Add --capacity-multiplier option to SimLN plugin for random activity #729

b-l-u-e · 2025-07-25T13:14:44Z

This PR adds support for the --capacity-multiplier option to the SimLN plugin, addressing issue #721. This option allows users to scale payment amounts based on channel capacity for more realistic Lightning Network simulations.

Changes Made

Core Implementation

resources/plugins/simln/plugin.py: Added CAPACITY_MULTIPLIER enum and --capacity-multiplier CLI option
resources/plugins/simln/charts/simln/values.yaml: Added Helm chart configuration for capacity multiplier
resources/plugins/simln/README.md: Updated documentation with usage examples

Testing

test/plugin_test.py: Updated integration test for capacity multiplier functionality

Testing

✅ New capacity multiplier functionality tested

Files Changed

resources/plugins/simln/plugin.py
resources/plugins/simln/charts/simln/values.yaml
resources/plugins/simln/README.md
test/plugin_test.py

Closes #721

bdp-DrahtBot · 2025-07-25T18:54:11Z

The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

Conflicts

Reviewers, this pull request conflicts with the following ones:

#732 (Improve installation docs by cndolo)

If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

pinheadmz

This is not working as expected and the test, which seems to pass, does not cover an increase in simln activity due to a multiplier being set.

The expected behavior can be produced (for testing purposes) by removing the activity from network.yaml (to force simln to generate random activity):

diff --git a/test/data/network_with_plugins/network.yaml b/test/data/network_with_plugins/network.yaml
index 6e4d64a3..98228473 100644
--- a/test/data/network_with_plugins/network.yaml
+++ b/test/data/network_with_plugins/network.yaml
@@ -69,7 +69,6 @@ plugins:  # Each plugin section has a number of hooks available (preDeploy, post
       helloTo: "postDeploy!"
     simln:  # You can have multiple plugins per hook
       entrypoint: "../../../resources/plugins/simln"
-      activity: '[{"source": "tank-0003-ln", "destination": "tank-0005-ln", "interval_secs": 1, "amount_msat": 2000}]'
   preNode:  # preNode plugins run before each node is deployed
     hello:
       entrypoint: "../plugins/hello"

Normal simln log:

Starting activity producer for tank-0003-ln(035f94...af68f9):
 activity generator for capacity: 50000000 with multiplier 2:
 26.31578947368421 payments per month (0.03654970760233918 per hour).
Starting activity producer for tank-0004-ln(0215a7...86a6f9):
 activity generator for capacity: 75000000 with multiplier 2:
 39.473684210526315 payments per month (0.05482456140350877 per hour).
Starting activity producer for tank-0005-ln(026c9d...73cadb):
 activity generator for capacity: 25000000 with multiplier 2:
 13.157894736842104 payments per month (0.01827485380116959 per hour).

... and then hard-code the multiplier value and restart:

diff --git a/resources/plugins/simln/charts/simln/templates/pod.yaml b/resources/plugins/simln/charts/simln/templates/pod.yaml
index 69790c9e..2aa8eca0 100644
--- a/resources/plugins/simln/charts/simln/templates/pod.yaml
+++ b/resources/plugins/simln/charts/simln/templates/pod.yaml
@@ -37,6 +37,7 @@ spec:
         - >
           cd /working;
           sim-cli
+          --capacity-multiplier=10000
       volumeMounts:
         - name: {{ .Values.workingVolume.name }}
           mountPath: {{ .Values.workingVolume.mountPath }}

Simln log with multiplier applied:

Starting activity producer for tank-0003-ln(03ea88...184e48):
 activity generator for capacity: 50000000 with multiplier 10000:
 131578.94736842104 payments per month (182.7485380116959 per hour).
Starting activity producer for tank-0004-ln(038fae...5d1ac3):
 activity generator for capacity: 75000000 with multiplier 10000:
 197368.42105263157 payments per month (274.12280701754383 per hour).
Starting activity producer for tank-0005-ln(023768...c1ad57):
 activity generator for capacity: 25000000 with multiplier 10000:
 65789.47368421052 payments per month (91.37426900584795 per hour).

pinheadmz · 2025-07-28T20:15:49Z

resources/plugins/simln/plugin.py

+        # Execute sim-cli with capacity multiplier if provided
+        if capacity_multiplier is not None:
+            # Wait for the main container to be ready
+            time.sleep(5)  # Give the container time to start
+            # Execute the command with capacity multiplier
+            _sh(
+                name,
+                "sh",
+                ("-c", f"cd /working && sim-cli --capacity-multiplier {capacity_multiplier}"),
+            )


I'm pretty sure this is going to start a second simln process inside the container which is undesirable. There is probably a better way to pass the parameter to the primary process of the container that is all helm stuff and doesn't need any python at all (i.e. add it to spec.containers.args in simln pod.yaml.

Or if you wanna stay in python you can probably just add the value to the sim.json that already configures the desired simln activity.

pinheadmz · 2025-07-28T20:16:22Z

resources/plugins/simln/plugin.py

@@ -42,6 +42,7 @@ class PluginError(Exception):

 class PluginContent(Enum):
    ACTIVITY = "activity"
+    CAPACITY_MULTIPLIER = "capacity_multiplier"


I think you meant this, because this would be the name of the field in the yaml examples?

Suggested change

CAPACITY_MULTIPLIER = "capacity_multiplier"

CAPACITY_MULTIPLIER = "capacityMultiplier"

pinheadmz · 2025-07-28T20:18:26Z

test/plugin_test.py

@@ -94,6 +95,36 @@ def assert_hello_plugin(self):
        wait_for_pod("tank-0005-post-hello-pod")
        wait_for_pod("tank-0005-pre-hello-pod")

+    def test_capacity_multiplier_option(self):


try testing the multiplier from the network.yaml file instead of using the plugin's commands. Personally I think giving plugins CLI commands like launch-activity was a mistake 🤷 At this point the plugin should already be running.

pinheadmz · 2025-07-28T20:20:10Z

resources/plugins/simln/README.md

      activity: '[{"source": "tank-0003-ln", "destination": "tank-0005-ln", "interval_secs": 1, "amount_msat": 2000}]'
-````
+      capacity_multiplier: 2.5 # Optional: Capacity multiplier for random activity


or is it capacityMultiplier ?

pinheadmz · 2025-07-28T20:21:31Z

resources/plugins/simln/plugin.py

+    if capacity_multiplier is not None:
+        command += f" --set capacityMultiplier={capacity_multiplier}"


not sure what this is for, you are reading a value from the network.yaml file but then also setting it using helm? (well, reading a snake_case value but then setting a camelCase so its confusing...)

b-l-u-e · 2025-07-30T14:49:38Z

Thank you for the review I will work on the changes

b-l-u-e closed this Jul 25, 2025

b-l-u-e deleted the feat/simln-capacity-multiplier branch July 25, 2025 13:18

b-l-u-e restored the feat/simln-capacity-multiplier branch July 25, 2025 14:00

b-l-u-e reopened this Jul 25, 2025

b-l-u-e force-pushed the feat/simln-capacity-multiplier branch from 4584c4e to ea0c739 Compare July 25, 2025 14:37

bdp-DrahtBot mentioned this pull request Jul 25, 2025

Improve installation docs #732

Merged

pinheadmz requested changes Jul 28, 2025

View reviewed changes

b-l-u-e force-pushed the feat/simln-capacity-multiplier branch from ea0c739 to 8dad44b Compare July 30, 2025 20:35

feat: add --capacity-multiplier option to simln plugin

ab9aed1

b-l-u-e force-pushed the feat/simln-capacity-multiplier branch from 8dad44b to ab9aed1 Compare July 30, 2025 20:52

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	CAPACITY_MULTIPLIER = "capacity_multiplier"
	CAPACITY_MULTIPLIER = "capacityMultiplier"

		if capacity_multiplier is not None:
		command += f" --set capacityMultiplier={capacity_multiplier}"

Add --capacity-multiplier option to SimLN plugin for random activity #729

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b-l-u-e commented Jul 25, 2025

Changes Made

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