node: Add graphman config setting

Author: lutter

node/src/bin/manager.rs

@@ -383,6 +383,15 @@ pub enum ConfigCommand {
         features: String,
         network: String,
     },
+    /// Show subgraph-specific settings
+    ///
+    /// GRAPH_EXPERIMENTAL_SUBGRAPH_SETTINGS can add a file that contains
+    /// subgraph-specific settings. This command determines which settings
+    /// would apply when a subgraph <name> is deployed and prints the result
+    Setting {
+        /// The subgraph name for which to print settings
+        name: String,
+    },
 }
 
 #[derive(Clone, Debug, Subcommand)]
@@ -1079,6 +1088,7 @@ async fn main() -> anyhow::Result<()> {
                     commands::config::provider(logger, &ctx.config, registry, features, network)
                         .await
                 }
+                Setting { name } => commands::config::setting(&name),
             }
         }
         Remove { name } => commands::remove::run(ctx.subgraph_store(), &name),

node/src/manager/commands/config.rs

@@ -1,14 +1,14 @@
 use std::{collections::BTreeMap, sync::Arc};
 
 use graph::{
-    anyhow::bail,
-    components::subgraph::Settings,
+    anyhow::{bail, Context},
+    components::subgraph::{Setting, Settings},
     endpoint::EndpointMetrics,
     env::EnvVars,
     itertools::Itertools,
     prelude::{
         anyhow::{anyhow, Error},
-        MetricsRegistry, NodeId,
+        MetricsRegistry, NodeId, SubgraphName,
     },
     slog::Logger,
 };
@@ -158,3 +158,25 @@ pub async fn provider(
     );
     Ok(())
 }
+
+pub fn setting(name: &str) -> Result<(), Error> {
+    let name = SubgraphName::new(name).map_err(|()| anyhow!("illegal subgraph name `{}`", name))?;
+    let env_vars = EnvVars::from_env().unwrap();
+    if let Some(path) = &env_vars.subgraph_settings {
+        let settings = Settings::from_file(path)
+            .with_context(|| format!("syntax error in subgraph settings `{}`", path))?;
+        match settings.for_name(&name) {
+            Some(Setting { history_blocks, .. }) => {
+                println!("setting for `{name}` will use history_blocks = {history_blocks}");
+            }
+            None => {
+                println!("no specific setting for `{name}`, defaults will be used");
+            }
+        }
+    } else {
+        println!("No subgraph-specific settings will be applied because");
+        println!("GRAPH_EXPERIMENTAL_SUBGRAPH_SETTINGS is not set");
+    };
+
+    Ok(())
+}