Connecting Phoenix app to MS SQL Azure database - sql-server

Question

I am trying to connect a phoenix application to MS SQL. After looking around online I came across a couple of adapters called mssql_ecto & mssqlex.
I have added them to the project following the instructions in the readme, installed odbc and checked that the db is online but I am now getting the following error..
[error] Mssqlex.Protocol (#PID<0.13069.0>) failed to connect: ** (Mssqlex.Error) odbc_not_started
My app is configured as below..
config :my_app, MyApp.Repo,
adapter: MssqlEcto,
username: "<my_username>",
password: "<my_password>",
database: "test",
hostname: "<my_server>.database.windows.net",
pool_size: 10
My environment is as follows..
MacOS Sierra 10.12.5
Elixir version: 1.4.4
There is an issue in the mssql_ecto repo already, and I have tried the suggestions from there, but it still has not worked.
If anyone has managed to connect their phoenix/elixir application to MSSQL on macOS and could provide some instructions it would be greatly appreciated (even if it was done in a completely different way to my approach 😉 ).
Side note: Tried it in node with the same db and was able to connect to and query the db.

Answer 1

I've been working through the same issue this week, connecting to an Azure SQL Database, and this is what I've got working.
You are seeing the first of 2 main problems I ran into:
Erlang installed without ODBC
Mssqlex adapter is missing required configuration options
#1: Erlang installed without ODBC
If you've installed Elixir and Erlang using brew, or something like it, you are getting an installation of Erlang that does not include erlang-odbc. In order to remedy this, you will need to install Erlang from source.
I recommend that you install both Erlang and Elixir from source using the method documented here:
http://www.lambdacat.com/how-to-install-elixir-on-mac/
Just make sure that you remove the Kerl option, --without-odbc, before you build Erlang.
Now that you have Erlang installed correctly, the odbc_not_started error should go away... to be replaced by connection errors to the database.
#2: Mssqlex adapter is missing required configuration options
As of this moment, the mssqlex adapter does not support the following configuration options that Azure is looking for:
Encrypt
TrustServerCertificate
Connection Timeout
To get around this issue, I forked the mssqlex library and added those options in a branch. I am not committing to maintaining this so feel free to fork it yourself.
In order to use the modified mssqlex, replace the mix dependency with the github location and branch name:
{:mssqlex, git: "https://github.com/tvanhouten/mssqlex.git", branch: "azure-settings", override: true}
The override: true is important because mssql_ecto has a dependency on the mssqlex version in hex.
Now you can update your configuration:
config :my_app, MyApp.Repo,
adapter: MssqlEcto,
username: "<my_username>",
password: "<my_password>",
database: "test",
hostname: "<my_server>.database.windows.net",
pool_size: 10,
encrypt: "yes",
trust_server_certificate: "no",
connection_timeout: "30
Other "Gotchas" to Look Out For
Azure requires TCP connection:
In order to connect to an Azure SQL Database, you will need to make sure that the hostname: option starts with tcp:. So, all together, it will look like
hostname: "tcp:.database.windows.net"
Mssql_ecto does not support Ecto 2.2+:
If you're getting errors related to Ecto or Ecto.SubQuery, you probably need to make sure that you are using a version of Ecto that is supported by mssql_ecto. At this point in time, that means Ecto 2.1.x. Again, this requires a slight change to your mix dependencies:
{:ecto, ">= 2.1.0 and < 2.2.0"}
Dependency cache and lock issues:
If everything seems to be in order according to the above but it just doesn't seem like the new dependencies are being updated and compiled as expected, do the following:
Run mix deps.clean --all
Delete the mix.lock file from your root project directory
Run mix deps.get
Run mix deps.compile
That should do it!