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Does this mean that 3 proxy servers serve all the traffic for ALL apps hosted on Heroku?

by armored 15y ago

joevandyk 15y ago
Yup. Amazon has 3 too! $ dig amazon.com ; <<>> DiG 9.7.0-P1 <<>> amazon.com ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 41998 ;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;amazon.com. IN A ;; ANSWER SECTION: amazon.com. 36 IN A 72.21.194.1 amazon.com. 36 IN A 72.21.211.176 amazon.com. 36 IN A 72.21.214.128
- imbriaco 15y ago
  Not exactly. The 3 IPs that are returned for proxy.heroku.com are not fixed. They are a just subset of the available front-end proxy servers.
  - 140am 15y ago
    Exactly - its a common practice to use DNS servers to spread load across backend instances. Example djbdns/tinydns by default "only" returns up to 8 IP addresses so if you setup more then that those IPs will be randomly returned. http://cr.yp.to/djbdns/balance.html http://cr.yp.to/djbdns/balance.html
tlrobinson 15y ago
It looks like they have about 6 total. Plus some customers pay $100/month for their own front-end proxy server so they can use SSL on a custom domain name. Of the domains I checked (a few hundred found through the "Find Subdomains" tool here: http://www.magic-net.info/ http://www.magic-net.info/), appname.heroku.com (including proxy.heroku.com) will return 3 of these: 50.16.215.196 50.16.232.130 50.16.233.102 75.101.145.87 174.129.212.2 It's possible Heroku's DNS is returning different IPs based the load of the reverse proxies, but when querying heroku.com's 4 nameservers directly I got different subsets of those 5 IPs. A random distribution of IPs probably gives good enough load distribution. And Heroku's documentation says to point A records to these three: 75.101.163.44 75.101.145.87 174.129.212.2 It's also interesting to note that apps aren't tied to specific proxy servers. If you set the "Host" header to your app's subdomain, a request to any one of those IPs will work. I'll add this info the the Quora answer.

Does this mean that 3 proxy servers serve all the traffic for ALL apps hosted on Heroku?

by armored 15y ago

Does this mean that 3 proxy servers serve all the traffic for ALL apps hosted on Heroku?

Yup. Amazon has 3 too! $ dig amazon.com ; <<>> DiG 9.7.0-P1 <<>> amazon.com ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 41998 ;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;amazon.com. IN A ;; ANSWER SECTION: amazon.com. 36 IN A 72.21.194.1 amazon.com. 36 IN A 72.21.211.176 amazon.com. 36 IN A 72.21.214.128

imbriaco 15y ago
Not exactly. The 3 IPs that are returned for proxy.heroku.com are not fixed. They are a just subset of the available front-end proxy servers.
- 140am 15y ago
  Exactly - its a common practice to use DNS servers to spread load across backend instances. Example djbdns/tinydns by default "only" returns up to 8 IP addresses so if you setup more then that those IPs will be randomly returned. http://cr.yp.to/djbdns/balance.html http://cr.yp.to/djbdns/balance.html

tlrobinson 15y ago

It looks like they have about 6 total. Plus some customers pay $100/month for their own front-end proxy server so they can use SSL on a custom domain name. Of the domains I checked (a few hundred found through the "Find Subdomains" tool here: http://www.magic-net.info/ http://www.magic-net.info/), appname.heroku.com (including proxy.heroku.com) will return 3 of these: 50.16.215.196 50.16.232.130 50.16.233.102 75.101.145.87 174.129.212.2 It's possible Heroku's DNS is returning different IPs based the load of the reverse proxies, but when querying heroku.com's 4 nameservers directly I got different subsets of those 5 IPs. A random distribution of IPs probably gives good enough load distribution. And Heroku's documentation says to point A records to these three: 75.101.163.44 75.101.145.87 174.129.212.2 It's also interesting to note that apps aren't tied to specific proxy servers. If you set the "Host" header to your app's subdomain, a request to any one of those IPs will work. I'll add this info the the Quora answer.