Divio’s containerised infrastructure is distributed over a number of geographical and vendor based regions. At any one time, the servers within each region are allocated an IP address from that region’s range.
Servers in our infrastructure (application builders and runners, and other services) are not permanent hosts but short-lived instances that can be provisioned at a moment’s notice and are regularly recycled.
An IP address within a particular pool can therefore be reallocated to a different server at any time, and there is no guarantee that a server’s address will remain the same from one moment to another.
In addition, vendors’ IP ranges themselves are not guaranteed and can be subject to change regularly and frequently, sometimes without notice.
Finally, even if a server’s IP remains the same, an application might be moved to a different server at any time.
This means that IP addresses are not to be relied upon as a means of reaching or identifying Divio applications or servers.
Load-balancer IP addresses#
A partial exception to this is the IP addresses of our load-balancers, which can be regarded as semi-static.
Customers’ applications may be attached to domains for which CNAMES cannot used (that is, bare domains such as
example.com, rather than sub-domains such as
www.example.com). In this case we recommend using ALIAS records.
Not all DNS providers support ALIAS, and in those cases it is necessary to use A records, which require IP addresses.
We take efforts to keep our load-balancers in each region on a very small number of IP addresses so that A records can rely on them. All the same, even these occasionally must be amended. In that event affected customers are informed in advance to minimise disruption.
Implications for customer applications#
Occasionally a fixed IP address for a customer’s application might be desired for:
incoming connections, such as a client connection to an API running in the application
outgoing connections, such as a connection to an external API, where the IP address is required for whitelisting purposes
For in-bound connections, our semi-static load-balancer IP addresses can be an adequate way of routing connections to a customer application, as long as the user remains aware that these addresses may need to be changed in the future.
Out-bound connections present more challenge. Cloud-based hosting is very well established, and very few services still insist upon using IP addresses as a way of guaranteeing the originator of a connection. However, IP addresses are widely used in firewall rules, and this can still present an issue (see below for other options).
In general though, an alternative, better of achieving a connection to or from Divio applications can and should be found.
In some cases, it may be strictly necessary for an application running on Divio to present an unvarying IP address or range of addresses to an external service.
In such cases, for applications running in private regions only, a number of solutions can be implemented:
a dedicated proxy to redirect traffic from a fixed IP address to the application
a NAT gateway with a fixed external IP address
a dedicated site-to-site VPN
Please contact Divio support to discuss these options.
We do not currently support IPv6 on our infrastructure, as IPv6 is not yet supported in key components provided by our vendors. Future IPv6 support will be introduced when possible.