# How to enable autoscaling? **URL:** \ **Category:** Questions / Help\ **Tags:** elixir\ **Created:** [May 9, 2022, 3:28pm UTC](https://community.fly.io/t/how-to-enable-autoscaling/5073 "2022-05-09T15:28:33Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![qqwy](https://sea1.discourse-cdn.com/fly1/user_avatar/community.fly.io/qqwy/32/7475_2.png) [@qqwy](https://community.fly.io/u/qqwy)\ **Post date:** [May 9, 2022, 3:28pm UTC](https://community.fly.io/t/how-to-enable-autoscaling/5073/1 "2022-05-09T15:28:33Z")
I am trying to test Fly’s autoscaling by deploying a simple app and load testing it. Steps taken: 1. Deploy a simple Elixir/Phoenix application, using the stock Dockerfile and fly.toml Fly creates for it. (I’ve also tried the same with a simple Ruby on Rails application) 2. Change `[services.concurrency]` hard\_limit to 250, leave soft\_limit at 20. 3. `fly scale count 1`. I run in one region, `ams`, as 95% of traffic of our real app will also be from the Netherlands. ( I have also tried running in two regions, `ams` and `cfr`, with the same, i.e. ‘no’, results.) 4. `fly autoscale balanced min=1 max=8` 5. Run Fly’s [burn](https://github.com/superfly/burn) tool to hit the app’s homepage many times for multiple minutes. I’ve tried in-between the soft and hard limit, twice the hard limit, thrice the hard limit. I would now expect autoscaling to occur, but no new VMs are started, even as “warn: hard limit reached” messages come in in the `fly logs`. Am I missing a crucial step somewhere? ---
**Author:** ![eli](https://sea1.discourse-cdn.com/fly1/user_avatar/community.fly.io/eli/32/49867_2.png) [@eli](https://community.fly.io/u/eli)\ **Post date:** [May 9, 2022, 8:59pm UTC](https://community.fly.io/t/how-to-enable-autoscaling/5073/2 "2022-05-09T20:59:25Z")
This all looks correct to me (and thank you for detailing the work you’ve done so far). Would you mind confirming a few things? Specifically: - The output of `fly autoscale status`; this will show us what flyctl thinks the autoscale settings currently are - The output of `fly releases` ; this will confirm that the app’s config was definitely updated. - the specific flags/values that you’re using with `burn`. As you’re likely aware, [autoscaling decisions are made based on a few minutes’ worth of traffic](https://community.fly.io/t/autoscale-doesnt-seem-to-launch-new-instances/2559/3) – so it’s useful to know exactly how long you’re running your tests for. - as much as your fly.toml as you’re comfortable sharing, to get a better idea of how your app is configured to receive traffic. On a related note, you [might try the setting](https://community.fly.io/t/recommended-services-concurrency-settings-for-elixir-phoenix-apps/3029/2) `type ="requests"` for your `[services.concurrency]` block. ---
**Author:** ![qqwy](https://sea1.discourse-cdn.com/fly1/user_avatar/community.fly.io/qqwy/32/7475_2.png) [@qqwy](https://community.fly.io/u/qqwy)\ **Post date:** [May 9, 2022, 9:11pm UTC](https://community.fly.io/t/how-to-enable-autoscaling/5073/3 "2022-05-09T21:11:18Z")
Thanks for your reply! The info you asked for: ```bash $ fly autoscale show Scale Mode: Balanced Min Count: 1 Max Count: 8 ``` ```bash $ fly scale show VM Resources for uptime-monitor-backend VM Size: shared-cpu-1x VM Memory: 256 MB Count: 1 Max Per Region: Not set ``` ```bash $ fly releases VERSION STABLE TYPE STATUS DESCRIPTION USER DATE v10 true scale succeeded Update autoscaling config 5h42m ago v9 false scale failed Scale VM count: ["app, 1"] 5h42m ago v8 true scale succeeded Update autoscaling config 5h48m ago v7 false scale cancelled updating region configuration 5h49m ago v6 false scale cancelled updating region configuration 5h49m ago v5 false scale cancelled updating region configuration 5h49m ago v4 true scale succeeded Update autoscaling config 5h54m ago v3 true release succeeded Deploy image 5h57m ago v2 true rollback succeeded Reverting to version 0 6h14m ago v1 false release failed Deploy image 6h15m ago v0 true release succeeded Deploy image 2022-02-06T19:20:07Z ``` For `burn`, I’ve most recently used `./burn -c 400 -d 120s https://uptime-monitor-backend.fly.dev/ --verbose --resume-tls`. Maybe two minutes is not long enough for autoscaling to kick in? I have also recently (on another app, but with a similar setup) tried to use `locust`, scaling the number of users up to 600 by adding 2 more per second (e.g. reaching the peak after ten minutes, although the `soft_limit` would be passed after the first ten seconds), with similarly no autoscaling happening. I have tried both `type = "connections"` and `type = "requests"`. * * * The topic you pointed to ([this one](https://community.fly.io/t/how-long-does-it-take-for-autoscaling-to-take-effect/3245/2)) did not actually seem to mention anywhere how much time is taken for autoscaling to kick in. I did find [this post by @kurt](https://community.fly.io/t/autoscale-doesnt-seem-to-launch-new-instances/2559/3) mentioning “it needs to be maxed out 30-60s”. But maybe that information is outdated? ---
**Author:** ![eli](https://sea1.discourse-cdn.com/fly1/user_avatar/community.fly.io/eli/32/49867_2.png) [@eli](https://community.fly.io/u/eli)\ **Post date:** [May 9, 2022, 9:18pm UTC](https://community.fly.io/t/how-to-enable-autoscaling/5073/4 "2022-05-09T21:18:39Z")
> The topic you pointed to ([this one](https://community.fly.io/t/how-long-does-it-take-for-autoscaling-to-take-effect/3245/2)) did not actually seem to mention anywhere how much time is taken for autoscaling to kick in. > I did find [this post by kurt](https://community.fly.io/t/autoscale-doesnt-seem-to-launch-new-instances/2559/3) mentioning “it needs to be maxed out 30-60s”. But maybe that information is outdated? Ah, my mistake-- I’ll edit my post to make that correction 🙂 I’ve been attempting to reproduce this issue, so having this information is super useful-- thanks for the quick response! ---
**Author:** ![eli](https://sea1.discourse-cdn.com/fly1/user_avatar/community.fly.io/eli/32/49867_2.png) [@eli](https://community.fly.io/u/eli)\ **Post date:** [May 10, 2022, 8:07pm UTC](https://community.fly.io/t/how-to-enable-autoscaling/5073/6 "2022-05-10T20:07:13Z")
> Maybe two minutes is not long enough for autoscaling to kick in? If you haven’t already, I’d definitely suggest trying for a bit longer than two minutes as a quick troubleshooting step. Generally speaking, the auto-scaling feature is a definitely bit slow to react, and difficult to induce via loadtest. For example, it requires that the concurrent connections limit be consistently exceeded for all an app’s VMs for over a minute while the app is running. Platform-wise, there are a lot of moving parts which add latency, too. We’re looking to improve autoscaling, so a major overhaul is in the works for (hopefully!) sometime later this year. It’s in its early stages, but you may want to check out [this thread](https://community.fly.io/t/tease-us-with-more-machine-info/4494/5) to follow our work on providing more VM-level features! ---
**Author:** ![wjordan](https://sea1.discourse-cdn.com/fly1/user_avatar/community.fly.io/wjordan/32/1280_2.png) [@wjordan](https://community.fly.io/u/wjordan)\ **Post date:** [July 26, 2022, 4:07pm UTC](https://community.fly.io/t/how-to-enable-autoscaling/5073/7 "2022-07-26T16:07:47Z")
Hello @qqwy! Just letting you know we just tracked down an internal bug in the autoscaling service that was causing scaling events to not get triggered properly, sorry for the inconvenience. It should be working correctly now so please give it another try! ---
**Author:** ![qqwy](https://sea1.discourse-cdn.com/fly1/user_avatar/community.fly.io/qqwy/32/7475_2.png) [@qqwy](https://community.fly.io/u/qqwy)\ **Post date:** [July 27, 2022, 7:12pm UTC](https://community.fly.io/t/how-to-enable-autoscaling/5073/8 "2022-07-27T19:12:03Z")
Thanks for letting us know; will do once I’m back from vacation! ---
**Author:** ![qqwy](https://sea1.discourse-cdn.com/fly1/user_avatar/community.fly.io/qqwy/32/7475_2.png) [@qqwy](https://community.fly.io/u/qqwy)\ **Post date:** [August 2, 2022, 1:23pm UTC](https://community.fly.io/t/how-to-enable-autoscaling/5073/9 "2022-08-02T13:23:54Z")
I had some time to revisit this with our apps today. I can confirm that it now works exactly as expected! Wonderful! 🥳