vip-manager

Manages a virtual IP based on state kept in etcd or Consul

Table of Contents

• Prerequisites
• Building
• Installing from package
• Installing from source
• Environment prerequisites
• PostgreSQL prerequisites
• Configuration
• Configuration - Hetzner
  • Credential File - Hetzmer
• Debugging
• Author

Prerequisites

• go >= 1.19
• make (optional)
• goreleaser (optional)

Building

1. clone this repo

git clone https://github.com/cybertec-postgresql/vip-manager.git

2. Build the binary using make or go build.
3. To build your own packages (.deb, .rpm, .zip, etc.), run

make package

or

goreleaser release --snapshot --skip-publish --rm-dist

Installing from package

You can download .rpm or .deb packages here, on the Releases page. On Debian and Ubuntu, the universe repositories should provide you with vip-manager, though the version may be not as recent.

Warning
Our packages are probably not compatible with the one from those repositories, do not try to install them side-by-side.

Installing from source

• Follow the steps to build vip-manager.
• Run DESTDIR=/tmp make install to copy the binary, service files and config file into the destination of your choice.
• Edit config to your needs, then run systemctl daemon-reload, then systemctl start vip-manager.

Note
systemd will only pick the service files up if you chose a DESTDIR so that it can find it. Usually DESTDIR='' should work.

Environment prerequisites

When vip-manager is in charge of registering and deregistering the VIP locally, it needs superuser privileges to do so. This is not required when vip-manager is used to manage a VIP through some API, e.g. Hetzner Robot API or Hetzner Cloud API.

Note
At some point it would be great to reduce this requirement to only the CAP_NET_RAW and CAP_NET_ADMIN capabilities, which could be added by a superuser to the vip-manager binary once. Right now, this is not possible since vip-manager launches plain shell commands to register and deregister virtual IP addresses locally (at least on linux), so the whole user would need these privileges. When vip-manager is eventually taught to directly use a library that directly uses the Linux kernel's API to register/deregister the VIP, the capabilities set for the binary will suffice.

PostgreSQL prerequisites

For any virtual IP based solutions to work in general with Postgres you need to make sure that it is configured to automatically scan and bind to all found network interfaces. So something like * or 0.0.0.0 (IPv4 only) is needed for the listen_addresses parameter to activate the automatic binding. This again might not be suitable for all use cases where security is paramount for example.

nonlocal bind

If you can't set listen_addresses to a wildcard address, you can explicitly specify only those adresses that you want to listen to. However, if you add the virtual IP to those addresses, PostgreSQL will fail to start when that address is not yet registered on one of the interfaces of the machine. You need to configure the kernel to allow "nonlocal bind" of IP (v4) addresses:

• temporarily:

sysctl -w net.ipv4.ip_nonlocal_bind=1

• permanently:

echo "net.ipv4.ip_nonlocal_bind = 1"  >> /etc/sysctl.conf
sysctl -p

Configuration

The configuration can be passed to the executable through argument flags, environment variables or through a YAML config file. Run vip-manager --help to see the available flags.

Note
The location of the YAML config file can be specified with the --config flag. An exemplary config file is installed into /etc/default/vip-manager.yml or is available in the vipconfig directory in the repository of the software.

Configuration is now (from release v1.0 on) handled using the viper library. This means that environment variables, command line flags, and config files can be used to configure vip-manager. When using different configuration sources simultaneously, this is the precedence order:

• flag
• env
• config

Note
So flags always overwrite env variables and entries from the config file. Env variables overwrite the config file entries.

All flags and file entries are written in lower case. To make longer multi-word flags and entries readable, they are separated by dashes, e.g. retry-num.

If you put a flag or file entry into uppercase and replace dashes with underscores, you end up with the format of environment variables. To avoid overlapping configuration with other applications, the env variables are additionall prefixed with VIP_, e.g. VIP_RETRY_NUM.

This is a list of all avaiable configuration items:

Configuration - Hetzner

To use vip-manager with Hetzner Robot API you need a Credential file, set hosting_type to hetzner in /etc/default/vip-manager.yml and your Floating-IP must be added on all Servers. The Floating-IP (VIP) will not be added or removed on the current Master node interface, Hetzner will route it to the current one.

Credential File - Hetzner

Add the File /etc/hetzner with your Username and Password

user="myUsername"
pass="myPassword"

Debugging

Either:

• run vip-manager with --verbose flag or
• set verbose to true in /etc/default/vip-manager.yml
• set VIP_VERBOSE=true

Note
Currently only supported for hetzner

Author

Cybertec Schönig & Schönig GmbH, https://www.cybertec-postgresql.com