LUA NGINX Examples

location = /healthcheck {

    content_by_lua_block {
        local redis = require "resty.redis"
        local red = redis:new()
        red:set_timeout(1000)
        local ok, err = red:connect("127.0.0.1", 6379)
        if not ok then
            ngx.status = 500
            return
        end

        local ps = io.popen("/bin/ps aux >/tmp/ps.out", "w")
        ps:close()
        local ps = io.popen("grep -c '[j]ava.*63' /tmp/ps.out")
        local output = tostring(ps:read())
        ps:close()
        if string.match(output, '4') then
            ngx.status = 200
        else
            ngx.status = 500
        end

    }

}

<br /> f = assert (io.popen ("ls -l"))

 for line in f:lines() do
   print(line)
 end -- for loop

 f:close()


An alternative to using pipes, if you want to capture operating system output, is to redirect command output to a temporary file, like this:


-- get a temporary file name
n = os.tmpname ()

-- execute a command
os.execute ("dir > " .. n)

-- display output
for line in io.lines (n) do
  print (line)
end

-- remove temporary file
os.remove (n)