Saturday, April 03, 2010

Connecting to twist server

Once your development environment is set up, it is useful to know what is required to connect to the twist server.

#! /opt/opsware/smopython2/python2

import sys
from pytwist import *

# Establish an unauthenticated connection to twist server.  Note that the
# hostname "twist" must resolve either through /etc/hosts or DNS.
ts = twistserver.TwistServer()

In the event the hostname twist does not resolve or points to the wrong twist server, you can do...

ts = twistserver.TwistServer("")

See the TwistServer Method Syntax section on page 75 of the Developer's Guide for other options that may be important to you.

It is also quite likely that you will need to do an authenticated session. This is covered in the Error Handling section on page 76 of the Developer's Guide. In order to prompt for a username and password, I have found something like the following works well...

def authenticate(server):
        for tries in range(1,3):
                        sys.stdout.write("HPSA login: ")
                        user = sys.stdin.readline().strip()
                        pw = getpass.getpass("HPSA password: ")
                        server.authenticate(user, pw)
                        return True
                        sys.stderr.write("Authentication failed.\n")
        return False

ts = twistserver.TwistServer()

Opsware/HPSA API: Getting Started

The HP Server Automation Platform Developer's Guide (for HPSA 7.50, September, 2008) and any other resources I've been able to find are far from complete and sometimes misleading with respect to using the HPSA API. As I've tried to clear up my confusion with the API, google has helped me exactly 0% of the time. Maybe my rambling on the subject will lead to someone leading me to a better approach...

In this first post on the subject, let's start out with enough to get a working Python environment. Chapter 3 of the developer's guide indicates that Pytwist relies on Python 1.5.2. Ugh. However, pytwist can be used with Python 2.4. Rather than following the advice to install the /Opsware/Tools/Opsware API Access software policy, instead install the following policies:

  • /Opsware/Tools/Python 2/Python 2 for Server Modules
  • /Opsware/Tools/Python 2 Opsware API Access for Server Modules/Python 2 Opsware API Access for Server Modules

The permissions are likely such that you need to be root to execute. Fix this with:

# chmod -R a+r /opt/opsware/smopython2
# exit
$ /opt/opsware/smopython2/python -V
Python 2.4.4

Ahhh, much better.

Notice the path to python above. It is actually a shell script that sets PYTHON_HOME then tries to execute python. Unfortunately, Solaris doesn't like a shebang line in one script referring to another script. The resulting error looks like:

$ ./twister1 
import: Unable to connect to X server ().
./twister1: line 4: syntax error near unexpected token `"/opt/opsware/smopylibs2"'
./twister1: line 4: `sys.path.append("/opt/opsware/smopylibs2")'

In other words, the shebang (#!) line python scripts will be useless as the software policy installs it.

Workaround 1:

$ export PYTHONHOME=/opt/opsware/smopython2/34c.

Then use a shebang line like:

#! /opt/opsware/smopython2/34c.

Workaround 2: Compile this program and put it at /opt/opsware/smoptyhon2/python2

#include <stdlib.h>
#include <unistd.h>

#define PYTHONHOME "/opt/opsware/smopython2/34c."

int main(int argc, char **argv) {
        char *python = PYTHONHOME "/bin/python2";

        argv[0] = python;
        setenv("PYTHONHOME", PYTHONHOME, 1);

        return execv(python, argv);

Then use a shebang line like:

#! /opt/opsware/smopython2/python2

In any case (even if you used Python 1.5 like the developer's guide suggests) the path to python does not match reality. Adjust your scripts accordingly.