Run ucarp in hostnetwork mode. Following environment variables control ucarp operation:
| Variable | Description | Default value |
|---|---|---|
| UCARP_ADDR | Virtual IP Address | - |
| UCARP_MASKLEN | Virtual IP Address netmask length | 32 |
| UCARP_INTERFACE | Interface to run ucarp on | guessed from routing table |
| UCARP_SRCIP | Source IP address to use | guessed from $UCARP_INTERFACE |
| UCARP_VHID | Virtual host ID | 1 |
| UCARP_PASS | Password | password |
| UCARP_PASS_FILE | File containing password | - |
| UCARP_GARP_TIMEOUT | Timeout during sending GARP packets after becoming master | - |
At least UCARP_ADDR must be specified. Also, recommended to specify UCARP_PASS. Specifying UCARP_PASS_FILE will override UCARP_PASS.
Capabilities CAP_NET_RAW and CAP_NET_ADMIN are needed for correct operation.
Example invocation:
docker run -it --rm -e UCARP_ADDR=10.10.10.10 -e UCARP_PASS=g3n3r4t3d --network host --cap-add CAP_NET_RAW --cap-add CAP_NET_ADMIN ghcr.io/kubernetize/ucarpThe image can also be run in its on network namespace too, possibly with additional network interfaces facing uplink or other networks (e.g. using multus-cni in Kubernetes to provide access to public network). Then ucarp must be told which interface to use, what ip address to advertise, and if desired, upon becoming master, set up a dedicated routing table for traffic originating from the advertised address. For this, additional variables can be defined:
| Variable | Description | Default value |
|---|---|---|
| UCARP_RTABLE | Routing table to create and to place routes into | - |
| UCARP_RTABLE_NETWORK_LENGTH | Network length overriding UCARP_MASKLEN in specific routing table | UCARP_MASKLEN |
| UCARP_GATEWAY | Default gateway for traffic originating from Virtual IP | - |
| UCARP_RULE_PRIORITY | Priority to use in lookup rule | - |
At least UCARP_RTABLE must be set to an integer to enable this operation. Usually 2 will do, but if you have multiple ucarp containers in a Kubernetes POD, you must specify different IDs for each. Also you will probably want to set UCARP_RTABLE_NETWORK_LENGTH to real network netmask instead of the default 32. Specify UCARP_GATEWAY to set up a default route in the selected routing table.