Auspice servers

The Auspice client (i.e. what you see in the web browser) requires a server behind it to - (a) serve the client HTML, CSS & JavaScript to the browser and - (b) handle certain GET requests from the client, for instance “give me the zika dataset to display”.

We provide a basic server to run Auspice locally – any time you run auspice view or auspice develop you’re running a server! In these cases, the server is running on your computer, sending datasets and narratives, which are stored on your machine, to the Auspice client. Alternatively, you can build your own server – it just needs to satisfy the above two requirements.

GET Requests

Currently the client is able to make three requests:




return a list of available datasets and narratives


return the requested dataset


return the requested narrative

For instance, when you’re running auspice view if you go to localhost:4000/charon/getAvailable you’ll see a list of the available datasets and narratives known to the server. Similarly, is a server which has handlers for these three API endpoints, so if you visit you’ll see Nextstrain’s available datasets.

See the server API for details about each of these requests.


Note that “/charon” can be changed to any address you wish by customising the client at build time. See the client-cusomisation API <../customise-client/api.html> for more details.

The “Default” Auspice Server

The server provided with Auspice is intended to be run on your local setup. It thus scans the directories you provide when you run it in order to find datasets and narratives to serve. It has “handlers” for each of the above 3 requests – i.e. bits of code that tell it how to handle each request.

Customising the Default Auspice Server

You can customise the default Auspice server by supplying your own handlers for each of the three GET requests. See the API documentation for how to define these and provide them to auspice view.

Writing Your Own Custom Server

The provided Auspice server also lets you define your own handlers, allowing plenty of flexibility in how requests are handled. But if you _really_ want to implement your own server, then you only need to implement two things: - serve the index.html file (and linked javascript bundles) which are created by auspice build _and_ - handle the three GET requests detailed above

(If you’re interested, this is what we do with, where only some of the pages use Auspice. You can see all the code behind that server [here](

Deploying via Heroku

It should be simple to deploy a custom version of auspice to any server, but we have experience using Heroku apps for this. Deploying to Heroku is straightforward, but there are a few points to note: 1. You must set the config var HOST to for the app. 1. You will need to either create a Procfile or a npm run start script which calls auspice view (or npx auspice view depending on how you implement auspice) 1. Make sure the datasets to be served are either (a) included in your git repo or (b) downloaded by the heroku build pipeline. We use option (b) by specifing a npm script called heroku-postbuild.

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