HOSTstrThe listening address of the server (eg: or
PORTintThe port the server will listen at (eg: 8080).
IPV6boolIf IPv6 should be enabled for the server/client, by default the created socket is either IPV4 or IPv6 only, note that under Linux dual stack is provided for "free" for IPv6 stacks (defaults to False).
SSLboolIf the server is going to use SSL/TLS (Secure Sockets Layer).
UNIX_PATHstrThe path to the file that is going to be used for Unix domain sockets (defaults to $PORT), note that under the hood the port variable is used as the path for the socket.
BACKLOGintThe number of connections to be hold waiting in queue while pending accept operation.
ALLOWEDlistSequence of IP or Subnet addresses (eg: that are considered to be allowed as clients for a given server, any client connection with an IP address not contained in the list will be dropped (defaults to []).
CHILDRENintNumber of child processes that are meant to be created upon launch using a pre-fork approach. (defaults to 0).
MIDDLEWARElistThe middleware as a set of strings (eg: proxy) that is going to be loaded into the instance, the notation used to define the modules to be loaded should be underscore based (notice that loading extra middleware into an instance may impact the performance of the same).
SECUREboolControl if a secure production environment should be ensured by hiding some critical information (eg: version) (defaults to True).


ASYNCIOboolIf the asyncio mode should be used, meaning that the loop retrieval method to be used is the one provided by the asyncio module, in case no asyncio support exists the flag is ignored (defaults to False).
COMPATboolIf the "heavyweight" compatibility mode should be ensured so that some operations will use an asyncio compatible way of performing execution, using this mode has performance implications (defaults to False).
POLLstrThe name of the polling system to be used for the controlling of the main event loop by default this values is inferred automatically based on the current system capabilities.
POLL_TIMEOUTfloatThe timeout in seconds for each of the iteration of the event loop, this value should be carefully chosen as it controls the minimum resolution of a delayed execution.
KEEPALIVE_TIMEOUTintThe amount of time in seconds that a connection is set as idle until a new refresh token is sent to it to make sure that it's still online and not disconnected, make sure that this value is high enough that it does not consume to much bandwidth.
KEEPALIVE_INTERVALintThe time between the retrying of "ping" packets, this value does not need to be too large and should not be considered too important (may be calculated automatically).
KEEPALIVE_COUNTintThe amount of times the "ping" packet is re-sent until the connection is considered to be offline and is dropped.


DIAGboolFalseIf the diagnostics system should be launched for the current system, if launched the system will be running as an HTTP server on localhost under port 5050.
DIAG_SERVERstrnetiusThe server that is going to be used for serving the diagnostics system infrastructure.
DIAG_HOSTstr127.0.0.1The hostname that is going to be used when launching the diagnostics system.
DIAG_PORTint5050The TCP port that is going to be used when launching the diagnostics system.


CER_FILEstrThe path to the certificate file to be used for SSL (PEM format).
KEY_FILEstrThe path to the private key file to be used for SSL (PEM format).
CA_FILEstrThe path to the CA (certificate authority) file to be used for SSL (PEM format).
CA_ROOTboolIf the default CA file/files should be loaded from the current environment (defaults to True).
SSL_VERIFYboolIf the standard SSL verification process (CA) should be performed for the connection, if the current instance is a client the host verification will also be performed for the server side host.
SSL_HOSTstrThe hostname that is going to be used in for domain verification, this value is only user in server to be able to verify client certificates against an expected host.
SSL_FINGERPRINTstrThe fingerprint (SHA1 digest of certificate) that is going to be used to verify the integrity of a peer/client certificate against the expected one.
SSL_DUMPboolIf the certificate information should be dumped to the directory specified by the SSL_PATH configuration value (defaults to False).
SSL_PATHstrPath to the directory where the SSL dump information is going to be placed, in case the directory does not exist it's created (defaults to /tmp/ssl).
SSL_SECUREintThe level of security to be used for the suite of SSL (eg: some protocols removed) (defaults to 1).
SSL_CONTEXT_OPTIONSlistList of strings that defined the options to be used in the SSL context creation (eg: OP_NO_SSLv2) for more information check ssl module documentation (defaults to []).
SSL_CONTEXTSdictThe dictionary that associates the various domains that may be served with different context values (certificate, key, etc) for such domain.
CER_DATAstrEquivalent to CER_FILE but with explicit (data) contents of the file (\n escaped).
KEY_DATAstrEquivalent to KEY_FILE but with explicit (data) contents of the file (\n escaped).
CA_DATAstrEquivalent to CA_FILE but with explicit (data) contents of the file (\n escaped).

File Serving

BASE_PATHstrThe base directory path to be used for the file serving, if not defined the current directory is used instead (defaults to None).
STYLE_URLSlistThe list of URLs that are going to be used to include stylesheets at directory listing.
INDEX_FILESlistList of file names that should be considered for eligible for index operation (eg: index.html).
PATH_REGEXlistThe list of regex to path values (separated by the : character) that provide a simple way of URL re-writing like behaviour under the file serving extension (eg: .*:index.html).
LIST_DIRSboolIf directory listing is enabled (may pose a security issue) (defaults to True).
LIST_ENGINEstrThe name of the HTML generation engine to be used while listing files (eg: base, apache, legacy, etc.) (defaults to base).


SAFEboolIf safe execution should be enforced, (eg: avoiding HTTP2 execution) (defaults to False).
COMMON_LOGstrThe path to the file to log the HTTP request in "Common Log Format (defaults to None).


DYNAMICboolIn case this value is active dynamic connection encoding is applied, meaning that extra heuristics will be applied on a response basis to determine the proper encoding of the response (eg: plain, chunked, gzip, etc.).
THROTTLEboolIf throttling of the connection stream should be applied on both ways to avoid starvation of the producer consumer relation.
TRUST_ORIGINboolIf the origin connection (eg: http client, proxy client, etc.) is meant to be trusted meaning that its information is considered reliable, this value is especially important for proxy to proxy relations (defaults to False).

Proxy Reverse

STSintDefines the strict transport security header value (in seconds) for the reverse proxy, in case the value is zero the strict transport security is disabled (defaults to 0).
ECHOboolIf enabled allows for more verbose output of the rules associated with the reverse proxy (defaults to False).
RESOLVEboolIf the DNS based resolution of the hosts should be enabled meaning that from time to time the hostname associated with the target URLs is resolved (defaults to True).
RESOLVE_TIMEOUTfloatThe amount of seconds between DNS resolution queries (defaults to 120).
HOST_FORWARDboolIf the Host header for HTTP back-end connections should be resolved from rules, avoiding Host header populated with the IP address (defaults to False).
REUSEboolIf HTTP connections/rules should be re-used from a proxy point of view, this options may pose a problem when different suffixes are used for the same host (defaults to True).
STRATEGYstrThe load balancing strategy that is going to be used for multiple back-end connections (defaults to smart).
X_FORWARDED_PORTstrIf defined allow "forcing" the X-Forwarded-Port HTTP header (defaults to None).
X_FORWARDED_PROTOstrIf defined allow "forcing" the X-Forwarded-Proto HTTP header (defaults to None).

DNS Client

NAMESERVERSlistThe sequence of DNS servers to be used for forward of resolution requests (defaults to []).
NAMESERVERS_IP4listSame as NAMESERVERS but just for IPv4 resolution (defaults to []).
NAMESERVERS_IP6listSame as NAMESERVERS but just for IPv6 resolution (defaults to []).

Blacklist Middleware

BLACKLISTlistList of IP addresses of the connections that should be dropped immediately, use * to drop all of the connections.
WHITELISTlistSequence of IP addresses that should be allowed explicitly, use * to allow all of the connection to be accepted.

Flood (Mitigation) Middleware

CONNS_PER_MINintThe maximum number of connections per minute allowed per a certain IP before it becomes black listed and connections are dropped (default to 600).
WHITELISTlistSequence of IP addresses that should be allowed explicitly, use * to allow all of the connection to be accepted.

PROXY Middleware

PROXY_VERSIONintThe version of the PROXY protocol that is going to be used (defaults to 1).

Annoyer Middleware

ANNOYER_PERIODfloatThe period (in seconds) to wait in between the printing of the "annoying" diagnostics message, this is opposite of the frequency (defaults to 10).