How Nginx computes the ETag header for files.

Curious how the ETag: header is generated in Nginx?

Turns out it's a combination of the last modified time and the content length:

etag->value.len = ngx_sprintf(etag->value.data, "\"%xT-%xO\"",
                                  r->headers_out.last_modified_time,
                                  r->headers_out.content_length_n)
                      - etag->value.data;

You can determine the last modified time in hex by using this Unix line:

printf "%x" $(stat -c%Y <file>)

The content length is determined here:

stat --format="%s" <file>

Implementing Splunk SSO with Google Apps

Trying to setup Splunk with Google Apps authentication?

1. You can download a reverse proxy module for Nginx released by Bit.ly's engineering team. It requires installing Go (apt-get install go). You can compile it by typing go build, and the binary should be built.  The download link is listed below:

https://github.com/bitly/google_auth_proxy

The instructions in the README walk you through what you need to do to setup with Google's API console. Since Google is phasing out OpenID support, using Google Oauth is now the expected way to authenticate.

To start running the proxy, you'll need the accepted Google Apps domain, the callback URL (should end with /oauth2/callback), client ID, and client secret from the Google API console.

./google_auth_proxy -cookie-domain=mydomain.com -cookie-secret=abcd -google-apps-domain=googleappsdomain.com -http-address=127.0.0.1:4180 -redirect-url=http://myhost.com/oauth2/callback -upstream=http://www.cnn.com --client-id=1234.apps.googleusercontent.com --client-secret=1234

2. Setup your Nginx configuration to reverse proxy to 4180:

server {
  listen 80;

  location / {
      proxy_pass http://127.0.0.1:4180;
      proxy_set_header Host $host;
      proxy_set_header X-Real-IP $remote_addr;
      proxy_set_header X-Scheme $scheme;
      proxy_connect_timeout 1;
      proxy_send_timeout 30;
      proxy_read_timeout 30;
  }
}

3. Next, you'll have to setup your configuration in etc/system/local/web.conf with this config. The goal is to use the email address used during login, which gets passed as X-Forwarded-Email, to Splunk. SSOMode set to strict will require all logins to depend on this header.  The tools.proxy.on seems to be used for older Apache reverse proxy setups, but doesn't need to be used for this setup.

SSOMode = strict
trustedIP = 127.0.0.1
remoteUser = X-Forwarded-Email
tools.proxy.on = False

4. Before you restart Splunk, make sure to create your usernames as the email address.  If you need to rename your existing ones, you'll need to edit the Splunk etc/passwd entries manually.

5. Once you restart, Splunk provides a /debug/sso endpoint, which lets you verify that the X-Forwarded-Email is being set correctly.   If you have any issues, turn off SSOMode = permissive until your are confident that the reverse proxy is setup correctly.

Why do you need colons for gesture recognizers

Apparently stuff that interacts with Objective C API's needs them..

http://stackoverflow.com/questions/24007650/selector-in-swift

https://developer.apple.com/library/ios/documentation/Swift/Conceptual/BuildingCocoaApps/InteractingWithObjective-CAPIs.html#//apple_ref/doc/uid/TP40014216-CH4-XID_26

What does the parenthesis in Swift does..

http://stackoverflow.com/questions/24071334/blocks-on-swift-animatewithdurationanimationscompletion

The completion parameter in animateWithDuration takes a block which takes one boolean parameter. In swift, like in Obj C blocks, you must specify the parameters that a closure takes:

UIView.animateWithDuration(0.2, animations: {
    self.blurBg.alpha = 1
}, completion: {
    (value: Bool) in
    self.blurBg.hidden = true
})

The important part here is the (value: Bool) in. That tells the compiler that this closure takes a Bool labeled 'value' and returns void.

For reference, if you wanted to write a closure that returned a bool the syntax would be

{(value: Bool) -> bool in
    //your stuff
}

pip lxml fails

Not sure when these errors started showing up for lxml, but pip install lxml started failing without disabling these CLANG options:

export CFLAGS=-Qunused-arguments
export CPPFLAGS=-Qunused-arguments

Internet Explorer 10's new compatibility view list

LinkedIn is listed as Emulate-IE9, which explains why anyone logging in via LinkedIn authentication has a User-Agent string that denotes IE9 even though they may have a later IE version.

https://community.mcafee.com/thread/58177?start=0&tstart=0

http://iecvlist.microsoft.com/IE10/1152921505002013023/iecompatviewlist.xml

Why themes are not taken into account when using custom ArrayAdapters..

While trying to implement basic extensions of ArrayAdapter with a ListView (see
https://github.com/thecodepath/android_guides/wiki/Using-an-ArrayAdapter-with-ListView), I noticed none of the themes that I used was being followed by the adapter:

   if (convertView == null) {
          convertView = LayoutInflater.from(getContext()).inflate(R.layout.item_user, parent, false);
       }

It turns out that the use of getContext() matters a lot.  I found that if I used parent.getContext(), the styles do get applied.

   if (convertView == null) {
          convertView = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_user, parent, false);
       }

Here is more background of why getContext() use matters..

http://www.doubleencore.com/2013/06/context/

The less obvious issue is inflating layouts. If you read my last piece on layout inflation, you already know that it can be a slightly mysterious process with some hidden behaviors; using the right Context is linked to another one of those behaviors. While the framework will not complain and will return a perfectly good view hierarchy from a LayoutInflater created with the application context, the themes and styles from your app will not be considered in the process. This is because Activity is the only Context on which the themes defined in your manifest are actually attached. Any other instance will use the system default theme to inflate your views, leading to a display output you probably didn’t expect.