Captain Codeman

Category: server-side

Access Firebase Database and Authenticated User Accounts Using Go

No Firebase Admin SDK for Go? No Problem ...

Firebase is great and makes serverless apps very easy to spin up but there’s always going to be times you need to access the Firebase data and / or user accounts from your server code (e.g. to sync accounts with a legacy system while we move to a Firebase auth enabled client).

There is an Official Admin SDK for Node.js, Java and Python but not all of them support user administration and poor Go doesn’t even get a mention (sad face).

But it turns out, we don’t need an official Firebase SDK for Go to be able to access the database and / or manage user accounts - all the packages to do it are already available and it’s very easy to use.

go golang firebase auth

How to access Firebase from Go ...

Golang Buffer Pool Gotcha

Because you might still be using that memory ...

We all know that Go is extremely fast and very easy to develop with but as with any managed language, it’s easy to inadvertently generate large quantities of garbage. No, I’m not talking about poorly written code (yeah, I’m guilty of that!) but garbage as in “memory that has to be reclaimed”. This is done via Garbage Collection and the GC in Go keeps getting faster with each release but you still want to avoid it when you can.

One common culprit is creating temporary buffers for things like rendering, encoding and compression so an easy fix is to re-use these buffers instead of creating new ones each time. There’s a sync.Pool in the standard library that can be used for this but there is a subtle “gotcha” which I’ll explain.


Read how to prevent it ...

Automatic HTTPS With Free SSL Certificates Using Go + Let's Encrypt

Adding SSL doesn't have to be complicated or expensive

If you’re still paying $$$’s for SSL certificates it may be time to look at Let’s Encrypt which describe themselves as “a free, automated and open certificate authority”.

SSL certificates are now effectively free.

Sounds too good to be true? Unless you need some fancy green-bar EV certificate there’s really no need to be paying for SSL certificates anymore. Especially now there is a Go package to support automatic certificate generation.

It turned out to be easier to setup the auto-certificate system than it was to renew a paid-for SSL certificate, here’s how …


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How Google Cloud Platform Trace Helps Optimization

Powerful insights into what your app is doing in the cloud

There are many challenges to understanding what our code is really doing at runtime:

  • The source code we work with is just a representation of the code that the compiler produces and which actually executes.
  • Systems are handling multiple requests at the same time.
  • Serving a request often relies on remote calls that our systems make to other services.
  • Systems are running in the cloud on virtual machines.

We can’t always just attach a debugger and step through our code unless it’s running locally. But when it’s running locally, it’s not really representative of the live system. The only way to see what the live system is doing is to instrument it.

Fortunately, Google provide a fantastic tracing tool for their cloud platform which can provide valuable insights into your application even when calls span multiple services.

Here’s an example of using it to optimize code.


Read more ...

Simple Service Bus / Message Queue with MongoDB

A service bus or message queue allow producers and subscribers to communicate asynchronously so that a system can handle disconnects, processes being stopped and started or enable peaks of demand to be handled beyond what the subscriber can immediately cope with. The queue acts as a buffer that the producer writes to and the subscriber reads from.

There are lots of implementations such as NServiceBus, MassTransit, Rhino Service Bus and the cloud-provided services such as Amazon’s Simple Queue Service and Window Azure’s AppFabric Service Bus. Some take a little time to get started with and the cloud ones can also rack up charges pretty quickly if you are doing too much polling.

Often, all that is needed is something fairly simple to buffer messages between processes and persist them. I’ve been making good use of MongoDB recently in conjunction with Jonathan Oliver’s EventStore library for a CQRS-based project so it seemed the obvious place to start – why not use MongoDB to store the queue?!


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Running ElasticSearch as a Service on Windows 2008 x64

I think I first started using Apache Lucene for full-text indexing as part of NHibernate Search. At some point I decided I needed more control and did my own indexing using Lucene directly. Now, it seems the easiest approach is to make use of a packaged up search service and so I’ve been looking at ElasticSearch. So far, I’m very happy with it – it’s doing everything it say’s on the box and lets me offload all the full-text indexing and search functionality.

The only issue I’ve come across is trying to run it as a service on 64-bit Windows 7 or Windows 2008. While there is a service-wrapper available it just wasn’t working for me and I think the x64 platform may be part of that as there was only a elasticsearch-windows-x86-32.exe included, no elasticsearch-windows-x86-64.exe. This service wrapper seems to be based off a product that doesn’t appear to have a free community edition for 64-bit Windows.

So, I had a hunt around for ‘how to run a Java app as a Windows Service’ and came across the Apache Commons Daemon or ‘procrun‘. This worked so I thought I’d share it here in case anyone else is trying to do the same thing.


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Absolute URLs using MVC (without extension methods)

Do you need to generate absolute URLs within your MVC application?

Often this will be in the form of URLs used outside of the web-browser such as those used within Atom Publishing Protocol collections or maybe links that are going to be sent out in emails. Basically, anything where the regular relative URL won’t do.

A quick search of Google will turn up a number of blog posts or forum answers showing how to do this by creating extension methods for the Url helper class but really, everything that is needed is already baked into the MVC framework already … and I’ve only just realized it after using it since the CTP releases!

mvc dotnet asp-net

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When to use RenderAction vs RenderPartial with ASP.NET MVC

dotnet mvc asp-net

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RenderSubAction alternative to RenderAction for Sub-Controllers in MVC

mvc dotnet asp-net

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