UTProxy - An uptime monitor proxy for internal services

UTProxy is a HTTP(S) proxy service for uptime monitors to access internal services without having to directly expose those services to the internet. It provides different internal checks (HTTP, TCP, MySQL, ping or a command) and returns a HTTP response and status to the uptime monitor. It has built-in flood protection (ie: multiple monitoring services) to cache successful requests for 55 seconds, and error responses for 25 seconds.

Configuration

You have to set up a configuration file, see contrib/utproxy.yaml for an example. Save this configuration in /etc/utproxy.yaml, or alternatively use the -c flag to specify a different configuration location.

The configuration has two main sections, firstly the service configuration:

listen: 0.0.0.0:3500 # interface and port to listen on
#sslcert: /etc/letsencrypt/live/example.com/fullchain.pem # SSL certificate (optional)
#sslkey: /etc/letsencrypt/live/example.com/privkey.pem    # SSL key (optional)
#log: /var/log/utproxy.log                                # log file (optional)

If both sslcert and sslkey are set, then UTProxy should be accessed via https://, otherwise http://. In this example we would be accessing the proxy via http://example.com:3500. UTProxy does not register or renew SSL certificates, so the service should be restarted manually if you update the certificates.

And then secondly the services you wish to test. Each service is added as an array to the services: section.

services:
  # an array of services to test, see below

Each service must contain a unique "check key", which will correspond to the URL on our UTProxy for the uptime monitor, eg: http://example.com:3500/intranet, http://example.com:3500/smtp etc. You can also use keys such as web/service1 which would translate to http://example.com:3500/web/service1.

Checks can be set up with one of the following types:

Check type http

A check for a HTTP response.

services:
  intranet: # check key
    type: http # check type
    endpoint: http://192.168.0.10 # check url
    status: 200 # expected response, default 200
    method: HEAD # request type (HEAD, GET, POST), default HEAD

Check type tcp

A check for a TCP connection.

services:
  smtp: # check key
    type: tcp # check type
    endpoint: localhost:25 # check <destination>:<port>

Check type mysql

A check for a MySQL connection.

services:
  database: # check key
    type: mysql # check type
    endpoint: localhost:3306 # mysql <destination>:<port (TCP only, no sockets)
    user: secretuser # MySQL username
    pass: secretpass # MySQL password

Check type ping

This will send a single ping to a given host with a 1-second timeout. Please see this if you are getting a socket: permission denied error on Linux. Alternatively you can perform a ping as an "exec" task (see below).

services:
  modem: # check key
    type: ping # check type
    endpoint: 192.168.0.100 # host or ip

Check type exec

A check to run a command. The command should exit with a 0 status (success).

The following example is how to ping an internal machine using the native ping:

services:
  printer: # check key
    type: exec # check type
    command: ping # command to run
    args: # an optional array of command arguments
      - "-c"
      - "1"
      - "-W"
      - "2"
      - "-q"
      - "192.168.0.100"

Your exec check can be any command that the UTProxy daemon is allowed to run.

Testing

You can test all your configured services by running utproxy test

Setting up an uptime monitor

There are plenty of uptime monitors you can use both free and commercial, so pick one you are happy with. Some examples are:

• HetrixTools (free plans)
• Uptime Robot (free plans)
• Pingdom

You need to set up your uptime monitors to monitor the HTTP status of each of your server checks.

http://example.com:3500/intranet, http://example.com:3500/smtp, http://example.com:3500/database, http://example.com:3500/printer etc

Checks should return a 200 status, otherwise they are considered failing.

Running as a systemd service

See the example utproxy.service.