don't require shared_preload_libraries in spec in local tests -

we don't pass settings this way in local setup

compute_tools/src/config.rs

@@ -168,6 +168,35 @@ pub fn write_postgres_conf(
         writeln!(file, "# Managed by compute_ctl: end")?;
     }
 
+    // Always add pgaudit to shared_preload_libraries.
+    //
+    // This is needed to handle the downgrade scenario.
+    // pgaudit extension creates event triggers that require library to be loaded.
+    // so, once extension was installed it must always be present in shared_preload_libraries.
+    let mut extra_shared_preload_libraries = String::new();
+
+    let libs = {
+        // We don't distribute pgaudit in the testing image,
+        // and don't pass shared_preload_libraries via spec,
+        // so disable this logic there.
+        #[cfg(feature = "testing")]
+        {
+            String::new()
+        }
+        #[cfg(not(feature = "testing"))]
+        {
+            spec.cluster
+                .settings
+                .find("shared_preload_libraries")
+                .expect("shared_preload_libraries setting is missing in the spec")
+        }
+    };
+
+    #[cfg(not(feature = "testing"))]
+    if !libs.contains("pgaudit") {
+        extra_shared_preload_libraries.push_str(",pgaudit");
+    };
+
     // If base audit logging is enabled, configure it.
     // In this setup, the audit log will be written to the standard postgresql log.
     //
@@ -177,29 +206,22 @@ pub fn write_postgres_conf(
     // This way we always override the settings from the spec
     // and don't allow the user or the control plane admin to change them.
     match spec.audit_log_level {
-        ComputeAudit::Disabled => {}
+        ComputeAudit::Disabled => {
+            // this is the default, but let's be explicit
+            writeln!(file, "pgaudit.log='none'")?;
+        }
         ComputeAudit::Log | ComputeAudit::Base => {
             writeln!(file, "# Managed by compute_ctl base audit settings: start")?;
             writeln!(file, "pgaudit.log='ddl,role'")?;
             // Disable logging of catalog queries to reduce the noise
             writeln!(file, "pgaudit.log_catalog=off")?;
 
-            if let Some(libs) = spec.cluster.settings.find("shared_preload_libraries") {
-                let mut extra_shared_preload_libraries = String::new();
-                if !libs.contains("pgaudit") {
-                    extra_shared_preload_libraries.push_str(",pgaudit");
-                }
-                writeln!(
-                    file,
-                    "shared_preload_libraries='{}{}'",
-                    libs, extra_shared_preload_libraries
-                )?;
-            } else {
-                // Typically, this should be unreacheable,
-                // because we always set at least some shared_preload_libraries in the spec
-                // but let's handle it explicitly anyway.
-                writeln!(file, "shared_preload_libraries='neon,pgaudit'")?;
-            }
+            writeln!(
+                file,
+                "shared_preload_libraries='{}{}'",
+                libs, extra_shared_preload_libraries
+            )?;
+
             writeln!(file, "# Managed by compute_ctl base audit settings: end")?;
         }
         ComputeAudit::Hipaa | ComputeAudit::Extended | ComputeAudit::Full => {
@@ -228,28 +250,15 @@ pub fn write_postgres_conf(
             // The caller who sets the flag is responsible for ensuring that the necessary
             // shared_preload_libraries are present in the compute image,
             // otherwise the compute start will fail.
-            if let Some(libs) = spec.cluster.settings.find("shared_preload_libraries") {
-                let mut extra_shared_preload_libraries = String::new();
-                if !libs.contains("pgaudit") {
-                    extra_shared_preload_libraries.push_str(",pgaudit");
-                }
-                if !libs.contains("pgauditlogtofile") {
-                    extra_shared_preload_libraries.push_str(",pgauditlogtofile");
-                }
-                writeln!(
-                    file,
-                    "shared_preload_libraries='{}{}'",
-                    libs, extra_shared_preload_libraries
-                )?;
-            } else {
-                // Typically, this should be unreacheable,
-                // because we always set at least some shared_preload_libraries in the spec
-                // but let's handle it explicitly anyway.
-                writeln!(
-                    file,
-                    "shared_preload_libraries='neon,pgaudit,pgauditlogtofile'"
-                )?;
+            if !libs.contains("pgauditlogtofile") {
+                extra_shared_preload_libraries.push_str(",pgauditlogtofile");
             }
+            writeln!(
+                file,
+                "shared_preload_libraries='{}{}'",
+                libs, extra_shared_preload_libraries
+            )?;
+
             writeln!(
                 file,
                 "# Managed by compute_ctl compliance audit settings: end"