devstack on centos7 on virtualbox

when trying to install devstack on centos7 on virtualbox, you may run into an error about "Could not determine host IP address".

a workaround for this is;
- open stackrc
- find HOST_IP
- change it to read HOST_IP=${HOST_IP:-10.0.2.15}

and you're off!

https://bugs.launchpad.net/devstack/+bug/1644145/comments/4

Java to .Net - REST APIs and Controllers - Some notes

some quick notes about using .NET Core controllers in C#;
- the url maps to the name of the controller class

so, class BlahController : Controller will create a URL of /blah

Agile - User Stories

i'm going to try and capture some points about user stories here as a rough guide;

- a user has a context --> always understand the persona, entering context, and exit context of a user.  "User A is an anonymous user of the site.  We know nothing about them when the first enter but we want to at least identify them when they leave."  "User B is an admin of the site, we know who they should be and once they leave, we want to know what they've done."

- a story should be simple --> "as User A, I want to do x, and have y at the end".

- big stories can become epics really quick --> "as a Known User, I want to login and see my dashboard".  This is an epic because there's authentication stories, ("as a Known user, I want to enter my username and password and be granted access/shown an error"), there's setting the authentication (2FA? administration? etc.) and then there's the last, dashboard.

- a simple user story --> "as an Anonymous User, I want to send a contact request and get a contact request receipt"

- every story should have an acceptance criteria and/or definition of done --> "... and get a contact request receipt"

References 

https://www.alexandercowan.com/best-agile-user-story/#Creating_a_User_Story
https://www.scrumalliance.org/community/articles/2014/march/stories-versus-themes-versus-epics

Forwarding Ports with IPTables

to use IPTables to forward ports...

iptables -t nat -A PREROUTING -p tcp --dport 80 -j REDIRECT --to-port 8080

all this from http://richardfergie.com/redirect-port-80-to-a-different-port-using-iptables

and how to remove the routing

iptables -t nat --line-numbers -L
iptables -t nat -D PREROUTING [number]

Using the Docker Embedded DNS

this is an easy way I just discovered and am noting it here so I don't forget.

to leverage docker's embedded dns, you can setup a custom network and then each container can resolve to each other via the 'name' attribute.

for example;

1. docker network create internaldns
2. docker run --name rmq -p 15672:15672 --net=internaldns -d rabbitmq:management
3. docker run --name httpcontainer -p 8080:8080 --net=internaldns -d scbs/http-rmq

this gives you;
- ability to connect to the host network via bridge
- ability to have httpcontainer look up the rabbitmq container using the dns entry 'rmq'

i love weave.works and think weave net is particularly awesome, but if you're just doing dns lookup on 1 docker host, this seems pretty light and easy

NativeScript WebView - Getting the HTML Content

If you're trying to get the content from a NativeScript WebView, try the following from StackOverflow

if (webView.ios) {
    var webHeader = webView.ios.stringByEvaluatingJavaScriptFromString("document.head.innerHTML").trim();
    console.log(webHeader);

    var webBody = webView.ios.stringByEvaluatingJavaScriptFromString("document.body.innerHTML").trim();
    console.log(webBody);

} else if (webView.android) {
    webTitle = webView.android.getTitle(); //getting the title title
    console.log(webTitle)
}

http://stackoverflow.com/questions/40639473/get-content-of-webview-in-nativescript

Docker on Ubuntu: http:///var/run/docker.sock/v1.18/containers/json: dial unix /var/run/docker.sock: permission denied

after installing 1.12.3 on Ubuntu 16.04, the permission denied issue came up.  after trying the docker group settings without any luck, the only thing left was to actually chmod the socket.

chmod 777 /var/run/docker.sock

and everything works

probably not the wisest thing to do and you can try chmod'ing with more restrictions, but after hours of google and frustration, it works.

Get the Guest IP Address for a VM in VMWare Fusion

Great little trick from here...

/Applications/VMware\ Fusion.app/Contents/Library vmrun getGuestIPAddress [location of your VM's .vmx]

Jenkins on Docker - Admin Password

try this from the comments on hub.docker.com --> full credit to sidmalani

docker exec -it jenkins_test cat /var/jenkins_home/secrets/initialAdminPassword

Docker Remote API and Docker for Mac

How to get the HTTP API on Docker for Mac

a fantastic tutorial and helper for setting up HTTP access to docker on mac

https://www.ivankrizsan.se/2016/05/21/docker-api-over-http-on-mac-os-x-with-docker-for-mac-beta/