d12696c20f
Provide an administrator a streaming view of journal logs on Linux systems using journalctl, and event logs on Windows systems using the Get-WinEvent PowerShell cmdlet without them having to implement a client side reader. Only available to cluster admins. The implementation for journald on Linux was originally done by Clayton Coleman. Introduce a heuristics approach to query logs The logs query for node objects will follow a heuristics approach when asked to query for logs from a service. If asked to get the logs from a service foobar, it will first check if foobar logs to the native OS service log provider. If unable to get logs from these, it will attempt to get logs from /var/foobar, /var/log/foobar.log or /var/log/foobar/foobar.log in that order. The logs sub-command can also directly serve a file if the query looks like a file. Co-authored-by: Clayton Coleman <ccoleman@redhat.com> Co-authored-by: Christian Glombek <cglombek@redhat.com>
75 lines
2.2 KiB
Go
75 lines
2.2 KiB
Go
//go:build linux
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/*
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Copyright 2022 The Kubernetes Authors.
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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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http://www.apache.org/licenses/LICENSE-2.0
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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 kubelet
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import (
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"context"
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"fmt"
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"os/exec"
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"strings"
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)
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// getLoggingCmd returns the journalctl cmd and arguments for the given nodeLogQuery and boot. Note that
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// services are explicitly passed here to account for the heuristics
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func getLoggingCmd(n *nodeLogQuery, services []string) (string, []string, error) {
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args := []string{
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"--utc",
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"--no-pager",
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"--output=short-precise",
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}
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if n.SinceTime != nil {
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args = append(args, fmt.Sprintf("--since=%s", n.SinceTime.Format(dateLayout)))
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}
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if n.UntilTime != nil {
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args = append(args, fmt.Sprintf("--until=%s", n.SinceTime.Format(dateLayout)))
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}
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if n.TailLines != nil {
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args = append(args, "--pager-end", fmt.Sprintf("--lines=%d", *n.TailLines))
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}
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for _, service := range services {
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if len(service) > 0 {
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args = append(args, "--unit="+service)
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}
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}
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if len(n.Pattern) > 0 {
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args = append(args, "--grep="+n.Pattern)
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}
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if n.Boot != nil {
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args = append(args, "--boot", fmt.Sprintf("%d", *n.Boot))
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}
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return "journalctl", args, nil
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}
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// checkForNativeLogger checks journalctl output for a service
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func checkForNativeLogger(ctx context.Context, service string) bool {
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// This will return all the journald units
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cmd := exec.CommandContext(ctx, "journalctl", []string{"--field", "_SYSTEMD_UNIT"}...)
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output, err := cmd.CombinedOutput()
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if err != nil {
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// Returning false to allow checking if the service is logging to a file
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return false
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}
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// journalctl won't return an error if we try to fetch logs for a non-existent service,
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// hence we search for it in the list of services known to journalctl
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return strings.Contains(string(output), service+".service")
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}
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