Connect to HTTPS upstream with lua-resty-http (LUA)

Category: LUA

The lua-resty-http is incredbily useful when you need some LUA in OpenResty to place external HTTP requests.

However, when you need it to do HTTPS things are just a little more complex - it's not a simple as passing it https as a scheme, instead you need to make a specific call to trigger the SSL handshake

This snippet shows how to do that (using a keepalive pool to reduce connection overhead between requests)

Details

Snippet

function fetch_via_https(server,path)
    local httpc = http.new()
    ok,err = httpc:connect(server,443)
    then
       ngx.log(ngx.ERR,"Connection Failed")
    end

    -- Trigger the SSL handshake
    session, err = httpc:ssl_handshake(False, server, false)

    local res, err = httpc:request {
        path = path,
        method = 'GET'
    }

    if not res then
        ngx.log(ngx.ERR,"Request Failed")
        httpc:close()
        return False
    end

    -- Return the connection to the keepalive pool
    httpc:set_keepalive()

    -- Check the status, dispatcher will serve us a 302
    if res.status == 200
    then
        body, err = res:read_body()
        return body
    end

    return False
end

Usage Example

local res = fetch_via_https("www.example.invalid","/robots.txt")