Example Chef recipe to install Consul Template

config.ctmpl

{{
# /opt/my-app/consul.ctmpl
#
# This file is read by Consul Template and rendered onto disk using
# the configuration placed in /etc/consul-template.d.
}}

{{ with vault "postgresql/creds/readonly" }}
[config]
  username = "{{ .Data.username }}"
  password = "{{ .Data.password }}"
{{ end }}

default.rb

# NOTE: This recipe is designed to be informational and is not a copy-paste
# implementation. Please see the following blog post for more information:
#
#     https://www.hashicorp.com/blog/using-hashicorp-vault-with-chef.html
#

# Install the unzip package because Consul and Consul Template are 
# published as ZIP files.
package "unzip"

# Download the latest version of Consul Template using the remote_file
# resource in Chef and trigger an extraction.
remote_file "/tmp/consul-template.zip" do
  source "https://releases.hashicorp.com/consul-template/0.12.1/consul-template_0.12.1_linux_amd64.zip"
  owner "root"
  group "root"
  mode "0755"
  backup false
  action :create_if_missing
  notifies :run, "execute[extract_consul_template]", :immediately
end

# Unzips the binary.
execute "extract_consul_template" do
  command <<-EOH
    unzip /tmp/consul-template.zip
    mv consul-template /usr/local/bin/consul-template
    chmod +x /usr/local/bin/consul-template
  EOH
  action :nothing
end

# Create the configuration directory where the template configurations
# will reside.
directory "/etc/consul-template.d" do
  owner "root"
  group "root"
  action :create
end

# Create an upstart script - this could also be systemd or some other
# init system of your preference.
template "/etc/init/consul-template.conf" do
  source "upstart-consul-template.conf"
  owner "root"
  group "root"
  mode "0644"
end

# Start the service and register it with Chef.
service "consul-template" do
  provider Chef::Provider::Service::Upstart
  action :enable
end

# This writes the Consul Template template that Consul Template will
# read, parse, communicate with Vault, and render as the application
# configuration. Since Consul Template is running as a process, it
# will read all files in /etc/consul-template.d as configured in the
# upstart script above.
template "/etc/consul-template.d/my-app.hcl" do
  source "my-app-ct.hcl"
  owner "root"
  group "root"
  mode "0644"
  notifies :reload, "service[consul-template]", :delayed
end

my-app.hcl

# templates/my-app.hcl
#
# This file is used to configure an instance of the Consul
# Template process. This tells Consul Template to ingress
# the file at /etc/my-app/config.ctmpl, communicate with Vault,
# and then write the resulting contents to /opt/my-app/config.
# If the template changes, Consul Template will restart the
# application.
template {
  source = "/opt/my-app/config.ctmpl"
  destination = "/opt/my-app/config"
  command = "service my-app reload"
}

upstart-consul-template.conf

# templates/upstart-consul-template.conf
#
# This is a sample upstart configuration template for Consul 
# Template that tells Consul Template to read all configuration
# from /etc/consul-template.d.

description "consul-template"

start on runlevel [2345]
stop on runlevel [!2345]

respawn

script
  /usr/local/bin/consul-template \
    -config="/etc/consul-template.d/" \
    >> /var/log/consul-template.log 2>&1
end script

post-stop exec sleep 10