python-textFSM parse multiple line config

Question

I've a task to parse Cisco ACE config. I'm using python textFSM module. This template should parse "serverfarm " part of the config:

Value Required Serverfarm_name (\S+)
Value load_balance_method (\S+)
Value probe_name (\S+)
Value List rserver_name (\S*)

Start
  ^serverfarm\s+host\s+$Serverfarm_name
  ^\s+predictor\s+$load_balance_method
  ^\s+probe\s+$probe_name
  ^\s+rserver\s+$rserver_name -> RServer

RServer
  ^\s+rserver\s+$rserver_name -> Continue.Record
  ^\s+inservice

Part of the Cisco ACE config: ......

serverfarm host SF-TEST1-3.8083
  predictor hash address source
  probe TEST-3.8083
  rserver lala_server438
    inservice
  rserver lala_server439
    inservice
serverfarm host SF-TEST1-4.8084
  predictor hash address source
  probe TEST-4.8084
  rserver lala_server438
    inservice
  rserver lala_server439
    inservice
serverfarm host SF-TEST1-5.8085
  predictor hash address source
  probe TEST-5.8085
  rserver lala_server438
    inservice
  rserver lala_server439
    inservice

......

After running ace.py script I don't have desired result as a textFSM table :

$ ./ace.py
 --- [2018-05-30 16:47:52.892697] --- Start Timestamp ---
 --- [+0.000116 sec] --- Parse: ./textFSM/ace_serverfarm_template.textfsm ---
['Serverfarm_name', 'load_balance_method', 'probe_name', 'rserver_name']
['SF-TEST1-3.8083', 'hash', 'TEST-3.8083', ['lala_server438', 'lala_server439']]
Write 1 records

What is my error in the template file? How to change it in order to parse every serverfarm. (I've only first record as a result)?

Answer 1

Here are some of things you should consider

1. You should Record when you have all data.
2. Textfsm parses each line at time
3. Since you have two instances of rserver_name, consider using List option for Value
4. Regarding the 'Required' field - Normally the FSM will discard empty rows when it terminates, but here the 'Filldown' option will populated the 'serverfarm' column, so the FSM will keep an non-empty row and saves it when the FSM terminates. In order to fix this, I have used Value option - Required. This option specifies that the value must have been matched otherwise a row will not be saved. Here it ensures that 'load_balance_method' and 'probe_name' both contain a value.

Value Filldown Serverfarm_name (\S+)
Value Required load_balance_method (\S+)
Value Required probe_name (\S+)
Value List rserver_name (\S+)

Start
  ^serverfarm\s+host\s+$Serverfarm_name
  ^\s+predictor\s+$load_balance_method
  ^\s+probe\s+$probe_name
  ^\s+rserver\s+$rserver_name -> RServer1

RServer1
  ^\s+rserver\s+$rserver_name
  ^\s+inservice -> RServer2

RServer2
  ^\s+rserver\s+$rserver_name -> RServer3

RServer3
  ^\s+inservice -> Record Start

Output:

[['SF-TEST1-3.8083', 'hash', 'TEST-3.8083', ['lala_server438', 'lala_server439']], ['SF-TEST1-4.8084', 'hash', 'TEST-4.8084', ['lala_server438', 'lala_server439']], ['SF-TEST1-5.8085', 'hash', 'TEST-5.8085', ['lala_server438', 'lala_server439']]]

Answer 2

I found temporary solution for this but it'll be more convinient to make rserver column fields as a "List" of rservers.

Workaround:

Value Filldown Serverfarm_name (\S+)
Value Filldown load_balance_method (\S+)
Value Filldown probe_name (\S+)
Value Required rserver_name (\S+)

Start
  ^serverfarm\s+host\s+$Serverfarm_name
  ^\s+predictor\s+$load_balance_method
  ^\s+probe\s+$probe_name
  ^\s+rserver\s+$rserver_name -> Record RServer

RServer
  ^\s+rserver\s+$rserver_name
  ^\s+inservice -> Start

But this will produce more rows in the FSM table. If I've let's say 4 servers for one serverfarm there will be 4 rows .. not one.

Somebody with am idea how to change the template in order to get one row per serverfarm and list of rservers as a field in the last column "rserver_name"

Output:

 --- [2018-05-30 20:07:53.906280] --- Start Timestamp ---
 --- [+0.000106 sec] --- Parse: ./textFSM/ace_serverfarm_template.textfsm ---
['Serverfarm_name', 'load_balance_method', 'probe_name', 'rserver_name']
['SF-TEST1-3.8083', 'hash', 'TEST-3.8083', 'lala_server438']
['SF-TEST1-3.8083', 'hash', 'TEST-3.8083', 'lala_server439']
['SF-TEST1-4.8084', 'hash', 'TEST-4.8084', 'lala_server438']
['SF-TEST1-4.8084', 'hash', 'TEST-4.8084', 'lala_server439']
['SF-TEST1-5.8085', 'hash', 'TEST-5.8085', 'lala_server438']
['SF-TEST1-5.8085', 'hash', 'TEST-5.8085', 'lala_server439']