fix/internal/txemail: add timeout for SMTP connection establishment

[ggilmore]

Before, the smtp.Dial function had no cancellation mechanism - meaning that you could be waiting for several minutes to try to establish a connection before it gives up.

I work around this by establishing a TCP connection myself to the appropriate address, and using net.DialContext to cancel the dial process if either:

1. The parent context cancels
2. 30 seconds have passed

Afterwards, we construct the smtp.Client ourselves using smtp.NewClient

This only changes what happens when we try to establish a connection - it doesn't change any behavior around sending emails afterwards.

Test plan

Manual testing.

1. On local dev, I edited the credentials in the dev-private site configuration file to point to an invalid port.

2. I attempted to create an access token, and after only30 seconds I saw this error print in the terminal:

[       frontend] WARN schemaResolver.CreateAccessToken graphqlbackend/access_tokens.go:127 Failed to send email to inform user of access token creation {"userID": 1, "error": "establishing TCP connection to \"smtp.gmail.com:57\": dial tcp 74.125.137.109:57: i/o timeout"}

Changelog

• Instead of waiting forever, we wait at most 30 seconds before giving up when trying to connect to the configured mail server when sending an email.

[ggilmore]

• feat/graphql/access_tokens: send access token creation/deletion emails in background and create special message for dial errors #63760
• fix/internal/txemail: add timeout for SMTP connection establishment #63759 👈
• main

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[ggilmore]

• feat/graphql/access_tokens: send access token creation/deletion emails in background and create special message for dial errors #63760
• fix/internal/txemail: add timeout for SMTP connection establishment #63759 👈
• main

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Join @ggilmore and the rest of your teammates on Graphite

[bobheadxi]

Nice, thanks :D

[camdencheek]

Upstream an smtp.DialContext?

[eseliger]

They froze the package. I personally think this is quite acceptable, it's just composing the net and smpt packages together into something we like to use 🤔

[ggilmore]

Merge activity

• Jul 10, 3:34 PM EDT: @ggilmore merged this pull request with Graphite.

[camdencheek]

I personally think this is quite acceptable

Oh, agreed! Mostly just thought this would be a fun little opportunity to contribute to stdlib since adding context-accepting variants is pretty standard across stdlib. Didn't realize the package was frozen though