haproxy

Loadbalancer Scripts

These scripts are meant to help set up load balancers on EC2 and Azure for a set of back-end Blockstack infrastructure, like Bitcoin nodes and Blockstack Indexer nodes.

Some assembly required and batteries not included. You will need to tailor them to your own needs.

Config files

• haproxy.cfg.in: This is a template file for HAProxy. The string @HAPROXY_BACKENDS will be replaced with a list of server backends by each of these contained scripts. The one here is meant for enabling HAProxy to balance both p2p and JSONRPC load across a set of bitcoind daemons. Put it in your /etc/haproxy directory.

• /etc/crontab: You will want to add a line like this to your crontab:

*/5 *   * * *   root    cd / && /etc/haproxy/haproxy-reload.sh

HAProxy Config-generation Scripts

These are a family of very similar scripts that, when invoked, will set up HAProxy to balance load across a set of VMs. The scripts fill in haproxy.cfg.in by querying the IaaS for the IP addresses of VMs with a particular tag. They only reload HAProxy if the config file actually changes.

Once installed, the workflow here is to spin up one or more VMs that run your backend process (like bitcoind or bitcored), give them an appropriate tag, and then run this script to update HAProxy. It is recommended that the script simply run as part of a frequent cron job.

• haproxy-reload-ec2.sh: This is a script for periodically re-generating /etc/haproxy/haproxy.cfg from /etc/haproxy/haproxy.cfg.in and the aws CLI tool. To use it, you will need to have installed and set up your aws credentials on the load-balancer node. The script itself finds any VMs tagged with haproxy=1 and puts their IP addresses into haproxy.cfg.in.

• haproxy-reload-azure.sh: This is a script for doing the same as haproxy-reload-ec2.sh, but with the azure tool. To use it, you will need to have installed and set up jq and azure-cli on your load balancer, and you will need to have signed into your subscription. You will want to edit this script and change SUBSCRIPTION= and RESOURCE_GROUP= to the appropriate fields. In addition, you will want to change LOADBALANCE_TAG= to whatever tag you want to use to identify the VMs this script queries.