FEATURE: Add basic connection check to DNS SRV resources (#563)

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Rafael dos Santos Silva 2024-04-12 10:39:19 -03:00 committed by GitHub
parent f6ac5cd0a8
commit 6090580e36
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2 changed files with 79 additions and 7 deletions

View File

@ -11,7 +11,7 @@ module DiscourseAi
.fetch("dns_srv_lookup:#{domain}", expires_in: 5.minutes) do .fetch("dns_srv_lookup:#{domain}", expires_in: 5.minutes) do
resources = dns_srv_lookup_for_domain(domain) resources = dns_srv_lookup_for_domain(domain)
select_server(resources) server_election(resources)
end end
end end
@ -36,9 +36,29 @@ module DiscourseAi
return resource if random_weight < 0 return resource if random_weight < 0
end end
end
# fallback def self.server_available?(server)
resources.first begin
conn = Faraday.new { |f| f.adapter FinalDestination::FaradayAdapter }
conn.head("https://#{server.target}:#{server.port}")
true
rescue StandardError
false
end
end
def self.server_election(resources)
return nil if resources.empty?
return resources.first if resources.length == 1
candidate = select_server(resources)
if server_available?(candidate)
candidate
else
server_election(resources - [candidate])
end
end end
end end
end end

View File

@ -5,10 +5,10 @@ describe DiscourseAi::Utils::DnsSrv do
let(:weighted_dns_results) do let(:weighted_dns_results) do
[ [
Resolv::DNS::Resource::IN::SRV.new(1, 1, 443, "service1.example.com"), Resolv::DNS::Resource::IN::SRV.new(1, 1, 443, "service1.example.com"),
Resolv::DNS::Resource::IN::SRV.new(1, 2, 443, "service2.example.com"), Resolv::DNS::Resource::IN::SRV.new(2, 2, 443, "service2.example.com"),
Resolv::DNS::Resource::IN::SRV.new(1, 2, 443, "service3.example.com"), Resolv::DNS::Resource::IN::SRV.new(2, 2, 443, "service3.example.com"),
Resolv::DNS::Resource::IN::SRV.new(2, 1, 443, "service4.example.com"), Resolv::DNS::Resource::IN::SRV.new(3, 1, 443, "service4.example.com"),
Resolv::DNS::Resource::IN::SRV.new(2, 1, 443, "service5.example.com"), Resolv::DNS::Resource::IN::SRV.new(3, 1, 443, "service5.example.com"),
] ]
end end
@ -17,6 +17,10 @@ describe DiscourseAi::Utils::DnsSrv do
Resolv::DNS.any_instance.stubs(:getresources).returns(weighted_dns_results) Resolv::DNS.any_instance.stubs(:getresources).returns(weighted_dns_results)
Discourse.cache.delete("dns_srv_lookup:#{domain}") Discourse.cache.delete("dns_srv_lookup:#{domain}")
(1..5).each do |i|
stub_request(:head, "https://service#{i}.example.com/").to_return(status: 200)
end
end end
it "picks a server" do it "picks a server" do
@ -31,4 +35,52 @@ describe DiscourseAi::Utils::DnsSrv do
expect(weighted_dns_results.filter { |r| r.priority == 1 }).to include(selected_server) expect(weighted_dns_results.filter { |r| r.priority == 1 }).to include(selected_server)
end end
end end
context "when the first server is not available" do
before do
Resolv::DNS.any_instance.stubs(:getresources).returns(weighted_dns_results)
Discourse.cache.delete("dns_srv_lookup:#{domain}")
stub_request(:head, "https://service1.example.com/").to_raise(Faraday::SSLError)
(2..5).each do |i|
stub_request(:head, "https://service#{i}.example.com/").to_return(status: 200)
end
end
it "picks another server" do
selected_server = DiscourseAi::Utils::DnsSrv.lookup(domain)
expect(weighted_dns_results).to include(selected_server)
expect(selected_server.port).to eq(443)
expect(selected_server.target.to_s).to_not eq("service1.example.com")
end
end
context "when the multiple servers are not available" do
before do
Resolv::DNS.any_instance.stubs(:getresources).returns(weighted_dns_results)
Discourse.cache.delete("dns_srv_lookup:#{domain}")
(1..3).each do |i|
stub_request(:head, "https://service#{i}.example.com/").to_raise(Faraday::SSLError)
end
(4..5).each do |i|
stub_request(:head, "https://service#{i}.example.com/").to_return(status: 200)
end
end
it "picks another server" do
selected_server = DiscourseAi::Utils::DnsSrv.lookup(domain)
expect(weighted_dns_results).to include(selected_server)
expect(selected_server.port).to eq(443)
expect(selected_server.target.to_s).to_not eq("service1.example.com")
expect(selected_server.target.to_s).to_not eq("service2.example.com")
expect(selected_server.target.to_s).to_not eq("service3.example.com")
end
end
end end