controls worker authentication within concourse

by stuckincustoms

TSA is the new way of allowing workers to join a Concourse deployment. It provides authentication and transport encryption (if required). Worker machines can ssh into TSA with a custom command to register or have traffic forwarded to them. Once an SSH session has been established then TSA begins to automatically heartbeat information about the worker into the ATC's pool.

The main advantage that this provides over the old style of registration is that Workers no longer need to be internet routable in order to have the ATC reach them. They open a reverse tunnel through the TSA which, when collocated with ATC, is far more likely to be easily routable. This also allows for simpler setup and better security as before you either had to expose your Garden server publicly or set up some interesting custom security if the workers and ATC were not in the same private network.

First, create two new SSH keys:

$ ssh-keygen -t rsa -f host_key
$ ssh-keygen -t rsa -f worker_key

Next, let's create an authorized keys file so that our workers are able to authenticate with us without providing a password:

cat worker_key.pub > authorized_keys

Now to start tsa itself:

tsa -forwardHost=$FORWARD_HOST \
      -hostKey=host_key \
      -authorizedKeys=authorized_keys \
      -heartbeatInterval=30s \
      -atcAPIURL=http://$USERNAME:$PASSWORD@$ATC_HOST:$ATC_PORT

The variables here should be set to:

In order to have a worker on the local network register with tsa you can run the following command:

ssh -p 2222 $TSA_HOST \
      -i worker_key \
      -o UserKnownHostsFile=host_key.pub \
      register-worker \
      < worker.json

The worker.json file should contain the following:

{
    "platform": "linux",
    "tags": [],
    "addr": "$GARDEN_ADDR",
    "resource_types": []
}

This should be set to whatever you want to advertise

The variables here should be set to:

In order to have a worker on a remote network register with tsa and have it's traffic forwarded you can run the following command:

ssh -p 2222 $TSA_HOST \
      -i worker_key \
      -o UserKnownHostsFile=host_key.pub \
      -R0.0.0.0:0:$GARDEN_ADDR \
      forward-worker \
      < worker.json

The worker.json file should contain the following:

{
    "platform": "linux",
    "tags": [],
    "resource_types": []
}

This should be set to whatever you want to advertise

The variables here should be set to: