Targets

Overview

You can specify a target on your cluster for mirrord, giving your local application access to the remote target’s network environment, file system and environment variables, according to the configuration. When a target is specified, a mirrord-agent pod will be created on the same node as the target pod. The several kinds of supported targets are detailed below. There are also multiple ways to specify a target for mirrord: you can do it in a configuration file, in an IDE dialog, or in the CLI with an argument or an environment variable.

Possible targets

You can either target a pod or a deployment, and you can also name a specific container in that deployment or pod to target. When targeting a pod without specifying a container, the first container found in that pod will be targeted. When targeting a deployment without specifying a container, the first container of the first pod found in the deployment will be used (impersonating all pods in a deployment is supported in mirrord for teams).

You can specify a target namespace if the target should be found in that namespace instead of the namespace that is currently used by kubectl. See the different interfaces below for possible ways of specifying the target and its namespace.

Specifying a target

There are multiple ways to specify a target. In all the possible interfaces for specifying a target, the basic format is <resource-type>/<resource-name> optionally followed by /container/<container-name>. So for specifying a target without specifying a container you can pass

deploy/<YOUR-DEPLOYMENT-NAME>

e.g. deploy/lolz,

or

pod/<YOUR-POD-NAME>

e.g. pod/lolz-64698df9b7-6plq8,

And for also specifying a container, you just add /container/<CONTAINER-NAME> at the end, e.g. pod/lolz-64698df9b7-6plq8/container/main-container.

Using a configuration file

The target path from the last section is set under the target.path field. The target’s namespace can be set under target.namespace. By default, the namespace currently specified in the local kubeconfig is used.

{
  "target": {
    "path": "pod/lolz-64698df9b7-6plq8/container/main-container",
    "namespace": "lolzspace"
  }
}

Using an IDE’s dialog

If you are running one of mirrord’s IDE extensions and you didn’t specify a target via a configuration file, a dialog will pop up for you to pick a target. If you want to choose a target from a different namespace you can set a target namespace in the configuration file, and the dialog will then contain targets in that namespace. Choose the No Target ("targetless") option in the dialog in order to run without a target.

Using a command line argument

If you are running mirrord from the command line, you can specify the target via -t and its namespace via -n, e.g. mirrord exec -t deploy/lolz -n lolzspace my-app. Values specified by command line arguments will be used even if other values are set in a configuration file or in environment variables.

Using an environment variable

You can set the target using the environment variable MIRRORD_IMPERSONATED_TARGET and the target’s namespace using the environment variable MIRRORD_TARGET_NAMESPACE. Values specified by environment variables will be used even if other values are set in a configuration file.

Running without a target

When no target is specified, mirrord will start a targetless agent. That can be useful when you want to connect to services from within the cluster, but you don’t have any target that you want to “impersonate” - like when running an external utility or a new microservice. When running targetless, mirrord will forward any connections initiated by your application to be sent out of the cluster, but it will not mirror or steal incoming traffic, as a targetless agent is not connected to any Kubernetes service and does not expose any ports. This means that if your application binds a port and listens on it, that will all happen locally, on your machine. So if you’re using a management program that exposes a web interface, you can have it listen for connections on localhost, and connect to remote services in the cluster.

In order to run targetless, you need to not specify a target in the configuration file, in case you are using one. In your IDE you can pick the No Target ("targetless") option in the target selection dialog (or just not make a selection). Moreover, you should make sure the environment variable used to specify a target isn’t set (or is set to an empty value).

Note: In order to set the namespace the agent is going to be created in, set the agent namespace, not the target namespace. That value can be set via the agent.namespace configuration file field, the -a CLI argument, or the MIRRORD_AGENT_NAMESPACE environment variable.