feat: Expose component configs as info metrics (#1584)

## What ❔

- Exposes configs of various components as info metrics
[defined](https://github.com/OpenObservability/OpenMetrics/blob/main/specification/OpenMetrics.md#info)
in the Open Metrics standard.
- Reworks mempool cache to be shared between API servers.

## Why ❔

- More idiomatic and observable than printing these configs to logs (or
not observing at all).
- Allows to use configs in Grafana dashboards, alerts etc.
- The mempool cache makes sense to share logically, and if multiple
instances are used, reported metrics can be bogus.

## Checklist

- [x] PR title corresponds to the body of PR (we generate changelog
entries from PRs).
- [x] Tests for the changes have been added / updated.
- [x] Documentation comments have been added / updated.
- [x] Code has been formatted via `zk fmt` and `zk lint`.
- [x] Spellcheck has been run via `zk spellcheck`.
- [ ] Linkcheck has been run via `zk linkcheck`.

.github/release-please/config.json

@@ -7,7 +7,13 @@
   "packages": {
       "core": {
         "release-type": "simple",
-        "component": "core"
+        "component": "core",
+        "extra-files": [
+          {
+            "type": "generic",
+            "path": "bin/external_node/Cargo.toml"
+          }
+        ]
       },
       "prover": {
         "release-type": "simple",

Cargo.toml

@@ -120,6 +120,7 @@ regex = "1"
 reqwest = "0.11"
 rlp = "0.5"
 rocksdb = "0.21.0"
+rustc_version = "0.4.0"
 secp256k1 = "0.27.0"
 semver = "1"
 sentry = "0.31"

core/bin/external_node/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "zksync_external_node"
-version = "0.1.0"
+version = "22.1.0" # x-release-please-version
 edition.workspace = true
 authors.workspace = true
 homepage.workspace = true
@@ -44,3 +44,6 @@ clap = { workspace = true, features = ["derive"] }
 serde_json.workspace = true
 semver.workspace = true
 tracing.workspace = true
+
+[build-dependencies]
+rustc_version.workspace = true

core/bin/external_node/build.rs

@@ -0,0 +1,46 @@
+//! Build script for the external node binary.
+
+use std::{
+    env, fs,
+    io::{self, Write},
+    path::Path,
+};
+
+use rustc_version::{Channel, LlvmVersion};
+
+fn print_rust_meta(out: &mut impl Write, meta: &rustc_version::VersionMeta) -> io::Result<()> {
+    writeln!(
+        out,
+        "pub(crate) const RUSTC_METADATA: RustcMetadata = RustcMetadata {{ \
+            version: {semver:?}, \
+            commit_hash: {commit_hash:?}, \
+            commit_date: {commit_date:?}, \
+            channel: {channel:?}, \
+            host: {host:?}, \
+            llvm: {llvm:?} \
+        }};",
+        semver = meta.semver.to_string(),
+        commit_hash = meta.commit_hash,
+        commit_date = meta.commit_date,
+        channel = match meta.channel {
+            Channel::Dev => "dev",
+            Channel::Beta => "beta",
+            Channel::Nightly => "nightly",
+            Channel::Stable => "stable",
+        },
+        host = meta.host,
+        llvm = meta.llvm_version.as_ref().map(LlvmVersion::to_string),
+    )
+}
+
+fn main() {
+    let out_dir = env::var("OUT_DIR").expect("`OUT_DIR` env var not set for build script");
+    let rustc_meta = rustc_version::version_meta().expect("Failed obtaining rustc metadata");
+
+    let metadata_module_path = Path::new(&out_dir).join("metadata_values.rs");
+    let metadata_module =
+        fs::File::create(metadata_module_path).expect("cannot create metadata module");
+    let mut metadata_module = io::BufWriter::new(metadata_module);
+
+    print_rust_meta(&mut metadata_module, &rustc_meta).expect("failed printing rustc metadata");
+}

core/bin/external_node/src/config/mod.rs

@@ -721,8 +721,6 @@ impl From<ExternalNodeConfig> for InternalApiConfig {
             req_entities_limit: config.optional.req_entities_limit,
             fee_history_limit: config.optional.fee_history_limit,
             filters_disabled: config.optional.filters_disabled,
-            mempool_cache_update_interval: config.optional.mempool_cache_update_interval(),
-            mempool_cache_size: config.optional.mempool_cache_size,
             dummy_verifier: config.remote.dummy_verifier,
             l1_batch_commit_data_generator_mode: config.remote.l1_batch_commit_data_generator_mode,
         }