host_switching2.md

HTTP Host Switching using Host Header

Load balance requests across different pools based on Host header. Assuming host header value/name is used to generate pool name. Example, if host header equals to 'www.example.com',' pool 'www.example.com_pool' will be selected. If 'www.example.com_pool' has servers up in the pool, pool will be selected. Pools has to be attached to datascript. Apply this to the "HTTP REQUEST" Event.

-- HTTP_REQUEST
default_pool = "default_pool"
host = avi.http.get_header("Host")
-- if host header exists
if host then
  -- assuming host header name is used to generate pool name
  -- example, if host header is www.example.com, pool name is www.example.com_pool
  -- Pools has to be attached to datascript
  pool = host .. "_pool"
  -- verify if pool exists
  pool_exists = pcall(avi.pool.get_servers,pool)
  -- if yes and pool has active servers, select it
  if pool_exists then
    servers_up, servers_total = avi.pool.get_servers(pool)
    -- verify that pool functional and has servers up
    if servers_up >= 1 then
      avi.pool.select(pool)
      avi.vs.log("SELECTED_POOL:" .. pool)
    -- if no, use default pool
    else
      avi.pool.select(default_pool)
      avi.vs.log("SELECTED_POOL:" .. default_pool)
    end
  -- if no, use default pool
  else
    avi.pool.select(default_pool)
    avi.vs.log("SELECTED_POOL:" .. default_pool)
  end
end