A Technical I.T./DevOps Blog
Update on 11/20/20: We recommend you see How Do You Install the docker.service File on RHEL 8.x? instead of the directions below. (Many times this command will work: sudo yum -y install docker )
Update on 9/10/19: These directions below work to install Docker version 17.05.0-ce on RHEL 8.x.
These “directions” to install Docker on RedHat Enterprise Linux include a script and how to run it.
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Continue reading “How To Install Docker on an AWS Instance of RedHat Linux”
Updated 12/26/18
Problem scenario
You want to install Docker. You can make changes to the Ubuntu Linux repositories so you can use apt-get to install it. How do you install Docker on an AWS EC-2 instance?
Solution
There is an alternative set of directions if you click on this link here (if you would prefer not to configure the apt-get repositories). These directions below to install Docker on Ubuntu Linux include a script and how to run it (but the script below will make a change to the repositories that the Linux server uses).
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Continue reading “How To Install Docker on an AWS Instance of Ubuntu”
Question
What is TCP port 8080 typically used for?
Answer
Jenkins, Docker, NodeJS, Apache Ambari, Apache Marathon, Apache Tomcat, Amazon Web Services’ Elastic Load Balancer, JBoss Application Server, GitLab, M2MLogger (remote monitoring), InfoSphere BigInsights Console (IBM’s proprietary Hadoop and Spark solution), JasperReports (because of Apache Tomcat), remote management of physical routers, and enterprise network proxy services all commonly use port 8080.
In part, taken from Learning AWS,
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Continue reading “What is TCP port 8080 typically used for?”
Problem scenario: You are trying to upload a file to S3 but get an error. You use a command like this:
curl -T /path/to/sourcefile.java http://s3.amazonaws.com/my.bucket/sourcefile.java
You get an error in XML that includes “The specified key does not exist.”
Solution: Check the path to your source file. Verify your source file is there with the name you expect it to be.
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Continue reading “AWS S3 Problem: “The specified key does not exist.” How do you solve this?”
Problem scenario
You are trying to use Python Eve. You are using Python’s interactive command prompt, and you run these two commands:
from eve import Eve
app = Eve()
But you get this error:
“File “/usr/local/lib/python2.7/dist-packages/eve/flaskapp.py”, line 138, in __init__
self.validate_domain_struct()
File “/usr/local/lib/python2.7/dist-packages/eve/flaskapp.py”, line 269, in validate_domain_struct
raise ConfigException(‘DOMAIN dictionary missing or wrong.’)
eve.exceptions.ConfigException: DOMAIN dictionary missing or wrong.”
What should you do?
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Problem scenario
You want to move copies of all the files in a given subdirectory (we’ll say /tmp/a/ for an example) on a Docker host to go into a Docker container.
Solution
From the server use the command “docker ps” to find the container ID. Now that you have the container ID, you can write a script to move copies of the files into the Docker container.
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Continue reading “How Do You Copy Many Files from Your Linux Server into a Docker Container?”
Updated on 12/26/18
These directions show how to install Docker on SUSE Linux. These commands are for installing Docker 1.x on an AWS instance of SUSE 15. These directions require that your AWS SUSE Linux server is in a security group that has access to the internet. (If you want to see more directions for install Docker on different distributions of Linux in different public clouds, see this posting.)
Step #1
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Continue reading “How To Install Docker on an AWS Instance of SUSE Linux?”
Problem scenario: When someone uses a .pp file (either through a puppet agent call from a Puppet Agent node or via a puppet apply on a Puppet Master server), what order can a human DevOps Engineer expect the order to be?
Answer: The execution order of a given manifest is the top of the manifest is executed and Puppet works its way down from there. ContinualIntegration.com tested and verified this,
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Continue reading “What is the Order of Execution of a Puppet Manifest?”
Updated on 6/8/20
This version is the unabridged version. For the abridged version, you may click here.
Problem scenario
A Puppet manifest is not working, but there are no obvious error messages. When running the puppet agent command, you use the -d flag for debugging. In your manifest, you use logoutput => true stanza. But still, you cannot figure out why your manifest is not working.
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Problem scenario: Using Bash you want to compute kB, MB, and GB with decimal values. But you only seem to be able to do arithmetic on integer values.
Root cause: Bash does not support “float” arithmetic with values to the right of the period. Decimal values cannot be calculated.
Solution: Install the bc utility/language (e.g. yum -y install bc). It is often used in Bash to augment the numeric processing features.
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Continue reading “Doing Bash Arithmetic with Greater Precision than Integer Values”