update readme (#55)

README.md

@@ -4,6 +4,118 @@
 
 This repository contains the code for the validator monitoring system. The system is designed to listen signatures request from different networks validate them and store the results in a database.
 
+In dappnode, the signature request and validation flow is as follows:
+
+1. The staking brain sends the signature request of type `PROOF_OF_VALIDATION` to the web3signer (see https://github.com/Consensys/web3signer/pull/982). The request has the following format:
+```json
+{
+  "type" : "PROOF_OF_VALIDATION",
+  "platform" : "dappnode",
+  "timestamp" : "1711338489397"
+}
+```
+
+2. The web3signer answers with the `PROOF_OF_VALIDATION` signature. Its important to notice that the order of the items in the JSON matters.
+
+3. The staking brain sends back all the `PROOF_OF_VALIDATION` signatures to the the signatures monitoring system. The listener will validate the requests, the validators and the signatures and finally store the result into a mongo db.
+
+## API
+
+- `/signatures?network=<network>`:
+    - `POST`: TODO
+    - `GET`: TODO
+
+## Validation
+
+The process of validating the request and the signature follows the next steps:
+
+1. Get network query parameter from the request: it is mandatory and must be one of "mainnet", "holesy", "gnosis", "lukso". 
+2. Decode and validate the request. The request body must have the following format:
+```go
+type SignatureRequest struct {
+	Payload   string `json:"payload"`
+	Pubkey    string `json:"pubkey"`
+	Signature string `json:"signature"`
+	Tag       Tag    `json:"tag"`
+}
+```
+The payload must be encoded in base64 and must have the following format:
+```go
+type DecodedPayload struct {
+	Type      string `json:"type"`
+	Platform  string `json:"platform"`
+	Timestamp string `json:"timestamp"`
+}
+```
+3. The validators must be in status "active_on_going" according to a standard beacon node API, see https://ethereum.github.io/beacon-APIs/#/Beacon/postStateValidators: 
+    3.1 The signatures from the validators that are not in this status will be discarded. 
+    3.2 If in the moment of querying the beacon node to get the validator status the beacon node is down the signature will be accepted storing the validator status as "unknown" for later validation.
+4. Only the signatures that have passed the previous steps will be validated. The validation of the signature will be done using the pubkey from the request.
+5. Only valid signatures will be stored in the database.
+
+## Crons
+
+There are 2 cron to ensure the system is working properly:
+
+- `removeOldSignatures`: this cron will remove from the db signatures older than 30 days
+- `updateSignaturesStatus`:
+    - This cron will update the status of the validators that are in status "unknown" to "active_on_going" if the validator is active in the beacon node. 
+    - If the beacon node is down the status will remain as "unknown". 
+    - If the validator is not active the signature will be removed from the database.
+
+## Database
+
+The database is a mongo db that stores the signatures as BSON's. There are considered as unique the combination of the following fields: `network`, `pubkey`, `tag`. In order to keep the size of the database as small as possible there is a `entries` collection that stores the payload signature and decodedPayload of each request.
+
+The BSON of each unique validator has the following format:
+```go
+bson.M{
+    "pubkey":  req.Pubkey,
+    "tag":     req.Tag,
+    "network": network,
+    "entries": bson.M{
+            "payload":   req.Payload,
+            "signature": req.Signature,
+            "decodedPayload": bson.M{
+                "type":      req.DecodedPayload.Type,
+                "platform":  req.DecodedPayload.Platform,
+                "timestamp": req.DecodedPayload.Timestamp,
+            },
+        },
+	}
+```
+
+**Mongo db UI**
+
+There is a express mongo db UI that can be accessed at `http://localhost:8080`. If its running in dev mode and the compose dev was deployed on a dappnode environment then it can be access through http://ui.dappnode:8080
+
+## Environment variables
+
+See `.env.example` file for the list of environment variables that can be set.
+
+```env
+MONGO_INITDB_ROOT_USERNAME=
+MONGO_INITDB_ROOT_PASSWORD=
+MONGO_DB_API_PORT=
+API_PORT=
+LOG_LEVEL=
+BEACON_NODE_URL_MAINNET=
+BEACON_NODE_URL_HOLESKY=
+BEACON_NODE_URL_GNOSIS=
+BEACON_NODE_URL_LUKSO=
+```
+
+## Development environment
+
+To run the development environment with all the pieces of the system (web3signer, staking brain and listener with the required infra), then you can run it with the following command:
+
+```bash
+docker compose -f docker-compose.dev.yml up -d --scale brain=5
+```
+
+The flag `--scale brain=5` is optional and it will run 5 instances of the staking brain in order to simulate a real environment.
+
+
 ## Running the system
 
 **Requirements:**