Dev switching for Nginx Reverse Proxy with cookies

I’m a fan of using Nginx as a reverse proxy, and I’ve now used it for multiple projects.

Essentially Nginx sits in front of multiple other web servers (Apache or other Nginx instances) and redirects traffic according to a series of simple rules.

There are numerous benefits, but one particular use case is proving very useful. This is the ability to switch between a production and dev website using cookies.

Here’s a broad example (note other proxy/server config instructions are omitted)…

server {
location / {
# By default, serve from the production server(s):
        proxy_pass https://production;
# If the special cookie appears in the request, redirect to the dev server:
        if ($http_cookie ~* "usedev31246") {
            proxy_pass https://development;
        }
}
# Special convenience URLs to enable/disable the cookies we need:
location /enable-dev {
    add_header Set-Cookie "usedev31246;Path=/;Max-Age=9999999";
    return 302 /;
}
location /disable-dev {
    add_header Set-Cookie "usedev31246;Path=/;Max-Age=0";
    return 302 /;
}
}

By default, a proxy connection will be made to the production server for all requests unless a cookie is provided in the request matching the string usedev31246, in which case it’ll be sent via the development server.

For convenience, any user can set the cookie by visiting /enable-dev (which will redirect back to the home page). They can clear it by visiting /disable-dev.

This means you can quickly help somebody get to the dev site by directing them to https://example.org/enable-dev

Of course, you probably don’t want anybody finding this so best to password protect and use a suitably secure cookie string, but I leave that as a challenge to the reader ūüėČ

This is quite nice for things like WordPress instances which tend to put the full URL in image and resource requests. By doing this, we don’t need to rewrite those URLs and worry about permalinks changing.

If you’re also using Nginx as a cache, beware as a user on the dev site might pollute/poison the cache with development code. Ensure the cache is disabled before dev requests are fulfilled (this is good practice anyway for a dev website).

Quarr Abbey, Goddards

Bit off-piste for my usual hunts, but this is from the Isle of Wight, so a local brew as well as a former stomping ground, and brewed in a Belgian “Dubbel” style.

Apparently, they don’t usually sell these in kegs, but the local shop had a supply so a 500ml “Crowler” was needed!

Can’t say I’m a huge fan of the beer on presentation. Weak, slightly metallic taste – hints of darker Belgian beers – creamy and chocolatey to taste. Just not quite meeting expectations. However, a bit disclaimer – that might well be down to the way it’s arrived (also worth noting this was near-end of stock). I’d be keen to try it again in bottled form and – being so close – a great opportunity to support local breweries.

Triple Secret des Moins

Light (in colour) blonde beer with a slight fermentation aftertaste. 8.0% … Aroma is a little sour on first impression, but the taste takes hold pretty quickly. It’s not a “bad” beer but I’m not fussed on finding it again.

Switching Virtual and Remote Desktops

If I’m using full-screen remote desktop in Windows 10, it can be handy to have my local computer on one virtual desktop, and the remote computer on another.

I usually turn off the title bar, so it’s a seamless experience.

Switching from local to remote is easy: Ctrl+Windows Key+Right Arrow

Switching back is more difficult, since the remote desktop will capture your keys.

Trick is to press Ctrl + Alt + Home first. This brings up the Remote Desktop title bar, which then means you can press Ctrl + Windows + Left to switch back.

Separators in multi-list in XSLT

Quick note: if inside an XSLT for-each loop and I need a separator, the following should be fine:

<xsl:if test="position() != 1">; </xsl:if> {...content...}

This will add the separator as a prefix before all but the first element.

IIS stops working after Windows 10 Fall Update

After installing the Fall Creators Update on Windows 10, IIS promptly stopped working.

In the event viewer, the following vague message appeared on various app pools:
The worker process for application pool 'DefaultAppPool' encountered an error 'Cannot read configuration file
' trying to read configuration data from file '\\?\', line number '0'. The data field contains the error code.

Ajeet Yelandur had a solution, and it works well:

Stop ‚ÄúWindows Process Activation Service‚ÄĚ and ‚ÄúW3SVC‚ÄĚ service and clean out (delete) all the files under C:\Inetpub\temp\AppPools*. Start your services and the sites should be back to work.

Thank you Ajeet!

(Posted here to help other searchers. It took me a while to find the solution amongst increasingly noisy Google results.)

Google Assistant on Nexus 5 and Nexus 7 (so close…)

I have an ageing Nexus 5 phone. I also have a Nexus 7 (2013) which – incidentally – has been the best tablet I’ve had at a fantastic price and I’m sorely disappointed they’re not making it any more. I digress.

On clicking the link, I get asked to open in Google Assistant… yes please!

Neither of these devices officially supports Google Assistant, the fancy chatbot/AI thing from Google, which is a shame as I do have a Google Home and quite like it.

Various articles online seem to suggest both devices are too old to be supported, which – if true – would be a shame but understandable given the age.

Strangely, it seems to be¬†almost there. It’s even ended up on my phone and tablet. If I click this link on either the phone or tablet (a Google I/O service) I am asked if I want to ‘open in Google Assistant. It seems that any clickable link (you have to click from an existing page) will open this if the URL begins https://assistant.google.com/services/a/

This is the resource opened in the native Google Assistant app on a Nexus 5

Not that I get far beyond that, but it’s interesting (and frustrating) to know that¬†somewhere beneath the surface and to some degree or other, Assistant is installed.

Compressing and Storing Time Correctly

After earlier work with DATETIME and indexes, I am still seeing some performance issues with storing logs with a full timestamp. Since a lot of the reporting is based on day-on-day and week-on-week comparisons, it could be more efficient to store the date and time components separately.

For my purposes, I’m using time to a resolution of about 15 minutes so there’s no real need to suffer the extra storage and performance overhead of working with a TIME field.

Instead, I’ve opted for a TINYINT with a value between 0-95 inclusive – one for every fifteen minutes of the day. Naturally, this is indexed.

The issue comes with how to convert time into these segments, and back again. Logically, 00:00 to 00:15 should be the first segment, but I have to be careful when reporting this back.

Technically if I’m quoting the range in a graph, there’s no problem. It’s between 00:00 and 00:15. If I’m forced to plot a point – say in a graph – the easiest solution would be to drop the dot at 00:00:00. The technically¬†most accurate¬†would be at 00:07:30.

That could be awfully messy, but it’s the midpoint of each range and better than¬†quoting a measurement (say, originally at 00:14:59.999999….) as 00:00:00 when it would clearly be better as 00:15:00.

In this case, I suspect simplicity prevails. Most normal people (i.e. not me) would be more comfortable seeing nice round numbers: 00:00, 00:15 and so on. Seeing 00:07:30, 00:22:30 and so on is likely to be unnecessarily confusing. Thankfully the incoming quality of data is not that precise, so nobody will scrutinise this.

Quoting the full range (00:00 Р00:15) would be more appropriate anyway, in tables and text reports.

Recent Movies

Some movies I’ve watched recently (and not so recently,¬†but recording for sake of reminder)

Captain Phillips
Inspired by an incident in 2009, this film follows the captain of the Maersk Alabama during a hijacking and subsequent hostage-taking. Great movie, very well portrayed. Highly recommended.

Hologram for the King
Another Tom Hanks film. This one’s a bit more laid-back and tells the story of a depressed, washed-up salesman in Saudi Arabia¬†trying to sell a videoconferencing system to the¬†government. Mostly enjoyable with light-hearted humour, but fairly slow-paced.

Sausage Party
Finally got round to watching this on New Year’s Eve. Very rude, crude and immature, but certainly not for kids. Entertaining enough, but I’m glad we waited for the price to drop before renting.

The Lobster
I saw this a few months ago on Netflix but worth remembering. Colin Farrell is wonderful in this odd, dark comedy about a hotel of sorts for helping people to find life partners in a world where – if you remain single – you turn into an animal. Bizarre, odd, and certainly not to everybody’s tastes, but I enjoyed it.

Fargo
Dark comedy set in Minnesota about a small town murder mystery and the people involved in it. A fair chunk of this movie is about the¬†location and the¬†relaxed nature of its population. Fun,¬†quirky and I’m interested in seeing¬†the TV series. On the other hand, it’s very slow-paced.

Tallulah
Appeared on Netflix a few months ago, so we gave it a watch. Decent enough movie and storyline with Ellen Page and Allison Janney. Warm, well-paced and interesting characters.

Austenland
Keri Russell is the American girl¬†looking for an authentic ‘Jane Austen” experience in an immersive themed vacation in England. I chose this from Netflix on a lazy day with low expectations. It wasn’t great, but¬†enjoyable enough.

Pride & Prejudice & Zombies
Somehow I thought this would be a good idea immediately after Austenland. Stopped it after about fifteen minutes. Maybe we’ll try again but it’s as silly as it sounds, and¬†wasn’t particularly engaging either.

Suicide Squad
Rambling and jumpy storyline, with no real background and character development. Good enough for some mindless action, but nothing captivating. On the plus side, soundtrack was great.

Jason Bourne
Something something Jason Bourne something something Treadstone. Bland and disappointing. The original was the only decent movie in this series.

London has Fallen
Gerard Butler saves the day again as London falls to a series of attacks. Lots of luck seems to help as well, but for mindless action this ticks all the boxes.

Gravity
Beautifully shot. Sandra Bullock gets attacked by bits of space debris. This film inspired me to download Kerbal Space Program. Can confirm Рspace is hard.

The Martian
Matt Damon recreates The Good Life in space, after his fellow crew members leave him on Mars following a tragic accident. Enjoyable and witty.

Independence Day: Resurgence
It’s hard to critique an alien movie for being unrealistic, but this movie manages it with a frankly stupid plot.¬†Will Smith added a charismatic element to the first film, which is sorely missing here.

The Secret Life of Pets
Annoying voiced creatures in a forgettable storyline. Watch the trailer to see all the funny bits.

Edge of Tomorrow
Tom Cruise and Emily Blunt on repeat. Quite a lot of fun. I enjoyed it.

Running Android apps in Chrome on Windows 10

Google has been working on a system for running Android apps on Chromebooks for a couple of years now. Since the underlying technology is roughly the same, it’s possible to run Android apps in Windows, using the Chrome browser as a host.

You will need the ARC Welder app from Chrome Web Store. I had to download this¬†twice for it to work. The first download was large (120Mb), presumably the runtime, and didn’t seem to install properly. On the second attempt it was a more modest 12Mb, and then worked fine.

Once the second attempt is complete, a new icon appears in the apps panel (available from chrome://apps )

When launched, the app requires an Android APK (packaged app) to work. I’ve been playing with a traffic management game in development called Traffic Lanes 3. The author publishes APKs as they continue¬†to grow the game,¬†which is perfect here.

As it happens, I find the editor tools on this game a bit fiddly on a tablet, and prefer a mouse. The developer has stated they have no plans to produce a desktop version, and frankly if ARC Welder continues to cover this gap there seems little point.