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Summary

Inspired by go-discover, go-netaddrs is a Go (golang) library and command line tool to discover ip addresses of nodes in a customizable fashion suitable for any environment. It returns IP addresses (IPv4 or IPv6) given a

  1. DNS name, OR
  2. custom executable with optional args which (refer to examples under the folder sample_scripts/):
    • on success - exits with 0 and prints whitespace delimited IP (v4/v6) addresses to stdout.
    • on failure - exits with a non-zero code and optionally prints an error message of up to 1024 bytes to stderr.

Command Line Tool Usage

Install the command line tool with:

go get -u github.com/hashicorp/go-netaddrs/cmd/netaddrs

Example usage

$ netaddrs -q ip "exec=/usr/local/bin/query_ec2.sh"

# Output
172.25.16.77 172.25.42.80 fe80::1ff:fe23:4567:890a%3

$ netaddrs -q ip "exec=discover -q addrs provider=aws region=us-west-2 tag_key=consul-server tag_value=true"

# Output
172.25.19.221 172.25.24.182 172.25.21.52

$ netaddrs -q ip "consul-cluster.private.consul.11eb5b95-2882-0215-b2c7-0242ac11000d.aws.hcp.dev"

# Output
172.25.19.221 172.25.24.182 172.25.21.52

Library Usage

Install the library with:

go get -u github.com/hashicorp/go-netaddrs

Usage sample:

import netaddrs "github.com/hashicorp/go-netaddrs"

func ServerAddresses(server_addresses_cfg string, logger hclog.Logger) ([]string, error) {


   // Example `server_addresses_cfg` values:
   // consul-cluster.private.consul.11eb5b95-2882-0215-b2c7-0242ac11000d.aws.hcp.dev
   // exec=query_ec2.sh
   // exec=discover -q addrs provider=aws region=us-west-2 tag_key=consul-server tag_value=true

   addresses, err := netaddrs.IPAddrs(context.Background(), server_addresses_cfg, logger)
   if err != nil {
       logger.Error("Error retrieving server addresses", err)
       return nil, err
   }


   logger.Info("Server addresses", addresses)
   return addresses, err
}

Testing

$ go test

Future Enhancements