Add headers to curl request for executor sample

[glindsell]

Fixes #1770
Signed-off-by: glindsell [email protected]

[seldondev]

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[seldondev]

Thu Apr 30 14:03:57 UTC 2020
The logs for [lint] [2] will show after the pipeline context has finished.
https://github.com/SeldonIO/seldon-core/blob/gh-pages/jenkins-x/logs/SeldonIO/seldon-core/PR-1771/2.log

impatient try
jx get build logs SeldonIO/seldon-core/PR-1771 --build=2

[seldondev]

Thu Apr 30 14:04:14 UTC 2020
The logs for [pr-build] [1] will show after the pipeline context has finished.
https://github.com/SeldonIO/seldon-core/blob/gh-pages/jenkins-x/logs/SeldonIO/seldon-core/PR-1771/1.log

impatient try
jx get build logs SeldonIO/seldon-core/PR-1771 --build=1

[glindsell]

/retest

[seldondev]

Thu Apr 30 14:35:18 UTC 2020
The logs for [pr-build] [3] will show after the pipeline context has finished.
https://github.com/SeldonIO/seldon-core/blob/gh-pages/jenkins-x/logs/SeldonIO/seldon-core/PR-1771/3.log

impatient try
jx get build logs SeldonIO/seldon-core/PR-1771 --build=3

[glindsell]

@ryandawsonuk I spoke to @cliveseldon about this one - he suggested you might have worked on this area of SC before. Do you know if this is expected behaviour that we force the client to specify the Content-Type in the Header of a request? Or should there be logic to work out what the Content-Type is from the payload?

[RafalSkolasinski]

Isn't requesting Conte-Type to be application/json just a web standard (when json is expected ofc)?
When sending requests from Python if you specify your post data using json=... argument in requests it adds that automatically for example.