Amazon-Ec2

命令不在 crontab 中執行，而命令本身工作得很好

  • July 25, 2017

我在 Github 上有 Colin Johnson 的這個腳本 - https://github.com/colinbjohnson/aws-missing-tools/tree/master/ec2-automate-backup

看起來很棒。我已將其修改為每次創建或刪除 EBS 快照時向自己發送電子郵件。以下作品就像一個魅力

ec2-automate-backup.sh -v “vol-myvolumeid” -k 3

但是，它根本不作為我的 crontab 的一部分執行（我沒有收到任何電子郵件）

#一些被註釋掉的命令

*/5 * * * * ec2-automate-backup.sh -v “vol-fb2fbcdf” -k 3;

          • 日期 >> /root/logs/crontab.log;

*/5 * * * * 日期 >> /root/logs/crontab2.log

請注意，第二次和第三次執行很好，因為我可以在日誌文件中看到日期和時間。

我在這裡錯過了什麼？

完整的 ec2-automate-backup.sh 如下：

#!/bin/bash -
# Author: Colin Johnson / colin@cloudavail.com
# Date: 2012-09-24
# Version 0.1
# License Type: GNU GENERAL PUBLIC LICENSE, Version 3
#
#confirms that executables required for succesful script execution are available

prerequisite_check()
{
   for prerequisite in basename ec2-create-snapshot ec2-create-tags ec2-describe-snapshots ec2-delete-snapshot date
   do
       #use of "hash" chosen as it is a shell builtin and will add programs to hash table, possibly speeding execution. Use of type also considered - open to suggestions.
       hash $prerequisite &> /dev/null
       if [[ $? == 1 ]] #has exits with exit status of 70, executable was not found
           then echo "In order to use `basename $0`, the executable \"$prerequisite\" must be installed." 1>&2 | mailx -s "Error happened 0" eric@mydomain.com ; exit 70
       fi
   done
}

#get_EBS_List gets a list of available EBS instances depending upon the selection_method of EBS selection that is provided by user input
get_EBS_List()
{
   case $selection_method in
       volumeid)
           if [[ -z $volumeid ]]
               then echo "The selection method \"volumeid\" (which is $app_name's default selection_method of operation or requested by using the -s volumeid parameter) requires a volumeid (-v volumeid) for operation. Correct usage is as follows: \"-v vol-6d6a0527\",\"-s volumeid -v vol-6d6a0527\" or \"-v \"vol-6d6a0527 vol-636a0112\"\" if multiple volumes are to be selected." 1>&2 | mailx -s "Error happened 1" eric@mydomain.com ; exit 64
           fi
           ebs_selection_string="$volumeid"
           ;;
       tag) 
           if [[ -z $tag ]]
               then echo "The selected selection_method \"tag\" (-s tag) requires a valid tag (-t key=value) for operation. Correct usage is as follows: \"-s tag -t backup=true\" or \"-s tag -t Name=my_tag.\"" 1>&2 | mailx -s "Error happened 2" eric@mydomain.com ; exit 64
           fi
           ebs_selection_string="--filter tag:$tag"
           ;;
       *) echo "If you specify a selection_method (-s selection_method) for selecting EBS volumes you must select either \"volumeid\" (-s volumeid) or \"tag\" (-s tag)." 1>&2 | mailx -s "Error happened 3" eric@mydomain.com ; exit 64 ;;
   esac
   #creates a list of all ebs volumes that match the selection string from above
   ebs_backup_list_complete=`ec2-describe-volumes --show-empty-fields --region $region $ebs_selection_string 2>&1`
   #takes the output of the previous command 
   ebs_backup_list_result=`echo $?`
   if [[ $ebs_backup_list_result -gt 0 ]]
       then echo -e "An error occured when running ec2-describe-volumes. The error returned is below:\n$ebs_backup_list_complete" 1>&2 | mailx -s "Error happened 4" eric@mydomain.com ; exit 70
   fi
   ebs_backup_list=`echo "$ebs_backup_list_complete" | grep ^VOLUME | cut -f 2`
   #code to right will output list of EBS volumes to be backed up: echo -e "Now outputting ebs_backup_list:\n$ebs_backup_list"
}

create_EBS_Snapshot_Tags()
{
   #snapshot tags holds all tags that need to be applied to a given snapshot - by aggregating tags we ensure that ec2-create-tags is called only onece
   snapshot_tags=""
   #if $name_tag_create is true then append ec2ab_${ebs_selected}_$date_current to the variable $snapshot_tags
   if $name_tag_create
       then
       ec2_snapshot_resource_id=`echo "$ec2_create_snapshot_result" | cut -f 2`
       snapshot_tags="$snapshot_tags --tag Name=ec2ab_${ebs_selected}_$date_current"
   fi
   #if $purge_after_days is true, then append $purge_after_date to the variable $snapshot_tags
   if [[ -n $purge_after_days ]]
       then
       snapshot_tags="$snapshot_tags --tag PurgeAfter=$purge_after_date --tag PurgeAllow=true"
   fi
   #if $snapshot_tags is not zero length then set the tag on the snapshot using ec2-create-tags
   if [[ -n $snapshot_tags ]]
       then echo "Tagging Snapshot $ec2_snapshot_resource_id with the following Tags:"
       ec2-create-tags $ec2_snapshot_resource_id --region $region $snapshot_tags
       #echo "Snapshot tags successfully created" | mailx -s "Snapshot tags successfully created" eric@mydomain.com
   fi
}

date_command_get()
{
   #finds full path to date binary
   date_binary_full_path=`which date`
   #command below is used to determine if date binary is gnu, macosx or other
   date_binary_file_result=`file -b $date_binary_full_path`
   case $date_binary_file_result in
       "Mach-O 64-bit executable x86_64") date_binary="macosx" ;;
       "ELF 64-bit LSB executable, x86-64, version 1 (SYSV)"*) date_binary="gnu" ;;
       *) date_binary="unknown" ;;
   esac
   #based on the installed date binary the case statement below will determine the method to use to determine "purge_after_days" in the future
   case $date_binary in
       gnu) date_command="date -d +${purge_after_days}days -u +%Y-%m-%d" ;;
       macosx) date_command="date -v+${purge_after_days}d -u +%Y-%m-%d" ;;
       unknown) date_command="date -d +${purge_after_days}days -u +%Y-%m-%d" ;;
       *) date_command="date -d +${purge_after_days}days -u +%Y-%m-%d" ;;
   esac
}

purge_EBS_Snapshots()
{
   #snapshot_tag_list is a string that contains all snapshots with either the key PurgeAllow or PurgeAfter set
   snapshot_tag_list=`ec2-describe-tags --show-empty-fields --region $region --filter resource-type=snapshot --filter key=PurgeAllow,PurgeAfter`
   #snapshot_purge_allowed is a list of all snapshot_ids with PurgeAllow=true
   snapshot_purge_allowed=`echo "$snapshot_tag_list" | grep .*PurgeAllow'\t'true | cut -f 3`

   for snapshot_id_evaluated in $snapshot_purge_allowed
   do
       #gets the "PurgeAfter" date which is in UTC with YYYY-MM-DD format (or %Y-%m-%d)
       purge_after_date=`echo "$snapshot_tag_list" | grep .*$snapshot_id_evaluated'\t'PurgeAfter.* | cut -f 5`
       #if purge_after_date is not set then we have a problem. Need to alter user.
       if [[ -z $purge_after_date ]]
           #Alerts user to the fact that a Snapshot was found with PurgeAllow=true but with no PurgeAfter date.
           then echo "A Snapshot with the Snapshot ID $snapshot_id_evaluated has the tag \"PurgeAllow=true\" but does not have a \"PurgeAfter=YYYY-MM-DD\" date. $app_name is unable to determine if $snapshot_id_evaluated should be purged." 1>&2 | mailx -s "Error happened 5" eric@mydomain.com
       else
           #convert both the date_current and purge_after_date into epoch time to allow for comparison
           date_current_epoch=`date -j -f "%Y-%m-%d" "$date_current" "+%s"`
           purge_after_date_epoch=`date -j -f "%Y-%m-%d" "$purge_after_date" "+%s"`
           #perform compparison - if $purge_after_date_epoch is a lower number than $date_current_epoch than the PurgeAfter date is earlier than the current date - and the snapshot can be safely removed
           if [[ $purge_after_date_epoch < $date_current_epoch ]]
               then
               echo "The snapshot \"$snapshot_id_evaluated\" with the Purge After date of $purge_after_date will be deleted."
               ec2-delete-snapshot --region $region $snapshot_id_evaluated
               echo "Old snapshots successfully deleted for $volumeid" | mailx -s "Old snapshots successfully deleted for $volumeid" eric@mydomain.com
           fi
       fi
   done
}

#calls prerequisitecheck function to ensure that all executables required for script execution are available
prerequisite_check

app_name=`basename $0`

#sets defaults
selection_method="volumeid"
region="ap-southeast-1"
#date_binary allows a user to set the "date" binary that is installed on their system and, therefore, the options that will be given to the date binary to perform date calculations
date_binary=""

#sets the "Name" tag set for a snapshot to false - using "Name" requires that ec2-create-tags be called in addition to ec2-create-snapshot
name_tag_create=false
#sets the Purge Snapshot feature to false - this feature will eventually allow the removal of snapshots that have a "PurgeAfter" tag that is earlier than current date
purge_snapshots=false
#handles options processing
while getopts :s:r:v:t:k:pn opt
   do
       case $opt in
           s) selection_method="$OPTARG";;
           r) region="$OPTARG";;
           v) volumeid="$OPTARG";;
           t) tag="$OPTARG";;
           k) purge_after_days="$OPTARG";;
           n) name_tag_create=true;;
           p) purge_snapshots=true;;
           *) echo "Error with Options Input. Cause of failure is most likely that an unsupported parameter was passed or a parameter was passed without a corresponding option." 1>&2 ; exit 64;;
       esac
   done

#sets date variable
date_current=`date -u +%Y-%m-%d`
#sets the PurgeAfter tag to the number of days that a snapshot should be retained
if [[ -n $purge_after_days ]]
   then
   #if the date_binary is not set, call the date_command_get function
   if [[ -z $date_binary ]]
       then date_command_get
   fi
   purge_after_date=`$date_command`
   echo "Snapshots taken by $app_name will be eligible for purging after the following date: $purge_after_date."
fi

#get_EBS_List gets a list of EBS instances for which a snapshot is desired. The list of EBS instances depends upon the selection_method that is provided by user input
get_EBS_List

#the loop below is called once for each volume in $ebs_backup_list - the currently selected EBS volume is passed in as "ebs_selected"
for ebs_selected in $ebs_backup_list
do
   ec2_snapshot_description="ec2ab_${ebs_selected}_$date_current"
   ec2_create_snapshot_result=`ec2-create-snapshot --region $region -d $ec2_snapshot_description $ebs_selected 2>&1`
   if [[ $? != 0 ]]
       then echo -e "An error occured when running ec2-create-snapshot. The error returned is below:\n$ec2_create_snapshot_result" 1>&2 ; exit 70
   else
       ec2_snapshot_resource_id=`echo "$ec2_create_snapshot_result" | cut -f 2`
       echo "Snapshots successfully created for volume $volumeid" | mailx -s "Snapshots successfully created for $volumeid" eric@mydomain.com
   fi  
   create_EBS_Snapshot_Tags
done

#if purge_snapshots is true, then run purge_EBS_Snapshots function
if $purge_snapshots
   then echo "Snapshot Purging is Starting Now."
   purge_EBS_Snapshots
fi

定時日誌

Oct 23 10:24:01 ip-10-130-153-227 CROND[28214]: (root) CMD (root (ec2-automate-backup.sh -v "vol-myvolumeid" -k 3;))
Oct 23 10:24:01 ip-10-130-153-227 CROND[28215]: (root) CMD (date  >> /root/logs/crontab.log;)
Oct 23 10:25:01 ip-10-130-153-227 CROND[28228]: (root) CMD (date  >> /root/logs/crontab.log;)
Oct 23 10:25:01 ip-10-130-153-227 CROND[28229]: (root) CMD (date >> /root/logs/crontab2.log)
Oct 23 10:26:01 ip-10-130-153-227 CROND[28239]: (root) CMD (date  >> /root/logs/crontab.log;)
Oct 23 10:27:01 ip-10-130-153-227 CROND[28247]: (root) CMD (root (ec2-automate-backup.sh -v "vol-myvolumeid" -k 3;))
Oct 23 10:27:01 ip-10-130-153-227 CROND[28248]: (root) CMD (date  >> /root/logs/crontab.log;)
Oct 23 10:28:01 ip-10-130-153-227 CROND[28263]: (root) CMD (date  >> /root/logs/crontab.log;)
Oct 23 10:29:01 ip-10-130-153-227 CROND[28275]: (root) CMD (date  >> /root/logs/crontab.log;)
Oct 23 10:30:01 ip-10-130-153-227 CROND[28292]: (root) CMD (root (ec2-automate-backup.sh -v "vol-myvolumeid" -k 3;))
Oct 23 10:30:01 ip-10-130-153-227 CROND[28293]: (root) CMD (date  >> /root/logs/crontab.log;)
Oct 23 10:30:01 ip-10-130-153-227 CROND[28294]: (root) CMD (date >> /root/logs/crontab2.log)
Oct 23 10:31:01 ip-10-130-153-227 CROND[28312]: (root) CMD (date  >> /root/logs/crontab.log;)
Oct 23 10:32:01 ip-10-130-153-227 CROND[28319]: (root) CMD (date  >> /root/logs/crontab.log;)
Oct 23 10:33:01 ip-10-130-153-227 CROND[28325]: (root) CMD (date  >> /root/logs/crontab.log;)
Oct 23 10:33:01 ip-10-130-153-227 CROND[28324]: (root) CMD (root (ec2-automate-backup.sh -v "vol-myvolumeid" -k 3;))
Oct 23 10:34:01 ip-10-130-153-227 CROND[28345]: (root) CMD (date  >> /root/logs/crontab.log;)
Oct 23 10:35:01 ip-10-130-153-227 CROND[28362]: (root) CMD (date  >> /root/logs/crontab.log;)
Oct 23 10:35:01 ip-10-130-153-227 CROND[28363]: (root) CMD (date >> /root/logs/crontab2.log)

發給根的郵件

From root@ip-10-130-153-227.ap-southeast-1.compute.internal  Tue Oct 23 06:00:01 2012
Return-Path: <root@ip-10-130-153-227.ap-southeast-1.compute.internal>
Date: Tue, 23 Oct 2012 06:00:01 GMT
From: root@ip-10-130-153-227.ap-southeast-1.compute.internal (Cron Daemon)
To: root@ip-10-130-153-227.ap-southeast-1.compute.internal
Subject: Cron <root@ip-10-130-153-227> root ec2-automate-backup.sh -v "vol-myvolumeid" -k 3
Content-Type: text/plain; charset=UTF-8
Auto-Submitted: auto-generated
X-Cron-Env: <SHELL=/bin/sh>
X-Cron-Env: <HOME=/root>
X-Cron-Env: <PATH=/usr/bin:/bin>
X-Cron-Env: <LOGNAME=root>
X-Cron-Env: <USER=root>
Status: R

/bin/sh: root: command not found

更新 顯然，undx 關於 cron 環境有限（x-cron-env）是正確的備份腳本位於 /usr/local/bin/ 中，它不包含在 x-cron-env 的 PATH 中。這為我打開了一個新的視野，因為我假設 cron 只是像執行腳本本身一樣執行 shell 腳本。現在讓 AWS CLI 工具與 cron 一起工作

正如 Colin Johnson 更新了他的劇本，正如你們中的一些人指出的那樣，我實際上沒有必要編輯這樣的劇本。我只需要正確使用它（正確理解 CRON 和一些 AWS CLI 工具）。對於像我這樣的業餘愛好者來說，嘗試改變像科林這樣的大師的精彩劇本也是沒有意義的。

從那以後，備份腳本一直很好地工作。向大家強烈推薦AWS Missing Tools 。

在預設的類 UNIX 系統上，cron 定義了一個最小環境。通常HOME, SHELL,LOGNAME被定義並PATH設置為/bin.

你有兩個解決方案：

  • 輸入腳本的完整路徑。IE：/home/me/bin/ec2-automate-backup.sh
  • 改變PATH環境變數。

如果您想從 cron 守護程序接收電子郵件，請定義該MAILTO變數。

MAILTO=me@example.org
PATH=/bin:/home/me/bin
*/5 * * * * ec2-automate-backup.sh -v "vol-fb2fbcdf" -k 3
# OR
*/5 * * * * /path/to/script/ec2-automate-backup.sh -v "vol-fb2fbcdf" -k 3

引用自：https://serverfault.com/questions/441281

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