Make UI URL links relative

[karol-brejna-i]

Fixes #149

When using proxy or exposing Locust UI in Kubernetes (via ingress) the URLs get prefixed (for example, served under http://domain.com/locust instead of http://domain.com).

On the other hand, links in html template and JS (rest calls) are absolute (starting with '/') which makes the UI inoperable.

This PR makes the links relative - they work fine both with and without a prefix.

To validate:

git clone https://github.com/karol-brejna-i/locust.git
git checkout origin/149_url-prefix-for-web-ui
pip3.6 uninstall locustio -y 
pip3.6 install ./locust/ 
locust -f locust/examples/basic.py --host=http://localhost:8089

When looking at HTML page sources you should see <link rel="stylesheet" type="text/css" href="./static/style.css?v=0.8" media="screen"> somewhere at the beginning of the doc.

Verify if the UI works: starting, stopping the tests, browsing the stats produce valid rest calls.
(Be aware of browser caching; sometimes "old" HTML and JS are served.)

[codecov]

Codecov Report

Merging #692 into master will not change coverage.
The diff coverage is n/a.

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  Coverage   65.93%   65.93%           
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  Files          14       14           
  Lines        1374     1374           
  Branches      214      214           
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  Hits          906      906           
  Misses        421      421           
  Partials       47       47

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[karol-brejna-i]

Rebased against latest master.

[cgoldberg]

👍 let's merge this

[kasturichavan]

@cgoldberg Im facing this issue even now.
I am on locustio - 0.11.0
But im seeing the same issue when running locust in kubernetes and when the path is is changed in kubernetes ingress from / to /locust. Everything should work right ? Considering this bug is fixed.

[cgoldberg]

@kasturichavan
please open a new issue and provide more detail (fill out the issue template)

[w32-blaster]

@cgoldberg Im facing this issue even now.
I am on locustio - 0.11.0
But im seeing the same issue when running locust in kubernetes and when the path is is changed in kubernetes ingress from / to /locust. Everything should work right ? Considering this bug is fixed.

Did you find any solution for this? We would like to expose locust on different paths in k8s using the nginx ingress rewrite annotation feature. Looks like static files are still served from wrong path.

[dchourasia]

@karol-brejna-i does this PR make url-prefix configurable for the web-ui... did not see any such parameter in locust documentation.. not sure if I am missing something. if you can help please.

[awalker125]

If anyone comes here looking for the annotations to make this work with k8s ingress-nginx then here is what I used:

- apiVersion: networking.k8s.io/v1
  kind: Ingress
  metadata:
    annotations:
      nginx.ingress.kubernetes.io/rewrite-target: /$2
      nginx.ingress.kubernetes.io/use-regex: "true"
    name: locust
    namespace: locust
  spec:
    ingressClassName: nginx
    rules:
    - http:
        paths:
        - backend:
            service:
              name: locust-master
              port:
                number: 8089
          path: /locust(/|$)(.*)
          pathType: Prefix

This is based on https://kubernetes.github.io/ingress-nginx/examples/rewrite/