Edge Control

Edge Control is the command-line tool for installing and managing the Ambassador Edge Stack. And Edge Control's outbound and intercept features allow developers to preview changes to their services while sharing a single development cluster.

If you are a developer working on a service that depends on other in-cluster services, use edgectl connect to set up connectivity from your laptop to the cluster. This allows software on your laptop, such as your work-in-progress service running in your debugger, to connect to other services in the cluster.

When you want to test your service with traffic from the cluster, use edgectl intercept to designate a subset of requests for this service to be redirected to your laptop. You can use those requests to test and debug your local copy of the service. All other requests will go to the existing service running in the cluster without disruption.

Installing Edge Control

Edge Control is available as a downloadable executable for both Mac OS X and Linux. While Edge Control clients are available for Windows, these binaries do not support Service Preview.

For MacOS:

For Linux:

Upgrading

Make sure you've terminated the daemon.

Download the latest binary, as above, and replace your existing binary.

Service Preview Quick Start

Service Preview creates a connection between your local environment and the cluster. These connections are managed through the Traffic Manager, which is deployed in your cluster, and the edgectl daemon, which runs in your local environment.

There are three basic commands that are used for Service Preview:

1. Launch the edgectl daemon:

2. Connect your laptop to the cluster. This will enable your local environment to initiate traffic to the cluster.

3. Set up an intercept rule. This will enable the cluster initiate traffic to your local environment.

Edge Control commands

edgectl connect

Connect to the cluster. This command allows your local environment to initiate traffic to the cluster, allowing services running locally to send and receive requests to cluster services.

edgectl daemon

In order to mediate traffic to your clusters, Edge Control inserts itself into the DNS for your host (this is why it requires root access to run). It intercepts queries to your system’s primary DNS server, responds to queries that have to do with connected clusters, and forwards any other queries on to a fallback DNS server.

By default, the daemon intercepts queries to the primary DNS server listed in /etc/resolv.conf, and uses Google DNS on 8.8.8.8 or 8.8.4.4 for its fallback DNS server. You can override the choice of which DNS server to intercept using the --dns option, and you can override the fallback server using the --fallback option.

It's important that the primary DNS server and the fallback server be different. Otherwise Edge Control would forward queries to itself, resulting in a DNS loop.

The daemon’s logging output may be found in /tmp/edgectl.log.

Examples

Launch Daemon:

If /etc/resolv.conf is correct, but you have a local DNS server available on 10.0.0.1 that should be used for non-cluster queries, you could run Configure fallback server:

edgectl disconnect

Disconnect from the cluster.

edgectl intercept

Intercept enables the cluster to initiate traffic to the local environment. To prevent unwanted traffic from being routed to the cluster, intercept creates routing rules that specify which traffic to send to the local environment. An intercept is created on a per (Kubernetes) deployment basis. Each deployment must have a traffic agent installed in order for intercept to function.

edgectl intercept available

List available Kubernetes deployments for intercept.

edgectl intercept list

List the current active intercepts.

edgectl intercept add

Add an intercept. The basic format of this command is:

• DEPLOYMENT specifies a Kubernetes deployment with a traffic agent installed. You can get the list of available deployments with the intercept available command.
• --name or -n specifies a name for an intercept.
• --target or -t specifies the target of an intercept. Typically, this is a service running in the local environment that is a virtual replacement for the deployment in the cluster.
• --match or -m specifies a match rule on requests. Requests that are sent to the traffic agent that match this rule will be routed to the target.

A few other options to intercept include:

• --namespace to specify the Kubernetes namespace in which to create a mapping for intercept
• --prefix or -p which specifies a prefix to intercept (the default is /)

Example

Intercept all requests to the hello deployment that match the HTTP x-dev header with a value of jane to a service running locally on port 9000:

edgectl pause

Pause the daemon. The network overrides used by the edgectl daemon are temporarily disabled. Typically, this is used for connecting with a VPN that is not compatible with Edge Control.

edgectl quit

Quit the daemon. Ensure that the daemon has quit prior to upgrades.

edgectl resume

Resume the daemon. Used after edgectl pause.

edgectl status

Print the status of Edge Control, including the Kubernetes context that is currently being used.

Usage: Outbound Services

1. Starting with an empty cluster, add the simple microservice from above.

2. Use Edge Control to set up outbound connectivity to your cluster.

You are now able to connect to services directly from your laptop, as demonstrated by the curl command above.

3. When you’re done working with this cluster, disconnect.

Usage: Intercept

1. Install the traffic manager in your cluster and the traffic agent in the simple microservice as described above.

2. Launch a local service on your laptop. If you were debugging the hello service, you might run a local copy in your debugger. In this example, we will start an arbitrary service on port 9000.

3. Connect to the cluster to set up outbound connectivity and check that you can access the hello service in the cluster with curl.

4. Set up an intercept. In this example, we’ll capture requests that have the x-dev header set to $USER.

As you can see, the second request, which includes the specified x-dev header, is served by the local server.

5. Next, remove the intercept to restore normal operation.

Requests are no longer intercepted.

What's Next?

Multiple intercepts of the same deployment can run at the same time too. You can direct them to the same machine, allowing you to “or” together intercept conditions. Also, multiple developers can intercept the same deployment simultaneously. As long as their match patterns don’t collide, they don’t need to worry about disrupting one another.