A Technical I.T./DevOps Blog
Problem scenario: Some manifests kick off a non-Puppet script that has a long duration. By default the manifest will time out after 300 seconds. That means the manifest will not run properly if it cannot complete in five minutes. How do you run long-duration manifests?
Solution (Part 1 of 2): Use the timeout => directive. For example in the Puppet manifest, have a stanza like this:
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Problem scenario: On some servers you try this command: “apt-get -y install sar”, but this command does not work. On some servers with sar installed, you get an error when you run “sar”. The error says “Cannot open /var/log/sysstat/sa25: No such file or directory.”
Background: The sar utility comes from the acronym for system activity report. It is useful in performance tuning situations.
Solution: If you type “man sar” and get a man page,
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Continue reading “How Do You Get The sar Utility to Work On Ubuntu?”
Problem Scenario
You are writing a PowerShell script. You want to extract one value from the results of a command. You get a set of values all on one line. It is difficult to parse just what you need. The output values for each attribute are separated by spaces. Sometimes the output values are blank. You want to reliably extract one property value from the command. You know that piping the output to an “sls” command will retrieve an entire row.
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Problem scenario: You know how to assign variables in a Bash script. But how do you assign the output of a complex command such as this?
cat foo.txt | grep continual | grep integration | uniq
To push the output of some compound statement into a text file is simple. Sometimes you want to redirect everything to a variable. How do you do this?
Solution:
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Two problem scenarios and solutions.
Problem scenario: You installed Cloudera 5 (Hadoop) on CentOS 7.2 for the first time. You tried to start the Cloudera database service. But you get an error that it failed.
You run this: systemctl status cloudera-scm-server-db.service
The results include this fragment: ” … Failed to start LSB: Cloudera SCM Server’s Embedded DB.”
How do you start the Cloudera DB service?
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Continue reading “How Do You Configure Linux To Be Ready for Cloudera 5 (Hadoop)?”
Problem scenario: You try to mount a file share with this command:
mount continualintegration.com:/export/path/to /mnt
You get this error:
” mount: wrong fs type, bad option, bad superblock on continualintegration.com:/export/path/to,
missing codepage or helper program, or other error
(for several filesystems (e.g. nfs, cifs) you might
need a /sbin/mount.<type> helper program)
In some cases useful info is found in syslog – try dmesg | tail”
Solution:
#1
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Question: How do you see the exact time when previous commands were entered on a Linux server when you use the “history” command?
Background: Linux by default logs the time and day when commands were issued. (There is a limit to the number of previous commands that stay logged.) The timestamps by default are not visible.
Solution: For the session, until you log out,
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Continue reading “How Do You See The Time Previous Commands Were Entered On A Linux Server?”
Problem Scenario: You are using Puppet Master on Linux and Puppet Agent on Windows servers. The manifest attempts to copy to or from a Windows network file share, but you are getting an error about the network path not existing. The network file share has permissions that are open to Everyone. What do you do?
Solution: Puppet Agent will run PowerShell commands under the security context of the user who runs the “puppet agent -t -d” command.
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Continue reading “Puppet Needs To Use a Windows Network File Share: How Is This Done Consistently?”
Problem scenario: One Puppet manifest relies on another manifest to work. Trying to apply them at the same time is not working. The “require” and “before” keywords only seem to work for packages, exec, and file resources. What do you do to order the manifests to satisfy dependency requirements of other manifests?
Solution: The relationship dependency can be solved by the order in which they are applied.
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Background: Text-based browsers are fast. Operations can be scriptable and repeatable.
Question: How Do You Use a Text-Based Web Browser on RedHat Linux?
Prerequisites: You have access to the Internet and root access.
Solution: As root, enter these two commands (where “#” is the command prompt).
# yum-config-manager –enable rhui-REGION-rhel-server-extras rhui-REGION-rhel-server-optional
# yum -y install lynx
To test it out,
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Continue reading “How Do You Use a Text-Based Web Browser on RedHat Linux?”