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check.go
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check.go
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package main
import (
"encoding/json"
"strings"
"fmt"
log "github.com/Sirupsen/logrus"
"github.com/hashicorp/consul/api"
)
const alertingKVRoot = "service/consul-alerting"
// CheckState is used for storing recent state for a given health check on a specific node,
// in order to preserve alert state across restarts
type CheckState struct {
Status string `json:"status"`
}
// Returns a map of nodename/checkname strings to CheckStates from the given KV prefix
func getCheckStates(kvPath string, client *api.Client) (map[string]*CheckState, error) {
checkStates := make(map[string]*CheckState)
keys, _, err := client.KV().Keys(kvPath, "", nil)
if err != nil {
log.Error("Error loading previous check states: ", err)
return checkStates, err
}
for _, path := range keys {
checkState, err := getCheckState(path, client)
if err != nil {
log.Error("Error loading check states: ", err)
return checkStates, err
} else if checkState == nil {
continue
}
keyName := strings.Split(path, "/")
if keyName[len(keyName)-1] != "alert" && keyName[len(keyName)-1] != "leader" {
checkName := keyName[len(keyName)-2] + "/" + keyName[len(keyName)-1]
checkStates[checkName] = checkState
}
}
return checkStates, nil
}
// Parses a CheckState from a given Consul K/V path
func getCheckState(kvPath string, client *api.Client) (*CheckState, error) {
kvPair, _, err := client.KV().Get(kvPath, nil)
check := &CheckState{}
if err != nil {
log.Error("Error loading check state: ", err)
return nil, err
}
if kvPair == nil {
return check, nil
}
if string(kvPair.Value) == "" {
return nil, nil
}
err = json.Unmarshal(kvPair.Value, check)
if err != nil {
log.Error("Error parsing check state: ", err)
return nil, err
}
return check, nil
}
type CheckUpdate struct {
ServiceTag string
*api.HealthCheck
}
// Updates the last known state of a check in Consul. Returns true if succeeded.
func updateCheckState(update CheckUpdate, client *api.Client) bool {
check := update.HealthCheck
kvPath := alertingKVRoot
if check.ServiceID != "" {
tagPath := ""
if update.ServiceTag != "" {
tagPath = fmt.Sprintf("%s/", update.ServiceTag)
}
kvPath = kvPath + fmt.Sprintf("/service/%s/%s%s/%s", check.ServiceName, tagPath, check.Node, check.CheckID)
} else {
kvPath = kvPath + fmt.Sprintf("/node/%s/%s", check.Node, check.CheckID)
}
status, err := json.Marshal(CheckState{
Status: check.Status,
})
if err != nil {
log.Errorf("Error forming state for alert in Consul: %s", err)
return false
}
_, err = client.KV().Put(&api.KVPair{
Key: kvPath,
Value: status,
}, nil)
if err != nil {
log.Errorf("Error storing state for alert in Consul: %s", err)
return false
}
return true
}
// Given a map of node/checkID:statuses, compute the health of the node/service
func computeHealth(checks map[string]string) string {
health := api.HealthPassing
for _, status := range checks {
switch status {
case api.HealthWarning:
if health != api.HealthCritical {
health = api.HealthWarning
}
case api.HealthCritical:
health = api.HealthCritical
}
}
return health
}