Category: Technology

Git Log

Git log can be used to get a quick summary of the differences between two branches. The three dots between the branch names indicates you want a “symmetric difference”. That is the set of commits that are in the branch on the left or the branch on the right but not in both branches.

The –left-right option prefixes each commit with an ‘<’ or ‘>’ indicating which “side” has the commit. The –oneline option prints the abbreviated commit ID and the first line of the commit message.

Showing the differences between your local uat branch and the remote uat branch:

D:\git\gittest>git log –left-right –oneline origin/uat…uat

> 961f53a (uat) Merge branch ‘ossa-123’ into uat

> 803096b (origin/ossa-123, ossa-123) Added additional files

> cf9c419 Added initial code to branch

The top line is the most recent commit, the bottom line is the oldest commit that does not exist in both branches. I can see that the uat branch in my local repo is not missing anything from the remote (there are no commits with “<” indicating changes in the remote that do not exist in my local copy) but I have local changes which have not yet been pushed: two code commits plus the merge commit which incorporated the code commits to my local repo’s uat branch. The head of the local and remote ossa-123 branch are at the commit just prior to the merge, so on my local repo that branch has been fully merged into UAT and I just need to push uat up to the remote.

Additional options to enhance output:

–cherry-pick will omit any changes that represent the same changes in both branches (or –cherry-mark to mark those commits with an “=” flag)

–graph uses an ASCII chart to depict branch relationships.

* The three dots mean something different in git diff than in git log. In git diff, mean “what are the differences between the right-hand branch and the common ancestor shared by both the right and left-hand branches”.

Two dots in git diff mean is the differences that are in the branch on the left or the branch on the right but not in both branches.

In git log, two dots displays only commits unique to the second branch. Since commits and differences are not exactly the same thing, two and three dots don’t exactly have the opposite meaning between diff and log. But the meaning is not logically consistent.

 

Postfix IPv6 Loopback Failure

I needed to send email messages from a PHP form, and the web server at work uses Postfix. So … I’m getting Postfix set up to relay mail for the first time in a decade or two 🙂 I thought I’d just have to edit /etc/postfix/main.cf and add “relayhost = [something.example.com]”.

Nope. The service fails to start with nothing particularly indicative — just a [FAILED] status from the init script. Attempting to start Postfix outside of the init script is far more informative:

[lisa@564240601ac2 init.d]# /usr/sbin/postfix start
postfix: fatal: parameter inet_interfaces: no local interface found for ::1

Turns out I’ve got to edit /etc/postfix/main.cf and tell it to use IPv4 only:

# Enable IPv4, and IPv6 if supported
inet_protocols = ipv4

 

Testing Procedural Code with PHPUnit

You can use PHPUnit to test procedural code — in this case, I’m testing the output of a website. I have some Selenium tests for UI components but wanted to use the shell executor for functional testing. In the test code, you can populate the _SERVER and _POST (or _GET) arrays and simulate the web environment.

<?php
    namespace phpUnitTests\CircuitSearch;
    class CircuitExportTest extends \PHPUnit_Framework_TestCase{
        private function _execute(array $paramsPost = array(), array $paramsServer = array() ) {
            $_POST = $paramsPost;
            $_SERVER = $paramsServer;
            ob_start();
            include "../../myWebSitePage.php";
            return ob_get_clean();
        }
        public function testUsageLogging(){
            $argsPost = array('strInput'=>'SearchValue', 'strReportFormat'=>'JSON');
            $argsServer = array("DOCUMENT_ROOT" => '/path/to/website/code/html/', "HOSTNAME" => getHostByName(),
                                "SERVER_ADDR" => getHostByName(php_uname('n')), "PWD" => '/path/to/website/code/html/subcomponent/path');
            $this->assertEquals('{}', $this->_execute($argsPost, $argsServer));
        }
    }
?>

Running the test, my web output is compared to the static string in assertEquals. In this case, I am searching for a non-existent item, nothing is returned, and I expect to get empty braces. I could use AssertsRegExp or or AssertsStringContainsString to verify the specifics of a real result set.

Docker for Windows: Using Built-in k8s

I just started using k8s built into Docker for Windows, but I couldn’t connect because the target machine actively refused the connection.

C:\Users\lisa>kubectl version
Client Version: version.Info{Major:"1", Minor:"14", GitVersion:"v1.14.6", GitCommit:"96fac5cd13a5dc064f7d9f4f23030a6aeface6cc", GitTreeState:"clean", BuildDate:"2019-08-19T11:13:49Z", GoVersion:"go1.12.9", Compiler:"gc", Platform:"windows/amd64"}
Unable to connect to the server: dial tcp [::1]:8080: connectex: No connection could be made because the target machine actively refused it.

No idea — it’s all internal traffic, but I resorted to turning off my firewall anyway just to see what would happen. Nothing. Turns out I need a KUBECONFIG environment variable pointing to the config file

C:\Users\lisa>set | grep KUB
KUBECONFIG=C:\Users\lisa.RUSHWORTH.000\.kube\config

Applied the yaml file and started the proxy

C:\Users\lisa>kubectl apply -f https://raw.githubusercontent.com/kubernetes/dashboard/v1.10.1/src/deploy/recommended/kubernetes-dashboard.yaml
secret/kubernetes-dashboard-certs created
serviceaccount/kubernetes-dashboard created
role.rbac.authorization.k8s.io/kubernetes-dashboard-minimal created
rolebinding.rbac.authorization.k8s.io/kubernetes-dashboard-minimal created
deployment.apps/kubernetes-dashboard created
service/kubernetes-dashboard created

C:\Users\lisa>kubectl proxy
Starting to serve on 127.0.0.1:8001

Working! Get the token from

kubectl -n kube-system describe secret default

And access the dashboard.

 

A reminder for myself — the totally not obvious package name for the kubeadm binary on the CHANGELOG link list is Node. Go figure!

Python f-strings

I’m accustomed to using variables directly in strings — most of my scripting experience was with Bash, Perl, and PHP. It’s something I have to think about when I would write Java or C++ code, and it’s one of the few things that struck me as a step backward in Python. This is basically the advantage that kwargs have over args, except changing a string common where changing a function definition is pretty rare.

I’ve taken to using the arg identifier numbers in the print statement.

>>> first=”Lisa”
>>> last=”Rushworth”
>>> print(“Hi {0}, you are {0} {1}.”.format(first, last))
Hi Lisa, you are Lisa Rushworth.

This allows me to append a new variable to the format argument list and use it anywhere in the string
>>> salutation=”Hello”
>>> print(“{2} {0}, you are {0} {1}.”.format(first, last, salutation))
Hello Lisa, you are Lisa Rushworth.

Python 3 introduced f-strings, which go beyond the functionality I was missing. You *can* use variable names within the string:

>>> print(f”{salutation} {first}, you are {first} {last}”)
Hello Lisa, you are Lisa Rushworth

You can have multi-line strings — notice that newlines aren’t being magically added. If you *want* newlines, add \n!

>>> strString = (
… f”{salutation} {first}, ”
… f”You are {first} {last} ”
… f”And I have more ”
… f”data down here”
… )
>>> print(strString)
Hello Lisa, You are Lisa Rushworth And I have more data down here

But you can also perform operations:
>>> print(f”{2 ** 3}”)
8

And use the f-string in classes
>>> class MyThing:
… def __init__(self, thing1, thing2, thing3):
… self.thing1 = thing1
… self.thing2 = thing2
… self.age = thing3
…
… def __str__(self):
… return f”{self.thing1} has 2 {self.thing2} and 3 {self.age}.”
…
>>>
>>> thingSample = MyThing(“Something1”, “Something2”, “Something3″)
>>> print(f”{thingSample}”)
Something1 has 2 Something2 and 3 Something3.

What if you need to have a literal curly brace?
>>> print(f”Hi {first}, this output needs a {{curly brace}}”)
Hi Lisa, this output needs a {curly brace}

VS Code Keyboard Shortcut: Commenting

We’ve been watching Microsoft’s Python programming course series — only the first couple so far, so it’s a lot of “yeah, knew that”. *But* there’s the occasional cool tip. You can comment line(s) of code with a keyboard shortcut:

Ctrl k,c comment current line (or selection)
Ctrl k,u uncomment current line (or selection)

 

Highlight the section of code that you want to comment out.

Hit ctrl-k and then ctrl-c … voila, a whole section of commented code. Denoting a comment is language specific, so this does not do anything if VS Code has not yet identified the language for your file.

To remove comments, use ctrl-k then ctrl-u. This works with code that already includes comments – you’ll get an additional comment in front of the commented line, and that additional comment will be removed leaving a commented line.

yEd: Item Alignment

I’ve been using yEd as a free not-quite-Visio, and happened across a feature that I love — as you move items around, little marks pop up when things are lined up and with multiple alignments? When they’re equidistant.

And once you have something lined up and equidistant, you can hold the shift key and drag the item to move it along one axis. In this case, I wanted the middle circle to be, well, in the middle. But I didn’t want it on the same horizontal line, so I was able to drag it up without losing the vertical spacing.

yEd Color Gradient

I don’t want to buy Visio — for one thing, I’m using it for work, and I don’t want to buy anything for work. But I don’t use Visio frequently enough to warrant paying for a license. I tried a few open source iterations with no success (OpenOffice Draw gave me the exact feeling I remember when trying to use the spreadsheet product — halfway there, but missing a LOT of features that are important to me). I happened across a free-but-not-open-source program called yEd. It’s got a basic shape gallery, I can draw lines between shapes, I can add labels to my lines and shapes. Perfect!

Their sample diagram, though, had a cool gradient effect. Not something I’m apt to use on a serious diagram … but I wanted to know how to achieve the same look. A lot of clicking later:

Select two nodes where the gradient starts. Select “Tools” => “Colorize Graph”. On the “General” tab, set “Highlight Feature” to “Graph Distance”. On the “Graph Distance” tab, ensure “Rainbow Interpolation” is unchecked. Pick your starting color, ending color, and a max distance (I used 250). Apply and you’ll have a vertical gradient across your document.

Certificate Generation Script

I finally put together a script that gathers some basic information (hostname & SAN’s) and creates a certificate signed against my CA. I’ve got a base myssl.cnf file that ends with

[ req_ext ]
subjectAltName = @alt_names

[ alt_names ]

The script appends all of the alternate names to the myssl.cnf file.

#!/bin/bash

RED_DARK='\033[38;5;196m'
GREEN_DARK='\033[38;5;35m'
BLUE_DARK='\033[38;5;57m'
NC='\033[0m' # Reset

function getInput {
        echo -e "${BLUE_DARK}Please input the short hostname you wish to use (e.g. server123):${NC}"
        read HOST

        echo -e "${BLUE_DARK}Please input the domain name you wish to use with this hostname (e.g. rushworth.us):${NC}"
        read DOMAIN

        echo -e "${GREEN_DARK}Please enter any SAN values for this certificate, separated by spaces (must be fully qualified):${NC}"
        read SANS

        FQHOST="${HOST}.${DOMAIN}"

        echo -e "Short hostname: $HOST"
        echo -e "Fully qualified hostname: $FQHOST"
        echo -e "SAN: $SANS"

        echo -e "${RED_DARK}Is this correct? (Y/N):${NC}"
        read boolCorrect

        if [ $boolCorrect == 'Y' ] || [ $boolCorrect == 'y' ]
        then
                mkdir $HOST
                echo $HOST
                cp myssl.cnf "./$HOST/myssl.cnf"

                cd "./$HOST"

                echo "The following SANs will be used on this certificate: "
                echo "DNS.1 = ${FQHOST}"
                echo "DNS.1 = ${FQHOST}" >> ./myssl.cnf
                echo "DNS.2 = ${HOST}"
                echo "DNS.2 = ${HOST}" >> ./myssl.cnf

                if [ -n "$SANS" ]
                then
                        SANARRAY=( $SANS )
                        iSANCounter=2
                        for SANITEM in "${SANARRAY[@]}" ; do
                                let iSANCounter=iSANCounter+1
                                echo "DNS.${iSANCounter} = ${SANITEM}"
                                echo "DNS.${iSANCounter} = ${SANITEM}" >> ./myssl.cnf
                        done
                fi
                export strCertKeyPassword=Wh1t2v2rP144w9rd
                export strPFXPassword=123abc456
                openssl genrsa -passout env:strCertKeyPassword -aes256 -out $FQHOST.passwd.key 2048
                openssl req -new -key $FQHOST.passwd.key -passin env:strCertKeyPassword -config ./myssl.cnf -reqexts req_ext -out $FQHOST.csr -subj "/C=US/ST=Ohio/L=Cleveland/O=Rushworth/OU=Home/CN=$FQHOST"
                openssl x509 -req -in $FQHOST.csr -passin env:strCertKeyPassword -extensions req_ext -extfile ./myssl.cnf -out $FQHOST.cer -days 365 -CA /ca/ca.cer -CAkey /ca/ca.key -sha256
                openssl rsa -in $FQHOST.passwd.key -out $FQHOST.key -passin pass:$strCertKeyPassword -passin env:strCertKeyPassword
                openssl pkcs12 -export -out $FQHOST.pfx -inkey $FQHOST.key -in $FQHOST.cer -passout env:strPFXPassword

        else
                getInput
        fi
}

getInput

There’s an encrypted private key and a non-encrypted private key. Because I have some Windows servers — Exchange and Active Directory — I create a PFX file too.