sample restore code

gistfile1.txt

    def create_replica(self, master_connection, env):
        # create the replica according to the replica_method
        # defined by the user.  this is a list, so we need to
        # loop through all methods the user supplies
        connstring = self.build_connstring(master_connection)
        # get list of replica methods from config
        replica_method = config.get('create_replica_method', 'basebackup')
        self.replica_methods = [rm.strip() for rm in replica_method.split(',')]
        # go through them in priority order
        for replica_method in replica_methods:
            # if the method is basebackup, then use the built-in
            if replica_method == "basebackup":
                ret = self.basebackup()
                if ret == 0:
                    # if basebackup succeeds, exit with success
                    return 0
            else:
                # user-defined method; check for configuration
                # not required, actually
                if replica_method in self.config:
                    # look to see if the user has supplied a full command path
                    # if not, use the method name as the command
                    if "command" in self.config[replica_method]:
                        cmd = self.config[replica_method]["command"]
                    else:
                        cmd = replica_method
                        
                    # get the rest of the replica config
                    method_config = self.config[replica_method].copy()
                    # remove the command and turn it into a shlex set
                    del method_config["command"]
                    # add the default parameters
                    method_config.update({"scope": self.scope, 
                                          "role" : "replica",
                                          "datadir" : self.data_dir
                                          "connstring" : self.connstring})
                    params = ["--{0}={1}".format(arg, val) for arg, val in method_config.iteritems()]
                    
                try:
                    # call script with the full set of parameters
                    ret = subprocess.call(shlex.split(cmd) + shlex.split(method_config), env=env)
                except Exception as e:
                    logger.exception('Error creating replica using method {0}: {1}'.format(replica_method, e.str))
                    ret = 1
            
        return ret
        
        
    def basebackup(self):
        # creates a replica data dir using pg_basebackup.  
        # this is the default, built-in create_replica_method
        # tries twice, then returns failure (as 1)
        # uses "stream" as the xlog-method to avoid sync issues
        bbfailures = 0;
        maxfailures = 2;
        while bbfailures < maxfailures:
            try:
                ret = subprocess.call(['pg_basebackup', '-R', '-D', '--xlog-method=stream',
                                    self.data_dir, '--host=' + self.master_connection['host'],
                                    '--port=' + str(self.master_connection['port']),
                                    '-U', self.master_connection['user']],
                                    env=self.env)
            except Exception as e:
                    logger.error('Error when fetching backup with pg_basebackup: {0}'.format(e))
                    ret = 1
                    bbfailures += 1
                    if bbfailures < maxfailures:
                        logger.error('Trying again in 5 seconds')
                    sleep 5
            else:
                    break
                
        return ret