Add a new hostname string parameter to the network block which
allows operators to specify the hostname of the network namespace.
Changing this causes a destructive update to the allocation and it
is omitted if empty from API responses. This parameter also supports
interpolation.
In order to have a hostname passed as a configuration param when
creating an allocation network, the CreateNetwork func of the
DriverNetworkManager interface needs to be updated. In order to
minimize the disruption of future changes, rather than add another
string func arg, the function now accepts a request struct along with
the allocID param. The struct has the hostname as a field.
The in-tree implementations of DriverNetworkManager.CreateNetwork
have been modified to account for the function signature change.
In updating for the change, the enhancement of adding hostnames to
network namespaces has also been added to the Docker driver, whilst
the default Linux manager does not current implement it.
When `network.mode = "bridge"`, we create a pause container in Docker with no
networking so that we have a process to hold the network namespace we create
in Nomad. The default `/etc/hosts` file of that pause container is then used
for all the Docker tasks that share that network namespace. Some applications
rely on this file being populated.
This changeset generates a `/etc/hosts` file and bind-mounts it to the
container when Nomad owns the network, so that the container's hostname has an
IP in the file as expected. The hosts file will include the entries added by
the Docker driver's `extra_hosts` field.
In this changeset, only the Docker task driver will take advantage of this
option, as the `exec`/`java` drivers currently copy the host's `/etc/hosts`
file and this can't be changed without breaking backwards compatibility. But
the fields are available in the task driver protobuf for community task
drivers to use if they'd like.
* ar: refactor network bridge config to use go-cni lib
* ar: use eth as the iface prefix for bridged network namespaces
* vendor: update containerd/go-cni package
* ar: update network hook to use TODO contexts when calling configurator
* unnecessary conversion
Adds a new Prerun and Postrun hooks to manage set up of network namespaces
on linux. Work still needs to be done to make the code platform agnostic and
support Docker style network initalization.
James Rasell