minio/cmd/healthcheck-handler.go
Harshavardhana 157ed65c35 Fix healthcheck handler to check errors in local disks only (#6184)
Healthcheck handler in current implementation was
performing ListBuckets() to check for liveness of Minio
service. ListBuckets() implementation on the other hand
doesn't do quorum based listing and if one of the disks
returned error, an I/O error it would be lead to kubernetes
taking the minio pod down prematurely even if the disk
is not local to that minio server.

The reason is ListBuckets() call cannot be trusted to
provide us the valid information that we need, Minio is a
clustered application which is designed to handle disk
failures. Error on one of the disks doesn't mean the pod
should become fully non-operational.

This PR attempts to fix this by only checking for alive
disks which are local to each setup and also by simply
performing a Stat() operation, if the Stat() returned
error on all disks local to a particular server then
we can let kubernetes safely take it down, until then
we should be operational.
2018-07-23 12:21:25 -07:00

92 lines
3.1 KiB
Go

/*
* Minio Cloud Storage, (C) 2018 Minio, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package cmd
import (
"fmt"
"net/http"
"os"
"runtime"
"github.com/minio/minio/cmd/logger"
)
const (
minioHealthGoroutineThreshold = 1000
)
// ReadinessCheckHandler -- checks if there are more than threshold number of goroutines running,
// returns service unavailable.
// Readiness probes are used to detect situations where application is under heavy load
// and temporarily unable to serve. In a orchestrated setup like Kubernetes, containers reporting
// that they are not ready do not receive traffic through Kubernetes Services.
func ReadinessCheckHandler(w http.ResponseWriter, r *http.Request) {
if err := goroutineCountCheck(minioHealthGoroutineThreshold); err != nil {
writeResponse(w, http.StatusServiceUnavailable, nil, mimeNone)
return
}
writeResponse(w, http.StatusOK, nil, mimeNone)
}
// LivenessCheckHandler -- checks if server can reach its disks internally.
// If not, server is considered to have failed and needs to be restarted.
// Liveness probes are used to detect situations where application (minio)
// has gone into a state where it can not recover except by being restarted.
func LivenessCheckHandler(w http.ResponseWriter, r *http.Request) {
ctx := newContext(r, w, "LivenessCheckHandler")
objLayer := newObjectLayerFn()
// Service not initialized yet
if objLayer == nil {
writeResponse(w, http.StatusServiceUnavailable, nil, mimeNone)
return
}
var totalLocalDisks int
var erroredDisks int
for _, endpoint := range globalEndpoints {
// Check only if local disks are accessible, we do not have
// to reach to rest of the other servers in a distributed setup.
if endpoint.IsLocal {
totalLocalDisks++
// Attempt a stat to backend, any error resulting
// from this Stat() operation is considered as backend
// is not available, count them as errors.
if _, err := os.Stat(endpoint.Path); err != nil {
logger.LogIf(ctx, err)
erroredDisks++
}
}
}
// If all exported local disks have errored, we simply let kubernetes
// take us down.
if totalLocalDisks == erroredDisks {
writeResponse(w, http.StatusServiceUnavailable, nil, mimeNone)
return
}
writeResponse(w, http.StatusOK, nil, mimeNone)
}
// checks threshold against total number of go-routines in the system and throws error if
// more than threshold go-routines are running.
func goroutineCountCheck(threshold int) error {
count := runtime.NumGoroutine()
if count > threshold {
return fmt.Errorf("too many goroutines (%d > %d)", count, threshold)
}
return nil
}