Mojo::UserAgent − Non−blocking I/O HTTP and WebSocket user agent
use
Mojo::UserAgent;
# Fine grained response handling (dies on connection errors)
my $ua = Mojo::UserAgent−>new;
my $res =
$ua−>get('docs.mojolicious.org')−>result;
if ($res−>is_success) { say $res−>body }
elsif ($res−>is_error) { say $res−>message
}
elsif ($res−>code == 301) { say
$res−>headers−>location }
else { say 'Whatever...' }
# Say hello to the Unicode snowman and include an Accept
header
say $ua−>get('www.â.net?hello=there' =>
{Accept => '*/*'})−>result−>body;
# Extract data from HTML and XML resources with CSS
selectors
say
$ua−>get('www.perl.org')−>result−>dom−>at('title')−>text;
# Scrape the latest headlines from a news site
say
$ua−>get('blogs.perl.org')−>result−>dom−>find('h2
>
a')−>map('text')−>join("\n");
# IPv6 PUT request with Content−Type header and
content
my $tx = $ua−>put('[::1]:3000' =>
{'Content−Type' => 'text/plain'} => 'Hi!');
# Quick JSON API request with Basic authentication
my $url =
Mojo::URL−>new('https://example.com/test.json')−>userinfo('sri:â');
my $value =
$ua−>get($url)−>result−>json;
# JSON POST (application/json) with TLS certificate
authentication
my $tx =
$ua−>cert('tls.crt')−>key('tls.key')−>post('https://example.com'
=> json => {top => 'secret'});
# Form POST
(application/x−www−form−urlencoded)
my $tx = $ua−>post('https://metacpan.org/search'
=> form => {q => 'mojo'});
# Search DuckDuckGo anonymously through Tor
$ua−>proxy−>http('socks://127.0.0.1:9050');
say
$ua−>get('api.3g2upl4pq6kufc4m.onion/?q=mojolicious&format=json')−>result−>json('/Abstract');
# GET request via UNIX domain socket
"/tmp/myapp.sock" (percent encoded slash)
say
$ua−>get('http+unix://%2Ftmp%2Fmyapp.sock/test')−>result−>body;
# Follow redirects to download Mojolicious from GitHub
$ua−>max_redirects(5)
−>get('https://www.github.com/mojolicious/mojo/tarball/main')
−>result−>save_to('/home/sri/mojo.tar.gz');
# Non−blocking request
$ua−>get('mojolicious.org' => sub ($ua, $tx) {
say
$tx−>result−>dom−>at('title')−>text
});
Mojo::IOLoop−>start unless
Mojo::IOLoop−>is_running;
# Concurrent non−blocking requests (synchronized with
promises)
my $mojo_promise = $ua−>get_p('mojolicious.org');
my $cpan_promise = $ua−>get_p('cpan.org');
Mojo::Promise−>all($mojo_promise,
$cpan_promise)−>then(sub ($mojo, $cpan) {
say
$mojo−>[0]−>result−>dom−>at('title')−>text;
say
$cpan−>[0]−>result−>dom−>at('title')−>text;
})−>wait;
# WebSocket connection sending and receiving JSON via UNIX
domain socket
$ua−>websocket('ws+unix://%2Ftmp%2Fmyapp.sock/echo.json'
=> sub ($ua, $tx) {
say 'WebSocket handshake failed!' and return unless
$tx−>is_websocket;
$tx−>on(json => sub ($tx, $hash) {
say "WebSocket message via JSON:
$hash−>{msg}";
$tx−>finish;
});
$tx−>send({json => {msg => 'Hello World!'}});
});
Mojo::IOLoop−>start unless
Mojo::IOLoop−>is_running;
Mojo::UserAgent is a full featured non-blocking I/O HTTP and WebSocket user agent, with IPv6, TLS, SNI, IDNA, HTTP/SOCKS5 proxy, UNIX domain socket, Comet (long polling), Promises/A+, keep-alive, connection pooling, timeout, cookie, multipart, gzip compression and multiple event loop support.
All connections will be reset automatically if a new process has been forked, this allows multiple processes to share the same Mojo::UserAgent object safely.
For better scalability (epoll, kqueue) and to provide non-blocking name resolution, SOCKS5 as well as TLS support, the optional modules EV (4.32+), Net::DNS::Native (0.15+), IO::Socket::Socks (0.64+) and IO::Socket::SSL (2.009+) will be used automatically if possible. Individual features can also be disabled with the "MOJO_NO_NNR", "MOJO_NO_SOCKS" and "MOJO_NO_TLS" environment variables.
See "USER AGENT" in Mojolicious::Guides::Cookbook for more.
Mojo::UserAgent inherits all events from Mojo::EventEmitter and can emit the following new ones.
$ua−>on(prepare => sub ($ua, $tx) {...});
Emitted whenever a new transaction is being prepared, before relative URLs are rewritten and cookies added. This includes automatically prepared proxy "CONNECT" requests and followed redirects.
$ua−>on(prepare
=> sub ($ua, $tx) {
$tx−>req−>url(Mojo::URL−>new('/mock−mojolicious'))
if $tx−>req−>url−>host eq
'mojolicious.org';
});
$ua−>on(start => sub ($ua, $tx) {...});
Emitted whenever a new transaction is about to start. This includes automatically prepared proxy "CONNECT" requests and followed redirects.
$ua−>on(start
=> sub ($ua, $tx) {
$tx−>req−>headers−>header('X−Bender'
=> 'Bite my shiny metal ass!');
});
Mojo::UserAgent implements the following attributes.
my $ca =
$ua−>ca;
$ua = $ua−>ca('/etc/tls/ca.crt');
Path to TLS certificate authority file used to verify the peer certificate, defaults to the value of the "MOJO_CA_FILE" environment variable.
# Show
certificate authorities for debugging
IO::Socket::SSL::set_defaults(SSL_verify_callback => sub
{ say "Authority: $_[2]" and return $_[0] });
my $cert =
$ua−>cert;
$ua = $ua−>cert('/etc/tls/client.crt');
Path to TLS certificate file, defaults to the value of the "MOJO_CERT_FILE" environment variable.
my $timeout =
$ua−>connect_timeout;
$ua = $ua−>connect_timeout(5);
Maximum amount of time in seconds establishing a connection may take before getting canceled, defaults to the value of the "MOJO_CONNECT_TIMEOUT" environment variable or 10.
my $cookie_jar =
$ua−>cookie_jar;
$ua =
$ua−>cookie_jar(Mojo::UserAgent::CookieJar−>new);
Cookie jar to use for requests performed by this user agent, defaults to a Mojo::UserAgent::CookieJar object.
# Ignore all
cookies
$ua−>cookie_jar−>ignore(sub { 1 });
# Ignore cookies for public suffixes
my $ps = IO::Socket::SSL::PublicSuffix−>default;
$ua−>cookie_jar−>ignore(sub ($cookie) {
return undef unless my $domain = $cookie−>domain;
return ($ps−>public_suffix($domain))[0] eq '';
});
# Add custom cookie to the jar
$ua−>cookie_jar−>add(
Mojo::Cookie::Response−>new(
name => 'foo',
value => 'bar',
domain => 'docs.mojolicious.org',
path => '/Mojolicious'
)
);
my $timeout =
$ua−>inactivity_timeout;
$ua = $ua−>inactivity_timeout(15);
Maximum amount of time in seconds a connection can be inactive before getting closed, defaults to the value of the "MOJO_INACTIVITY_TIMEOUT" environment variable or 40. Setting the value to 0 will allow connections to be inactive indefinitely.
my $bool =
$ua−>insecure;
$ua = $ua−>insecure($bool);
Do not require a valid TLS certificate to access HTTPS/WSS sites, defaults to the value of the "MOJO_INSECURE" environment variable.
# Disable TLS
certificate verification for testing
say
$ua−>insecure(1)−>get('https://127.0.0.1:3000')−>result−>code;
my $loop =
$ua−>ioloop;
$ua = $ua−>ioloop(Mojo::IOLoop−>new);
Event loop object to use for blocking I/O operations, defaults to a Mojo::IOLoop object.
my $key =
$ua−>key;
$ua = $ua−>key('/etc/tls/client.crt');
Path to TLS key file, defaults to the value of the "MOJO_KEY_FILE" environment variable.
my $max =
$ua−>max_connections;
$ua = $ua−>max_connections(5);
Maximum number of keep-alive connections that the user agent will retain before it starts closing the oldest ones, defaults to 5. Setting the value to 0 will prevent any connections from being kept alive.
my $max =
$ua−>max_redirects;
$ua = $ua−>max_redirects(3);
Maximum number of redirects the user agent will follow before it fails, defaults to the value of the "MOJO_MAX_REDIRECTS" environment variable or 0.
my $max =
$ua−>max_response_size;
$ua = $ua−>max_response_size(16777216);
Maximum response size in bytes, defaults to the value of "max_message_size" in Mojo::Message::Response. Setting the value to 0 will allow responses of indefinite size. Note that increasing this value can also drastically increase memory usage, should you for example attempt to parse an excessively large response body with the methods "dom" in Mojo::Message or "json" in Mojo::Message.
my $proxy =
$ua−>proxy;
$ua =
$ua−>proxy(Mojo::UserAgent::Proxy−>new);
Proxy manager, defaults to a Mojo::UserAgent::Proxy object.
# Detect proxy
servers from environment
$ua−>proxy−>detect;
# Manually configure HTTP proxy (using CONNECT for
HTTPS/WebSockets)
$ua−>proxy−>http('http://127.0.0.1:8080')−>https('http://127.0.0.1:8080');
# Manually configure Tor (SOCKS5)
$ua−>proxy−>http('socks://127.0.0.1:9050')−>https('socks://127.0.0.1:9050');
# Manually configure UNIX domain socket (using CONNECT for
HTTPS/WebSockets)
$ua−>proxy−>http('http+unix://%2Ftmp%2Fproxy.sock')
−>https('http+unix://%2Ftmp%2Fproxy.sock');
my $timeout =
$ua−>request_timeout;
$ua = $ua−>request_timeout(5);
Maximum amount of time in seconds establishing a connection, sending the request and receiving a whole response may take before getting canceled, defaults to the value of the "MOJO_REQUEST_TIMEOUT" environment variable or 0. Setting the value to 0 will allow the user agent to wait indefinitely. The timeout will reset for every followed redirect.
# Total limit of
5 seconds, of which 3 seconds may be spent connecting
$ua−>max_redirects(0)−>connect_timeout(3)−>request_timeout(5);
my $server =
$ua−>server;
$ua =
$ua−>server(Mojo::UserAgent::Server−>new);
Application server relative URLs will be processed with, defaults to a Mojo::UserAgent::Server object.
# Mock web
service
$ua−>server−>app(Mojolicious−>new);
$ua−>server−>app−>routes−>get('/time'
=> sub ($c) {
$c−>render(json => {now => time});
});
my $time =
$ua−>get('/time')−>result−>json−>{now};
# Change log level
$ua−>server−>app−>log−>level('fatal');
# Port currently used for processing relative URLs blocking
say $ua−>server−>url−>port;
# Port currently used for processing relative URLs
non−blocking
say
$ua−>server−>nb_url−>port;
my $options =
$ua−>socket_options;
$ua = $ua−>socket_options({LocalAddr =>
'127.0.0.1'});
Additional options for IO::Socket::IP when opening new connections.
my $options =
$ua−>tls_options;
$ua = $ua−>tls_options({SSL_cipher_list =>
'DEFAULT:!DH@SECLEVEL=1'});
Additional options for IO::Socket::SSL when opening new connections.
my $t =
$ua−>transactor;
$ua =
$ua−>transactor(Mojo::UserAgent::Transactor−>new);
Transaction builder, defaults to a Mojo::UserAgent::Transactor object.
# Change name of
user agent
$ua−>transactor−>name('MyUA 1.0');
# Disable compression
$ua−>transactor−>compressed(0);
Mojo::UserAgent inherits all methods from Mojo::EventEmitter and implements the following new ones.
my $tx =
$ua−>build_tx(GET => 'example.com');
my $tx = $ua−>build_tx(PUT =>
'http://example.com' => {Accept => '*/*'} =>
'Content!');
my $tx = $ua−>build_tx(PUT =>
'http://example.com' => {Accept => '*/*'} => form
=> {a => 'b'});
my $tx = $ua−>build_tx(PUT =>
'http://example.com' => {Accept => '*/*'} => json
=> {a => 'b'});
Generate Mojo::Transaction::HTTP object with "tx" in Mojo::UserAgent::Transactor.
# Request with
custom cookie
my $tx = $ua−>build_tx(GET =>
'https://example.com/account');
$tx−>req−>cookies({name => 'user',
value => 'sri'});
$tx = $ua−>start($tx);
# Deactivate gzip compression
my $tx = $ua−>build_tx(GET => 'example.com');
$tx−>req−>headers−>remove('Accept−Encoding');
$tx = $ua−>start($tx);
# Interrupt response by raising an error
my $tx = $ua−>build_tx(GET =>
'http://example.com');
$tx−>res−>on(progress => sub ($res) {
return unless my $server =
$res−>headers−>server;
$res−>error({message => 'Oh noes, it is IIS!'})
if $server =˜ /IIS/;
});
$tx = $ua−>start($tx);
my $tx =
$ua−>build_websocket_tx('ws://example.com');
my $tx = $ua−>build_websocket_tx(
'ws://example.com' => {DNT => 1} =>
['v1.proto']);
Generate Mojo::Transaction::HTTP object with "websocket" in Mojo::UserAgent::Transactor.
# Custom
WebSocket handshake with cookie
my $tx =
$ua−>build_websocket_tx('wss://example.com/echo');
$tx−>req−>cookies({name => 'user',
value => 'sri'});
$ua−>start($tx => sub ($ua, $tx) {
say 'WebSocket handshake failed!' and return unless
$tx−>is_websocket;
$tx−>on(message => sub ($tx, $msg) {
say "WebSocket message: $msg";
$tx−>finish;
});
$tx−>send('Hi!');
});
Mojo::IOLoop−>start unless
Mojo::IOLoop−>is_running;
my $tx =
$ua−>delete('example.com');
my $tx = $ua−>delete('http://example.com' =>
{Accept => '*/*'} => 'Content!');
my $tx = $ua−>delete('http://example.com' =>
{Accept => '*/*'} => form => {a => 'b'});
my $tx = $ua−>delete('http://example.com' =>
{Accept => '*/*'} => json => {a => 'b'});
Perform blocking "DELETE" request and return resulting Mojo::Transaction::HTTP object, takes the same arguments as "tx" in Mojo::UserAgent::Transactor (except for the "DELETE" method, which is implied). You can also append a callback to perform requests non-blocking.
$ua−>delete('http://example.com'
=> json => {a => 'b'} => sub ($ua, $tx) { say
$tx−>result−>body });
Mojo::IOLoop−>start unless
Mojo::IOLoop−>is_running;
my $promise = $ua−>delete_p('http://example.com');
Same as "delete", but performs all requests non-blocking and returns a Mojo::Promise object instead of accepting a callback.
$ua−>delete_p('http://example.com'
=> json => {a => 'b'})−>then(sub ($tx) {
say $tx−>result−>body;
})−>catch(sub ($err) {
warn "Connection error: $err";
})−>wait;
my $tx =
$ua−>get('example.com');
my $tx = $ua−>get('http://example.com' =>
{Accept => '*/*'} => 'Content!');
my $tx = $ua−>get('http://example.com' =>
{Accept => '*/*'} => form => {a => 'b'});
my $tx = $ua−>get('http://example.com' =>
{Accept => '*/*'} => json => {a => 'b'});
Perform blocking "GET" request and return resulting Mojo::Transaction::HTTP object, takes the same arguments as "tx" in Mojo::UserAgent::Transactor (except for the "GET" method, which is implied). You can also append a callback to perform requests non-blocking.
$ua−>get('http://example.com'
=> json => {a => 'b'} => sub ($ua, $tx) { say
$tx−>result−>body });
Mojo::IOLoop−>start unless
Mojo::IOLoop−>is_running;
my $promise = $ua−>get_p('http://example.com');
Same as "get", but performs all requests non-blocking and returns a Mojo::Promise object instead of accepting a callback.
$ua−>get_p('http://example.com'
=> json => {a => 'b'})−>then(sub ($tx) {
say $tx−>result−>body;
})−>catch(sub ($err) {
warn "Connection error: $err";
})−>wait;
my $tx =
$ua−>head('example.com');
my $tx = $ua−>head('http://example.com' =>
{Accept => '*/*'} => 'Content!');
my $tx = $ua−>head('http://example.com' =>
{Accept => '*/*'} => form => {a => 'b'});
my $tx = $ua−>head('http://example.com' =>
{Accept => '*/*'} => json => {a => 'b'});
Perform blocking "HEAD" request and return resulting Mojo::Transaction::HTTP object, takes the same arguments as "tx" in Mojo::UserAgent::Transactor (except for the "HEAD" method, which is implied). You can also append a callback to perform requests non-blocking.
$ua−>head('http://example.com'
=> json => {a => 'b'} => sub ($ua, $tx) { say
$tx−>result−>body });
Mojo::IOLoop−>start unless
Mojo::IOLoop−>is_running;
my $promise = $ua−>head_p('http://example.com');
Same as "head", but performs all requests non-blocking and returns a Mojo::Promise object instead of accepting a callback.
$ua−>head_p('http://example.com'
=> json => {a => 'b'})−>then(sub ($tx) {
say $tx−>result−>body;
})−>catch(sub ($err) {
warn "Connection error: $err";
})−>wait;
my $tx =
$ua−>options('example.com');
my $tx = $ua−>options('http://example.com' =>
{Accept => '*/*'} => 'Content!');
my $tx = $ua−>options('http://example.com' =>
{Accept => '*/*'} => form => {a => 'b'});
my $tx = $ua−>options('http://example.com' =>
{Accept => '*/*'} => json => {a => 'b'});
Perform blocking "OPTIONS" request and return resulting Mojo::Transaction::HTTP object, takes the same arguments as "tx" in Mojo::UserAgent::Transactor (except for the "OPTIONS" method, which is implied). You can also append a callback to perform requests non-blocking.
$ua−>options('http://example.com'
=> json => {a => 'b'} => sub ($ua, $tx) { say
$tx−>result−>body });
Mojo::IOLoop−>start unless
Mojo::IOLoop−>is_running;
my $promise = $ua−>options_p('http://example.com');
Same as "options", but performs all requests non-blocking and returns a Mojo::Promise object instead of accepting a callback.
$ua−>options_p('http://example.com'
=> json => {a => 'b'})−>then(sub ($tx) {
say $tx−>result−>body;
})−>catch(sub ($err) {
warn "Connection error: $err";
})−>wait;
my $tx =
$ua−>patch('example.com');
my $tx = $ua−>patch('http://example.com' =>
{Accept => '*/*'} => 'Content!');
my $tx = $ua−>patch('http://example.com' =>
{Accept => '*/*'} => form => {a => 'b'});
my $tx = $ua−>patch('http://example.com' =>
{Accept => '*/*'} => json => {a => 'b'});
Perform blocking "PATCH" request and return resulting Mojo::Transaction::HTTP object, takes the same arguments as "tx" in Mojo::UserAgent::Transactor (except for the "PATCH" method, which is implied). You can also append a callback to perform requests non-blocking.
$ua−>patch('http://example.com'
=> json => {a => 'b'} => sub ($ua, $tx) { say
$tx−>result−>body });
Mojo::IOLoop−>start unless
Mojo::IOLoop−>is_running;
my $promise = $ua−>patch_p('http://example.com');
Same as "patch", but performs all requests non-blocking and returns a Mojo::Promise object instead of accepting a callback.
$ua−>patch_p('http://example.com'
=> json => {a => 'b'})−>then(sub ($tx) {
say $tx−>result−>body;
})−>catch(sub ($err) {
warn "Connection error: $err";
})−>wait;
my $tx =
$ua−>post('example.com');
my $tx = $ua−>post('http://example.com' =>
{Accept => '*/*'} => 'Content!');
my $tx = $ua−>post('http://example.com' =>
{Accept => '*/*'} => form => {a => 'b'});
my $tx = $ua−>post('http://example.com' =>
{Accept => '*/*'} => json => {a => 'b'});
Perform blocking "POST" request and return resulting Mojo::Transaction::HTTP object, takes the same arguments as "tx" in Mojo::UserAgent::Transactor (except for the "POST" method, which is implied). You can also append a callback to perform requests non-blocking.
$ua−>post('http://example.com'
=> json => {a => 'b'} => sub ($ua, $tx) { say
$tx−>result−>body });
Mojo::IOLoop−>start unless
Mojo::IOLoop−>is_running;
my $promise = $ua−>post_p('http://example.com');
Same as "post", but performs all requests non-blocking and returns a Mojo::Promise object instead of accepting a callback.
$ua−>post_p('http://example.com'
=> json => {a => 'b'})−>then(sub ($tx) {
say $tx−>result−>body;
})−>catch(sub ($err) {
warn "Connection error: $err";
})−>wait;
my $tx =
$ua−>put('example.com');
my $tx = $ua−>put('http://example.com' =>
{Accept => '*/*'} => 'Content!');
my $tx = $ua−>put('http://example.com' =>
{Accept => '*/*'} => form => {a => 'b'});
my $tx = $ua−>put('http://example.com' =>
{Accept => '*/*'} => json => {a => 'b'});
Perform blocking "PUT" request and return resulting Mojo::Transaction::HTTP object, takes the same arguments as "tx" in Mojo::UserAgent::Transactor (except for the "PUT" method, which is implied). You can also append a callback to perform requests non-blocking.
$ua−>put('http://example.com'
=> json => {a => 'b'} => sub ($ua, $tx) { say
$tx−>result−>body });
Mojo::IOLoop−>start unless
Mojo::IOLoop−>is_running;
my $promise = $ua−>put_p('http://example.com');
Same as "put", but performs all requests non-blocking and returns a Mojo::Promise object instead of accepting a callback.
$ua−>put_p('http://example.com'
=> json => {a => 'b'})−>then(sub ($tx) {
say $tx−>result−>body;
})−>catch(sub ($err) {
warn "Connection error: $err";
})−>wait;
my $tx = $ua−>start(Mojo::Transaction::HTTP−>new);
Perform blocking request for a custom Mojo::Transaction::HTTP object, which can be prepared manually or with "build_tx". You can also append a callback to perform requests non-blocking.
my $tx =
$ua−>build_tx(GET => 'http://example.com');
$ua−>start($tx => sub ($ua, $tx) { say
$tx−>result−>body });
Mojo::IOLoop−>start unless
Mojo::IOLoop−>is_running;
my $promise = $ua−>start_p(Mojo::Transaction::HTTP−>new);
Same as "start", but performs all requests non-blocking and returns a Mojo::Promise object instead of accepting a callback.
my $tx =
$ua−>build_tx(GET => 'http://example.com');
$ua−>start_p($tx)−>then(sub ($tx) {
say $tx−>result−>body;
})−>catch(sub ($err) {
warn "Connection error: $err";
})−>wait;
$ua−>websocket('ws://example.com'
=> sub {...});
$ua−>websocket('ws://example.com' => {DNT =>
1} => ['v1.proto'] => sub {...});
Open a non-blocking WebSocket connection with transparent handshake, takes the same arguments as "websocket" in Mojo::UserAgent::Transactor. The callback will receive either a Mojo::Transaction::WebSocket or Mojo::Transaction::HTTP object, depending on if the handshake was successful.
$ua−>websocket('wss://example.com/echo'
=> ['v1.proto'] => sub ($ua, $tx) {
say 'WebSocket handshake failed!' and return unless
$tx−>is_websocket;
say 'Subprotocol negotiation failed!' and return unless
$tx−>protocol;
$tx−>on(finish => sub ($tx, $code, $reason) {
say "WebSocket closed with status $code." });
$tx−>on(message => sub ($tx, $msg) {
say "WebSocket message: $msg";
$tx−>finish;
});
$tx−>send('Hi!');
});
Mojo::IOLoop−>start unless
Mojo::IOLoop−>is_running;
You can activate "permessage−deflate" compression by setting the "Sec−WebSocket−Extensions" header, this can result in much better performance, but also increases memory usage by up to 300KiB per connection.
$ua−>websocket('ws://example.com/foo'
=> {
'Sec−WebSocket−Extensions' =>
'permessage−deflate'
} => sub {...});
my $promise = $ua−>websocket_p('ws://example.com');
Same as "websocket", but returns a Mojo::Promise object instead of accepting a callback.
$ua−>websocket_p('wss://example.com/echo')−>then(sub
($tx) {
my $promise = Mojo::Promise−>new;
$tx−>on(finish => sub {
$promise−>resolve });
$tx−>on(message => sub ($tx, $msg) {
say "WebSocket message: $msg";
$tx−>finish;
});
$tx−>send('Hi!');
return $promise;
})−>catch(sub ($err) {
warn "WebSocket error: $err";
})−>wait;
You can set the "MOJO_CLIENT_DEBUG" environment variable to get some advanced diagnostics information printed to "STDERR".
MOJO_CLIENT_DEBUG=1
Mojolicious, Mojolicious::Guides, <https://mojolicious.org>.