tabletop-companion/.kamal/hooks/pre-connect.sample

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2024-06-19 10:16:56 +00:00
#!/usr/bin/env ruby
# A sample pre-connect check
#
# Warms DNS before connecting to hosts in parallel
#
# These environment variables are available:
# KAMAL_RECORDED_AT
# KAMAL_PERFORMER
# KAMAL_VERSION
# KAMAL_HOSTS
# KAMAL_ROLE (if set)
# KAMAL_DESTINATION (if set)
# KAMAL_RUNTIME
hosts = ENV["KAMAL_HOSTS"].split(",")
results = nil
max = 3
elapsed = Benchmark.realtime do
results = hosts.map do |host|
Thread.new do
tries = 1
begin
Socket.getaddrinfo(host, 0, Socket::AF_UNSPEC, Socket::SOCK_STREAM, nil, Socket::AI_CANONNAME)
rescue SocketError
if tries < max
puts "Retrying DNS warmup: #{host}"
tries += 1
sleep rand
retry
else
puts "DNS warmup failed: #{host}"
host
end
end
tries
end
end.map(&:value)
end
retries = results.sum - hosts.size
nopes = results.count { |r| r == max }
puts "Prewarmed %d DNS lookups in %.2f sec: %d retries, %d failures" % [ hosts.size, elapsed, retries, nopes ]