CloudFront wasn't able to connect to the origin

Question

I had set up Cloudfront correctly over http. It fetched data from my website (dev.pie.video) fine. I'm now moving to https. Things are working fine at https://dev.pie.video but Cloudfront is unable to server any content. For instance https://dev.pie.video/favicon-96x96.png works but https://d1mbpc40mdbs3p.cloudfront.net/favicon-96x96.png fails with status 502, even though my Cloudfront distribution d1mbpc40mdbs3p points to dev.pie.video.

More details if that's helpful:

• d1mbpc40mdbs3p.cloudfront.net uses the default CloudFront Certificate for https
• the cloudfront distribution's origin is set to work over SSL and TLS, and to use the viewer's protocol.

===== Edit 1 =====

screenshots of the cloudfront settings:

General:

Origin:

Behaviors:

==== Edit 2 ====

if that's helpful, the logs I'm getting from cloudfront look like

<timestamp> SFO20   924 96.90.217.130   GET d1mbpc40mdbs3p.cloudfront.net   /favicon-96x96.png  502 -   <someInfoOnTheClientBrowser>    2   -   Error   poZyhl63JNGFk8dIIjCluGDm4dxF8EdMZFhjg82NgHGPNqcmx6ArHA==    d1mbpc40mdbs3p.cloudfront.net   https   494 0.002   -   TLSv1.2 ECDHE-RSA-AES128-GCM-SHA256 Error   HTTP/1.1

Solution

Your origin server is incorrectly configured for SSL. CloudFront requires a valid configuration, and may be more stringent than some browsers -- so a green lock in the browser doesn't necessarily mean your SSL setup is complete and universally compatible with all clients.

$ true | openssl s_client -connect dev.pie.video:443 -showcerts
CONNECTED(00000003)
depth=0 OU = Domain Control Validated, CN = dev.pie.video
verify error:num=20:unable to get local issuer certificate
verify return:1
depth=0 OU = Domain Control Validated, CN = dev.pie.video
verify error:num=27:certificate not trusted
verify return:1
depth=0 OU = Domain Control Validated, CN = dev.pie.video
verify error:num=21:unable to verify the first certificate
verify return:1
---
Certificate chain
 0 s:/OU=Domain Control Validated/CN=dev.pie.video
   i:/C=US/ST=Arizona/L=Scottsdale/O=GoDaddy.com, Inc./OU=http://certs.godaddy.com/repository//CN=Go Daddy Secure Certificate Authority - G2
-----BEGIN CERTIFICATE-----
MIIFMzCCBBugAwIBAgIJAL96wtFpu1ZpMA0GCSqGSIb3DQEBCwUAMIG0MQswCQYD
VQQGEwJVUzEQMA4GA1UECBMHQXJpem9uYTETMBEGA1UEBxMKU2NvdHRzZGFsZTEa
MBgGA1UEChMRR29EYWRkeS5jb20sIEluYy4xLTArBgNVBAsTJGh0dHA6Ly9jZXJ0
cy5nb2RhZGR5LmNvbS9yZXBvc2l0b3J5LzEzMDEGA1UEAxMqR28gRGFkZHkgU2Vj
dXJlIENlcnRpZmljYXRlIEF1dGhvcml0eSAtIEcyMB4XDTE2MDgwODE4MzQ0MFoX
DTE3MDgwODE4MzQ0MFowOzEhMB8GA1UECxMYRG9tYWluIENvbnRyb2wgVmFsaWRh
dGVkMRYwFAYDVQQDEw1kZXYucGllLnZpZGVvMIIBIjANBgkqhkiG9w0BAQEFAAOC
AQ8AMIIBCgKCAQEAz/wT5j/zHKzmt3oRvst74Knqxc0pl3sp5imUJ7UegoxcTISm
xJC5qQiDsD0U08kAFxvXDd91jlozh4QDcfLE8N7X9fsxC7OW2pDv3ks/LO7tiCxn
gNmxjvYvOQ/vASrLHIal+oGWJNdBMB1eckV4xHCeBDDEizDneq/qvjN0M0k5hQ+/
qk7RjVhJUmFAfvhXpxXaCbVDq1d3V1iRBo3oP3SGV++bj/m55QPFfKCZqGPTiM5G
c9+8ru16EVCpvs0wCWBVxjTiOCGtrMLgvp9LOs8AN369Yk/3AynpgAI0DDhb5y8I
KEuCdbUaIg5Zo029iZz4nWRsZFd5CSwgX8tZNQIDAQABo4IBvjCCAbowDAYDVR0T
AQH/BAIwADAdBgNVHSUEFjAUBggrBgEFBQcDAQYIKwYBBQUHAwIwDgYDVR0PAQH/
BAQDAgWgMDcGA1UdHwQwMC4wLKAqoCiGJmh0dHA6Ly9jcmwuZ29kYWRkeS5jb20v
Z2RpZzJzMS0yODIuY3JsMF0GA1UdIARWMFQwSAYLYIZIAYb9bQEHFwEwOTA3Bggr
BgEFBQcCARYraHR0cDovL2NlcnRpZmljYXRlcy5nb2RhZGR5LmNvbS9yZXBvc2l0
b3J5LzAIBgZngQwBAgEwdgYIKwYBBQUHAQEEajBoMCQGCCsGAQUFBzABhhhodHRw
Oi8vb2NzcC5nb2RhZGR5LmNvbS8wQAYIKwYBBQUHMAKGNGh0dHA6Ly9jZXJ0aWZp
Y2F0ZXMuZ29kYWRkeS5jb20vcmVwb3NpdG9yeS9nZGlnMi5jcnQwHwYDVR0jBBgw
FoAUQMK9J47MNIMwojPX+2yz8LQsgM4wKwYDVR0RBCQwIoINZGV2LnBpZS52aWRl
b4IRd3d3LmRldi5waWUudmlkZW8wHQYDVR0OBBYEFEPW+uDOOtZfUEdXuBs+960C
zQRKMA0GCSqGSIb3DQEBCwUAA4IBAQBLkLYJEc9E+IGv6pXaPCcYowJfji651Ju6
3DNzGXdyWfOXG+UVCMtPZuC9J66dID4Rc7HWzLveTPEI32z4IgtSjvRwRk9YyWVx
uCOpsP3e/Vgriwg5ds4NyrelQfshA3KaiTLohuiVEOBZgZgIwBEmwR2ZNFuL375E
uEn909zF9+sGkTbFnMm1zlqB2oh2UlSkUT3mj009vWF416W6kZQdFFFEmaI8uSmo
+Thd8HSxQytzWvB3dR4lCteiC09lkQPHU5t10tPgK9BtkLv05ICQQoDhFJmLeAcC
WNEmCcDnSHPxXjPi8kcyM6aqNofL1D0e1pYYvcpYQQDayWdY3tUh
-----END CERTIFICATE-----
---
Server certificate
subject=/OU=Domain Control Validated/CN=dev.pie.video
issuer=/C=US/ST=Arizona/L=Scottsdale/O=GoDaddy.com, Inc./OU=http://certs.godaddy.com/repository//CN=Go Daddy Secure Certificate Authority - G2
---
No client certificate CA names sent
---
SSL handshake has read 2010 bytes and written 431 bytes
---
New, TLSv1/SSLv3, Cipher is ECDHE-RSA-AES128-GCM-SHA256
Server public key is 2048 bit
...clipped...

Your certificate is signed by "Go Daddy Secure Certificate Authority - G2" which is an intermediate certificate (not a root), and you don't have that intermediate certificate installed on your server -- so CloudFront reports that it is "unable" to connect, when in fact it is more accurately "unwilling" to connect, as a security precaution, because it can't verify the validity of your SSL certificate. You should see these as SSL negotiation failures in your web server's log. The connection itself is working, but CloudFront considers it invalid, and therefore unsafe to use, due to the trust issue.

Caution

If the origin server returns an expired certificate, an invalid certificate or a self-signed certificate, or if the origin server returns the certificate chain in the wrong order, CloudFront drops the TCP connection, returns HTTP error code 502, and sets the X-Cache header to Error from cloudfront.

http://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/SecureConnections.html

Add your intermediate certificate to your server configuration, and you should be set. This should have been bundled with the cert when you downloaded it, but if not, it can be obtained from your CA, Go Daddy in this case.

This is not a limitation specific to Go Daddy certificates. All CAs that follow standard practice use intermediate certificates to establish a chain of trust back to a trusted root.

See also:

https://www.godaddy.com/help/what-is-an-intermediate-certificate-868

https://certs.godaddy.com/repository