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00ba5bdb98
...in preparation for upgrading containerd. Signed-off-by: Cory Snider <csnider@mirantis.com>
135 lines
4.1 KiB
Go
135 lines
4.1 KiB
Go
// Copyright 2016 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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/*
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Package logging contains a Cloud Logging client suitable for writing logs.
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For reading logs, and working with sinks, metrics and monitored resources,
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see package cloud.google.com/go/logging/logadmin.
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This client uses Logging API v2.
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See https://cloud.google.com/logging/docs/api/v2/ for an introduction to the API.
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Creating a Client
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Use a Client to interact with the Cloud Logging API.
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// Create a Client
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ctx := context.Background()
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client, err := logging.NewClient(ctx, "my-project")
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if err != nil {
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// TODO: Handle error.
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}
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Basic Usage
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For most use cases, you'll want to add log entries to a buffer to be periodically
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flushed (automatically and asynchronously) to the Cloud Logging service.
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// Initialize a logger
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lg := client.Logger("my-log")
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// Add entry to log buffer
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lg.Log(logging.Entry{Payload: "something happened!"})
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Closing your Client
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You should call Client.Close before your program exits to flush any buffered log entries to the Cloud Logging service.
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// Close the client when finished.
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err = client.Close()
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if err != nil {
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// TODO: Handle error.
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}
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Synchronous Logging
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For critical errors, you may want to send your log entries immediately.
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LogSync is slow and will block until the log entry has been sent, so it is
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not recommended for normal use.
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err = lg.LogSync(ctx, logging.Entry{Payload: "ALERT! Something critical happened!"})
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if err != nil {
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// TODO: Handle error.
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}
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Payloads
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An entry payload can be a string, as in the examples above. It can also be any value
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that can be marshaled to a JSON object, like a map[string]interface{} or a struct:
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type MyEntry struct {
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Name string
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Count int
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}
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lg.Log(logging.Entry{Payload: MyEntry{Name: "Bob", Count: 3}})
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If you have a []byte of JSON, wrap it in json.RawMessage:
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j := []byte(`{"Name": "Bob", "Count": 3}`)
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lg.Log(logging.Entry{Payload: json.RawMessage(j)})
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The Standard Logger
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You may want use a standard log.Logger in your program.
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// stdlg is an instance of *log.Logger.
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stdlg := lg.StandardLogger(logging.Info)
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stdlg.Println("some info")
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Log Levels
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An Entry may have one of a number of severity levels associated with it.
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logging.Entry{
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Payload: "something terrible happened!",
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Severity: logging.Critical,
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}
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Viewing Logs
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You can view Cloud logs for projects at
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https://console.cloud.google.com/logs/viewer. Use the dropdown at the top left. When
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running from a Google Cloud Platform VM, select "GCE VM Instance". Otherwise, select
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"Google Project" and then the project ID. Logs for organizations, folders and billing
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accounts can be viewed on the command line with the "gcloud logging read" command.
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Grouping Logs by Request
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To group all the log entries written during a single HTTP request, create two
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Loggers, a "parent" and a "child," with different log IDs. Both should be in the same
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project, and have the same MonitoredResource type and labels.
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- Parent entries must have HTTPRequest.Request (strictly speaking, only Method and URL are necessary),
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and HTTPRequest.Status populated.
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- A child entry's timestamp must be within the time interval covered by the parent request. (i.e., before
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the parent.Timestamp and after the parent.Timestamp - parent.HTTPRequest.Latency. This assumes the
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parent.Timestamp marks the end of the request.)
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- The trace field must be populated in all of the entries and match exactly.
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You should observe the child log entries grouped under the parent on the console. The
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parent entry will not inherit the severity of its children; you must update the
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parent severity yourself.
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*/
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package logging // import "cloud.google.com/go/logging"
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