feat: support checking ns existence by label (#11)

that will speed up namespace switching in big clusters

README.md

@@ -68,14 +68,20 @@ NOTE:
   - Also short names like "kchc/kchn/kchu" are available.
 
 VARS:
-  KUBECONFIG_SRC_DIR  : Set directory with extra kubectl config files to read in kubech commands.
-                        This allow to have multiple config files in addition to
-                        the one at "$HOME/.kube/config".
-                        Default: "$HOME/.kube/config.src.d"
-  KUBECONFIG_DEST_DIR : Set directory for temporary kubectl config files. The files
-                        in this directory are auto-generated by kubech commands
-                        and you don't need to interact with them or even change that var.
-                        Default: "$HOME/.kube/config.dest.d"
+  KUBECONFIG_SRC_DIR     : Set directory with extra kubectl config files to read in kubech commands.
+                           This allow to have multiple config files in addition to
+                           the one at "\$HOME/.kube/config".
+                           Default: "$HOME/.kube/config.src.d"
+  KUBECONFIG_DEST_DIR    : Set directory for temporary kubectl config files. The files
+                           in this directory are auto-generated by kubech commands
+                           and you don't need to interact with them or even change that var.
+                           Default: "$HOME/.kube/config.dest.d"
+  KUBECH_NAMESPACE_CHECK : Method used to check if namespace exists before switching to it.
+                           The default lists all namespaces which can be slow in large
+                           clusters. After kubernetes 1.22+ all namespaces have a label
+                           that can be used to speed this up. Set to "label" to enable this.
+                           Available options: "list", "label".
+                           Default: "list"
 
 USAGE:
   kubechc             : List all contexts

kubech

@@ -11,6 +11,7 @@ KUBECONFIG_ORIG="${KUBECONFIG:-$HOME/.kube/config}"
 KUBECONFIG_SRC_DIR="${KUBECONFIG_SRC_DIR:-$HOME/.kube/config.src.d}"
 KUBECONFIG_DEST_DIR="${KUBECONFIG_DEST_DIR:-$HOME/.kube/config.dest.d}"
 KUBECONFIG_ACTIVE=""
+KUBECH_NAMESPACE_CHECK="${KUBECH_NAMESPACE_CHECK:-list}"
 
 
 #
@@ -22,14 +23,20 @@ NOTE:
   - Also short names like "kchc/kchn/kchu" are available.
 
 VARS:
-  KUBECONFIG_SRC_DIR  : Set directory with extra kubectl config files to read in kubech commands.
-                        This allow to have multiple config files in addition to
-                        the one at "\$HOME/.kube/config".
-                        Default: "${KUBECONFIG_SRC_DIR}"
-  KUBECONFIG_DEST_DIR : Set directory for temporary kubectl config files. The files
-                        in this directory are auto-generated by kubech commands
-                        and you don't need to interact with them or even change that var.
-                        Default: "${KUBECONFIG_DEST_DIR}"
+  KUBECONFIG_SRC_DIR     : Set directory with extra kubectl config files to read in kubech commands.
+                           This allow to have multiple config files in addition to
+                           the one at "\$HOME/.kube/config".
+                           Default: "${KUBECONFIG_SRC_DIR}"
+  KUBECONFIG_DEST_DIR    : Set directory for temporary kubectl config files. The files
+                           in this directory are auto-generated by kubech commands
+                           and you don't need to interact with them or even change that var.
+                           Default: "${KUBECONFIG_DEST_DIR}"
+  KUBECH_NAMESPACE_CHECK : Method used to check if namespace exists before switching to it.
+                           The default lists all namespaces which can be slow in large
+                           clusters. After kubernetes 1.22+ all namespaces have a label
+                           that can be used to speed this up. Set to "label" to enable this.
+                           Available options: "list", "label".
+                           Default: "${KUBECH_NAMESPACE_CHECK}"
 
 USAGE:
   kubechc             : List all contexts
@@ -132,19 +139,28 @@ alias kchc='kubechc'
 # Change kubectl namespace
 kubechn () {
     kube_namespace="${1:-default}"
-    kube_namespace_all=$(kubectl get namespaces -o=jsonpath='{range .items[*]}{.metadata.name}{"\n"}{end}')
+    if [[ "${KUBECH_NAMESPACE_CHECK}" == "label" ]]; then
+        kube_namespace_exists=$(kubectl get namespaces -l "kubernetes.io/metadata.name=${kube_namespace}" -o name)
+    else
+        kube_namespace_all=$(kubectl get namespaces -o=jsonpath='{range .items[*]}{.metadata.name}{"\n"}{end}')
+        kube_namespace_exists=$(echo "${kube_namespace_all}" | grep -E "^${kube_namespace}$")
+    fi
 
     if [[ -n ${1} ]]; then
         # Only switch namespace if it exists.
-        if echo "${kube_namespace_all}" | grep -qE "^${kube_namespace}$"; then
+        if [[ -n "${kube_namespace_exists}" ]]; then
             kubechc "$(kubectl config current-context)" "${kube_namespace}"
             kubectl config set-context --current --namespace="${kube_namespace}"
             echo "Switched to namespace \"${kube_namespace}\""
         else
             echo "The namespace \"${kube_namespace}\" doesn't exist"
         fi
     else
-        echo "${kube_namespace_all}"
+        if [[ -n "${kube_namespace_all}" ]]; then
+            echo "${kube_namespace_all}" 
+        else
+            kubectl get namespaces -o=jsonpath='{range .items[*]}{.metadata.name}{"\n"}{end}'
+        fi
     fi
 }