{"id":72,"date":"2018-03-27T06:48:21","date_gmt":"2018-03-27T06:48:21","guid":{"rendered":"https:\/\/blogs-staging.imperial.ac.uk\/research-software-engineering\/?p=72"},"modified":"2019-06-11T12:38:54","modified_gmt":"2019-06-11T12:38:54","slug":"cloud-first-rapid-webapp-deployment-using-containers","status":"publish","type":"post","link":"https:\/\/blogs-staging.imperial.ac.uk\/research-software-engineering\/2018\/03\/27\/cloud-first-rapid-webapp-deployment-using-containers\/","title":{"rendered":"Cloud-first: Rapid webapp deployment using containers"},"content":{"rendered":"

This is the second in a series of posts<\/a> describing activities funded by our RSE Cloud Computing Award<\/a>. We are exploring the use of selected Microsoft Azure<\/a> services to accelerate the delivery of RSE projects via a cloud-first approach.<\/em><\/p>\n

In our previous post<\/a> we described the deployment of a fairly typical web application to the cloud, using an Azure Virtual Machine in place of an on-premise server. Such VMs offer familiarity and a great deal of flexibility, but require initial provisioning followed by ongoing maintenance and monitoring. Our team<\/a> at Imperial College is increasingly using containers to package applications and their dependencies, using Docker images as our unit of deployment. Can we do better than provisioning servers on a case-by-case basis to get web applications into production, and thereby more rapidly deliver services to our users?<\/p>\n

The Azure App Service<\/a>\u00a0provides a solution named\u00a0Web App for Containers<\/a>, which essentially allows you to deploy a container directly without provisioning a VM. It handles updates to the underlying OS, load balancing and scaling. In this post we’ll demonstrate how to run pre-built and custom Docker images on Azure, without having to manually configure any OS or container runtime. As previously, we’ll use the Azure Cloud Shell<\/a>, and arguments that you’ll want to set yourself are highlighted in bold<\/strong>.<\/p>\n

Getting started<\/strong><\/h3>\n

First of all we create an App Service plan. This only needs to be performed once for your active subscription:<\/p>\n

az group create --name myResourceGroup --location \"West Europe\"<\/pre>\n
az appservice plan create --name myAppServicePlan --resource-group myResourceGroup --sku S1 --is-linux<\/pre>\n
Deploying a pre-built, public container image<\/strong><\/h3>\n
It’s then just one command to run a Docker container. In this case we’ll deploy Nginx<\/a>\u00a0using its Docker Hub image<\/a>:<\/p>\n
az webapp create --resource-group myResourceGroup --plan myAppServicePlan --name ic-nginx<\/strong> --deployment-container-image-name nginx<\/pre>\n
We can then visit our public site at https:\/\/ic-nginx<\/strong>.azurewebsites.net\/<\/a><\/p>\n
You can use a custom DNS name by following these further instructions<\/a>.\u00a0Note that the site automatically has HTTPS enabled.<\/p>\n
Decommissioning the webapp (thereby avoiding any further charges) is similarly straightforward:<\/p>\n
az webapp delete --resource-group myResourceGroup --name ic-nginx<\/strong><\/pre>\n
Deploying a custom container image<\/strong><\/h3>\n
Running your own app is as simple as providing a valid container identifier to az webapp create.\u00a0 This can point to either a public or private image on Docker Hub or any other container registry, including Azure’s native registry.<\/span><\/span><\/p>\n
For demonstration purposes we’ll build a Datasette<\/a>\u00a0image to publish the UK responses from the 2017 RSE Survey<\/a>. Datasette is a great tool for automatically converting an SQLite database to a public website, providing not only a means to browse and query the data (including query bookmarking) but also an API for programmatic access to the underyling data. It has a sister tool,\u00a0csvs-to-sqlite, that takes CSV files and produces a suitable SQLite file.<\/p>\n
First we need to install both tools, download the survey data, and convert it from CSV to SQLite:<\/p>\n
pip install https:\/\/github.com\/simonw\/csvs-to-sqlite\/zipball\/master datasette<\/pre>\n
curl -O https:\/\/raw.githubusercontent.com\/softwaresaved\/international-survey\/master\/analysis\/2017\/uk\/data\/cleaned_data.csv<\/pre>\n
csvs-to-sqlite --table responses cleaned_data.csv uk-rse-survey-2017.db<\/pre>\n
Then we can create a Docker image containing the data and the Datasette app with one command, annotating with the appropriate licence information:<\/p>\n
datasette package uk-rse-survey-2017.db\r\n--tag mwoodbri\/uk-rse-survey:2017\r\n--title \"UK RSE Survey (2017)\"\r\n--license \"Attribution 2.5 UK: Scotland (CC BY 2.5 SCOTLAND)\"\r\n--license_url \"https:\/\/creativecommons.org\/licenses\/by\/2.5\/scotland\/deed.en_GB\"\r\n--source \"The University of Edinburgh on behalf of the Software Sustainability Institute\"\r\n--source_url \"https:\/\/github.com\/softwaresaved\/international-survey\"<\/pre>\n
Then we push the image to Docker Hub:<\/p>\n
docker push mwoodbri<\/strong>\/uk-rse-survey:2017<\/pre>\n
And, as previously, create an Azure Web App:<\/p>\n
az webapp create --resource-group myResourceGroup --plan myAppServicePlan --name rse-survey<\/strong> --deployment-container-image-name mwoodbri<\/strong>\/uk-rse-survey:2017<\/pre>\n
Using Datasette<\/strong><\/h3>\n
After a brief delay the app is publicly available: https:\/\/rse-survey<\/strong>.azurewebsites.net\/<\/a><\/p>\n
Note that the App Service automatically detects the right port to expose (8001 in this case) and maps it to port 80.<\/p>\n
Datasette enables you to run and bookmark SQL queries, for example this query<\/a> which lists the contributors’ organisations in order of the\u00a0number of responses received:<\/p>\n
\"\"<\/a><\/p>\n
Private registries<\/strong><\/h3>\n
If you’re hosting your images on a publicly accessible that requires authentication then you can use the previous az webapp create<\/span> command into two steps: one to create the app and then to assign the relevant image. In this case we’ll use the Azure Container Registry<\/a>\u00a0but this approach is compatible with any Docker Hub compatible registry.<\/p>\n
First we’ll provision a container registry. These steps are unnecessary if you already have one:<\/p>\n
az acr create --name myrepo<\/strong>\u00a0--resource-group myResourceGroup --sku Basic --admin-enabled true<\/pre>\n
az acr credential show --name myrepo<\/strong><\/pre>\n
Then we can login to our private registry and push our appropriately tagged image:<\/p>\n
docker login myrepo<\/strong>.azurecr.io --username username<\/strong>\r\n\r\ndocker push myrepo<\/strong>.azurecr.io\/uk-rse-survey:2017<\/pre>\n
Finally we can create our webapp and configure it to be created using the image from our private registry:<\/p>\n
az webapp create --resource-group myResourceGroup --plan myAppServicePlan --name rse-survey<\/strong><\/pre>\n
az webapp config container set --resource-group myResourceGroup --name rse-survey<\/strong> --docker-custom-image-name myrepo<\/strong>.azurecr.io\/rse-survey --docker-registry-server-url https:\/\/myrepo<\/strong>.azurecr.io --docker-registry-server-user username<\/strong> --docker-registry-server-password password<\/strong><\/pre>\n
The end result should be exactly the same as when using the same image but from the public registry.<\/p>\n
Tidying up<\/strong><\/h3>\n
As usual, you can delete your entire resource group, including your App Service plan, registry (if created) and webapps by running:<\/p>\n
az group delete --name myResourceGroup<\/pre>\n
Summary<\/strong><\/h3>\n
In this post we’ve demonstrated how a Docker image can be run on Azure using one command, and how to build an deploy a simple app that presents a simple interface to explore data provided in CSV format. We’ve also shown how to use images from private registries.<\/p>\n
This approach is ideal for deploying self-contained apps, but doesn’t present an immediate solution for orchestrating more complex, multi-container applications. We’ll revisit this in a subsequent post.<\/p>\n
Many thanks to the Software Sustainability Institute<\/a> for curating and sharing the the RSE survey data (reused under\u00a0CC BY 2.5 SCOTLAND<\/a>) and Simon Willison<\/a> for Datasette.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"
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