Problem
You would like to set up HAProxy as the load balancer in your Vault cluster configuration. Vault is set up with internal storage (Raft), and you would also like to be able to pass the connection encrypted from the client to the Vault cluster member, without having HAProxy decrypt/encrypt the message.
Solution
Looking and searching around in the internet provides a few examples of how to do this. During this process there are different errors that you can see happening. There are certain things that you will need to do in order to debug and find the correct setup.
One of the main points is that HAProxy’s frontend and backend mode should be tcp instead of http.
Another thing that will help with debugging would be having access to both HAProxy’s and Vault (active) member logs.
Using curl with the -v flag is also very helpful.
One of the attempts of having HAProxy and Vault server communicate through HTTP/2 was resulting in the following errors:
kosmas:$ curl -v https://proxy_dn:8200/v1/sys/health * Trying xxx.xxx.xxx.xxx... * TCP_NODELAY set * Connected to proxy_dn (xxx.xxx.xxx.xxx) port 8200 (#0) * ALPN, offering h2 * ALPN, offering http/1.1 * successfully set certificate verify locations: * CAfile: /etc/ssl/certs/ca-certificates.crt CApath: /etc/ssl/certs * TLSv1.3 (OUT), TLS handshake, Client hello (1): * TLSv1.3 (IN), TLS handshake, Server hello (2): * TLSv1.3 (IN), TLS Unknown, Certificate Status (22): * TLSv1.3 (IN), TLS handshake, Unknown (8): * TLSv1.3 (IN), TLS Unknown, Certificate Status (22): * TLSv1.3 (IN), TLS handshake, Certificate (11): * TLSv1.3 (IN), TLS Unknown, Certificate Status (22): * TLSv1.3 (IN), TLS handshake, CERT verify (15): * TLSv1.3 (IN), TLS Unknown, Certificate Status (22): * TLSv1.3 (IN), TLS handshake, Finished (20): * TLSv1.3 (OUT), TLS change cipher, Client hello (1): * TLSv1.3 (OUT), TLS Unknown, Certificate Status (22): * TLSv1.3 (OUT), TLS handshake, Finished (20): * SSL connection using TLSv1.3 / TLS_AES_256_GCM_SHA384 * ALPN, server accepted to use h2 * Server certificate: * subject: CN=proxy_dn * start date: Sep 15 08:30:43 2020 GMT * expire date: Dec 14 08:30:43 2020 GMT * subjectAltName: host "proxy_dn" matched cert's "proxy_dn" * issuer: C=US; O=Let's Encrypt; CN=Let's Encrypt Authority X3 * SSL certificate verify ok. * Using HTTP2, server supports multi-use * Connection state changed (HTTP/2 confirmed) * Copying HTTP/2 data in stream buffer to connection buffer after upgrade: len=0 * TLSv1.3 (OUT), TLS Unknown, Unknown (23): * TLSv1.3 (OUT), TLS Unknown, Unknown (23): * TLSv1.3 (OUT), TLS Unknown, Unknown (23): * Using Stream ID: 1 (easy handle 0x55c06f25e580) * TLSv1.3 (OUT), TLS Unknown, Unknown (23): > GET /v1/sys/health HTTP/2 > Host: proxy_dn:8200 > User-Agent: curl/7.58.0 > Accept: */* > * TLSv1.3 (IN), TLS Unknown, Certificate Status (22): * TLSv1.3 (IN), TLS handshake, Newsession Ticket (4): * TLSv1.3 (IN), TLS Unknown, Certificate Status (22): * TLSv1.3 (IN), TLS handshake, Newsession Ticket (4): * TLSv1.3 (IN), TLS Unknown, Unknown (21): * TLSv1.3 (IN), TLS alert, Client hello (1): * Unexpected EOF * Connection #0 to host proxy_dn left intact curl: (56) Unexpected EOF
on an external client (not HAProxy, or Vault).
the following on the HAProxy log:
Sep 25 13:07:27 localhost haproxy[33169]: xxx.xxx.xxx.xxx:38196 [25/Sep/2020:13:07:26.985] vault_https~ vault_https_backend/vault1 46/1/57 0 -- 1/1/0/0/0 0/0
and the following on the Vault log
Sep 25 13:07:27 vault1 vault[607]: 2020-09-25T13:07:27.031Z [INFO] http: TLS handshake error from xxx.xxxx.xxxx.xxxx(proxy_ip):56632: tls: first record does not look like a TLS handshake
Changing the configuration on HAProxy to use http1.1 solves the issue (/etc/haproxy/haproxy.cfg
frontend vault_https bind *:443 ssl crt /etc/haproxy/certs/proxy_dn_certificate.pem alpn http/1.1
Which results in the correct response now by using the HAProxy as a ssl pass_through load balancer.
kosmas:$ curl -v https://proxy_dn:8200/v1/sys/health
* Trying xxx.xxx.xxx.xxx...
* TCP_NODELAY set
* Connected to proxy_dn (xxx.xxx.xxx.xxx) port 8200 (#0)
* ALPN, offering h2
* ALPN, offering http/1.1
* successfully set certificate verify locations:
* CAfile: /etc/ssl/certs/ca-certificates.crt
CApath: /etc/ssl/certs
* TLSv1.3 (OUT), TLS handshake, Client hello (1):
* TLSv1.3 (IN), TLS handshake, Server hello (2):
* TLSv1.3 (IN), TLS Unknown, Certificate Status (22):
* TLSv1.3 (IN), TLS handshake, Unknown (8):
* TLSv1.3 (IN), TLS Unknown, Certificate Status (22):
* TLSv1.3 (IN), TLS handshake, Certificate (11):
* TLSv1.3 (IN), TLS Unknown, Certificate Status (22):
* TLSv1.3 (IN), TLS handshake, CERT verify (15):
* TLSv1.3 (IN), TLS Unknown, Certificate Status (22):
* TLSv1.3 (IN), TLS handshake, Finished (20):
* TLSv1.3 (OUT), TLS change cipher, Client hello (1):
* TLSv1.3 (OUT), TLS Unknown, Certificate Status (22):
* TLSv1.3 (OUT), TLS handshake, Finished (20):
* SSL connection using TLSv1.3 / TLS_AES_256_GCM_SHA384
* ALPN, server accepted to use http/1.1
* Server certificate:
* subject: CN=proxy_dn
* start date: Sep 15 08:30:43 2020 GMT
* expire date: Dec 14 08:30:43 2020 GMT
* subjectAltName: host "proxy_dn" matched cert's "proxy_dn"
* issuer: C=US; O=Let's Encrypt; CN=Let's Encrypt Authority X3
* SSL certificate verify ok.
* TLSv1.3 (OUT), TLS Unknown, Unknown (23):
> GET /v1/sys/health HTTP/1.1
> Host: proxy_dn:8200
> User-Agent: curl/7.58.0
> Accept: */*
>
* TLSv1.3 (IN), TLS Unknown, Certificate Status (22):
* TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):
* TLSv1.3 (IN), TLS Unknown, Certificate Status (22):
* TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):
* TLSv1.3 (IN), TLS Unknown, Unknown (23):
< HTTP/1.1 200 OK
< Cache-Control: no-store
< Content-Type: application/json
< Date: Fri, 25 Sep 2020 14:12:59 GMT
< Content-Length: 294
<
{"initialized":true,"sealed":false,"standby":false,"performance_standby":false,"replication_performance_mode":"disabled","replication_dr_mode":"disabled","server_time_utc":1601043179,"version":"1.5.0","cluster_name":"vault-cluster-123455","cluster_id":"xxxx-xxxx-xxxx-xxx-xxxx"}
* Connection #0 to host proxy_dn left intact