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Questions tagged [kemal]

This is for questions regarding the Kemal framework for the Crystal language.

34 questions
6
votes
1 answer

How to free memory allocated for some structure in Crystal - manually?

I have a Kemal-based RESTful web service that returns "very big" (from 10 to 17M in size) chunks of JSON data, which is produced by to_json method from the "big" Hash structure. According to GC warning messages my code "may lead to memory leaks"…
drvtiny
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6
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2 answers

Starting crystal in production mode

I've been running my Crystal webapp by building it, and then running the executable. However, it always listens on port 3000. How do I build/run Crystal webapps listening on 80 and 443? I'm using Kemal as well. Here is my sample app. require…
Tyler
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5
votes
1 answer

Cycling between Fibers with no IO

As far as I know, crystal cycles Fibers with io, meaning that if one fiber is waiting for io, crystal will switch to an another fiber. What if we spawn two fibers but one of them does constant computation/loop with no io? For example, with the code…
Oguz Bilgic
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4
votes
2 answers

Using Crystal/Kemal to listen for UDP packets

I have been trying to create a non-blocking server using Crystal and Kemal which will (a) listen for a stream of UDP messages being sent to it, and (b) then forwarding that message to a WebSocket to any browsers who have started a ws connection. So…
CyberFerret
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3
votes
2 answers

Crystal build fails with "ld: library not found for -lssl"

I've just started a brand new Crystal app, added Kemal, and when building the "Hello World!" app from the Kemal documentation, I get: $ crystal build --release src/orderprinterlinks.cr ld: library not found for -lssl clang: error: linker command…
Bjorn Forsberg
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3
votes
1 answer

Using Kemal-sessions with websocket

The documentation for the kemal-session module for the Kemal web framework in Crystal provides this example: require "kemal" require "kemal-session" get "/set" do |env| env.session.int("number", rand(100)) # set the value of "number" "Random…
Clement J.
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2
votes
1 answer

View metrics or more insights on HTTP::Server

We're running a production system on Crystal/Kemal. The calling service sees quite often a Connection refused error. I was wondering how can I see more insights/metrics into a running instance of HTTP::Server/Kemal. I'm referring to the number of…
linkyndy
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2
votes
1 answer

Kemal configuration using blocks

Kemal currently allows setting configuration options via: Kemal.config.env = "development" Kemal.config.port = "3456" I want to do something like with a block: configuration do |config| config.env = "development" config.port = "3456" …
lewis
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2
votes
1 answer

Crystal lang fiber and web socket

I'm beginner in crystal. I have question, maybe somebody can help me. I use Kemal framework. Have this code: require "kemal" require "json" channel = Channel(Card).new post "/posts" do |env| json = JSON.parse(env.request.body as String) url =…
schumi
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1
vote
1 answer

Parsing JSON as Array(String) in Kemal

I want to create an endpoint that receives JSON data and should parse it as an array of strings. POST / { "keys": ["foo", "bar"] } I'm running into problems with the type system. This is what I tried (.as(Array(String))) but it does not…
Philipp Claßen
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1
vote
1 answer

Slow exception report in Kemal

I use crystal 32.1 and Kemal. In case I have runtime exception it take 21 seconds to print backtrace. Any idea why it take so long? 500 GET /chats/by_sale/1 21280.52ms Backtrace: web_1 | I, [2020-02-07 17:57:33 +00:00 #1] INFO -- : [1] web_1 …
Sergey Makridenkov
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1
vote
1 answer

How do you access the return value of the route in Kemal after_all method?

From the after_all handler in a Kemal file, how do I modify the response from the route? [See example below] VERSION = "0.1.0" require "kemal" # Configure kemal parameters serve_static false get "/" do "Hello world!" end after_all do |env| #…
Oeste
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1
vote
1 answer

How to process html form data with kemal and crystal

I want to get user input in an html form and use the data to populate a database table. Sinatra returns the form data in a hash, params. Can I do this with Kemal and Crystal? Please note, I am in the process of learning Crystal, so this may not even…
lewis
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1
vote
1 answer

Kemal caching responses with handler middleware

Kemal caching responses with handler middleware I'm trying to do caching of some GET request with Kemal. class CachingHandler < Kemal::Handler property cache : Hash(String, IO::Memory) def initialize @cache = Hash(String,…
Javier Valencia
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1
vote
1 answer

Get JSON in POST in kemal

What I want is a POST request in kemal where the body has a certain number of keys/values that I want to access and then an arbitrary JSON Object that I just want to stringify and pass on and later parse back to JSON. My problem is that I apparently…
tpei
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