(Legacy) Network Resiliency and Availability
This documentation is for the legacy Konnect environment at
konnect.konghq.com. For the
cloud.konghq.com environment, see the
current Konnect documentation.
Konnect Cloud deployments run in hybrid mode, which means that there is
a separate control plane attached to one or more data plane nodes. These planes
must communicate with each other to receive and send configuration. If
communication is interrupted and either side can’t send or receive config, data
plane nodes still continue proxying traffic to clients.
Whenever a data plane node receives new configuration from the control plane,
it immediately loads that config into memory. At the same time, it caches
the config as
/usr/local/kong by default.
- How do the control plane and data planes communicate?
- Data travelling between control planes and data planes is secured through a
mutual TLS handshake.
Normally, the data plane maintains a persistent connection with the control
plane. The data plane sends a heartbeat to the control plane every 30 seconds to
keep the connection alive. If it receives no answer, it tries to reconnect to the
control plane node after a 5-10 second random delay.
- What types of data travel between the Konnect Cloud control plane and the data planes, and how?
- There are two types of data that travel between the planes: configuration
and telemetry. Both use the secure TCP port
- Configuration: the control plane sends configuration data to any connected
data planes in the cluster.
- Telemetry: data plane nodes send usage information to the control plane
for Vitals and for account billing. Vitals tracks aggregate traffic by
service, route, and the consuming application. For billing, Kong tracks the
number of services, API calls, and active dev portals.
Telemetry data does not include any customer information or any data processed
by the data plane. All telemetry data is encrypted using mTLS.
- How frequently does data travel between the control plane and data planes?
- When you make a configuration change on the control plane, that change is
immediately pushed to any connected data plane nodes.
Connection behavior and incident recovery
- What happens if Konnect Cloud goes down?
- If the Kong-hosted control plane goes down, the control plane/data plane
connection gets interrupted. You can’t access the control plane or
change any configuration during this time.
A connection interruption has no negative effect on the function of your
data plane proxies. They continue to proxy and route traffic normally, and any
services implemented through the ServiceHub continue to work as before.
- What happens if the control plane and data plane disconnect?
- If the control plane and data plane become disconnected, configuration can’t
travel between them. In that situation, the data plane continues to use cached
configuration until it reconnects to the control plane and receives new
Whenever a connection is re-established with the CP node, the control plane
always pushes the latest configuration to the data plane. It doesn’t queue up
or try to apply older changes.
- How long can data plane nodes remain disconnected from the control plane?
- In theory, indefinitely. A data plane node will keep pinging the
control plane forever, until the connection is re-established or the data plane
The data plane proxy needs to connect to the control plane at least once.
The control plane pushes configuration to the data plane, and each data plane
node caches that configuration in-memory. It continues to use this cached
configuration until it receives new instructions from the control plane.
There are situations that can cause further problems:
- If the license that the data plane received from the control plane expires,
the data plane stops working.
- If the data plane node’s configuration cache file (
gets deleted, it loses access to the last known configuration and starts
- Can I restart a data plane node if the control plane is down or disconnected?
- Yes. If you restart a data plane, it uses cached configuration to continue
functioning the same as before the restart.
- Can I create a new data plane node when the connection is down?
Backups and alternative options
- Can I create a backup configuration to use in case the cache fails?
- You can set the
option to load a fallback YAML config.
- Can I change a data plane node’s configuration when it’s disconnected from the control plane?
- Yes, if necessary, though any manual configuration will be overwritten the next
time the control plane connects to the node.
You can load configuration manually in one of the following ways:
- Copy the configuration cache file (
config.json.gz) from another data
plane node with a working connection and overwrite the cache file on disk
for the disconnected node.
- Remove the cache file, then start the data plane node with
to load a fallback YAML config.