feat: service restart support for file config plugin by albinsuresh · Pull Request #3931 · thin-edge/thin-edge.io

albinsuresh · 2026-01-15T18:15:12Z

Proposed changes

extract system_services module from tedge into a standalone crate to use from the plugin
service restart support for file config plugin
update config_update workflow with granular operation steps
handle plugins restarting the tedge-agent itself
~~how to detect a "reload" when service action is reload instead if restart~~ to be handled using dedicated plugins as a generic logic in the file plugin is not possible

Types of changes

Bugfix (non-breaking change which fixes an issue)
New feature (non-breaking change which adds functionality)
Improvement (general improvements like code refactoring that doesn't explicitly fix a bug or add any new functionality)
Documentation Update (if none of the other choices apply)
Breaking change (fix or feature that would cause existing functionality to not work as expected)

Paste Link to the issue

Checklist

I have read the CONTRIBUTING doc
I have signed the CLA (in all commits with git commit -s. You can activate automatic signing by running just prepare-dev once)
I ran just format as mentioned in CODING_GUIDELINES
I used just check as mentioned in CODING_GUIDELINES
I have added tests that prove my fix is effective or that my feature works
I have added necessary documentation (if appropriate)

Further comments

codecov · 2026-01-15T18:27:21Z

Codecov Report

❌ Patch coverage is 42.24000% with 361 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...rates/extensions/tedge_config_manager/src/actor.rs	27.66%	176 Missing and 7 partials ⚠️
...ates/extensions/tedge_config_manager/src/plugin.rs	16.12%	49 Missing and 3 partials ⚠️
plugins/tedge_file_config_plugin/src/lib.rs	60.43%	34 Missing and 2 partials ⚠️
plugins/tedge_file_config_plugin/src/bin.rs	8.57%	31 Missing and 1 partial ⚠️
crates/extensions/tedge_config_manager/src/lib.rs	15.78%	15 Missing and 1 partial ⚠️
crates/core/tedge/src/cli/common.rs	0.00%	12 Missing ⚠️
.../core/tedge_agent/src/operation_workflows/actor.rs	0.00%	7 Missing and 1 partial ⚠️
...ates/extensions/tedge_config_manager/src/config.rs	0.00%	7 Missing ⚠️
crates/core/tedge/src/cli/connect/command.rs	0.00%	4 Missing ⚠️
crates/core/tedge/src/main.rs	0.00%	0 Missing and 3 partials ⚠️
... and 7 more

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github-actions · 2026-01-15T18:51:07Z

Robot Results

✅ Passed	❌ Failed	⏭️ Skipped	Total	Pass %	⏱️ Duration
863	0	3	863	100	2h41m5.955277s

didier-wenzek

Approved

reubenmiller · 2026-01-19T16:14:11Z

A few missing pieces/open questions:

Missing log statements that the service is being restarted. No logs were present in the tedge-agent logs nor the workflow log (/var/log/tedge/agent/*.log)
What happens if the "tedge-agent" is used in the service property? does this break the workflow? If so, then we might need to use the background action perform the restart of the tedge-agent

albinsuresh · 2026-01-21T09:18:14Z

+on_success = "apply"
+
+[apply]
+background_script = "sudo /usr/share/tedge/config-plugins/file apply ${.payload.type}"


Even when we convert this step into a builtin task, this plugin apply command should be executed as a background task, irrespectve of the type of the config and whethere that type restarts tedge-agent or not. That'll smplify this workflow.

Though the downside of doing the background task is that the "verify" state will be executed before the "apply" command is done.

Since we have a workdir available (introduced in 55c2d76), how about using that in the apply state to write a "completion marker file" to that directory, which the verify phase can check for afterwards with a timeout? We just need to formalize the "completion marker file" contract.

Though can't we just tell people not to restart the tedge-agent from within a plugin? And if they want to restart a service then pass back some data via the workflow state exchange mechanism (e.g. :::begin-tedge:::)?

And if they want to restart a service then pass back some data via the workflow state exchange mechanism (e.g. :::begin-tedge:::)?

Yeah, I had considered that option. But, these are the reasons why I tried to avoid this "restart request" exchange from the plugin to the agent via the command state:

We'll have to introduce yet another state after apply for the the agent to receive the restart request from the plugin, and then process it by restarting the agent. It feels like an optional state in the workflow only there for once specific case (the agent restart).

We'll be exposing the workflow state update contract (:::begin-tedge::: and :::begin-tedge:::) with the plugin, which was otherwise unaware of the workflow contracts. That's why I was looking for a simple file-system based contract via the workdir.

Consistency in the sense that they don't need to care if they are restarting the agent or any other service and don't need to do things differently for one vs the other. It would have been different if all service restarts were done by the agent. But since the agent running as tedge can't do that, it brings that inconsistency. Though, we can get arround this problem by making the agent use tedgectl.

But, I agree that this workdir approach introduces yet another mechanism for metdata exchange between states, when the MQTT state is already available. I thought this would be less of a problem as the workdir would anyway be used for config backups and even other things like service restart detection using persisted metadata(pids). So, this would be just one additional thing to that list.

Resolved by 7b83421

We decided to explore a more flexible design, using workflows.

didier-wenzek · 2026-03-02T16:26:40Z

+    #[error("A shutdown has been requested")]
+    Shutdown,


This doesn't look like an error.

Suggested change

#[error("A shutdown has been requested")]

Shutdown,

#[error("A restart is required: not running latest version and configuration ")]

RestartRequired,

reubenmiller

I ran into an issue when trying to trigger a tedge-agent restart after applying a new tedge.toml file, but the operation fails for some reason, this line was found in the operation log at least:

ERROR: builtin action 'builtin:config_update:verify' failed: No builtin operation step handler registered for config_update operation verify step

Below is tedge-configuration-plugin.toml that I configured in my test:

file: /etc/tedge/plugins/tedge-configuration-plugin.toml

files = [
    { path = '/etc/tedge/system.toml', type = 'system.toml', service = 'tedge-agent' },
    { path = '/etc/tedge/tedge.toml', type = 'tedge.toml', service = 'tedge-agent' },
    { path = '/etc/lighttpd/lighttpd.conf', type = 'lighttpd-conf', service = 'lighttpd', service_action = 'restart' }
]

And the full operation log of the failed operation:
TST_actualize_shiny_bend_workflow-config_update-c8y-mapper-53005959.log

albinsuresh · 2026-03-11T17:29:21Z

tedge-configuration-plugin.toml

The issue was caused by using a tedge.toml that was intentionally or unintentionally disabling the config management feature of the tedge-agent with the following setting in it:

[agent.enable]
config_snapshot = false

So, the config manager actor did the first part of the config update until the agent restart, but could not resume it post-restart as the actor itself is not present.

That single config_snapshot flag determines whether the config manager actor is loaded or not. We should fix that logic to check both config_snapshot && config_update.

albinsuresh · 2026-03-12T09:51:42Z

tedge-configuration-plugin.toml

The issue was caused by using a tedge.toml that was intentionally or unintentionally disabling the config management feature of the tedge-agent with the following setting in it:
[agent.enable]
config_snapshot = false
So, the config manager actor did the first part of the config update until the agent restart, but could not resume it post-restart as the actor itself is not present.

That single config_snapshot flag determines whether the config manager actor is loaded or not. We should fix that logic to check both config_snapshot && config_update.

Resolved by 945642f

albinsuresh · 2026-03-12T10:18:39Z

    ...    tedge.toml
    ...    tedge-log-plugin

+Config update restarts service if configured in plugin configuration


To be removed, as I can't remember why I added this back then and the Set Configuration Should Restart Service test above covers what was intended anyway.

reubenmiller

The problem I ran into earlier has been resolved, and it's working nicely now. There is a related followup action tracked in #4000, but as of now the PR is working as expected.

didier-wenzek

Approved. Thank you for you perseverance on this long standing work.

I really like the new design for the communications between the workflow engine and an operation actor.

This has also been an opportunity to fix a hack used to request an agent restart.

didier-wenzek · 2026-03-16T10:21:37Z

                        // Make sure the operation status is properly reported before the restart
                        tokio::time::sleep(Duration::from_secs(5)).await;
-                        return Err(RuntimeError::ActorError(Box::new(SoftwareManagerError::NotRunningLatestVersion)));
+                        return Err(RuntimeError::RestartRequired);


Good point.

The plugin now accepts the following sub-commands: - `prepare`: No-op - `apply`: Restarts the associated service if configured - `verify`: Checks if the associated service is running - `finalize`: No-op - `rollback`: No-op

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albinsuresh marked this pull request as ready for review January 15, 2026 20:08

albinsuresh requested review from a team, didier-wenzek, jarhodes314, reubenmiller and rina23q as code owners January 15, 2026 20:08

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reubenmiller reviewed Jan 16, 2026

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Comment thread crates/common/tedge_system_services/src/services.rs Outdated

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Comment thread plugins/tedge_file_config_plugin/src/config.rs

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reubenmiller added the theme:configuration Theme: Configuration management label Jan 19, 2026

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albinsuresh added 10 commits March 17, 2026 14:51

refactor: extract system_services module into standalone crate

5000c5f

feat: service restart support for file config plugin

e0f8c60

poc: composite config update workflow representation

af96b18

poc: prepare and finalize states

c6b0e48

feat: granular config_update workflow

e0dd2cd

feat: granular subcommands for file config plugin

2551638

The plugin now accepts the following sub-commands: - `prepare`: No-op - `apply`: Restarts the associated service if configured - `verify`: Checks if the associated service is running - `finalize`: No-op - `rollback`: No-op

feat: restart-agent builtin action

133c0ca

feat: config plugin signal agent restart via output

5cb5e3d

fix: reduce config_update workflow states

e1917db

fix: handle partial disabling of config snapshot or update operation

ab35950

albinsuresh force-pushed the feat/file-config-plugin-service-restart branch from 945642f to ab35950 Compare March 17, 2026 15:23

albinsuresh temporarily deployed to Test Pull Request March 17, 2026 15:23 — with GitHub Actions Inactive

albinsuresh temporarily deployed to Test Auto March 17, 2026 15:32 — with GitHub Actions Inactive

albinsuresh added this pull request to the merge queue Mar 17, 2026

Merged via the queue into thin-edge:main with commit 853fb00 Mar 17, 2026
34 checks passed

albinsuresh deleted the feat/file-config-plugin-service-restart branch March 18, 2026 05:24

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