Symptoms
Task APS application ... executing configuration script fails with:
SOAP FAULT: Error Fetching http headers
or some other similar error.
These entries could be found in strace output, if it's attached to php process forked to process the task:
3657 04:10:24.358184 connect(4, {sa_family=AF_INET, sin_port=htons(53), sin_addr=inet_addr("x.x.x.x")}, 28) = 0 <0.000039>
3657 04:10:24.358427 sendto(4, "\242\362\1\0\0\1\0\0\0\0\0\0\7rradc75\vcarrierzone\3com\0\0\34\0\1", 41, MSG_NOSIGNAL, NULL, 0) = 41 <0.000022>
3657 04:10:24.358501 poll([{fd=4, events=POLLIN}], 1, 3000) = 0 (Timeout) <3.000717>
Cause
DNS server could not resolve RRAD address, taking part in the task.
Resolution
Check the health of the DNS servers configured on the Provisioning Gateway server. As a temporary workaround, remove internal nameservers from /etc/resolv.conf and add the public DNS, provided by Google:
nameserver 8.8.8.8
Additionally, increase the socket timeout in /etc/php.ini if the error persists after modifying NS servers list:
default_socket_timeout = 3600