Spawn a process per MQTT message, provide message on stdin
Usage:
./mqtt-spawn.py <host> <cmd> <topic1> <topic2> ..
Example:
./mqtt-spawn.py 172.16.68.10 'dotty -' oneshot/dot
will plot every graphviz message received on oneshot/dot.
(My actual usage is ./mqtt-spawn.py 172.16.68.10 'sponge ../test.dot' oneshot/dot with GraphViz.app for OS X opened on test.dot. cat > ../test.dot also works but is not as clean).
Example message from actual usage:
mosquitto_pub -s -t oneshot/dot << EOF
digraph oneshot {
subgraph cluster_ { DS_ -> DNSKEY_ [ label = "19036/2" ]; label = "zone: "; }
DNSKEY_ -> DNSKEY_;
DNSKEY_ -> DS_org;
DNSKEY_ -> DS_org;
subgraph cluster_org { DS_org -> DNSKEY_org [ label = "21366/1" ]; label = "zone: org"; }
subgraph cluster_org { DS_org -> DNSKEY_org [ label = "21366/2" ]; label = "zone: org"; }
DNSKEY_org -> DNSKEY_org;
DNSKEY_org -> DNSKEY_org;
DNSKEY_org -> DS_powerdnssec_org;
subgraph cluster_powerdnssec_org { DS_powerdnssec_org -> DNSKEY_powerdnssec_org [ label = "2224/1" ]; label = "zone: powerdnssec.org"; }
DNSKEY_powerdnssec_org -> DNSKEY_powerdnssec_org;
}
EOF
Mandatory screencast:
