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feat: add support for a lazy refresh
When creating a Dialer with the WithLazyRefresh option, the connection info and ephemeral certificate will be refreshed only when the cache certificate has expired. No background goroutines run with this option, making it ideal for use in Cloud Run and other serverless environments where the CPU may be throttled.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,139 @@ | ||
| // Copyright 2024 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 | ||
| // | ||
| // https://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 cloudsql | ||
|
|
||
| import ( | ||
| "context" | ||
| "crypto/rsa" | ||
| "sync" | ||
| "time" | ||
|
|
||
| "cloud.google.com/go/cloudsqlconn/debug" | ||
| "cloud.google.com/go/cloudsqlconn/instance" | ||
| "golang.org/x/oauth2" | ||
| sqladmin "google.golang.org/api/sqladmin/v1beta4" | ||
| ) | ||
|
|
||
| // LazyRefreshCache is caches connection info and refreshes the cache only when | ||
| // a caller requests connection info and the current certificate is expired. | ||
| type LazyRefreshCache struct { | ||
| connName instance.ConnName | ||
| logger debug.Logger | ||
| key *rsa.PrivateKey | ||
| r refresher | ||
| mu sync.Mutex | ||
| useIAMAuthNDial bool | ||
| needsRefresh bool | ||
| cached ConnectionInfo | ||
| } | ||
|
|
||
| // NewLazyRefreshCache initializes a new LazyRefreshCache. | ||
| func NewLazyRefreshCache( | ||
| cn instance.ConnName, | ||
| l debug.Logger, | ||
| client *sqladmin.Service, | ||
| key *rsa.PrivateKey, | ||
| _ time.Duration, | ||
| ts oauth2.TokenSource, | ||
| dialerID string, | ||
| useIAMAuthNDial bool, | ||
| ) *LazyRefreshCache { | ||
| return &LazyRefreshCache{ | ||
| connName: cn, | ||
| logger: l, | ||
| key: key, | ||
| r: newRefresher( | ||
| l, | ||
| client, | ||
| ts, | ||
| dialerID, | ||
| ), | ||
| useIAMAuthNDial: useIAMAuthNDial, | ||
| } | ||
| } | ||
|
|
||
| // ConnectionInfo returns connection info for the associated instance. New | ||
| // connection info is retrieved under two conditions: | ||
| // - the current connection info's certificate has expired, or | ||
| // - a caller has separately called ForceRefresh | ||
| func (c *LazyRefreshCache) ConnectionInfo( | ||
| ctx context.Context, | ||
| ) (ConnectionInfo, error) { | ||
| c.mu.Lock() | ||
| defer c.mu.Unlock() | ||
| // strip monotonic clock with UTC() | ||
| now := time.Now().UTC() | ||
| // Pad expiration with a buffer to give the client plenty of time to | ||
| // establish a connection to the server with the certificate. | ||
| exp := c.cached.Expiration.UTC().Add(-refreshBuffer) | ||
| if !c.needsRefresh && now.Before(exp) { | ||
| c.logger.Debugf( | ||
| "[%v] Connection info is still valid, using cached info", | ||
| c.connName.String(), | ||
| ) | ||
| return c.cached, nil | ||
| } | ||
|
|
||
| c.logger.Debugf( | ||
| "[%v] Connection info refresh operation started", | ||
| c.connName.String(), | ||
| ) | ||
| ci, err := c.r.ConnectionInfo(ctx, c.connName, c.key, c.useIAMAuthNDial) | ||
| if err != nil { | ||
| c.logger.Debugf( | ||
| "[%v] Connection info refresh operation failed, err = %v", | ||
| c.connName.String(), | ||
| err, | ||
| ) | ||
| return ConnectionInfo{}, err | ||
| } | ||
| c.logger.Debugf( | ||
| "[%v] Connection info refresh operation complete", | ||
| c.connName.String(), | ||
| ) | ||
| c.logger.Debugf( | ||
| "[%v] Current certificate expiration = %v", | ||
| c.connName.String(), | ||
| ci.Expiration.UTC().Format(time.RFC3339), | ||
| ) | ||
| c.cached = ci | ||
| c.needsRefresh = false | ||
| return ci, nil | ||
| } | ||
|
|
||
| // UpdateRefresh updates the refresh operation to either enable or disable IAM | ||
| // authentication for the cached connection info. | ||
| func (c *LazyRefreshCache) UpdateRefresh(useIAMAuthNDial *bool) { | ||
| c.mu.Lock() | ||
| defer c.mu.Unlock() | ||
| if useIAMAuthNDial != nil && *useIAMAuthNDial != c.useIAMAuthNDial { | ||
| c.useIAMAuthNDial = *useIAMAuthNDial | ||
| c.needsRefresh = true | ||
| } | ||
| } | ||
|
|
||
| // ForceRefresh invalidates the caches and configures the next call to | ||
| // ConnectionInfo to retrieve a fresh connection info. | ||
| func (c *LazyRefreshCache) ForceRefresh() { | ||
| c.mu.Lock() | ||
| defer c.mu.Unlock() | ||
| c.needsRefresh = true | ||
| } | ||
|
|
||
| // Close is a no-op and provided purely for a consistent interface with other | ||
| // caching types. | ||
| func (c *LazyRefreshCache) Close() error { | ||
| return nil | ||
| } |
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