I ran into an issue recently trying to utilize Mandrill’s web hooks on a site forcing HTTPS (duh). After sending the test webhook from the web interface, I saw the following error:

Webhook failed with error: POST to 
http://staging.mysite.com/invites/mandrill/callback failed: 
SSL certificate problem, verify that the CA cert is OK. 
Details: error:14090086:SSL 
certificate verify failed

After doing a bit of internet searching, and testing different server configurations, I figured out that I did not concatentate my SSL certificates correctly.

I bought my SSL cert from Comodo, and after paying for the certs I received four files: AddTrustExternalCARoot.crt, STAR_mysite_com.crt,COMODORSAAddTrustCA.crt and COMODORSADomainValidationSecureServerCA.crt

The final solution was to concatentate them together in the following order:

cat STAR_mysite_com.crt COMODORSADomainValidationSecureServerCA.crt 
AddTrustExternalCARoot.crt COMODORSAAddTrustCA.crt > ssl-bundle.crt

And finally, place the following blog in your NGINX config:

server {

	listen	443 default_server ssl;
	client_max_body_size 4M;
	server_name _;

	ssl on;
	ssl_certificate			/home/ubuntu/.keys/ssl-bundle.crt;
	ssl_certificate_key		/home/ubuntu/.keys/mysite.com.key;

Restart your NGINX server, and the test webhook will be successful!

P.S - Fuck Dev Ops