# Vespa client This app contains the **Query Builder** and the **Trace Visualizer**. Install and start: $ nvm install --lts node # in case the installed node.js is too old $ yarn install $ yarn dev # then open link, like http://127.0.0.1:3000/ Alternatively, use Docker to start it without installing node: $ docker run -v `pwd`:/w -w /w --publish 3000:3000 node:16 sh -c 'yarn install && yarn dev --host' When started, open [http://127.0.0.1:3000/](http://127.0.0.1:3000/). _Troubleshooting:_ Remove the generated `node_modules` directory and try again. This is also relevant when switching between running local and in the container. ## Query Builder The Query Builder is a tool for creating Vespa queries to send to a local Vespa application. The tool provides all of the options for query parameters from dropdowns. The input fields provide hints to what is the expected type of value.  To access a Vespa endpoint from the Query Builder, deploy with [CORS filters](https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS). To the query-serving container, add an `http` element in _services.xml_ like: ``` * http://*/search/ * http://*/search/ ``` Deploy again, and (possibly) restart Vespa (internal port changes can be triggered by this). ## Trace Visualizer The Trace Visualizer is a tool for converting and visualizing traces from Vespa in a flame graph. To use the visualizer, a [Jaeger](https://www.jaegertracing.io/) instance must be run locally with Docker: docker run -d --rm \ -p 16685:16685 \ -p 16686:16686 \ -p 16687:16687 \ -e SPAN_STORAGE_TYPE=memory \ jaegertracing/jaeger-query:latest The Jaeger UI can then be reached at **localhost:16686/search** To use the visualizer, paste the Vespa trace into the text box and press the button to convert the trace to a format supported by Jaeger and download it. Only traces using _trace.timestamps=true_ **and** _traceLevel_ between 3 and 5 (inclusive) will work correctly - see [query tracing](https://docs.vespa.ai/en/query-api.html#query-tracing):  After downloading the converted trace, it can be used with the Jaeger UI. Press the _JSON File_ button as shown in the image, and drag and drop the trace you just downloaded:  Then click on the newly added trace and see it displayed as a flame graph: