MINOR: httpclient: allow to configure the retries

When using the httpclient, one could be bothered with it returning after
a very long time when failing. By default the httpclient has a retries
of 3 and a timeout connect of 5s, which can results in pause of 20s
upon failure.

This patch allows the user to configure the retries of the httpclient so
it could reduce the time to return an error.

This patch helps fixing part of the issue #2269.

Could be backported in 2.7 if needed.

doc/configuration.txt

@@ -1088,6 +1088,7 @@ The following keywords are supported in the "global" section :
    - httpclient.resolvers.disabled
    - httpclient.resolvers.id
    - httpclient.resolvers.prefer
+   - httpclient.retries
    - httpclient.ssl.ca-file
    - httpclient.ssl.verify
    - insecure-fork-wanted
@@ -1729,6 +1730,13 @@ httpclient.resolvers.prefer <ipv4|ipv6>
   which is convenient when IPv6 is not available on your network. Default
   option is "ipv6".
 
+httpclient.retries <number>
+  This option allows to configure the number of retries attempt of the
+  httpclient when a request failed. This does the same as the "retries" keyword
+  in a backend.
+
+  Default value is 3.
+
 httpclient.ssl.ca-file <cafile>
   This option defines the ca-file which should be used to verify the server
   certificate. It takes the same parameters as the "ca-file" option on the

src/http_client.c

@@ -55,6 +55,8 @@ static char *resolvers_id = NULL;
 static char *resolvers_prefer = NULL;
 static int resolvers_disabled = 0;
 
+static int httpclient_retries = CONN_RETRIES;
+
 /* --- This part of the file implement an HTTP client over the CLI ---
  * The functions will be  starting by "hc_cli" for "httpclient cli"
  */
@@ -1218,7 +1220,7 @@ struct proxy *httpclient_create_proxy(const char *id)
 	px->mode = PR_MODE_HTTP;
 	px->maxconn = 0;
 	px->accept = NULL;
-	px->conn_retries = CONN_RETRIES;
+	px->conn_retries = httpclient_retries;
 	px->timeout.client = TICK_ETERNITY;
 	/* The HTTP Client use the "option httplog" with the global log server */
 	px->conf.logformat_string = httpclient_log_format;
@@ -1529,10 +1531,29 @@ static int httpclient_parse_global_verify(char **args, int section_type, struct
 }
 #endif /* ! USE_OPENSSL */
 
+static int httpclient_parse_global_retries(char **args, int section_type, struct proxy *curpx,
+                                        const struct proxy *defpx, const char *file, int line,
+                                        char **err)
+{
+	if (too_many_args(1, args, err, NULL))
+		return -1;
+
+	if (*(args[1]) == 0) {
+		ha_alert("parsing [%s:%d] : '%s' expects an integer argument.\n",
+			 file, line, args[0]);
+		return -1;
+	}
+	httpclient_retries = atol(args[1]);
+
+	return 0;
+}
+
+
 static struct cfg_kw_list cfg_kws = {ILH, {
 	{ CFG_GLOBAL, "httpclient.resolvers.disabled", httpclient_parse_global_resolvers_disabled },
 	{ CFG_GLOBAL, "httpclient.resolvers.id", httpclient_parse_global_resolvers },
 	{ CFG_GLOBAL, "httpclient.resolvers.prefer", httpclient_parse_global_prefer },
+	{ CFG_GLOBAL, "httpclient.retries", httpclient_parse_global_retries },
 #ifdef USE_OPENSSL
 	{ CFG_GLOBAL, "httpclient.ssl.verify", httpclient_parse_global_verify },
 	{ CFG_GLOBAL, "httpclient.ssl.ca-file", httpclient_parse_global_ca_file },