Enable external DNS for ipvlan-l3, and disable it for macvlan/ipvlan with no parent interface #47677
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Signed-off-by: Rob Murray <rob.murray@docker.com>
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The internal DNS resolver should only forward requests to external resolvers if the libnetwork.Sandbox served by the resolver has external network access (so, no forwarding for '--internal' networks). The test for external network access was whether the Sandbox had an Endpoint with a gateway configured. However, an ipvlan-l3 networks with external network access does not have a gateway, it has a default route bound to an interface. Also, we document that an ipvlan network with no parent interface is equivalent to a '--internal' network. But, in this case, an ipvlan-l2 network was configured with a gateway. So, DNS proxying would be enabled in the internal resolver (and, if the host's resolver was on a localhost address, requests to external resolvers from the host's network namespace would succeed). So, this change adjusts the test for enabling DNS proxying to include a check for '--internal' (as a shortcut) and, for non-internal networks, checks for a default route as well as a gateway. It also disables configuration of a gateway or a default route for an ipvlan Endpoint if no parent interface is specified. (Note if a parent interface with no external network is supplied as '-o parent=<dummy>', the gateway/default route will still be set up and external DNS proxying will be enabled. The network must be configured as '--internal' to prevent that from happening.) Signed-off-by: Rob Murray <rob.murray@docker.com>
We document that an macvlan network with no parent interface is equivalent to a '--internal' network. But, in this case, an macvlan network was still configured with a gateway. So, DNS proxying would be enabled in the internal resolver (and, if the host's resolver was on a localhost address, requests to external resolvers from the host's network namespace would succeed). This change disables configuration of a gateway for a macvlan Endpoint if no parent interface is specified. (Note if a parent interface with no external network is supplied as '-o parent=<dummy>', the gateway will still be set up. Documentation will need to be updated to note that '--internal' should be used to prevent DNS request forwarding in this case.) Signed-off-by: Rob Murray <rob.murray@docker.com>
This reverts commit a77e147. The ipvlan integration tests have been skipped in CI because of a check intended to ensure the kernel has ipvlan support - which failed, but seems to be unnecessary (probably because kernels have moved on). Signed-off-by: Rob Murray <rob.murray@docker.com>
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Thanks, I'll get this one in! |
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- What I did
The internal DNS resolver should only forward requests to external resolvers if the libnetwork.Sandbox served by the resolver has external network access (so, no forwarding for '--internal' networks).
The test for external network access was whether the Sandbox had an Endpoint with a gateway configured.
However, an ipvlan-l3 networks with external network access does not have a gateway, it has a default route bound to an interface.
Also, we document that an ipvlan/macvlan network with no parent interface is equivalent to a '--internal' network. But, in these cases, endpoints were still configured with a gateway (or a default route). So, DNS proxying would be enabled in the internal resolver (and, if the host's resolver was on a localhost address, requests to external resolvers from the host's network namespace would succeed).
Also also, CI hasn't been running most of the ipvlan tests becuase a check that the kernel supports ipvlan has been failing. However, without that check, tests pass (locally, and on the CI test runners). I want the new ipvlan/dns tests to run in CI, and it'd be weird to run only those and not the existing tests. So, removed the kernel-check.
- How I did it
Adjusted the test for enabling DNS proxying to include a check for '--internal' (as a shortcut) and, for non-internal networks, check for a default route as well as a gateway.
Disable configuration of a gateway or a default route for an ipvlan/macvlan Endpoint when no parent interface is specified. (Note that if a parent interface with no external network is supplied as '-o parent=', the gateway/default route will still be set up and external DNS proxying will be enabled. The network must be configured as '--internal' to prevent that from happening.)
Revert the changes from #39358 ... run ipvlan tests without a kernel-check (but not in rootless mode).
- How to verify it
New macvlan/ipvlan integration tests.
- Description for the changelog