openstapps/README.md

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# backend (a reference implementation of a StApps backend)
This project is a reference implementation for a StApps backend. It provides an HTTP API to index data into a database,
perform full text search, sorts and filters. It also delivers the configuration needed by the app. The API is specified
within the [@openstapps/core](https://gitlab.com/openstapps/core).

If you want to perform requests, index data or search within JavaScript or TypeScript you should consider using
[@openstapps/api](https://gitlab.com/openstapps/api)

# Usage
This backend is not a standalone software. It needs a database like Elasticsearch to work.

If you just want to use the backend you should consider using
[minimal-deployment](https://gitlab.com/openstapps/minimal-deployment). The minimal-deployment will provide
you with everything you need to run this backend.

# Local usage for development purposes
## Requirements
* Elasticsearch (5.5)
* Node.js (~10) / NPM
* Docker

## Generating Elasticsearch Mapping
The mappings will be generated automatically on the first start. If there are any errors, the backend will inform you and stop
the execution, however it will do its best to complete the mappings. You can then either resolve these errors in the `core-tools` or the `core`, depending on where it originated.
If you need a quick solution, you can also take the generated output file and manually correct the errors, then rename it to `template_[coreVersion].json`
and restart the backend. This time it will take your file. The filenames and the path will be displayed in the log of the backend.

### Manually Resolving Errors
There are multiple types of errors the backend can run into. Manual error resolving requires you to be familiar with Elasticsearch
mappings.
An error will be represented in the output through an Elasticsearch type written in CAPS. Refer to either the console output
or the `error_report_[coreVersion].txt` for more info. If you feel lucky you can try to replace every error (`"type": "MISSING_PREMAP"`,
`"type": "PARSE_ERROR"`, `"type": "TYPE_CONFLICT"`) with
```json
"dynamic": true,
"properties": {}
```
This should ONLY be used as a temporary workaround.

### Startup Behaviour
*This might be important if you work on the Core*


By default, the backend creates a local copy of the generated mappings in `src/storage/elasticsearch/templates/template_[coreVersion].json`.
On each start, it first checks if this file exists, if it does, it will just use that file and *not* generate a new mapping to cut down the time
it takes to start the backend. When you are working on the Core, you might not want to have this behaviour, you can then either delete
the generated file at each start or run the backend with the environment variable `ES_FORCE_MAPPING_UPDATE=true`. This will cause it to generate the mapping
each time starts regardless of whether there are already files there.

## Start Database (Elasticsearch)
Elasticsearch needs some configuration and plugins to be able to work
with the backend. To save you some work we provide a
[docker image](https://gitlab.com/openstapps/database) which
only needs to be executed to work with the backend.

Run `docker run -d -p 9200:9200 registry.gitlab.com/openstapps/database:master`

Elasticsearch should be running at port 9200 now. If you have problems with
getting elasticsearch to work, have a look in the
[README](https://gitlab.com/openstapps/database) of the image
first.

## Start backend
Run `npm install` and `npm run build`, then start with `npm start`. The server should now be accepting connections at `http://localhost:3000`.

# Environment Variables
To select a database implementation you have to set the `NODE_CONFIG_ENV` variable. At the time only `NODE_CONFIG_ENV=elasticsearch` is supported.
Set `NODE_ENV=production` to run backend for production usages. In production the backend expects some kind of monitoring to be set via the
environment. At the time only SMTP is being implemented. The backend wouldn't start if you don't provide SMTP authentification. Alternatively
you can set `ALLOW_NO_TRANSPORT=true`. To set up an SMTP configuration have a look at
[@openstapps/logger](https://gitlab.com/openstapps/logger).

## Config files
Each university can have it's specific config for the general backend and app and for all databases.

All config files can be found in `./config/`. There is a `default.ts` which is used by default. You can create an
university specific file with following naming scheme: `default-<university license plate>.ts`

A university specific file will only overwrite all properties of the `default.ts` that are set in the file itself.
To start the backend using your configuration you have to provide the `NODE_APP_INSTANCE` environment variable
with your university license plate.

To set a database you have to provide the `NODE_CONFIG_ENV` environment variable with the name of the database.
At the time only Elasticsearch is implemented.

To create your university specific config file for the elasticsearch you have to create a file with following naming
scheme: `elasticsearch-<university license plate>.ts`.

## Debugging
Set `ES_DEBUG=true` to enable verbose Elasticsearch tracing information.
This can be useful to debug some issues between backend and elasticsearch.

## Setting a different url for elasticsearch
Set `ES_PORT_9200_TCP_ADDR` to change the elasticsearch-http-address which by default is `localhost`.
Set `ES_PORT_9200_TCP_PORT` to change the elasticsearch port which by default is `9200` .

## [Contributing](https://gitlab.com/openstapps/projectmanagement/blob/master/CONTRIBUTING.md)