[fm] factor out fmt_json_value into its own module (#10511)

`nexus_types::fm` has a little utility for formatting
`serde_json::Value`s as bulleted lists. Currently, this is only used for
formatting sitrep analysis reports. #10460 factored it out of the
`analysis_reports` module to use it for formatting case facts. While
working on #10505, I realized it would also be useful to have this for
use in `omdb` commands for reconstructing analysis reports from CRDB.
Since #10460 isn't going to merge until after R20, I figured it would be
helpful to just pull out the change to factor this out into its own
commit that both our branches could depend on.

Author: hawkw

nexus/types/src/fm.rs

@@ -12,6 +12,7 @@ pub mod ereport;
 pub use ereport::{Ereport, EreportId};
 pub mod case;
 pub use case::Case;
+pub(crate) mod json_display;
 
 use case::AlertRequest;
 use chrono::{DateTime, Utc};

nexus/types/src/fm/analysis_reports.rs

@@ -7,6 +7,7 @@
 
 use super::case;
 use super::ereport::EreportId;
+use super::json_display::fmt_json_value;
 use iddqd::IdOrdMap;
 use omicron_uuid_kinds::{CaseUuid, CollectionUuid, SitrepUuid};
 use serde::{Deserialize, Serialize};
@@ -158,85 +159,6 @@ impl DebugLog {
     }
 }
 
-/// Recursively format a JSON value as a bulleted list entry, nesting any
-/// object or array children as indented sub-bullets.
-fn fmt_json_value(
-    f: &mut fmt::Formatter<'_>,
-    key: &str,
-    value: &serde_json::Value,
-    indent: usize,
-) -> fmt::Result {
-    match value {
-        serde_json::Value::Object(map) => {
-            writeln!(f, "{:indent$}* {key}:", "")?;
-            for (k, v) in map {
-                fmt_json_value(f, k, v, indent + 2)?;
-            }
-            Ok(())
-        }
-        serde_json::Value::Array(arr) => {
-            writeln!(f, "{:indent$}* {key}:", "")?;
-            let indent = indent + 2;
-            for (i, v) in arr.iter().enumerate() {
-                fmt_json_array_item(f, i + 1, v, indent)?;
-            }
-            Ok(())
-        }
-        serde_json::Value::String(s) => {
-            writeln!(f, "{:indent$}* {key}: {s}", "")
-        }
-        serde_json::Value::Null => {
-            writeln!(f, "{:indent$}* {key}: <none>", "")
-        }
-        serde_json::Value::Bool(b) => {
-            writeln!(f, "{:indent$}* {key}: {b}", "")
-        }
-        serde_json::Value::Number(n) => {
-            writeln!(f, "{:indent$}* {key}: {n}", "")
-        }
-    }
-}
-
-/// Format a single element of a JSON array as a numbered list item,
-/// e.g. `1. value` for scalars or `1.` followed by indented children for
-/// objects and nested arrays.
-fn fmt_json_array_item(
-    f: &mut fmt::Formatter<'_>,
-    n: usize,
-    value: &serde_json::Value,
-    indent: usize,
-) -> fmt::Result {
-    match value {
-        serde_json::Value::Object(map) => {
-            writeln!(f, "{:indent$}{n}.", "")?;
-            for (k, v) in map {
-                fmt_json_value(f, k, v, indent + 2)?;
-            }
-            Ok(())
-        }
-        serde_json::Value::Array(arr) => {
-            writeln!(f, "{:indent$}{n}.", "")?;
-            let indent = indent + 2;
-            for (i, v) in arr.iter().enumerate() {
-                fmt_json_array_item(f, i + 1, v, indent)?;
-            }
-            Ok(())
-        }
-        serde_json::Value::String(s) => {
-            writeln!(f, "{:indent$}{n}. {s}", "")
-        }
-        serde_json::Value::Null => {
-            writeln!(f, "{:indent$}{n}. <none>", "")
-        }
-        serde_json::Value::Bool(b) => {
-            writeln!(f, "{:indent$}{n}. {b}", "")
-        }
-        serde_json::Value::Number(num) => {
-            writeln!(f, "{:indent$}{n}. {num}", "")
-        }
-    }
-}
-
 impl LogEntry {
     pub fn new(event: impl ToString) -> Self {
         Self { event: event.to_string(), comment: None, kvs: BTreeMap::new() }

nexus/types/src/fm/json_display.rs

@@ -0,0 +1,87 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+//! Shared helpers for rendering `serde_json::Value`s as bulleted lists in
+//! `Display` impls.
+
+use std::fmt;
+
+/// Recursively format a JSON value as a bulleted list entry, nesting any
+/// object or array children as indented sub-bullets.
+pub(crate) fn fmt_json_value(
+    f: &mut fmt::Formatter<'_>,
+    key: &str,
+    value: &serde_json::Value,
+    indent: usize,
+) -> fmt::Result {
+    match value {
+        serde_json::Value::Object(map) => {
+            writeln!(f, "{:indent$}* {key}:", "")?;
+            for (k, v) in map {
+                fmt_json_value(f, k, v, indent + 2)?;
+            }
+            Ok(())
+        }
+        serde_json::Value::Array(arr) => {
+            writeln!(f, "{:indent$}* {key}:", "")?;
+            let indent = indent + 2;
+            for (i, v) in arr.iter().enumerate() {
+                fmt_json_array_item(f, i + 1, v, indent)?;
+            }
+            Ok(())
+        }
+        serde_json::Value::String(s) => {
+            writeln!(f, "{:indent$}* {key}: {s}", "")
+        }
+        serde_json::Value::Null => {
+            writeln!(f, "{:indent$}* {key}: <none>", "")
+        }
+        serde_json::Value::Bool(b) => {
+            writeln!(f, "{:indent$}* {key}: {b}", "")
+        }
+        serde_json::Value::Number(n) => {
+            writeln!(f, "{:indent$}* {key}: {n}", "")
+        }
+    }
+}
+
+/// Format a single element of a JSON array as a numbered list item,
+/// e.g. `1. value` for scalars or `1.` followed by indented children for
+/// objects and nested arrays.
+pub(crate) fn fmt_json_array_item(
+    f: &mut fmt::Formatter<'_>,
+    n: usize,
+    value: &serde_json::Value,
+    indent: usize,
+) -> fmt::Result {
+    match value {
+        serde_json::Value::Object(map) => {
+            writeln!(f, "{:indent$}{n}.", "")?;
+            for (k, v) in map {
+                fmt_json_value(f, k, v, indent + 2)?;
+            }
+            Ok(())
+        }
+        serde_json::Value::Array(arr) => {
+            writeln!(f, "{:indent$}{n}.", "")?;
+            let indent = indent + 2;
+            for (i, v) in arr.iter().enumerate() {
+                fmt_json_array_item(f, i + 1, v, indent)?;
+            }
+            Ok(())
+        }
+        serde_json::Value::String(s) => {
+            writeln!(f, "{:indent$}{n}. {s}", "")
+        }
+        serde_json::Value::Null => {
+            writeln!(f, "{:indent$}{n}. <none>", "")
+        }
+        serde_json::Value::Bool(b) => {
+            writeln!(f, "{:indent$}{n}. {b}", "")
+        }
+        serde_json::Value::Number(num) => {
+            writeln!(f, "{:indent$}{n}. {num}", "")
+        }
+    }
+}