Connnections handling - karate

Question

So I've been using karate for a while now, and there has been an issue we were facing since over the last year: org.apache.http.conn.ConnectTimeoutException
Other threads about that mentioned connectionTimeout exception were solvable by specifying proxy, but taht did not help us.
After tons of investigation, it turned out that our Azure SNAT was exhausted, meaning Karate was opening way too many connections.
To verify this I enabled log debugging and used this feature
Background:
* url "https://www.karatelabs.io/"
Scenario:
* method GET
* method GET
the logs then had following lines
13:10:17.868 [main] DEBUG com.intuit.karate - request:
1 > GET https://www.karatelabs.io/
1 > Host: www.karatelabs.io
1 > Connection: Keep-Alive
1 > User-Agent: Apache-HttpClient/4.5.13 (Java/17.0.4.1)
1 > Accept-Encoding: gzip,deflate
13:10:17.868 [main] DEBUG o.a.h.i.c.PoolingHttpClientConnectionManager - Connection request: [route: {s}->https://www.karatelabs.io:443][total available: 0; route allocated: 0 of 5; total allocated: 0 of 10]
13:10:17.874 [main] DEBUG o.a.h.i.c.PoolingHttpClientConnectionManager - Connection leased: [id: 0][route: {s}->https://www.karatelabs.io:443][total available: 0; route allocated: 1 of 5; total allocated: 1 of 10]
13:10:17.875 [main] DEBUG o.a.h.impl.execchain.MainClientExec - Opening connection {s}->https://www.karatelabs.io:443
13:10:17.883 [main] DEBUG o.a.h.i.c.DefaultHttpClientConnectionOperator - Connecting to www.karatelabs.io/34.149.87.45:443
13:10:17.883 [main] DEBUG o.a.h.c.s.SSLConnectionSocketFactory - Connecting socket to www.karatelabs.io/34.149.87.45:443 with timeout 30000
13:10:17.924 [main] DEBUG o.a.h.c.s.SSLConnectionSocketFactory - Enabled protocols: [TLSv1.3, TLSv1.2]
13:10:17.924 [main] DEBUG o.a.h.c.s.SSLConnectionSocketFactory - Enabled cipher suites:[...]
13:10:17.924 [main] DEBUG o.a.h.c.s.SSLConnectionSocketFactory - Starting handshake
13:10:18.012 [main] DEBUG o.a.h.c.s.SSLConnectionSocketFactory - Secure session established
13:10:18.012 [main] DEBUG o.a.h.c.s.SSLConnectionSocketFactory - negotiated protocol: TLSv1.3
13:10:18.012 [main] DEBUG o.a.h.c.s.SSLConnectionSocketFactory - negotiated cipher suite: TLS_AES_256_GCM_SHA384
13:10:18.012 [main] DEBUG o.a.h.c.s.SSLConnectionSocketFactory - peer principal: CN=karatelabs.io
13:10:18.012 [main] DEBUG o.a.h.c.s.SSLConnectionSocketFactory - peer alternative names: [karatelabs.io, www.karatelabs.io]
13:10:18.012 [main] DEBUG o.a.h.c.s.SSLConnectionSocketFactory - issuer principal: CN=Sectigo RSA Domain Validation Secure Server CA, O=Sectigo Limited, L=Salford, ST=Greater Manchester, C=GB
13:10:18.014 [main] DEBUG o.a.h.i.c.DefaultHttpClientConnectionOperator - Connection established localIp<->serverIp
13:10:18.015 [main] DEBUG o.a.h.i.c.DefaultManagedHttpClientConnection - http-outgoing-0: set socket timeout to 120000
13:10:18.015 [main] DEBUG o.a.h.impl.execchain.MainClientExec - Executing request GET / HTTP/1.1
...
13:10:18.066 [main] DEBUG o.a.h.impl.execchain.MainClientExec - Connection can be kept alive indefinitely
...
...
13:10:18.196 [main] DEBUG com.intuit.karate - request:
2 > GET https://www.karatelabs.io/
13:10:18.196 [main] DEBUG o.a.h.i.c.PoolingHttpClientConnectionManager - Connection request: [route: {s}->https://www.karatelabs.io:443][total available: 0; route allocated: 0 of 5; total allocated: 0 of 10]
13:10:18.196 [main] DEBUG o.a.h.i.c.PoolingHttpClientConnectionManager - Connection leased: [id: 1][route: {s}->https://www.karatelabs.io:443][total available: 0; route allocated: 1 of 5; total allocated: 1 of 10]
13:10:18.196 [main] DEBUG o.a.h.impl.execchain.MainClientExec - Opening connection {s}->https://www.karatelabs.io:443
13:10:18.196 [main] DEBUG o.a.h.i.c.DefaultHttpClientConnectionOperator - Connecting to www.karatelabs.io/34.149.87.45:443
13:10:18.196 [main] DEBUG o.a.h.c.s.SSLConnectionSocketFactory - Connecting socket to www.karatelabs.io/34.149.87.45:443 with timeout 30000
13:10:18.206 [main] DEBUG o.a.h.c.s.SSLConnectionSocketFactory - Enabled protocols: [TLSv1.3, TLSv1.2]
13:10:18.206 [main] DEBUG o.a.h.c.s.SSLConnectionSocketFactory - Enabled cipher suites:[...]
13:10:18.206 [main] DEBUG o.a.h.c.s.SSLConnectionSocketFactory - Starting handshake
13:10:18.236 [main] DEBUG o.a.h.c.s.SSLConnectionSocketFactory - Secure session established
13:10:18.236 [main] DEBUG o.a.h.c.s.SSLConnectionSocketFactory - negotiated protocol: TLSv1.3
13:10:18.236 [main] DEBUG o.a.h.c.s.SSLConnectionSocketFactory - negotiated cipher suite: TLS_AES_256_GCM_SHA384
13:10:18.236 [main] DEBUG o.a.h.c.s.SSLConnectionSocketFactory - peer principal: CN=karatelabs.io
13:10:18.236 [main] DEBUG o.a.h.c.s.SSLConnectionSocketFactory - peer alternative names: [karatelabs.io, www.karatelabs.io]
13:10:18.236 [main] DEBUG o.a.h.c.s.SSLConnectionSocketFactory - issuer principal: CN=Sectigo RSA Domain Validation Secure Server CA, O=Sectigo Limited, L=Salford, ST=Greater Manchester, C=GB
13:10:18.236 [main] DEBUG o.a.h.i.c.DefaultHttpClientConnectionOperator - Connection established localIp<->serverIp
13:10:18.236 [main] DEBUG o.a.h.i.c.DefaultManagedHttpClientConnection - http-outgoing-1: set socket timeout to 120000
...
13:10:18.279 [main] DEBUG o.a.h.impl.execchain.MainClientExec - Connection can be kept alive indefinitely
...
...
13:10:18.609 [Finalizer] DEBUG o.a.h.i.c.PoolingHttpClientConnectionManager - Connection manager is shutting down
13:10:18.610 [Finalizer] DEBUG o.a.h.i.c.DefaultManagedHttpClientConnection - http-outgoing-1: Shutdown connection
13:10:18.611 [Finalizer] DEBUG o.a.h.i.c.PoolingHttpClientConnectionManager - Connection manager shut down
13:10:18.612 [Finalizer] DEBUG o.a.h.i.c.PoolingHttpClientConnectionManager - Connection manager is shutting down
13:10:18.612 [Finalizer] DEBUG o.a.h.i.c.DefaultManagedHttpClientConnection - http-outgoing-2: Shutdown connection
13:10:18.612 [Finalizer] DEBUG o.a.h.i.c.PoolingHttpClientConnectionManager - Connection manager shut down
13:10:18.612 [Finalizer] DEBUG o.a.h.i.c.PoolingHttpClientConnectionManager - Connection manager is shutting down
"Connecting to socket" and "handshake" indicate that karate is establishing a new connection instead of using an already opened one, even though I am sending a request to the same host.
On the other hand, on longer scenarios, I was seeing "http-outgoing-x: Shutdown connection" after about ~1s from opening it, in the middle of the run, despite having "karate.configure('readTimeout', 120000)" specified.
I don't think that was intentional, especially after seeing the "keep-alive" header and the "Connection can be kept alive indefinitely" in the log"
That being said, is there any way to force karate to use the same connection instead of establishing a new one each request?

Answer 1

As far as we know, we use the Apache HTTP Client API the right way.
But you never know. The best thing is for you to dive into the code and see what we could be missing. Or you could provide a way to replicate following these instructions: https://github.com/karatelabs/karate/wiki/How-to-Submit-an-Issue