A Technical I.T./DevOps Blog
Problem scenario
You are trying to run a pip command. But you get “/bin/python3.7: bad interpreter: Permission denied”. What should you do about these “bad interpreter” errors in response to having run pip commands?
Solution
Use “sudo” before the pip command. It should allow you to run the pip command. You may need to be a different user or obtain sudoer rights.
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Problem scenario
You want to list the Route Tables in your AWS account (under VPC). You are using Python and Boto3. What should you do?
Solution
Run this program with Python 3:
import boto3
ec2 = boto3.client(‘ec2’)
rts = ec2.describe_route_tables()
print(rts) …
Continue reading “How Do You Use Python and Boto3 to List VPC Route Tables?”
Problem scenario
You have found an AWS CLI command that shows you output consistent with the console. You run this:
aws ec2 describe-vpc-peering-connection –region us-west-2 | grep pcx-abcd1234
The results show you a peering connection called pcx-abcd1234
You run this from a Python3 interpreter prompt:
import boto3
foo = boto3.resource(‘ec2’)
foo.describe_vpc_peering.connections()
print(foo)
You then search the output for pcx-abcd1234. You do not see it.
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Continue reading “Why Would Boto3 Not Show a Peering Connection That the AWS CLI Shows?”
Problem scenario
You try to install the AWS CLI version 2.x
You run this command:
$ sudo python3 setup.py install
You get a message like this:
Processing dependencies for awscli==2.0.7
Searching for botocore==2.0.0dev11
Reading https://pypi.org/simple/botocore/
No local packages or working download links found for botocore==2.0.0dev11
error: Could not find suitable distribution for Requirement.parse(‘botocore==2.0.0dev11’)
What should you do?
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Problem scenario
You want to install Django and have it working for browsing from a desktop workstation. You do not want to leverage Django’s API functionality. How do you install and configure Django from scratch?
Prerequisite
pip3 is probably installed. If you are not sure, you could run this: sudo find / -name pip3
You must have pip or pip3 installed.
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Continue reading “How Do You Install Django on a CentOS/RHEL/Fedora server?”
Problem scenario
You are running a Python program that uses “import json”. You get this error: “json.decoder.JSONDecode..”Expecting property name enclosed in double quotes…” You are not allowed to use bson, but you can use other Python packages. What should you do?
Solution
This solution only works if you can eliminate single quotes in the content to be serialized (or translated into JSON).
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Problem scenario
Your Python program is trying to invoke a Bash command. But you get an error like this: “FileNotFoundError: [Errno 2] No such file or directory”. What should you do?
Possible Solution #1 Use the shell=True command if your environment is secure. This is not a recommended practice from a security perspective. We have found that this with shell=True syntax can make the error go away:
subprocess.Popen(variableofcommand,
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Problem scenario
You have some JSON files like this:
$cat first.json
{“bird”: {“name”: “singy”, “species”: “sparrow”, “amount”: “45”}}
$ cat second.json
{“bird”: {“name”: “flighty”, “species”: “seagull”, “amount”: “21”}}
Within the “bird” key there are other keys. How do you create a tuple with the species values?
Solution
Place first.json, second.json and the Python program below (called reader.py) in the same directory.
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Problem scenario
You want to list all the VPC Peering Connections for a specific region using Python.
You want the equivalent of aws ec2 describe-vpc-peering-connections
How do you show (retrieve or fetch) the VPC peering connections using Boto3?
Solution
import boto3
contint = boto3.client(‘ec2’)
var1 = contint.describe_vpc_peering_connections()
print(var1) …
Continue reading “How Do You Display the VPC Peering Connections with Boto3?”
Problem scenario
You want to write a program to call a bound function in a new thread. How do you do this?
Solution
Run this program (e.g., python foobar.py):
from threading import Thread
class mighty:
def good():
print(“Good”)
def contint():
print(“Hello!”)
if __name__ == “__main__”:
thread = Thread(mighty.good())
thread.start()
thread.join()
print(“thread finished…exiting”) …