Hey sample function

[kylos101]

Description

Add a sample hey function.

Motivation and Context

It is important to load test. Why not have a function to help do it?

• I have raised an issue to propose this change, it is located here
• My issue has received approval from the maintainers or lead with the design/approved label

How Has This Been Tested?

1. I built the function on my local machine, and confirmed that subsequent builds were cached.
2. I pushed the function to my personal Docker Hub.
3. I deployed Nodeinfo and this temporary build of the hey function to my personnel OpenFaaS.
4. I confirmed hey provides results like it does on the CLI.

Impact to other areas of code

N/A

Test environment details

1. My cluster is running in Digital Ocean. I started using DO from a referral link from one of Alex's posts. I setup my cluster ark in about 15 minutes. I love ark.
2. After running the steps above (1-4), I deleted both functions from my cluster.
3. Screenshot of deployed function
   
4. Rresults

Summary:
  Total:	1.5234 secs
  Slowest:	1.5058 secs
  Fastest:	0.0027 secs
  Average:	0.1133 secs
  Requests/sec:	131.2876
  
  Total data:	20200 bytes
  Size/request:	101 bytes

Response time histogram:
  0.003 [1]	|
  0.153 [155]	|■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
  0.303 [34]	|■■■■■■■■■
  0.454 [2]	|■
  0.604 [1]	|
  0.754 [2]	|■
  0.905 [1]	|
  1.055 [1]	|
  1.205 [1]	|
  1.355 [1]	|
  1.506 [1]	|


Latency distribution:
  10% in 0.0057 secs
  25% in 0.0461 secs
  50% in 0.0582 secs
  75% in 0.1228 secs
  90% in 0.2117 secs
  95% in 0.3703 secs
  99% in 1.3049 secs

Details (average, fastest, slowest):
  DNS+dialup:	0.0240 secs, 0.0027 secs, 1.5058 secs
  DNS-lookup:	0.0024 secs, 0.0000 secs, 0.0118 secs
  req write:	0.0002 secs, 0.0000 secs, 0.0053 secs
  resp wait:	0.0883 secs, 0.0026 secs, 1.3968 secs
  resp read:	0.0001 secs, 0.0000 secs, 0.0003 secs

Status code distribution:
  [200]	200 responses

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I've read the CONTRIBUTION guide
• I have signed-off my commits with git commit -s
• I have added tests to cover my changes.
• All new and existing tests passed.

[alexellis]

Lgtm

[alexellis]

Thank you for submitting your first pull request to OpenFaaS!

Please could you update the stack.yml file one level up too? That way I can run a build/push and we can get your store PR going.

[kylos101]

Thank you for submitting your first pull request to OpenFaaS!

Please could you update the stack.yml file one level up too? That way I can run a build/push and we can get your store PR going.

Stack.yml is all set in #1498 . @alexellis , for the store PR, should I update templates.json, store.json, or both? I assume functions.json (cause its the most recent version, 0.2.0), but am just guessing.