TO GET /caches/stats panic converting string to uint64

[rawlinp]

I'm submitting a ...

• bug report

Traffic Control components affected ...

• Traffic Ops

Current behavior:

TO panics in the GET /api/x/caches/stats route doing an unchecked type assertion:

ERROR: api.go:209: 2021-02-23T13:28:59.128183143Z: 96.118.252.81:34068 panic: (err: interface conversion: interface {} is string, not uint64) stacktrace:
goroutine 47852 [running]:
github.com/apache/trafficcontrol/lib/go-util.Stacktrace(0xc00159f658, 0xe324e0, 0xc0284781e0)
	/tmp/go/src/github.com/apache/trafficcontrol/lib/go-util/util.go:32 +0x9f
github.com/apache/trafficcontrol/traffic_ops/traffic_ops_golang/routing/middleware.WrapPanicRecover.func1.1(0x107ebc0, 0xc020ab7230, 0xc00018ae00)
	/tmp/go/src/github.com/apache/trafficcontrol/traffic_ops/traffic_ops_golang/routing/middleware/wrappers.go:152 +0x58
panic(0xe324e0, 0xc0284781e0)
	/usr/local/go/src/runtime/panic.go:969 +0x1b9
github.com/apache/trafficcontrol/traffic_ops/traffic_ops_golang/cachesstats.addStats(0xc0066ac000, 0xa7e, 0xcaa, 0xc00ce7a190, 0x4b, 0xc0018c0400, 0x1c, 0xc020ab7a10, 0xc0018c0400, 0x1c, ...)
	/tmp/go/src/github.com/apache/trafficcontrol/traffic_ops/traffic_ops_golang/cachesstats/cachesstats.go:149 +0x353
github.com/apache/trafficcontrol/traffic_ops/traffic_ops_golang/cachesstats.getCachesStats(0xc0063ec400, 0x0, 0x0, 0x0, 0x0, 0x0)
	/tmp/go/src/github.com/apache/trafficcontrol/traffic_ops/traffic_ops_golang/cachesstats/cachesstats.go:94 +0xda5
github.com/apache/trafficcontrol/traffic_ops/traffic_ops_golang/cachesstats.Get(0x107ebc0, 0xc020ab7230, 0xc00018ae00)
	/tmp/go/src/github.com/apache/trafficcontrol/traffic_ops/traffic_ops_golang/cachesstats/cachesstats.go:45 +0x12e
github.com/apache/trafficcontrol/traffic_ops/traffic_ops_golang/routing/middleware.AuthBase.GetWrapper.func1.1(0x107ebc0, 0xc020ab7230, 0xc00018ae00)
	/tmp/go/src/github.com/apache/trafficcontrol/traffic_ops/traffic_ops_golang/routing/middleware/wrappers.go:107 +0x282
github.com/apache/trafficcontrol/traffic_ops/traffic_ops_golang/routing/middleware.WrapPanicRecover.func1(0x107ebc0, 0xc020ab7230, 0xc00018ae00)
	/tmp/go/src/github.com/apache/trafficcontrol/traffic_ops/traffic_ops_golang/routing/middleware/wrappers.go:156 +0x79
github.com/apache/trafficcontrol/traffic_ops/traffic_ops_golang/routing/middleware.WrapHeaders.func1(0x1081c40, 0xc0052927e0, 0xc00018ae00)
	/tmp/go/src/github.com/apache/trafficcontrol/traffic_ops/traffic_ops_golang/routing/middleware/wrappers.go:136 +0x64f
net/http.HandlerFunc.ServeHTTP(0xc00007e7a0, 0x1081c40, 0xc0052927e0, 0xc00018ae00)
	/usr/local/go/src/net/http/server.go:2042 +0x44
net/http.(*timeoutHandler).ServeHTTP.func1(0xc0052929c0, 0xc00f516600, 0xc0052927e0, 0xc00018ae00, 0xc00435ac00)
	/usr/local/go/src/net/http/server.go:3272 +0x7f
created by net/http.(*timeoutHandler).ServeHTTP
	/usr/local/go/src/net/http/server.go:3266 +0x22e

Expected behavior:

TO should properly convert the string into a uint64 rather than doing an unchecked type assertion.

Minimal reproduction of the problem with instructions:

Request GET /api/3.0/caches/stats, observe the above 500 internal server error and stacktrace in the TO logs.

[srijeet0406]

@rawlinp I can take this one