How to healthcheck in a different port than main application

1

Hello,

My app is using a different port rather than the main application process for checking the current state:

Screen Shot 2021-04-25 at 12.50.32
Screen Shot 2021-04-25 at 12.50.321956×790 69.5 KB

I’m trying to setup fly.tomlaccordingly. For doing that, I first tried toservices.http_checkswithport`:

[[services.http_checks]]
      grace_period = "5s"
      interval = "3s"
      path =  "/health"
      method = "get"
      port = 3001
      timeout = "2s"
      restart_limit = 2

And also tried services.script_checks:

[[services.script_checks]]
      grace_period = "5s"
      interval = "3s"
      command = "curl http://localhost:3001/health"
      timeout = "2s"
      restart_limit = 2

These two ways are actually not present in the documentation and I saw them from other forum topics, so probably they aren’t implemented? What am I doing wrong?

2

Adding a port services.http_checks should work!

Is your server binding to 127.0.0.1:3001? It needs to bind to 0.0.0.0:3001. Health checks come from outside the instance and therefore your server needs to listen on eth0. The easiest way to do this is to bind to all addresses by using 0.0.0.0.

3

totally my fault: I forgot to listen SIGTERM kill signal.

Now it’s working as expected, however, after the new instance is deployed I can see logs related to continuous incoming requests on my logs.

That’s a little weird because my app is just being used by me.

Could be possible although I don’t have a services.tcp_checks configured, it’s enabled with the default configuration? can I disable it?

Also, a thing it’s strange to me grace_period is specified using natural language (5s) while the rest of timing values (like timeout) is using numerical (e.g., 3000).

4

I added a silly log on the main process and looks like the healthcheck is not taking into consideration the port setting since the main process is actually logging it

021-04-25T21:53:37.711Z f447908d cdg [info] { reqUrl: '/health' }
2021-04-25T21:53:37.714Z f447908d cdg [info]   microlink-api:requests 0 [] → 1 [xqYP9dNU7oeT-pHMqGdO5] +10s
2021-04-25T21:53:37.718Z f447908d cdg [info]   microlink-api:requests 1 [xqYP9dNU7oeT-pHMqGdO5] → 0 [] +4ms
2021-04-25T21:53:37.724Z f447908d cdg [info]   microlink-api status=200 id=xqYP9dNU7oeT-pHMqGdO5 ip=::ffff:176.58.95.98 query="ttl=86400000&prerender=auto&meta=true&data=false&video=false&audio=false&screenshot=false&pdf=false&insights=false&iframe=false&ping=true&timeout=28000&retry=2" size="195 B" duration=3.355ms +10s
2021-04-25T21:53:37.913Z 22b04695 lhr [info] { reqUrl: '/health' }
2021-04-25T21:53:37.916Z 22b04695 lhr [info]   microlink-api:requests 0 [] → 1 [9ljSdhYuP4Rv2JLP1ukrP] +10s
2021-04-25T21:53:37.920Z 22b04695 lhr [info]   microlink-api:requests 1 [9ljSdhYuP4Rv2JLP1ukrP] → 0 [] +5ms
2021-04-25T21:53:37.924Z 22b04695 lhr [info]   microlink-api status=200 id=9ljSdhYuP4Rv2JLP1ukrP ip=::ffff:185.40.232.114 query="ttl=86400000&prerender=auto&meta=true&data=false&video=false&audio=false&screenshot=false&pdf=false&insights=false&iframe=false&ping=true&timeout=28000&retry=2" size="195 B" duration=3.380ms +10s
2021-04-25T21:53:47.720Z f447908d cdg [info] { reqUrl: '/health' }
2021-04-25T21:53:47.723Z f447908d cdg [info]   microlink-api:requests 0 [] → 1 [dFFZ1JYVMdVHylrcptn9E] +10s
2021-04-25T21:53:47.726Z f447908d cdg [info]   microlink-api:requests 1 [dFFZ1JYVMdVHylrcptn9E] → 0 [] +4ms
2021-04-25T21:53:47.733Z f447908d cdg [info]   microlink-api status=200 id=dFFZ1JYVMdVHylrcptn9E ip=::ffff:176.58.95.98 query="ttl=86400000&prerender=auto&meta=true&data=false&video=false&audio=false&screenshot=false&pdf=false&insights=false&iframe=false&ping=true&timeout=28000&retry=2" size="195 B" duration=1.235ms +10s
2021-04-25T21:53:47.920Z 22b04695 lhr [info] { reqUrl: '/health' }
2021-04-25T21:53:47.922Z 22b04695 lhr [info]   microlink-api:requests 0 [] → 1 [MQvOiO4_fll5JCt3k893N] +10s
2021-04-25T21:53:47.925Z 22b04695 lhr [info]   microlink-api:requests 1 [MQvOiO4_fll5JCt3k893N] → 0 [] +3ms
2021-04-25T21:53:47.929Z 22b04695 lhr [info]   microlink-api status=200 id=MQvOiO4_fll5JCt3k893N ip=::ffff:185.40.232.114 query="ttl=86400000&prerender=auto&meta=true&data=false&video=false&audio=false&screenshot=false&pdf=false&insights=false&iframe=false&ping=true&timeout=28000&retry=2" size="195 B" duration=0.840ms +10s
2021-04-25T21:53:57.727Z f447908d cdg [info] { reqUrl: '/health' }
2021-04-25T21:53:57.731Z f447908d cdg [info]   microlink-api:requests 0 [] → 1 [vKA-YjlnYKZKqxTS-y_Pe] +10s
2021-04-25T21:53:57.735Z f447908d cdg [info]   microlink-api:requests 1 [vKA-YjlnYKZKqxTS-y_Pe] → 0 [] +4ms
2021-04-25T21:53:57.741Z f447908d cdg [info]   microlink-api status=200 id=vKA-YjlnYKZKqxTS-y_Pe ip=::ffff:176.58.95.98 query="ttl=86400000&prerender=auto&meta=true&data=false&video=false&audio=false&screenshot=false&pdf=false&insights=false&iframe=false&ping=true&timeout=28000&retry=2" size="195 B" duration=1.710ms +10s
2021-04-25T21:53:57.926Z 22b04695 lhr [info] { reqUrl: '/health' }
2021-04-25T21:53:57.928Z 22b04695 lhr [info]   microlink-api:requests 0 [] → 1 [UQQ0JIyc1V5ftzUVOALyL] +10s
2021-04-25T21:53:57.930Z 22b04695 lhr [info]   microlink-api:requests 1 [UQQ0JIyc1V5ftzUVOALyL] → 0 [] +1ms
2021-04-25T21:53:57.935Z 22b04695 lhr [info]   microlink-api status=200 id=UQQ0JIyc1V5ftzUVOALyL ip=::ffff:185.40.232.114 query="ttl=86400000&prerender=auto&meta=true&data=false&video=false&audio=false&screenshot=false&pdf=false&insights=false&iframe=false&ping=true&timeout=28000&retry=2" size="195 B" duration=0.830ms +10s

so I suspect http check with custom port is not implemented yet?