diff --git a/docs/source/compute_config/kubernetes.md b/docs/source/compute_config/kubernetes.md
index 047ee1c8a..6183e621e 100644
--- a/docs/source/compute_config/kubernetes.md
+++ b/docs/source/compute_config/kubernetes.md
@@ -1,10 +1,10 @@
 # Kubernetes
 
-Lithops with kubernetes as serverless compute backend.
+Lithops with Kubernetes as serverless compute backend.
 
 ## Installation
 
-1. Install kubernetes backend dependencies:
+1. Install Kubernetes backend dependencies:
 
 ```bash
 python3 -m pip install lithops[kubernetes]
@@ -58,35 +58,34 @@ k8s:
     docker_namespace : <namespace>  # namespace name from https://cloud.ibm.com/registry/namespaces
 ```
 
-## Summary of configuration keys for kubernetes:
+## Summary of configuration keys for Kubernetes:
 
 |Group|Key|Default|Mandatory|Additional info|
 |---|---|---|---|---|
-|k8s | kubecfg_path | |no | Path to kubecfg file. Mandatory if config file not in `~/.kube/config` or KUBECONFIG env var not present|
-|k8s | kubecfg_context |  |no | kubernetes context to use from your kubeconfig file. It will use the default active context if not provided |
-|k8s | namespace | default |no | Kubernetes namespace to use for lithops execution |
+|k8s | kubecfg_path | |no | Path to the kubecfg file. Mandatory if the config file is not in `~/.kube/config` or the `KUBECONFIG` env var is not present|
+|k8s | kubecfg_context |  |no | Kubernetes context to use from your kubeconfig file. The default active context will be used if not provided |
+|k8s | namespace | default |no | Kubernetes namespace to use for Lithops execution |
 |k8s | docker_server | docker.io |no | Container registry URL |
 |k8s | docker_user | |no | Container registry user name |
 |k8s | docker_password | |no | Container registry password/token. In case of Docker hub, login to your docker hub account and generate a new access token [here](https://hub.docker.com/settings/security)|
-|k8s | rabbitmq_executor | False | no | Alternative K8s backend accelerating parallel function execution (map) thanks to rabbitmq group calls and warm-state pods of higher granularity. For more information [here](./kubernetes_rabbitmq.md).|
+|k8s | rabbitmq_executor | False | no | Alternative K8s backend that accelerates parallel function execution (map) by using RabbitMQ group calls and warm-state pods with higher granularity. For more information, see [here](./kubernetes_rabbitmq.md). |
 |k8s | max_workers | 100 | no | Max number of workers per `FunctionExecutor()`|
-|k8s | worker_processes | 1 | no | Number of Lithops processes within a given worker. This can be used to parallelize function activations within a worker. It is recommendable to set this value to the same number of CPUs of the container. |
+|k8s | worker_processes | 1 | no | Number of Lithops processes within a given worker. This can be used to parallelize function activations within a worker. It is recommended to set this value to the same number of CPUs as the container. |
 |k8s | runtime |  |no | Docker image name.|
 |k8s | runtime_cpu | 1 |no | CPU limit. Default 1vCPU |
 |k8s | runtime_memory | 512 |no | Memory limit in MB. Default 512MB |
 |k8s | runtime_timeout | 600 |no | Runtime timeout in seconds. Default 600 seconds |
 |k8s | master_timeout | 600 |no | Master pod timeout in seconds. Default 600 seconds |
 |k8s | container_security_context | PSS Baseline (drop ALL caps, no privilege escalation, RuntimeDefault seccomp) | no | Mapping injected as the container `securityContext` on every Lithops pod. Set to `null` to disable. |
-|k8s | pod_security_context | | no | Mapping injected as the pod-level `securityContext`. Required for clusters enforcing Pod Security Standards Restricted (e.g. EGI Rancher, GKE Autopilot, OpenShift). Requires a non-root runtime image. |
+|k8s | pod_security_context | | no | Mapping injected as the pod-level `securityContext`. Required for clusters enforcing Pod Security Standards Restricted (e.g. EGI Rancher, GKE Autopilot, OpenShift). The runtime image must have a non-root `USER` directive — the bundled `runtime/kubernetes/Dockerfile` and the auto-built default ship with `USER 1000:1000`. |
 |k8s | runtime_arch | auto-detected from cluster nodes; falls back to `amd64` if mixed or unknown | no | Architecture passed to `docker build --platform=linux/<arch>`. Set explicitly when targeting a specific architecture on a mixed-arch cluster. Allowed values: `amd64`, `arm64`. |
 
 ## Running on Pod Security Standards Restricted clusters
 
-Clusters enforcing the [Pod Security Standards "Restricted"](https://kubernetes.io/docs/concepts/security/pod-security-standards/) profile (Rancher with EGI policies, GKE Autopilot, OpenShift, AKS with Azure Policy, EKS with admission controllers) require pods to run as a non-root user with additional hardening. Set `pod_security_context` and use a runtime image that has a non-root `USER` directive:
+Clusters enforcing the [Pod Security Standards "Restricted"](https://kubernetes.io/docs/concepts/security/pod-security-standards/) profile (Rancher with EGI policies, GKE Autopilot, OpenShift, AKS with Azure Policy, EKS with admission controllers) require pods to run as a non-root user with additional hardening. The bundled runtime image and the auto-built default already ship as `USER 1000:1000`, so a custom non-root rebuild is no longer required — set `pod_security_context` to opt in:
 
 ```yaml
 k8s:
-    runtime: <your_user>/<non_root_runtime>:<tag>
     pod_security_context:
         runAsNonRoot: true
         runAsUser: 1000
diff --git a/lithops/serverless/backends/k8s/config.py b/lithops/serverless/backends/k8s/config.py
index ecb71a5a5..64a34fcad 100644
--- a/lithops/serverless/backends/k8s/config.py
+++ b/lithops/serverless/backends/k8s/config.py
@@ -48,36 +48,45 @@
 
 
 DOCKERFILE_DEFAULT = """
-RUN apt-get update && apt-get install -y \
-        zip redis-server curl \
-        && apt-get clean \
+RUN apt-get update && apt-get install -y --no-install-recommends \\
+        zip unzip redis-server curl ca-certificates \\
+        && apt-get clean \\
         && rm -rf /var/lib/apt/lists/*
 
-RUN pip install --upgrade --ignore-installed setuptools six pip \
-    && pip install --upgrade --no-cache-dir --ignore-installed \
-        flask \
-        pika \
-        boto3 \
-        ibm-cloud-sdk-core \
-        ibm-cos-sdk \
-        redis \
-        requests \
-        PyYAML \
-        kubernetes \
-        numpy \
-        cloudpickle \
-        ps-mem \
-        tblib \
+# Pin setuptools<81 (PEP 517 build envs included) so legacy sdists that
+# import pkg_resources still build.
+RUN echo 'setuptools<81' > /tmp/constraints.txt
+ENV PIP_CONSTRAINT=/tmp/constraints.txt
+
+RUN pip install --no-cache-dir 'setuptools<81' six wheel \\
+    && pip install --no-cache-dir \\
+        flask \\
+        pika \\
+        boto3 \\
+        ibm-cloud-sdk-core \\
+        ibm-cos-sdk \\
+        redis \\
+        requests \\
+        PyYAML \\
+        kubernetes \\
+        numpy \\
+        cloudpickle \\
+        ps-mem \\
+        tblib \\
         psutil
 
-ENV PYTHONUNBUFFERED TRUE
+ENV PYTHONUNBUFFERED=TRUE
+ENV APP_HOME=/lithops
+
+# Non-root user matches the PSS Restricted recipe in the k8s docs.
+RUN groupadd -g 1000 lithops && useradd -m -u 1000 -g 1000 lithops
 
-# Copy Lithops proxy and lib to the container image.
-ENV APP_HOME /lithops
 WORKDIR $APP_HOME
 
 COPY lithops_k8s.zip .
-RUN unzip lithops_k8s.zip && rm lithops_k8s.zip
+RUN unzip lithops_k8s.zip && rm lithops_k8s.zip && chown -R lithops:lithops $APP_HOME
+
+USER 1000:1000
 """
 
 JOB_DEFAULT = """
diff --git a/runtime/kubernetes/Dockerfile b/runtime/kubernetes/Dockerfile
index 6277be8b1..f743fd186 100644
--- a/runtime/kubernetes/Dockerfile
+++ b/runtime/kubernetes/Dockerfile
@@ -13,12 +13,17 @@ FROM python:3.10-slim-bookworm
 # Python 3.12
 #FROM python:3.12-slim-bookworm
 
-RUN apt-get update && apt-get install -y \
-        zip redis-server curl \
+RUN apt-get update && apt-get install -y --no-install-recommends \
+        zip unzip redis-server curl ca-certificates \
         && apt-get clean \
         && rm -rf /var/lib/apt/lists/*
 
-RUN pip install --upgrade setuptools six pip \
+# Pin setuptools<81 (PEP 517 build envs included) so legacy sdists that
+# import pkg_resources still build.
+RUN echo 'setuptools<81' > /tmp/constraints.txt
+ENV PIP_CONSTRAINT=/tmp/constraints.txt
+
+RUN pip install --no-cache-dir 'setuptools<81' six wheel \
     && pip install --no-cache-dir \
         flask \
         pika \
@@ -36,11 +41,15 @@ RUN pip install --upgrade setuptools six pip \
         tblib \
         psutil
 
-ENV PYTHONUNBUFFERED TRUE
+ENV PYTHONUNBUFFERED=TRUE
+ENV APP_HOME=/lithops
+
+# Non-root user matches the PSS Restricted recipe in docs/source/compute_config/kubernetes.md.
+RUN groupadd -g 1000 lithops && useradd -m -u 1000 -g 1000 lithops
 
-# Copy Lithops proxy and lib to the container image.
-ENV APP_HOME /lithops
 WORKDIR $APP_HOME
 
 COPY lithops_k8s.zip .
-RUN unzip lithops_k8s.zip && rm lithops_k8s.zip
+RUN unzip lithops_k8s.zip && rm lithops_k8s.zip && chown -R lithops:lithops $APP_HOME
+
+USER 1000:1000