ca-injector

README

ca-injector

A kubernetes MutatingAdmissionWebhook to inject certificate bundles into pods based on annotations, so that off-the-shelf deployments can be deployed in clusters with custom certificate authorities, with minimal disruption and minimal maintenance. No more building images off of upstream base images just to ADD yourca.crt /usr/share/ca-certificates/trust-source/anchors/ and RUN trust extract-compat || update-ca-certificates etc.

This webhook does three things:

1. Add to pods as a volume the certificate bundle specified by the value of the microcumul.us/injectssl annotation. The value should correspond with a secret in the same namespace as the pod which has a key ca.crt whose value is a CA bundle.
2. Add this volume to all containers as a volumemount
3. Add the SSL_CERT_FILE environment variable respected by OpenSSL and most tls libraries.

Just deploy this in your cluster, create CA bundles as e.g. foo-crt secret, with the key ca.crt (kubectl create secret generic foo-crt --from-file=ca.crt=my-bundle.crt), and use the microcumul.us/injectssl: foo-crt annotation on your pod or in your helm chart's appropriate annotations section. ca.crt can be changed by setting tls.ca.key in any of the typical ways (config files at /etc/ca-injector.yaml, $HOME/.config/ca-injector.yaml, or TLS_CA_KEY env var all work).

I highly suggest using this with replicator for a consistent experience across namespaces. Another great tool that may work well for building the bundle here is trust-manager.

Installation

kubectl apply -f k8s.yaml
kubectl apply -f mwh.yaml