Attaching Databases To Docker

Andrew Pruski shows one scenario where Docker on Windows is better than Docker on Linux:

One of the (if not the) main benefits of working with SQL in a container is that you can create a custom image to build container from that has all of your development databases available as soon as the container comes online.

This is really simple to do with Windows containers. Say I want to attach DatabaseA that has one data file (DatabaseA.mdf) and a log file (DatabaseA_log.ldf): –

ENV attach_dbs="[{'dbName':'DatabaseA','dbFiles':['C:\\SQLServer\\DatabaseA.mdf','C:\\SQLServer\\DatabaseA_log.ldf']}]"

Nice and simple! One line of code and any containers spun up from the image this dockerfile creates will have DatabaseA ready to go.

However this functionality is not available when working with Linux containers. Currently you cannot use an environment variable to attach a database to a SQL instance running in a Linux container.

Read on to see what you can do if you’re using a Linux container.

PSSDIAG On Linux

Denzil Ribeiro shows how to use PSSDIAG on a SQL Server on Linux installation:

When analyzing SQL Server performance related issues, customers often have their tools of choice, which can be a feature within the product, a third-party performance monitoring tool, or a home-grown tool that assists in monitoring live performance. For live monitoring, in the SQLCAT lab we use a home grown tool described in this blog. However, when our customers have a performance issue, we, just like support engineers and consultants, can’t always have them ship their third-party tools or associated data, and hence need a way to collect performance related data for post mortem analysis.

PSSDIAG is a popular tool used by Microsoft SQL Server support engineers to collect system data and troubleshoot performance issues. This is a well-known tool for SQL Server on Windows, and we needed equivalent functionality on Linux. PSSDIAG data collection for Linux is now available here. It is a set of bash scripts that collect all the necessary data for troubleshooting performance problems, similar to PSSDiag on Windows.

I haven’t used PSSDIAG outside of a support scenario, but it’s definitely good to know that this is available on Linux.

Backing Up That Linux-Based Database

David Klee shows how to back up a SQL Server on Linux database over the network:

As of SQL Server 2017 RC2, we’ll want to accomplish it in a way that is transparent to SQL Server. (Depending on the RTM version whenever it is released, I might change the recommendation on this.) To do this, we’ll want to create a folder on the local file system that actually maps to a remote network share for SQL Server backups.

SSH into your server without elevated privileges at this point.

The network share is presented from a Windows server with the SMB protocol. Linux can connect to this using a compatible protocol called CIFS, or Common Internet File System. We’ll need to install the packages so we can natively connect. On Ubuntu and other Linux distros, the easiest is with the cifs-utils package. To install from the package manager is as simple as this.

Sadly, that credentials file cannot be encrypted.

Auto-Install Docker And SQL Tools On Linux

Andrew Pruski has a script on GitHub:

So I’ve created a repository on GitHub that pulls together the code from Docker to install the Community Edition and the code from Microsoft to install the SQL command line tools.

The steps it performs are: –

  • Installs the Docker Community Edition

  • Installs the SQL Server command line tools

  • Pulls the latest SQL Server on Linux image from the Docker Hub

Read on for more details and some limitations.

SQL Server 2017 RC2

Microsoft has announced Release Candidate 2 of SQL Server 2017, hot on the heels of RC1:

Microsoft is pleased to announce availability of SQL Server 2017 Release Candidate 2 (RC2), which is now available for download.

The release candidate represents an important milestone for SQL Server.  Development of the new version of SQL Server along most dimensions needed to bring the industry-leading performance and security of SQL Server to Windows, Linux, and Docker containers is complete.  We are continuing to work on performance and stress testing of SQL Server 2017 to get it ready for your most demanding Tier 1 workloads, as well as some final bug fixes.

There are no new features and the Windows release notes are empty, but there are some Linux release notes as they firm up that offering before launch.

Resizing A Linux Partition

Steve Jones shows how to add disk space to a Linux partition:

While working with some SQL Server 2017 tests, I ran out of disk space. I tend to size my VMs around 40GB, and that works for some things, but I’ll run out of space.

I needed to expand the VMWare disk. That doesn’t mean Linux sees the space directly, and I had to figure out how to make the partition bigger. I could have added another disk, but I wanted to work through this process. I learned I needed to have an inactive partition, so I download gparted on a live cd and booted to that.

Steve uses the GUI approach; in the comments, David Klee links to his CLI approach.

Moving TempDB In Linux

David Klee shows how to migrate the tempdb database when running SQL Server on Linux:

We previously created a folder at /var/opt/mssql/data/tempdb01 for these files. Moving them is straightforward, once you know the file system structure. The following commands will move them to the new location, and I also add additional files to equal the four vCPUs I have on this SQL Server VM. The file growth is my model database’s default of 64MB for this instance. Do as you would normally do with SQL Server on Windows with tempdb file counts and separation of duties for your workload.

Read on for the process.  As a general spoiler, the “how to do this in Linux” answer is usually pretty close to the same as the “how to do this in Windows” answer, at least once you get into Management Studio.

Managing Drives On Linux

David Klee walks through some basics of Linux administration with respect to drives and mountpoints:

We see that all four of the drives show up in the list. Because of the nature of how I presented the disks to the VM, the bootable drives (sdd) show up at the end of the chain instead of the beginning, but that’s OK. It doesn’t change how the disks are bootable.

We are going to use the Logical Volume Manager (LVM) to manage the disks for us instead of using regular partitions. On Windows-based servers, Windows has the ability to expand partitions without incurring any downtime, and we want to have the same flexibility from a Linux standpoint. With elevated priviledges (for the rest of the commands), let’s scan the drives to look at what it sees.

Read the whole thing.

Linux Containers On Windows

Andrew Pruski shows how to run Linux-based Docker containers on Windows:

This post is a step-by-step guide to getting Linux containers running on your Windows 10 machine. The first thing to do is install the Docker Engine.

Installing Docker on Windows 10 is different than installing on Windows Server 2016, you’ll need to grab the Community Edition installer from the Docker Store.

Once installed, you’ll then need to switch the engine from Windows Container to Linux Containers by right-clicking the Docker icon in the taskbar and selecting “Switch to Linux Containers…”

Andrew walks us through step by step, so check it out.

Using SMO On Linux

Richie Lee explains how to get the SQL Tool Service running on Linux:

So, to briefly sum up, to use SMO on Linux, you need to do the following:

  • Install .NET Core 2.0
  • Install PowerShell beta 2
  • Install SQL Tool Service

You can use PowerShell from the Terminal, but I prefer something like an IDE so this is optional:

  • Download Visual Studio Code

  • Install PowerShell plugin

  • Change settings file to point explicitly to PowerShell beta 2.

Read the whole thing.

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