node: Document that --node-id must be unique but constant between res…

…tarts

README.md

@@ -117,11 +117,13 @@ OPTIONS:
         --ethereum-ws <NETWORK_NAME:[CAPABILITIES]:URL>
             Ethereum network name (e.g. 'mainnet'), optional comma-seperated capabilities (eg `full,archive), and an Ethereum WebSocket URL, separated by a ':'
 
+        --node-id <NODE_ID>
+            A unique identifier for this node instance. Should have the same value between consecutive node restarts [default: default]
+
         --http-port <PORT>                            Port for the GraphQL HTTP server [default: 8000]
         --ipfs <HOST:PORT>                            HTTP address of an IPFS node
-        --node-id <NODE_ID>                           a unique identifier for this node [default: default]
         --postgres-url <URL>                          Location of the Postgres database used for storing entities
-        --subgraph <[NAME:]IPFS_HASH>                 name and IPFS hash of the subgraph manifest
+        --subgraph <[NAME:]IPFS_HASH>                 Name and IPFS hash of the subgraph manifest
         --ws-port <PORT>                              Port for the GraphQL WebSocket server [default: 8001]
 ```
 

docs/environment-variables.md

@@ -125,7 +125,8 @@ those.
 
 - `GRAPH_NODE_ID`: sets the node ID, allowing to run multiple Graph Nodes
   in parallel and deploy to specific nodes; each ID must be unique among the set
-  of nodes.
+  of nodes. A single node should have the same value between consecutive restarts.
+  Subgraphs get assigned to node IDs and are not reassigned to other nodes automatically.
 - `GRAPH_LOG`: control log levels, the same way that `RUST_LOG` is described
   [here](https://docs.rs/env_logger/0.6.0/env_logger/)
 - `THEGRAPH_STORE_POSTGRES_DIESEL_URL`: postgres instance used when running

node/src/bin/manager.rs

@@ -55,7 +55,7 @@ pub struct Opt {
         default_value = "default",
         value_name = "NODE_ID",
         env = "GRAPH_NODE_ID",
-        help = "a unique identifier for this node\n"
+        help = "a unique identifier for this node.\nShould have the same value between consecutive node restarts\n"
     )]
     pub node_id: String,
     #[structopt(

node/src/opt.rs

@@ -139,7 +139,7 @@ pub struct Opt {
         default_value = "default",
         value_name = "NODE_ID",
         env = "GRAPH_NODE_ID",
-        help = "a unique identifier for this node"
+        help = "a unique identifier for this node. Should have the same value between consecutive node restarts"
     )]
     pub node_id: String,
     #[structopt(long, help = "Enable debug logging")]