initial inventory for automated update

This commit matches commit 581e902 in
branch dap/nexus-inventory.  I've just rebased the changes onto "main"
here.

Cargo.toml

@@ -40,6 +40,7 @@ members = [
     "nexus/db-model",
     "nexus/db-queries",
     "nexus/defaults",
+    "nexus/inventory",
     "nexus/test-interface",
     "nexus/test-utils-macros",
     "nexus/test-utils",
@@ -106,6 +107,7 @@ default-members = [
     "nexus/db-model",
     "nexus/db-queries",
     "nexus/defaults",
+    "nexus/inventory",
     "nexus/types",
     "oximeter/collector",
     "oximeter/db",
@@ -231,6 +233,7 @@ nexus-client = { path = "clients/nexus-client" }
 nexus-db-model = { path = "nexus/db-model" }
 nexus-db-queries = { path = "nexus/db-queries" }
 nexus-defaults = { path = "nexus/defaults" }
+nexus-inventory = { path = "nexus/inventory" }
 omicron-certificates = { path = "certificates" }
 omicron-passwords = { path = "passwords" }
 omicron-workspace-hack = "0.1.0"
@@ -369,8 +372,8 @@ tufaceous = { path = "tufaceous" }
 tufaceous-lib = { path = "tufaceous-lib" }
 unicode-width = "0.1.10"
 update-engine = { path = "update-engine" }
-uuid = { version = "1.4.1", features = ["serde", "v4"] }
 usdt = "0.3"
+uuid = { version = "1.4.1", features = ["serde", "v4"] }
 walkdir = "2.4"
 wicket = { path = "wicket" }
 wicket-common = { path = "wicket-common" }

common/src/nexus_config.rs

@@ -311,6 +311,8 @@ pub struct BackgroundTaskConfig {
     pub dns_external: DnsTasksConfig,
     /// configuration for external endpoint list watcher
     pub external_endpoints: ExternalEndpointsConfig,
+    /// configuration for inventory tasks
+    pub inventory: InventoryConfig,
 }
 
 #[serde_as]
@@ -345,6 +347,24 @@ pub struct ExternalEndpointsConfig {
     // allow/disallow wildcard certs, don't serve expired certs, etc.)
 }
 
+#[serde_as]
+#[derive(Clone, Debug, Deserialize, Eq, PartialEq, Serialize)]
+pub struct InventoryConfig {
+    /// period (in seconds) for periodic activations of this background task
+    ///
+    /// Each activation fetches information about all harware and software in
+    /// the system and inserts it into the database.  This generates a moderate
+    /// amount of data.
+    #[serde_as(as = "DurationSeconds<u64>")]
+    pub period_secs: Duration,
+
+    /// maximum number of past collections to keep in the database
+    ///
+    /// This is a very coarse mechanism to keep the system from overwhelming
+    /// itself with inventory data.
+    pub nkeep: u32,
+}
+
 /// Configuration for a nexus server
 #[derive(Clone, Debug, Deserialize, PartialEq, Serialize)]
 pub struct PackageConfig {
@@ -440,18 +460,15 @@ impl std::fmt::Display for SchemeName {
 
 #[cfg(test)]
 mod test {
-    use super::Tunables;
     use super::{
-        AuthnConfig, Config, ConsoleConfig, LoadError, PackageConfig,
-        SchemeName, TimeseriesDbConfig, UpdatesConfig,
+        AuthnConfig, BackgroundTaskConfig, Config, ConfigDropshotWithTls,
+        ConsoleConfig, Database, DeploymentConfig, DnsTasksConfig, DpdConfig,
+        ExternalEndpointsConfig, InternalDns, InventoryConfig, LoadError,
+        LoadErrorKind, PackageConfig, SchemeName, TimeseriesDbConfig, Tunables,
+        UpdatesConfig,
     };
     use crate::address::{Ipv6Subnet, RACK_PREFIX};
     use crate::api::internal::shared::SwitchLocation;
-    use crate::nexus_config::{
-        BackgroundTaskConfig, ConfigDropshotWithTls, Database,
-        DeploymentConfig, DnsTasksConfig, DpdConfig, ExternalEndpointsConfig,
-        InternalDns, LoadErrorKind,
-    };
     use dropshot::ConfigDropshot;
     use dropshot::ConfigLogging;
     use dropshot::ConfigLoggingIfExists;
@@ -596,6 +613,8 @@ mod test {
             dns_external.period_secs_propagation = 7
             dns_external.max_concurrent_server_updates = 8
             external_endpoints.period_secs = 9
+            inventory.period_secs = 10
+            inventory.nkeep = 11
             [default_region_allocation_strategy]
             type = "random"
             seed = 0
@@ -680,6 +699,10 @@ mod test {
                         },
                         external_endpoints: ExternalEndpointsConfig {
                             period_secs: Duration::from_secs(9),
+                        },
+                        inventory: InventoryConfig {
+                            period_secs: Duration::from_secs(10),
+                            nkeep: 11,
                         }
                     },
                     default_region_allocation_strategy:
@@ -733,6 +756,8 @@ mod test {
             dns_external.period_secs_propagation = 7
             dns_external.max_concurrent_server_updates = 8
             external_endpoints.period_secs = 9
+            inventory.period_secs = 10
+            inventory.nkeep = 3
             [default_region_allocation_strategy]
             type = "random"
             "##,