mini-reloader

Mini Reloader is a lightweight Kubernetes operator that automatically restarts deployments when their referenced ConfigMaps change.

It ensures your application pods always reflect the latest configuration without manual intervention or GitOps hacks.

Features

• Event-based ConfigMap watching

• Auto restarts Deployments referencing changed ConfigMaps

• Written using Operator SDK and controller-runtime

• No need for custom resources (CRDs)

• Can run with minimal RBAC (only needs access to watch & patch Deployments and ConfigMaps)

How It Works

1. Watches ConfigMaps and Secrets with label mini-reloader.pelabs/enabled = true in the cluster.

2. On change, it:

   • Lists all Deployments in the same namespace.

   • Checks if any of them reference the updated ConfigMap (via volume or envFrom).

   • If match found, patches the Deployment with a new label like:

         metadata:
           labels:
             restartedAt: <current-time>

   • This triggers a rolling update automatically.

Future Improvements

• Support for Secrets also

• Support StatefulSets and DaemonSets

• Add support for projected volumes

• Validate integrity using hashes instead of annotations

• Expose Prometheus metrics (e.g., restarts triggered)

• Optional dry-run mode for GitOps-safe environments

• Multi-namespace or cluster-scoped support

• Send alerts when restarts are triggered

Prerequisites

• go version v1.22.0+
• docker version 17.03+.
• kubectl version v1.11.3+.
• Access to a Kubernetes v1.11.3+ cluster.

To Deploy on the cluster

docker image build . -t <some-registry>/mini-reloader:tag

Deploy operator on a cluster

kubectl apply -f config/mini-reloader-deploy.yaml
kubectl apply -f config/role_binding.yaml

Test Operator

kubectl apply -f config/test-deploy.yaml