github.com/coreos/rocket@v1.30.1-0.20200224141603-171c416fac02/Documentation/networking/overriding-defaults.md (about)

     1  # Overriding defaults
     2  
     3  This document holds information about modifying or replacing builtin defaults and is only recommended to advanced users.
     4  Please make sure to have read the [networking overview page][overview] before treading into these things.
     5  
     6  ## Overriding the "default" network
     7  
     8  If a network has a name "default", it will override the default network added by rkt.
     9  It is strongly recommended that such network also has type "ptp" as it protects from the pod spoofing its IP address and defeating identity management provided by the metadata service.
    10  
    11  ## Overriding network settings
    12  
    13  The network backend CNI allows the passing of [arguments as plugin parameters][cni-plugin-parameters], specifically `CNI_ARGS`, at runtime.
    14  These arguments can be used to reconfigure a network without changing the configuration file.
    15  rkt supports the `CNI_ARGS` variable through the command line argument `--net`.
    16  
    17  ### Syntax
    18  
    19  The syntax for passing arguments to a network looks like `--net="$networkname1:$arg1=$val1;$arg2=val2"`.
    20  When executed from a shell, you can use double quotes to avoid `;` being interpreted as a command separator by the shell.
    21  To allow the passing of arguments to different networks simply append the arguments to the network name with a colon (`:`), and separate the arguments by semicolon (`;`).
    22  All arguments can either be given in a single instance of the `--net`, or can be spread across multiple uses of `--net`.
    23  *Reminder:* the separator for the networks (and their arguments) within one `--net` instance is the comma `,`.
    24  A network name must not be passed more than once, not within the same nor throughout multiple instances of `--net`.
    25  
    26  ### Example: Passing arguments to two different networks
    27  
    28  This example will override the IP in the networks _net1_ and _net2_.
    29  
    30  ```bash
    31  rkt run --net="net1:IP=1.2.3.4" --net="net2:IP=1.2.4.5" pod.aci
    32  ```
    33  
    34  ### Example: load all networks and override IPs for two different networks
    35  
    36  This example will load all configured networks and override the IP addresses for *net1* and *net2*.
    37  
    38  ```bash
    39  rkt run --net="all,net1:IP=1.2.3.4" --net="net2:IP=1.2.4.5" pod.aci
    40  ```
    41  
    42  ### Supported CNI\_ARGS
    43  
    44  This is not documented yet.
    45  Please follow CNI issue [#56][cni-56] to track the progress of the documentation.
    46  
    47  
    48  [cni-56]: https://github.com/containernetworking/cni/issues/56
    49  [cni-plugin-parameters]: https://github.com/containernetworking/cni/blob/master/SPEC.md#parameters
    50  [overview]: overview.md