTICATION=yes
+```
+
+To add more services, you can according follow example:
+
+```yaml
+services:
+  passport:
+    image: xsheep2010/passport:nightly
+    network_mode: "host"
+    restart: unless-stopped
+    depends_on:
+      nexus:
+        condition: service_healthy
+    volumes:
+      - "/srv/hypernet/passport.settings.toml:/settings.toml"
+      - "/srv/hypernet/keys:/keys"
+```