# Hubble Configuration¶

This page provides guidance to configure Hubble in a way that suits your environment. Instructions to enable Hubble are provided as part of each Cilium Installation guide.

## Use custom TLS certificates¶

When Hubble Relay is deployed, Hubble listens on a TCP port on the host network. This allows Hubble Relay to communicate with all Hubble instances in the cluster. Connections between Hubble server and Hubble Relay instances are secured using mutual TLS (mTLS) by default.

TLS certificates are automatically generated and distributed as Kubernetes secrets for use by Hubble and Hubble Relay provided that hubble.tls.auto.enabled is set to true (default). This is achieved either via Helm when using Helm or via a Kubernetes CronJob when using experimental-install.yaml.

Note

When using Helm, TLS certificates are (re-)generated every time Helm is used for install or upgrade. As Hubble server and Hubble Relay support TLS certificates hot reloading, including CA certificates, this does not disrupt any existing connection. New connections are automatically established using the new certificates without having to restart Hubble server or Hubble Relay.

Hubble allows using custom TLS certificates rather than relying on automatically generated ones. This can be useful when using Hubble Relay in a cluster mesh scenario for instance or when using certificates signed by a specific certificate authority (CA) is required.

In order to use custom TLS certificates hubble.tls.auto.enabled must be set to false and TLS certificates manually provided.

This can be done by specifying the options below to Helm at install or upgrade time:

--set hubble.tls.auto.enabled=false                          # disable automatic TLS certificate generation
--set-file hubble.tls.ca.cert=ca.crt.b64                     # certificate of the CA that signs all certificates
--set-file hubble.tls.server.cert=server.crt.b64             # certificate for Hubble server
--set-file hubble.tls.server.key=server.key.b64              # private key for the Hubble server certificate
--set-file hubble.relay.tls.client.cert=relay-client.crt.b64 # client certificate for Hubble Relay to connect to Hubble instances
--set-file hubble.relay.tls.client.key=relay-client.key.b64  # private key for Hubble Relay client certificate
--set-file hubble.relay.tls.server.cert=relay-server.crt.b64 # server certificate for Hubble Relay
--set-file hubble.relay.tls.server.key=relay-server.key.b64  # private key for Hubble Relay server certificate


Options hubble.relay.tls.server.cert and hubble.relay.tls.server.key only need to be provided when hubble.relay.tls.server.enabled is set to true to enable TLS for the Hubble Relay server (defaults to false).

Note

Provided files must be base64 encoded PEM certificates.

In addition, the Common Name (CN) and Subject Alternative Name (SAN) of the certificate for Hubble server MUST be set to *.{cluster-name}.hubble-grpc.cilium.io where {cluster-name} is the cluster name defined by cluster.name (defaults to default).