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feat: add support for health-check flag (#85)
This is an adaptation of GoogleCloudPlatform/cloud-sql-proxy#1271.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,110 @@ | ||
| // Copyright 2022 Google LLC | ||
| // | ||
| // 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 healthcheck tests and communicates the health of the AlloyDB Auth | ||
| // proxy. | ||
| package healthcheck | ||
|
|
||
| import ( | ||
| "context" | ||
| "errors" | ||
| "fmt" | ||
| "net/http" | ||
| "sync" | ||
|
|
||
| "github.com/GoogleCloudPlatform/alloydb-auth-proxy/alloydb" | ||
| "github.com/GoogleCloudPlatform/alloydb-auth-proxy/internal/proxy" | ||
| ) | ||
|
|
||
| // Check provides HTTP handlers for use as healthchecks typically in a | ||
| // Kubernetes context. | ||
| type Check struct { | ||
| once *sync.Once | ||
| started chan struct{} | ||
| proxy *proxy.Client | ||
| logger alloydb.Logger | ||
| } | ||
|
|
||
| // NewCheck is the initializer for Check. | ||
| func NewCheck(p *proxy.Client, l alloydb.Logger) *Check { | ||
| return &Check{ | ||
| once: &sync.Once{}, | ||
| started: make(chan struct{}), | ||
| proxy: p, | ||
| logger: l, | ||
| } | ||
| } | ||
|
|
||
| // NotifyStarted notifies the check that the proxy has started up successfully. | ||
| func (c *Check) NotifyStarted() { | ||
| c.once.Do(func() { close(c.started) }) | ||
| } | ||
|
|
||
| // HandleStartup reports whether the Check has been notified of startup. | ||
| func (c *Check) HandleStartup(w http.ResponseWriter, _ *http.Request) { | ||
| select { | ||
| case <-c.started: | ||
| w.WriteHeader(http.StatusOK) | ||
| w.Write([]byte("ok")) | ||
| default: | ||
| w.WriteHeader(http.StatusServiceUnavailable) | ||
| w.Write([]byte("error")) | ||
| } | ||
| } | ||
|
|
||
| var errNotStarted = errors.New("proxy is not started") | ||
|
|
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| // HandleReadiness ensures the Check has been notified of successful startup, | ||
| // that the proxy has not reached maximum connections, and that all connections | ||
| // are healthy. | ||
| func (c *Check) HandleReadiness(w http.ResponseWriter, _ *http.Request) { | ||
| ctx, cancel := context.WithCancel(context.Background()) | ||
| defer cancel() | ||
|
|
||
| select { | ||
| case <-c.started: | ||
| default: | ||
| c.logger.Errorf("[Health Check] Readiness failed: %v", errNotStarted) | ||
| w.WriteHeader(http.StatusServiceUnavailable) | ||
| w.Write([]byte(errNotStarted.Error())) | ||
| return | ||
| } | ||
|
|
||
| if open, max := c.proxy.ConnCount(); max > 0 && open == max { | ||
| err := fmt.Errorf("max connections reached (open = %v, max = %v)", open, max) | ||
| c.logger.Errorf("[Health Check] Readiness failed: %v", err) | ||
| w.WriteHeader(http.StatusServiceUnavailable) | ||
| w.Write([]byte(err.Error())) | ||
| return | ||
| } | ||
|
|
||
| err := c.proxy.CheckConnections(ctx) | ||
| if err != nil { | ||
| c.logger.Errorf("[Health Check] Readiness failed: %v", err) | ||
| w.WriteHeader(http.StatusServiceUnavailable) | ||
| w.Write([]byte(err.Error())) | ||
| return | ||
| } | ||
|
|
||
| w.WriteHeader(http.StatusOK) | ||
| w.Write([]byte("ok")) | ||
| } | ||
|
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||
| // HandleLiveness indicates the process is up and responding to HTTP requests. | ||
| // If this check fails (because it's not reachable), the process is in a bad | ||
| // state and should be restarted. | ||
| func (c *Check) HandleLiveness(w http.ResponseWriter, _ *http.Request) { | ||
| w.WriteHeader(http.StatusOK) | ||
| w.Write([]byte("ok")) | ||
| } |
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