This repository contains an application designed to execute health checks against a Hashicorp Consul Enterprise cluster. The goal of these health checks is to ensure an Autopilot-enabled cluster utilizing UpgradeVersionTag for automatic blue/green upgrades has successfully transferred voter status and cluster leadership, then output this information for observation using an outside (e.g. cloud platform) health checking service.
The impetus for developing this service lies with deploying Consul Autopilot Upgrade Migrations in environments where a signaling mechanism such as EC2 Instance Lifecycle Hooks or Azure VM Extensions does not exist. With the addition of this agent, we can observe and ensure a Consul cluster has fully transitioned voter and leader status to a set of replacement instances, before destroying the outgoing node set.
Support for this tool is provided by the HashiCorp Implementation Services team on a best-effort basis, and it comes with no guarantee or service level agreement. Bugs and feature requests should be entered as GitHub issues. If an existing issue matches your requirements, please add a 👍 reaction to bump it up our priority list.
Pull requests are welcome! We encourage you to fork this repository and send back a PR with any improvements.
A systemd unit file is included in this repository, which will launch the agent and ensure it is restarted in the event of failure. The unit file alone, however, is not enough to launch the application. It is necessary to provide a drop-in unit to configure environment variables the application relies on to communicate with the Consul cluster.
For example, if the loaded systemd unit is named consul-health.service, a drop-in may look like this:
/etc/systemd/system/consul-health.service.d/10-environment.conf:
[Service]
Environment=CONSUL_HTTP_ADDR=unix:///run/consul_kv/consul_kv_http.sock
Environment=CONSUL_CLUSTER_SIZE=5
Environment=CONSUL_HEALTH_PORT=8080
The supported environment variables are as follows:
| Environment Variable | Default | Description |
|---|---|---|
| CONSUL_HTTP_ADDR | http://127.0.0.1:8500 | Address at which Consul's HTTP listener may be reached. Prefix with http:// for TCP transport, or unix:// for UNIX Domain Sockets. |
| CONSUL_HTTP_TOKEN | None | ACL Token to use when connecting to Consul |
| CONSUL_CLUSTER_SIZE | None | REQUIRED Number of instances that should gain voter status before a cluster is considered healthy |
| CONSUL_HEALTH_PORT | 8080 | TCP port for the health check's HTTP server to listen on |
The latest binaries are available from the GitHub Releases page. To build manually, run the following on a computer with go1.13+ installed:
git clone [email protected]:hashicorp/is-consul-health-agent.git
cd is-consul-health-agent
go build