Add metrics middleware to spar.

[fisx]

tasks:

• make sure /metrics is the right URI path, or change it.
• add integration test that checks that metrics are generated?
• see if we have all the generate all any data at all, or all the data we want.

[fisx]

$ curl http://localhost:8088/i/monitoring
# HELP http_request_duration_seconds The HTTP request latencies in seconds.
# TYPE http_request_duration_seconds histogram
http_request_duration_seconds_bucket{handler="app",method="GET",status_code="200",le="0.005"} 18
http_request_duration_seconds_bucket{handler="app",method="GET",status_code="200",le="0.01"} 23
http_request_duration_seconds_bucket{handler="app",method="GET",status_code="200",le="0.025"} 24
http_request_duration_seconds_bucket{handler="app",method="GET",status_code="200",le="0.05"} 24
http_request_duration_seconds_bucket{handler="app",method="GET",status_code="200",le="0.1"} 24
http_request_duration_seconds_bucket{handler="app",method="GET",status_code="200",le="0.25"} 24
http_request_duration_seconds_bucket{handler="app",method="GET",status_code="200",le="0.5"} 24
http_request_duration_seconds_bucket{handler="app",method="GET",status_code="200",le="1.0"} 24
http_request_duration_seconds_bucket{handler="app",method="GET",status_code="200",le="2.5"} 24
http_request_duration_seconds_bucket{handler="app",method="GET",status_code="200",le="5.0"} 24
http_request_duration_seconds_bucket{handler="app",method="GET",status_code="200",le="10.0"} 24
http_request_duration_seconds_bucket{handler="app",method="GET",status_code="200",le="+Inf"} 24
http_request_duration_seconds_sum{handler="app",method="GET",status_code="200"} 7.236669000000001e-2
http_request_duration_seconds_count{handler="app",method="GET",status_code="200"} 24
http_request_duration_seconds_bucket{handler="app",method="GET",status_code="404",le="0.005"} 1
http_request_duration_seconds_bucket{handler="app",method="GET",status_code="404",le="0.01"} 1
http_request_duration_seconds_bucket{handler="app",method="GET",status_code="404",le="0.025"} 1
http_request_duration_seconds_bucket{handler="app",method="GET",status_code="404",le="0.05"} 1
http_request_duration_seconds_bucket{handler="app",method="GET",status_code="404",le="0.1"} 1
http_request_duration_seconds_bucket{handler="app",method="GET",status_code="404",le="0.25"} 1
http_request_duration_seconds_bucket{handler="app",method="GET",status_code="404",le="0.5"} 1
http_request_duration_seconds_bucket{handler="app",method="GET",status_code="404",le="1.0"} 1
http_request_duration_seconds_bucket{handler="app",method="GET",status_code="404",le="2.5"} 1
http_request_duration_seconds_bucket{handler="app",method="GET",status_code="404",le="5.0"} 1
http_request_duration_seconds_bucket{handler="app",method="GET",status_code="404",le="10.0"} 1
http_request_duration_seconds_bucket{handler="app",method="GET",status_code="404",le="+Inf"} 1
http_request_duration_seconds_sum{handler="app",method="GET",status_code="404"} 2.39014e-3
http_request_duration_seconds_count{handler="app",method="GET",status_code="404"} 1
http_request_duration_seconds_bucket{handler="app",method="HEAD",status_code="200",le="0.005"} 1
http_request_duration_seconds_bucket{handler="app",method="HEAD",status_code="200",le="0.01"} 3
http_request_duration_seconds_bucket{handler="app",method="HEAD",status_code="200",le="0.025"} 3
http_request_duration_seconds_bucket{handler="app",method="HEAD",status_code="200",le="0.05"} 3
http_request_duration_seconds_bucket{handler="app",method="HEAD",status_code="200",le="0.1"} 3
http_request_duration_seconds_bucket{handler="app",method="HEAD",status_code="200",le="0.25"} 3
http_request_duration_seconds_bucket{handler="app",method="HEAD",status_code="200",le="0.5"} 3
http_request_duration_seconds_bucket{handler="app",method="HEAD",status_code="200",le="1.0"} 3
http_request_duration_seconds_bucket{handler="app",method="HEAD",status_code="200",le="2.5"} 3
http_request_duration_seconds_bucket{handler="app",method="HEAD",status_code="200",le="5.0"} 3
http_request_duration_seconds_bucket{handler="app",method="HEAD",status_code="200",le="10.0"} 3
http_request_duration_seconds_bucket{handler="app",method="HEAD",status_code="200",le="+Inf"} 3
http_request_duration_seconds_sum{handler="app",method="HEAD",status_code="200"} 2.0847349e-2
http_request_duration_seconds_count{handler="app",method="HEAD",status_code="200"} 3
http_request_duration_seconds_bucket{handler="app",method="HEAD",status_code="404",le="0.005"} 1
http_request_duration_seconds_bucket{handler="app",method="HEAD",status_code="404",le="0.01"} 1
http_request_duration_seconds_bucket{handler="app",method="HEAD",status_code="404",le="0.025"} 1
http_request_duration_seconds_bucket{handler="app",method="HEAD",status_code="404",le="0.05"} 1
http_request_duration_seconds_bucket{handler="app",method="HEAD",status_code="404",le="0.1"} 1
http_request_duration_seconds_bucket{handler="app",method="HEAD",status_code="404",le="0.25"} 1
http_request_duration_seconds_bucket{handler="app",method="HEAD",status_code="404",le="0.5"} 1
http_request_duration_seconds_bucket{handler="app",method="HEAD",status_code="404",le="1.0"} 1
http_request_duration_seconds_bucket{handler="app",method="HEAD",status_code="404",le="2.5"} 1
http_request_duration_seconds_bucket{handler="app",method="HEAD",status_code="404",le="5.0"} 1
http_request_duration_seconds_bucket{handler="app",method="HEAD",status_code="404",le="10.0"} 1
http_request_duration_seconds_bucket{handler="app",method="HEAD",status_code="404",le="+Inf"} 1
http_request_duration_seconds_sum{handler="app",method="HEAD",status_code="404"} 9.2561e-4
http_request_duration_seconds_count{handler="app",method="HEAD",status_code="404"} 1
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="200",le="0.005"} 0
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="200",le="0.01"} 0
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="200",le="0.025"} 0
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="200",le="0.05"} 2
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="200",le="0.1"} 3
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="200",le="0.25"} 4
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="200",le="0.5"} 4
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="200",le="1.0"} 4
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="200",le="2.5"} 4
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="200",le="5.0"} 4
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="200",le="10.0"} 4
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="200",le="+Inf"} 4
http_request_duration_seconds_sum{handler="app",method="POST",status_code="200"} 0.37673793699999997
http_request_duration_seconds_count{handler="app",method="POST",status_code="200"} 4
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="201",le="0.005"} 0
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="201",le="0.01"} 0
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="201",le="0.025"} 1
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="201",le="0.05"} 2
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="201",le="0.1"} 2
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="201",le="0.25"} 2
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="201",le="0.5"} 2
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="201",le="1.0"} 2
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="201",le="2.5"} 2
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="201",le="5.0"} 2
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="201",le="10.0"} 2
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="201",le="+Inf"} 2
http_request_duration_seconds_sum{handler="app",method="POST",status_code="201"} 4.2691357e-2
http_request_duration_seconds_count{handler="app",method="POST",status_code="201"} 2
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="404",le="0.005"} 1
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="404",le="0.01"} 1
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="404",le="0.025"} 1
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="404",le="0.05"} 1
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="404",le="0.1"} 1
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="404",le="0.25"} 1
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="404",le="0.5"} 1
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="404",le="1.0"} 1
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="404",le="2.5"} 1
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="404",le="5.0"} 1
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="404",le="10.0"} 1
http_request_duration_seconds_bucket{handler="app",method="POST",status_code="404",le="+Inf"} 1
http_request_duration_seconds_sum{handler="app",method="POST",status_code="404"} 3.577483e-3
http_request_duration_seconds_count{handler="app",method="POST",status_code="404"} 1
http_request_duration_seconds_bucket{handler="prometheus",method="GET",status_code="200",le="0.005"} 13
http_request_duration_seconds_bucket{handler="prometheus",method="GET",status_code="200",le="0.01"} 13
http_request_duration_seconds_bucket{handler="prometheus",method="GET",status_code="200",le="0.025"} 13
http_request_duration_seconds_bucket{handler="prometheus",method="GET",status_code="200",le="0.05"} 13
http_request_duration_seconds_bucket{handler="prometheus",method="GET",status_code="200",le="0.1"} 13
http_request_duration_seconds_bucket{handler="prometheus",method="GET",status_code="200",le="0.25"} 13
http_request_duration_seconds_bucket{handler="prometheus",method="GET",status_code="200",le="0.5"} 13
http_request_duration_seconds_bucket{handler="prometheus",method="GET",status_code="200",le="1.0"} 13
http_request_duration_seconds_bucket{handler="prometheus",method="GET",status_code="200",le="2.5"} 13
http_request_duration_seconds_bucket{handler="prometheus",method="GET",status_code="200",le="5.0"} 13
http_request_duration_seconds_bucket{handler="prometheus",method="GET",status_code="200",le="10.0"} 13
http_request_duration_seconds_bucket{handler="prometheus",method="GET",status_code="200",le="+Inf"} 13
http_request_duration_seconds_sum{handler="prometheus",method="GET",status_code="200"} 1.245389e-3
http_request_duration_seconds_count{handler="prometheus",method="GET",status_code="200"} 13