github.com/yrj2011/jx-test-infra@v0.0.0-20190529031832-7a2065ee98eb/prow/config/agent.go (about)

     1  /*
     2  Copyright 2017 The Kubernetes Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package config
    18  
    19  import (
    20  	"os"
    21  	"sync"
    22  	"time"
    23  
    24  	"github.com/sirupsen/logrus"
    25  )
    26  
    27  // Agent watches a path and automatically loads the config stored
    28  // therein.
    29  type Agent struct {
    30  	sync.Mutex
    31  	c *Config
    32  }
    33  
    34  // Start will begin polling the config file at the path. If the first load
    35  // fails, Start with return the error and abort. Future load failures will log
    36  // the failure message but continue attempting to load.
    37  func (ca *Agent) Start(prowConfig, jobConfig string) error {
    38  	c, err := Load(prowConfig, jobConfig)
    39  	if err != nil {
    40  		return err
    41  	}
    42  	ca.c = c
    43  	go func() {
    44  		var lastModTime time.Time
    45  		// Rarely, if two changes happen in the same second, mtime will
    46  		// be the same for the second change, and an mtime-based check would
    47  		// fail. Reload periodically just in case.
    48  		skips := 0
    49  		for range time.Tick(1 * time.Second) {
    50  			if skips < 600 {
    51  				// Check if the file changed to see if it needs to be re-read.
    52  				// os.Stat follows symbolic links, which is how ConfigMaps work.
    53  				prowStat, err := os.Stat(prowConfig)
    54  				if err != nil {
    55  					logrus.WithField("prowConfig", prowConfig).WithError(err).Error("Error loading prow config.")
    56  					continue
    57  				}
    58  
    59  				recentModTime := prowStat.ModTime()
    60  
    61  				// TODO(krzyzacy): allow empty jobConfig till fully migrate config to subdirs
    62  				if jobConfig != "" {
    63  					jobConfigStat, err := os.Stat(jobConfig)
    64  					if err != nil {
    65  						logrus.WithField("jobConfig", jobConfig).WithError(err).Error("Error loading job configs.")
    66  						continue
    67  					}
    68  
    69  					if jobConfigStat.ModTime().After(recentModTime) {
    70  						recentModTime = jobConfigStat.ModTime()
    71  					}
    72  				}
    73  
    74  				if !recentModTime.After(lastModTime) {
    75  					skips++
    76  					continue // file hasn't been modified
    77  				}
    78  				lastModTime = recentModTime
    79  			}
    80  			if c, err := Load(prowConfig, jobConfig); err != nil {
    81  				logrus.WithField("prowConfig", prowConfig).
    82  					WithField("jobConfig", jobConfig).
    83  					WithError(err).Error("Error loading config.")
    84  			} else {
    85  				skips = 0
    86  				ca.Lock()
    87  				ca.c = c
    88  				ca.Unlock()
    89  			}
    90  		}
    91  	}()
    92  	return nil
    93  }
    94  
    95  // Config returns the latest config. Do not modify the config.
    96  func (ca *Agent) Config() *Config {
    97  	ca.Lock()
    98  	defer ca.Unlock()
    99  	return ca.c
   100  }
   101  
   102  // Set sets the config. Useful for testing.
   103  func (ca *Agent) Set(c *Config) {
   104  	ca.Lock()
   105  	defer ca.Unlock()
   106  	ca.c = c
   107  }