migrations: migrator for image-verifier-plugins on k8s

Add migration for these new settings for k8s variants. no-op on ecs
variants as these settings have previously existed

Signed-off-by: Gavin Inglis <giinglis@amazon.com>

Author: ginglis13

sources/Cargo.lock

@@ -63,6 +63,7 @@ members = [
     "settings-migrations/v1.56.0/image-verifier-plugins-extensible",
     "settings-migrations/v1.60.0/kubernetes-topology-manager-policy-options",
     "settings-migrations/v1.60.0/container-runtime-max-concurrent-unpacks",
+    "settings-migrations/v1.61.0/image-verifier-plugins-settings",
 
     "settings-plugins/aws-dev",
     "settings-plugins/aws-ecs-2",

sources/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "image-verifier-plugins-settings"
+version = "0.1.0"
+license = "Apache-2.0 OR MIT"
+edition = "2021"
+publish = false
+exclude = ["README.md"]
+
+[dependencies]
+migration-helpers.workspace = true

sources/settings-migrations/v1.63.0/image-verifier-plugins-settings/Cargo.toml

@@ -0,0 +1,58 @@
+use migration_helpers::common_migrations::{AddPrefixesMigration, NoOpMigration};
+use migration_helpers::{migrate, MigrationData, Result};
+use std::process;
+
+/// Added new image-verifier-plugins settings.
+/// For k8s variants: remove the settings on downgrade since they didn't exist before.
+/// For ecs-3 variants: no migration needed since these settings already exist.
+fn run() -> Result<()> {
+    // Create a custom migration that checks variant at runtime
+    migrate(VariantSpecificMigration)
+}
+
+struct VariantSpecificMigration;
+
+impl migration_helpers::Migration for VariantSpecificMigration {
+    fn forward(&mut self, input: MigrationData) -> Result<MigrationData> {
+        // No work needed on upgrade for any variant
+        println!("VariantSpecificMigration has no work to do on upgrade.");
+        Ok(input)
+    }
+
+    fn backward(&mut self, input: MigrationData) -> Result<MigrationData> {
+        // Check variant from runtime data
+        if let Some(variant_value) = input.data.get("os.variant_id") {
+            if let Some(variant_str) = variant_value.as_str() {
+                if variant_str.starts_with("aws-k8s-") || variant_str.starts_with("vmware-k8s-") {
+                    // For k8s variants, remove the settings on downgrade
+                    println!("k8s variant detected ({}), removing image-verifier-plugins settings on downgrade", variant_str);
+                    return AddPrefixesMigration(vec!["settings.image-verifier-plugins"])
+                        .backward(input);
+                } else if variant_str.starts_with("aws-ecs-") {
+                    // For ECS variants, no migration needed
+                    println!(
+                        "ECS variant detected ({}), no migration needed",
+                        variant_str
+                    );
+                    return NoOpMigration.backward(input);
+                }
+            }
+        }
+
+        // Default behavior for unknown variants
+        println!(
+            "Unknown or missing variant, using default behavior (remove settings on downgrade)"
+        );
+        AddPrefixesMigration(vec!["settings.image-verifier-plugins"]).backward(input)
+    }
+}
+
+// Returning a Result from main makes it print a Debug representation of the error, but with Snafu
+// we have nice Display representations of the error, so we wrap "main" (run) and print any error.
+// https://github.com/shepmaster/snafu/issues/110
+fn main() {
+    if let Err(e) = run() {
+        eprintln!("{e}");
+        process::exit(1);
+    }
+}