PGBouncer healthcheck

Introduction

This implements a http /health check for PGBouncer hosts. This healthcheck provides a simple yes/no health response based on attempting to connect to PGBouncer and execute a request, as well as checking the Datadog agent.

There are also several endpoints used for diagnostics.

Building and running

This can be built on a local system with docker using the provided Makefile.

$ make build

You can then run the server binary

$ ./pgbouncer-healthcheck

Configuration

The binary takes its configuration from several environment variables.

Postgres connection string for PGBouncer connection

The connection string comes from the env var CONNSTR. The default is host=localhost port=6543 dbname=pgbouncer sslmode=disable. This should be fine for most use cases.

The intention is that the username and password will be supplied by setting the PGUSER and PGPASSWORD standard variables.

Other parameters

PORT: The TCP port the daemon should use to listen for HTTP connections (default: 8000)
ENHANCED_CHECK: If true, test the PGBouncer health by connecting and sending a query. If false, use a simple port probe. (default: false)
CHECK_DDAGENT: If true, the /health endpoint will also run datadog-agent health and the return value will affect the health status (default: false)
PGBOUNCER_PORT: The TCP port used if using the basic port probe healthcheck (default: 6543)
ENABLE_DEBUG_ENDPOINTS: If true, the extra /debug/ endpoints will be enabled. See below (default: false)

The result of the defaults is that the standard mode is just to do a TCP port probe of 6543 on the localhost to test if PGBouncer is alive.

Main Endpoints

Note: See https://pgbouncer.github.io/usage.html for details of the PGBouncer SHOW command outputs.

/

This always returns a 200 OK

/health

The healthcheck returns a 200 OK response or a 500 Internal Server Error response. It will probe the PGBouncer using a method depending on ENHANCED_CHECK. If CHECK_DDAGENT is true it will also check the Datadog Agent.

PGBouncer Information Endpoints

/status/users

Returns the results of PGBouncer's SHOW USERS command formatted as JSON.

Example:

[
  {
    "Name": "dd-agent",
    "PoolMode": null
  },
  {
    "Name": "jasoirwjofjdsslkmcknmwofn",
    "PoolMode": null
  },
  {
    "Name": "pgbouncer",
    "PoolMode": null
  },
  {
    "Name": "sidekiq_realtime",
    "PoolMode": null
  }
]

/status/configs

Returns the results of PGBouncer's SHOW CONFIG command formatted as JSON.

Example:

[
  {
    "Key": "job_name",
    "Value": "pgbouncer",
    "Changeable": false
  },
  {
    "Key": "conffile",
    "Value": "/etc/pgbouncer/pgbouncer.ini",
    "Changeable": true
  },
  {
    "Key": "logfile",
    "Value": "",
    "Changeable": true
  },
  {
    "Key": "pidfile",
    "Value": "/var/run/postgresql/pgbouncer.pid",
    "Changeable": false
  },
  {
    "Key": "listen_addr",
    "Value": "0.0.0.0",
    "Changeable": false
  },
  {
    "Key": "listen_port",
    "Value": "6543",
    "Changeable": false
  }
]

(Truncated for brevity)

/status/databases

Returns the results of PGBouncer's SHOW DATABASES command formatted as JSON. This is essentially the content of the [databases] section in the config file.

Example:

[
  {
    "Name": "delivery_prod",
    "Host": "roo-prod-96.example.eu-west-1.rds.amazonaws.com",
    "Port": "12345",
    "Database": "prod",
    "ForceUser": null,
    "PoolSize": 100,
    "ReservePool": 1,
    "PoolMode": null,
    "MaxConnections": 0,
    "CurrentConnections": 0
  },
  {
    "Name": "delivery_prod_read1",
    "Host": "roo-prod-96-read1.example.eu-west-1.rds.amazonaws.com",
    "Port": "12345",
    "Database": "prod",
    "ForceUser": null,
    "PoolSize": 100,
    "ReservePool": 1,
    "PoolMode": null,
    "MaxConnections": 0,
    "CurrentConnections": 0
  }
]

/status/pools

Returns the results of PGBouncer's SHOW POOLS command formatted as JSON. This is similar to SHOW DATABASES, except it's a product of that set by the users, since the pooling is per user per logical DB.

Example:

[
  {
    "Database": "prod_read1_web",
    "User": "kldfwokoekrokerkreo",
    "ClActive": 459,
    "ClWaiting": 0,
    "SvActive": 2,
    "SvIdle": 5,
    "SvUsed": 0,
    "SvTested": 0,
    "SvLogin": 0,
    "MaxWait": 0,
    "PoolMode": "transaction"
  },
  {
    "Database": "prod_read1_worker",
    "User": "kldfwokoekrokerkreo",
    "ClActive": 127,
    "ClWaiting": 0,
    "SvActive": 0,
    "SvIdle": 4,
    "SvUsed": 0,
    "SvTested": 0,
    "SvLogin": 0,
    "MaxWait": 0,
    "PoolMode": "transaction"
  }
]

/status/clients

Returns the results of PGBouncer's SHOW CLIENTS command formatted as JSON.

Example:

  {
    "Type": "C",
    "User": "kldfwokoekrokerkreo",
    "Database": "prod_read1_web",
    "State": "active",
    "Addr": "10.0.129.60",
    "Port": 50962,
    "LocalAddr": "10.0.78.178",
    "LocalPort": 6543,
    "ConnectTime": "2018-11-05 08:18:34",
    "RequestTime": "2018-11-05 10:51:22",
    "Ptr": "0x55fb15292a18",
    "Link": "",
    "RemotePid": 0,
    "TLS": ""
  },
  {
    "Type": "C",
    "User": "kldfwokoekrokerkreo",
    "Database": "prod_read1_web",
    "State": "active",
    "Addr": "10.0.69.98",
    "Port": 39750,
    "LocalAddr": "10.0.78.178",
    "LocalPort": 6543,
    "ConnectTime": "2018-11-05 08:53:58",
    "RequestTime": "2018-11-05 10:18:28",
    "Ptr": "0x7f7159b2a420",
    "Link": "",
    "RemotePid": 0,
    "TLS": ""
  }
]

/status/servers

Returns the results of PGBouncer's SHOW SERVERS command formatted as JSON.

Example:

[
  {
    "Type": "S",
    "User": "kldfwokoekrokerkreo",
    "Database": "prod_read1_web",
    "State": "idle",
    "Addr": "34.254.85.1",
    "Port": 31872,
    "LocalAddr": "10.0.78.178",
    "LocalPort": 45492,
    "ConnectTime": "2018-11-05 12:03:12",
    "RequestTime": "2018-11-05 12:10:12",
    "Ptr": "0x55fb15589028",
    "Link": "",
    "RemotePid": 64451,
    "TLS": "TLSv1.2/ECDHE-RSA-AES256-GCM-SHA384/ECDH=prime256v1"
  },
  {
    "Type": "S",
    "User": "kldfwokoekrokerkreo",
    "Database": "prod_read1_web",
    "State": "idle",
    "Addr": "34.254.85.1",
    "Port": 31872,
    "LocalAddr": "10.0.78.178",
    "LocalPort": 44966,
    "ConnectTime": "2018-11-05 11:43:18",
    "RequestTime": "2018-11-05 12:10:12",
    "Ptr": "0x55fb159663e0",
    "Link": "",
    "RemotePid": 57603,
    "TLS": "TLSv1.2/ECDHE-RSA-AES256-GCM-SHA384/ECDH=prime256v1"
  }
]

/status/mems

Returns the results of PGBouncer's SHOW MEM command formatted as JSON.

Example:

[
  {
    "Name": "user_cache",
    "Size": 200,
    "Used": 5,
    "Free": 76,
    "MemTotal": 16200
  },
  {
    "Name": "db_cache",
    "Size": 208,
    "Used": 21,
    "Free": 57,
    "MemTotal": 16224
  },
  {
    "Name": "pool_cache",
    "Size": 408,
    "Used": 11,
    "Free": 39,
    "MemTotal": 20400
  },
  {
    "Name": "server_cache",
    "Size": 392,
    "Used": 78,
    "Free": 322,
    "MemTotal": 156800
  },
  {
    "Name": "client_cache",
    "Size": 392,
    "Used": 2708,
    "Free": 10092,
    "MemTotal": 5017600
  },
  {
    "Name": "iobuf_cache",
    "Size": 4112,
    "Used": 3,
    "Free": 797,
    "MemTotal": 3289600
  }
]

/status/stats

Returns the results of PGBouncer's SHOW STATS command formatted as JSON.

Example:

[
  {
    "Database": "pgbouncer",
    "TotalRequests": 16,
    "TotalReceived": 0,
    "TotalSent": 0,
    "TotalQueryTime": 0,
    "AvgReq": 0,
    "AvgRecv": 0,
    "AvgSent": 0,
    "AvgQuery": 0
  }
]

Server Debug Endpoints

These were added to help debug unreachable servers. You need to start the binary with ENABLE_DEBUG_ENDPOINTS=1 to make the available.

/debug/dmesg

Returns the raw output of dmesg

/debug/processes

Returns the raw output of ps -eo user,pid,ppid,c,stime,tty,%cpu,%mem,vsz,rsz,cmd

/debug/meminfo

Returns the contents of /proc/meminfo.

/debug/logs

Returns the output of journalctl --reverse -b --no-pager -n 50

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