migration: Delete namespaces obsolete since v0.20

Fixes #1585

Rollback not implemented because the namespaces have been obsolete so
long, plus this wouldn't restore any resources in the deleted namespaces
anyway, so restoring them on their own seems of little value.

migration/v0.34/README.md

@@ -94,6 +94,21 @@ As with all scripts in this repository `CK8S_CONFIG_PATH` is expected to be set.
     git switch -d v0.34.x
     ```
 
+1. Verify that no important resources are present in the `elastic-system` and `influxdb-prometheus` namespaces.
+
+    ``` bash
+    ./migration/v0.34/prepare/30-delete-obsolete-ns.sh
+    ```
+
+    Expected output:
+
+    ```
+    No resources found in elastic-system namespace.
+    No resources found in influxdb-prometheus namespace.
+    ```
+
+    If resources _are_ present, verify that they are not something important.
+
 1. Update apps configuration:
 
     This will take a backup into `backups/` before modifying any files.
@@ -127,6 +142,12 @@ As with all scripts in this repository `CK8S_CONFIG_PATH` is expected to be set.
     ./migration/v0.30/apply/11-prometheus-operator-crds.sh execute
     ```
 
+1. Delete obsolete namespaces:
+
+    ```bash
+    ./migration/v0.34/apply/30-delete-obsolete-ns.sh execute
+    ```
+
 1. Upgrade applications:
 
     ```bash

migration/v0.34/apply/30-delete-obsolete-ns.sh

@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+
+ROOT="$(readlink -f "$(dirname "${0}")/../../../")"
+
+# shellcheck source=scripts/migration/lib.sh
+source "${ROOT}/scripts/migration/lib.sh"
+
+run() {
+  case "${1:-}" in
+  execute)
+    for NS in elastic-system influxdb-prometheus; do
+      if kubectl_do sc get namespace $NS >/dev/null 2>/dev/null; then
+        log_info "  - deleting unused namespace $NS in sc"
+        kubectl_do sc delete namespace $NS
+      else
+        log_info "  - skip deleting not present namespace $NS in sc"
+      fi
+    done
+    ;;
+  rollback)
+    log_warn "  - restoration of unused namespaces not implemented"
+    ;;
+  *)
+    log_fatal "usage: \"${0}\" <execute|rollback>"
+    ;;
+  esac
+}
+
+run "${@}"

migration/v0.34/prepare/30-delete-obsolete-ns.sh

@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+
+HERE="$(dirname "$(readlink -f "${0}")")"
+ROOT="$(readlink -f "${HERE}/../../../")"
+
+# shellcheck source=scripts/migration/lib.sh
+source "${ROOT}/scripts/migration/lib.sh"
+
+for NS in elastic-system influxdb-prometheus; do
+  log_info "checking for resources in namespace $NS"
+  NS_RESOURCES="$(kubectl_do sc get all -n $NS 2>&1)"
+  if [[ "$NS_RESOURCES" == "No resources found in $NS namespace." ]]; then
+    log_info "$NS_RESOURCES - safe to delete"
+  else
+    log_warn "Resources found in namespace $NS, please verify that these are okay to delete before proceeding to apply"
+    echo "$NS_RESOURCES"
+  fi
+done