Mcpiper

Mcpiper is a debugging tool for mcrouter. It allows analysis of all the traffic that goes in and out mcrouter.

Differently from other similar tools, mcpiper is not a network sniffer (and do not require sudo to run). Instead, mcrouter creates a series debug fifos (aka named pipes), that mcpiper connects to read the data. Mcrouter automatically starts replicating network traffic to those fifos as soon as mcpiper starts to run.

Setup

If you haven't done it yet, you will need to follow the mcrouter installation instructions. Those instructions will build and install both mcrouter and mcpiper.

By default, mcrouter will try to create the debug fifos in /var/mcrouter/fifos/ directory. To change that directory, use the --debug-fifo-root argument. Make sure that the directory being used exists and is writable.

Now, simply start mcpiper and you should see data flowing.

$ mcpiper 
# If you started mcrouter using another directory as the debug fifos root:
$ mcpiper --fifo-root="<PATH>"

Common use cases

Search for an expression. Will match everything that contains the given BRE (basic regular expression):

$ mcpiper <BRE>
# Examples:
$ mcpiper "test" # Search for the string "test"
$ mcpiper a.c # Serach for any string that match the "a.c" BRE.
$ mcpiper -i abc # Do a case insensitive search for "abc"

Filter IP Address / Port:

$ mcpiper -H=<HOST> -p=<PORT>
# Example:
$ mcpiper -H "127.0.0.1" -p 5000

Only investigate fifos which the file name match the given pattern (BRE):

$ mcpiper --filename-pattern=<BRE> # or simply -f
# Examples:
$ mcpiper --filename-pattern="client" # Investigate client fifos (i.e. data sent to memcached).
$ mcpiper --filename-pattern="server" # Investigate server fifos (i.e. data received by mcrouter)

Do not print the values:

$ mcpiper -q

For more information on how to use mcpiper:

$ mcpiper --help