HTTP:persist(t)

Manages persistence/stickiness table operations, including reading, writing, dumping table contents, and retrieving server information.

Syntax

HTTP:persist(t);

Arguments

Name	Description
t	A table that specifies the operation and its parameters.

Events

Applicable in the following events:

• PERSISTENCE
• POST_PERSIST
• HTTP_REQUEST (supported since version 7.2.x)
• HTTP_DATA_REQUEST, HTTP_DATA_RESPONSE (supported since version 8.0.0)

Operations

The following sections detail all possible structures for the argument table t.

1. save_tbl — Saves a server assignment for a hash value in the persistence table.

2. read_tbl — Saves a server assignment for a hash value in the persistence table.

3. dump_tbl — Dumps a range of entries from the persistence table.

4. get_valid_server — Saves a server assignment for a hash value in the persistence table.

5. cal_server_from_hash — Saves a server assignment for a hash value in the persistence table.

6. get_current_assigned_server — Saves a server assignment for a hash value in the persistence table.

save_tbl

Saves a server assignment for a hash value in the persistence table.

Field	Type	Required	Description
operation	String	Yes	Must be "save_tbl".
hash_value	String	Yes	The hash key to store.
srv_name	Integer	String	The server name to associate with the hash.

Example

when PERSISTENCE {
    cip = HTTP:client_addr()
    hash_str_cip = sha512_hex(cip)
    debug("-----save_tbl-----\n")
    t={}
    t["operation"] = "save_tbl"
    t["hash_value"] = hash_str_cip
    t["srv_name"] = "pool1-2"
    ret = HTTP:persist(t)
    if ret then
	    debug("hash save table success\n");
	else
	    debug("save table failed\n");
	end
	t={};
	t["operation"] = "save_tbl";
	t["hash_value"] = "246810";
	t["srv_name"] = "pool1-3";
	ret = HTTP: persist(t);
	if ret then
	    debug("===server add success\n");
    else
        debug("===server add fail\n");
    end
}
Output:
true: success, false: failed

Note: Due to limitations in the stick table, it only supports 16 characters in the hash value. Otherwise, we will hash it to obtain 16 bytes as index.

Supported Version

FortiADC version 5.4.x and later. In 7.2.x, function extended to HTTP_REQUEST events.

read_tbl

Saves a server assignment for a hash value in the persistence table.

Field	Type	Required	Description
operation	String	Yes	Must be "read_tbl".
hash_value	String	Yes	The hash key to lookup

Example

when PERSISTENCE {
  	t={};
	t["operation"] = "save_tbl";
	t["hash_value"] = "246810";
	t["srv_name"] = "pool1-3";
	ret = HTTP: persist(t);
	if ret then
	    debug("===server add success\n");
    else
        debug("===server add fail\n");
    end

    t={}
    t["operation"] = "read_tbl"
    t["hash_value"] = "246810"
    ret_tbl = HTTP:persist(t)
    if ret_tbl then
        debug("246810-server: %s\n",ret_tbl)
    else
        debug("246810-server read fail\n")
end 
}
Output:
	Return server name of the entry, or false if no entry found

Supported Version

FortiADC version 5.4.x and later. In 7.2.x, function extended to HTTP_REQUEST events.

dump_tbl

Dumps a range of entries from the persistence table.

Field	Type	Required	Description
operation	String	Yes	Must be "dump_tbl".
index	Integer	No	Starting index for dump (default: 1).
count	Integer	No	Number of entries to return (default: all).

Example

when PERSISTENCE {
	t={};
	t["operation"] = "save_tbl";
	t["hash_value"] = "246810";
	t["srv_name"] = "pool1-3";
	ret = HTTP: persist(t);
	if ret then
	    debug("===server add success\n");
    else
        debug("===server add fail\n");
    end

    t={}
    t["operation"] = "dump_tbl"
    t[“index”] = 1
    t[“count”] = 15
    ret_tbl = HTTP:persist(t)
    if ret_tbl then
        for hash, srv in pairs(ret_tbl) do
            debug("tbl hash %s srv %s\n",hash,srv)
        end
    end
}
       “index”: 
      “count”: 
Output:
	Return A table include hash and server name

Supported Version

FortiADC version 5.4.x and later. In 7.2.x, function extended to HTTP_REQUEST events.

get_valid_server

Saves a server assignment for a hash value in the persistence table.

Field	Type	Required	Description
operation	String	Yes	Must be "get_valid_server".

Example

when PERSISTENCE {
    debug("-----get valid server-----\n")
    t={}
    t["operation"] = "get_valid_server"
    ret = HTTP:persist(t)
    if ret then
        for srv,stat in pairs(ret) do
            debug("server %s, status %s\n",srv,stat)
        end
    end
}
Output:
	Return the table of usable real server and server state(enable, backup)

Supported Version

FortiADC version 5.4.x and later. In 7.2.x, function extended to HTTP_REQUEST events.

cal_server_from_hash

Saves a server assignment for a hash value in the persistence table.

Field	Type	Required	Description
operation	String	Yes	Must be "cal_server_from_hash".
hash_value	String	Yes	The hash value to calculate from.

Example

when PERSISTENCE {
    debug("-----cal_server_from_hash-----\n")
    t={}
    t["operation"] = "cal_server_from_hash"
    t["hash_value"] = "246810"
    ret = HTTP:persist(t)
    if ret then
        debug("hash 246810, server %s\n",ret)
    end 
}
Output:
	Return the real server name according to the hash value using our algorithm or False if failed 

Supported Version

FortiADC version 5.4.x and later. In 7.2.x, function extended to HTTP_REQUEST events.

get_current_assigned_server

Saves a server assignment for a hash value in the persistence table.

Field	Type	Required	Description
operation	String	Yes	Must be "get_current_assigned_server".

Example

when PERSISTENCE {
    cip = HTTP:client_addr()
    hash_str_cip = sha512_hex(cip)   
    t={}
    t["operation"] = "save_tbl"
    t["hash_value"] = hash_str_cip
    t["srv_name"] = "pool1-3"
    ret = HTTP:persist(t)
    if ret then
	    debug("hash save table success\n");
	else
	    debug("save table failed\n");
	end 
    t={}
    t["hash_value"]=hash_str_cip
    ret = HTTP:lookup_tbl(t)
    if ret then 
        debug("hash LOOKUP success\n")
    else
        debug("hash lookup failed\n")
    end
}
when POST_PERSIST {
debug("-----event POST_PERSIST-----\n")
    debug("-----get current assigned server-----\n")
    t={}
    t["operation"]="get_current_assigned_server"
    ret=HTTP:persist(t)
    debug("current assigned server: %s\n",ret)
}
Output:
	Return the real server name which is assigned to current session or False if no server is assigned right now 

Supported Version

FortiADC version 5.4.x and later. In 7.2.x, function extended to HTTP_REQUEST events.