Topology Updater

Reminder !!

• Since the network has to get along without the P2P network module for the time being, it needs static topology files. This "TopologyUpdater" service, which is far from being perfect due to its centralization factor, is intended to be a temporary solution to allow everyone to activate their relay nodes without having to postpone and wait for manual topology completion requests.
• You should NOT set up topologyUpdater for your block producing nodes.

The topologyUpdater shell script must be executed on the relay node as a cronjob exactly every 60 minutes. After 4 consecutive requests (3 hours) the node is considered a new relay node in listed in the topology file. If the node is turned off, it's automatically delisted after 3 hours.

Download and Configure

If you have run guild-deploy.sh, this should already be available in your scripts folder and make this step unnecessary.

Before the updater can make a valid request to the central topology service, it must query the current tip/blockNo from the well-synced local node. It connects to your node through the configuration in the script as well as the common env configuration file. Customize these files for your needs.

To download topologyUpdater.sh manually, you can execute the commands below and test executing Topology Updater once (it's OK if first execution gives back an error):

cd $CNODE_HOME/scripts
curl -s -o topologyUpdater.sh https://raw.githubusercontent.com/cardano-community/guild-operators/master/scripts/cnode-helper-scripts/topologyUpdater.sh
curl -s -o env https://raw.githubusercontent.com/cardano-community/guild-operators/master/scripts/cnode-helper-scripts/env
chmod 750 topologyUpdater.sh
./topologyUpdater.sh

Examine and modify the variables within topologyUpdater.sh script

Out of the box, the scripts might come with some assumptions, that may or may not be valid for your environment. One of the common changes as an SPO would be to the complete CUSTOM_PEERS section as below to include your local relays/BP nodes (described in the How do I add my own nodes section), and any additional peers you'd like to be always available at minimum. Please do take time to update the variables in User Variables section in env & topologyUpdater.sh:

### topologyUpdater.sh

######################################
# User Variables - Change as desired #
######################################

CNODE_HOSTNAME="CHANGE ME"                                # (Optional) Must resolve to the IP you are requesting from
CNODE_VALENCY=1                                           # (Optional) for multi-IP hostnames
MAX_PEERS=15                                              # Maximum number of peers to return on successful fetch
#CUSTOM_PEERS="None"                                      # Additional custom peers to (IP,port[,valency]) to add to your target topology.json
                                                          # eg: "10.0.0.1,3001|10.0.0.2,3002|relays.mydomain.com,3003,3"
#BATCH_AUTO_UPDATE=N                                      # Set to Y to automatically update the script if a new version is available without user interaction

Any customisations you add above, will be saved across future guild-deploy.sh executions, unless you specify the -f flag to overwrite completely.

Deploy the script

systemd service
The script can be deployed as a background service in different ways but the recommended and easiest way if guild-deploy.sh was used, is to utilize the deploy-as-systemd.sh script to setup and schedule the execution. This will deploy both push & fetch service files as well as timers for a scheduled 60 min node alive message and cnode restart at the user set interval (default: 24 hours) when running the deploy script.

• cnode-tu-push.service : pushes a node alive message to Topology Updater API
• cnode-tu-push.timer : schedules the push service to execute once every hour
• cnode-tu-fetch.service : fetches a fresh topology file before the cnode.service file is started/restarted
• cnode-tu-restart.service : handles the restart of cardano-node (cnode.sh)
• cnode-tu-restart.timer : schedules the cardano-node restart service, default every 24h

systemctl list-timers can be used to to check the push and restart service schedule.

crontab job
Another way to deploy the topologyUpdater.sh script is as a crontab job. Add the script to be executed once per hour at a minute of your choice (eg xx:25 o'clock in the example below). The example below will handle both the fetch and push in a single call to the script once an hour. In addition to the below crontab job for topologyUpdater, it's expected that you also add a scheduled restart of the relay node to pick up a fresh topology file fetched by topologyUpdater script with relays that are alive and well.

25 * * * * /opt/cardano/cnode/scripts/topologyUpdater.sh

Logs

You can check the last result of push message in logs/topologyUpdater_lastresult.json.
If deployed as systemd service, use sudo journalctl -u <service> to check output from service.

If one of the parameters is outside the allowed ranges, invalid or missing the returned JSON will tell you what needs to be fixed.

Don't try to execute the script more often than once per hour. It's completely useless and may lead to a temporary blacklisting.

Why does my topology file only contain IOG peers?

Each subscribed node (4 consecutive requests) is allowed to fetch a subset of other nodes to prove loyalty/stability of the relay. Until reaching this point, your fetch calls will only return IOG peers combined with any custom peers added in USER VARIABLES section of topologyUpdater.sh script

The engineers of cardano-node network stack suggested to use around 20 peers. More peers create unnecessary and unwanted system load and delays.

In its default setting, topologyUpdater returns a list of 15 remote peers.

Note that the change in topology is only effective upon restart of your node. Make sure you account for some scheduled restarts on your relays, to help onboard newer relays onto the network (as described in the systemd section).

How do I add my own relays/static nodes in addition to dynamic list generated by topologyUpdater?

Most of the Stake Pool Operators may have few preferences (own relays, close friends, etc) that they would like to add to their topology by default. This is where the CUSTOM_PEERS variable in topologyUpdater.sh comes in. You can add a list of peers in the format of: hostname/IP:port[:valency] here and the output topology.json formed will already include the custom peers that you supplied. Every custom peer is defined in the form [address]:[port] and optional :[valency] (if not specified, the valency defaults to 1). Multiple custom peers are separated by |. An example of a valid CUSTOM_PEERS variable would be:

CUSTOM_PEERS="foo.bar.io,3001,2|198.175.21.197,6001|36.233.3.89,6000

The list above would add three custom peers with the specified addresses and ports, with the first one additionally specifying the optional valency parameter (in this case 2).

How are the peers for my topology file selected?

We calculate the distance on the Earth's surface from your node's IP to all subscribed peers. We then order the peers by distance (closest first) and start by selecting one peer. We then skip some, pick the next, skip, pick, skip, pick ... until we reach the end of the list (furthest away). The number of skipped records is calculated in a way to have the desired number of peers at the end.

Every requesting node has its personal distance to all other nodes.

We assume this should result in a well-distributed and interconnected peering network.