migrations: add migration for kubelet setting pod-pids-limit

Adds a migration for a new setting `kubelet-pod-pids-limit`.

Release.toml

@@ -117,4 +117,5 @@ version = "1.7.2"
 "(1.7.2, 1.8.0)" = [
     "migrate_v1.8.0_boot-setting.lz4",
     "migrate_v1.8.0_boot-setting-metadata.lz4",
+    "migrate_v1.8.0_kubelet-pod-pids-limit.lz4",
 ]

sources/Cargo.toml

@@ -50,6 +50,7 @@ members = [
     "api/migration/migrations/v1.7.0/public-control-container-v0-6-0",
     "api/migration/migrations/v1.8.0/boot-setting",
     "api/migration/migrations/v1.8.0/boot-setting-metadata",
+    "api/migration/migrations/v1.8.0/kubelet-pod-pids-limit",
 
     "bottlerocket-release",
 

sources/api/migration/migrations/v1.8.0/kubelet-pod-pids-limit/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "kubelet-pod-pids-limit"
+version = "0.1.0"
+authors = ["Tianhao Geng <tianhg@amazon.com>"]
+license = "Apache-2.0 OR MIT"
+edition = "2018"
+publish = false
+# Don't rebuild crate just because of changes to README.
+exclude = ["README.md"]
+
+[dependencies]
+migration-helpers = { path = "../../../migration-helpers", version = "0.1.0"}

sources/api/migration/migrations/v1.8.0/kubelet-pod-pids-limit/src/main.rs

@@ -0,0 +1,22 @@
+#![deny(rust_2018_idioms)]
+
+use migration_helpers::common_migrations::AddPrefixesMigration;
+use migration_helpers::{migrate, Result};
+use std::process;
+
+/// We added a new setting for configuring pod-pids-limit, `settings.kubernetes.pod-pids-limit`
+fn run() -> Result<()> {
+    migrate(AddPrefixesMigration(vec![
+        "settings.kubernetes.pod-pids-limit",
+    ]))
+}
+
+// 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);
+    }
+}