Ensure CF Cells info is shown for non cf admins

[richard-cox]

• Add new /metrics/cf/cells/:op endpoint which will allow non-admins to access specific cell queries
• Integrate new cells endpoint into front end & test with non-admin user
• Hide cell app instances tab if not cf admin

Also

• Minor tidy of isConnectedUserAdmin
• Fix console when navigating from app instances to app metrics (bug in v2-master)

[cfdreddbot]

Hey richard-cox!

Thanks for submitting this pull request! I'm here to inform the recipients of the pull request that you and the commit authors have already signed the CLA.

[codecov]

Codecov Report

Merging #3121 into v2-master will decrease coverage by 0.03%.
The diff coverage is 80%.

@@              Coverage Diff              @@
##           v2-master    #3121      +/-   ##
=============================================
- Coverage      71.16%   71.13%   -0.04%     
=============================================
  Files            627      627              
  Lines          27407    27412       +5     
  Branches        6229     6230       +1     
=============================================
- Hits           19504    19499       -5     
- Misses          7903     7913      +10

[richard-cox]

Had a look at improving the white list check and came up with the following. Let me know if I should swap it out or there's a better way to do it.

var (
	cellQueryWhiteList = map[string]int{
		"firehose_value_metric_rep_unhealthy_cell":                0,
		"firehose_value_metric_rep_capacity_remaining_containers": 0,
		"firehose_value_metric_rep_capacity_remaining_disk":       0,
		"firehose_value_metric_rep_capacity_remaining_memory":     0,
		"firehose_value_metric_rep_capacity_total_containers":     0,
		"firehose_value_metric_rep_capacity_total_disk":           0,
		"firehose_value_metric_rep_capacity_total_memory":         0,
		"firehose_value_metric_rep_num_cpus":                      0,
	}
)

func isAllowedCellMetricsQuery(query string) bool {
	safeQuery := query
	extrasIndex := strings.IndexAny(query, "{[")

	if extrasIndex >= 0 {
		safeQuery = query[0 : extrasIndex-1]
	}

	if _, ok := cellQueryWhiteList[query]; ok {
		return true
	}

	return false
}

Rather than the current

var (
	cellQueryWhiteList = []string{
		"firehose_value_metric_rep_unhealthy_cell",
		"firehose_value_metric_rep_capacity_remaining_containers",
		"firehose_value_metric_rep_capacity_remaining_disk",
		"firehose_value_metric_rep_capacity_remaining_memory",
		"firehose_value_metric_rep_capacity_total_containers",
		"firehose_value_metric_rep_capacity_total_disk",
		"firehose_value_metric_rep_capacity_total_memory",
		"firehose_value_metric_rep_num_cpus",
	}
)
func isAllowedCellMetricsQuery(query string) bool {
	for _, whiteListQuery := range cellQueryWhiteList {
		if strings.Index(query, whiteListQuery) == 0 {
			return true
		}
	}
	return false
}

[nwmac]

LGTM

[nwmac]

Tested locally - looks good.