# nginx.conf:

    lua_package_path "/path/to/lua-resty-upstream/lib/?.lua;;";
    lua_shared_dict upstream    1m;
    lua_shared_dict monitor 1m;
    
    server {
        location = /t {
            content_by_lua_block {
                local upstream = require "resty.upstream"
                upstream.init({
                    cache = "upstream",
                    cache_size = 100
                })
                -- update foo.com upstream
                local ok = upstream.update_upstream("foo.com", {
                    version = 1,
                    hosts = {
                        {
                            name = "127.0.0.1:8080", 
                            host = "127.0.0.1", 
                            port = 8080, 
                            weight = 100, 
                            max_fails = 3, 
                            fail_timeout = 10, 
                            default_down = false
                        }
                    }
                })
                if not ok then
                    return
                end

                local monitor = require "resty.upstream.monitor"
                local ok, err = monitor.spawn_checker({
                    shm = "monitor",
                    upstream = "foo.com",
                    type = "http",
                    http_req = "HEAD /status HTTP/1.0\r\nHost: foo.com\r\n\r\n",
                    -- if required "lua-resty-http"
                    -- http_req = {
                    --     method = "HEAD",
                    --     path = "/ok.htm"
                    --     headers = {
                    --         Host = "foo.com"
                    --     }
                    -- }
                    interval = 2000,
                    timeout = 1000,
                    fall = 3,
                    rise = 2,
                    valid_statuses = {200, 302},
                    concurrency = 10,
                })
                if not ok then
                    upstream.delete_upstream("foo.com")
                    ngx.log(ngx.ERR, "failed to spawn health checker: ", err)
                    return
                end
            }
        }
    }
    

    local upstream = require "resty.upstream"

local config = {
    cache = "upstream",
    cache_size = 1000
}

local ok = upstream.update_upstream("foo.com", {
    version = 1,
    hosts = {
        {
            name = "127.0.0.1:8080", 
            host = "127.0.0.1", 
            port = 8080,            -- default value
            weight = 100,           -- default value
            max_fails = 3,          -- default value
            fail_timeout = 10,      -- default value, 10 second
            default_down = false    -- default value
        }
    }
})
if not ok then
    return
end