The goal is to create a MS office 365 Flow which will call a homemade connector to get a random cat picture and post it on a yammer group. 

Yammer connector 

The first thing to do is check if there is a MS Office365 connector that can get use a random cat picture (who know…. Maybe someone already done one). After checking https://flow.microsoft.com/en-us/connectors/ it seems it s not the case. So we have to create one.  

I will not go too much in the details since the MS doc is quite good https://docs.microsoft.com/en-us/connectors/custom-connectors/define-openapi-definition. One interesting point was the fact it needs to be HTTPS so I played with Let’s encrypt and their docker version of certbot…. Nothing fancy apart that…. classical NodeJS server with only one endpoint with an hardcode to start with 

app.get(‘/v2/cat’, (req,res) => { 

var aCatUrl = “https://i.imgur.com/x7X0Fxf.jpg“; 

res.send(aCatUrl); 

console.log(‘Sent response’); 

}); 

The full code is here https://bitbucket.org/charly37/catpy/src/master/ 

Once the connector is ready to be used you can validate it with a quick postman call like: 

Then you can add it on your MS 365 personal connector as explain in the MS doc. I used the “from OpenApi file” method with the following file https://bitbucket.org/charly37/catpy/src/master/myapp/swagger.json 

Flow creation 

Now that the connector is publish on your Office365 space you can create a flow using it. I copy past and existing template “Post an update to my company’s Yammer page” that I customize with an extra step to call my connector and post the response of the connector into the yammer room 

Then you can test it and see that the result is not exactly what we excepted…. 

I was hoping to have the picture posted on yammer like it is the case when I post the URL myself on the UI like  

The reason why it did not work is that the YAMMER connector do not allow to post picture. There is already an open request on MS side so that it is supported in the future (feel free to vote for it) here: https://powerusers.microsoft.com/t5/Flow-Ideas/Post-on-Yammer-with-image-attachments/idi-p/14300

Conclusion 

I will wait until MS implement that like I done for the JS function in Excel online 😉 and in the meantime I will try to do a REST call directly to Yammer API to see if I can post an image directly (without going throw flow).