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is it nginx or the spring boot app? a 502 mystery with one clue

Solved502nginxreverse-proxy91 replies · 1.7K views · started
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  1. Kofi Arslan
    @kofi.arslan

    long time lurker first post lol our Spring Boot app sits behind nginx on teh same VM. It listens on 5000. Its been fine for months, but now after a reboot we get this:

    502 Bad Gateway

    502 Bad Gateway
nginx

    if i SSH in and curl localhost:5000 i get a 200 instantly. restarting nginx fixes it for a while, im out of ideas and support tickets are piling up.

    config hasnt changed in ages, as far as I know. the nginx config test passes, the apps own logs look normal, and CPU and memory on teh box are fine. what sohuld I check first so I stop guessing? im about to throw this thing out the window lol

    thinking

    2
  2. Liv
    @quiet_sage420

    ok so if it only happens under load or intermittently, look at keepalive mismatch. If the app closes idle connections sooner than nginx reuses them, u get sporadic 502s ;) Either raise teh apps keep-alive timeout above nginxs, or set proxy_http_version 1.1; with proxy_set_header Connection ""; and a sensible keepalive in teh upstream block. good luck man!

    2 0 helpful
  3. Tariq
    @copper_loop525

    for me it was the firmware. swapepd it and boom, fixed. exact same thing happened to my second monitor setup last month fingers crossed 🤞

    1 0 helpful
  4. Liv Mendes
    @buffergarage

    on RHEL/Fedora-family systems with SELinux enforcing, nginx is not alolwed to open outbound connections by default. look for Permission denied in the error log and run sudo setsebool -P httpd_can_network_connect 1.

    1 0 helpful
  5. Yuki
    @yukig187

    ok weird one spent 20 minutes on reboot and im still not done what am i doing wrong??

    1 0 helpful
  6. Lars Ferreira
    @lars_proxy

    long time lurker first post lol my old thinkpad is officially haunted

    0 1 helpful
  7. Chen Costa
    @regex_hound

    @buffergarage what did u end up doing in teh end ??

    1 2 helpful
  10. Yara Yilmaz
    @signalwrangler

    honestly just reset the default config and save yourself teh pain

    1 0 helpful
  11. Chen Costa
    @regex_hound

    i swear nginx is cursed pls help 🙏

    facepalm

    11 0 helpful
  14. Liv
    @quiet_sage420

    hmmmm ok told my boss it would take 10 minutes... its been a whole week

    rage

    1 0 helpful
  15. Yuki
    @yukig187

    is nginx even worth bothering with or should i just leave it

    1 0 helpful
  16. Liv Mendes
    @buffergarage

    unrelated but anyone elses coffee machine also judging them today... have u checked your spring settings?? mine were reset after an upadte

    15 0 helpful
  17. Yara Yilmaz
    @signalwrangler

    ok update: did what @lars_proxy said and its fine now

    mindblown

    2 0 helpful
  19. Liv
    @quiet_sage420

    is reboot even worth bothering with or should i just leave it

    0 2 helpful
  20. Yara Yilmaz
    @signalwrangler

    same issue here on my moms pc. driving me crazy worked for me anyway 🤷

    2 0 helpful

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