Dial only application servers that serve the requested application #12217
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atburke
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Apr 27, 2022
gabrielcorado
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…12217) * feat(reversetunnel): add a dial counter on fake remote site * refactor(app): change `MatchHealthy` to close connections * refactor(app): change `MatchAll` order to not dial all servers * refactor(app): only close connection when dial succeeds
gabrielcorado
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Apr 28, 2022
…12217) * feat(reversetunnel): add a dial counter on fake remote site * refactor(app): change `MatchHealthy` to close connections * refactor(app): change `MatchAll` order to not dial all servers * refactor(app): only close connection when dial succeeds
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Related to #12121.
When the service receives an application request, it checks for servers to which it can forward it. This is done by checking if the server is healthy (by dialing it) and if the application’s public address match. After that, it will cache this server list for future requests. Before this PR, the handler first tries to match healthy applications, meaning that all application servers returned by
GetApplicationServers, including the ones that could not serve the request were getting dialed.This PR changes the order of
MatchAllto first match the public address and then dial the servers, limiting theMatchHealthyto servers that can serve the request.For reviewers, here is a short guide on what was changed:
lib/srv/app/session.go: Change on theMatchAllorder (described earlier);lib/srv/app/handler_test.go: Contains a testTestMatchApplicationServersthat guarantees no additional servers are being dialed. The other changes on this file are the necessary setup for making application requests to theHandler(there is a lot of stuff, feel free to suggest any improvement).lib/srv/app/match.goandlib/srv/app/match_test.go: Additional change to close connections opened onMatchHealthy. This was found while writing the tests.