> For the complete documentation index, see [llms.txt](https://developer.harness.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.harness.io/harness-platform/use-harness-platform/triggers/trigger-pipelines-on-new-helm-chart.md).

# Trigger pipelines on new Helm chart

You can trigger Harness pipelines in response to a new Helm chart version being added to an HTTP Helm repo. For example, every time a new Helm chart is pushed to an HTTP Helm repo, it triggers a CD pipeline that deploys it automatically.

A Helm chart trigger is a simple way to automate deployments for new Helm charts.

{% hint style="info" %}
Currently, this feature is behind the feature flag `CD_TRIGGERS_REFACTOR`. Contact [Harness Support](mailto:support@harness.io) to enable it.
{% endhint %}

***

### What you will learn in this topic <a href="#what-you-will-learn-in-this-topic" id="what-you-will-learn-in-this-topic"></a>

By the end of this topic, you will be able to:

* Understand [how Helm chart triggers work](#how-helm-chart-triggers-work).
* [Create a Helm chart trigger](#create-a-helm-chart-trigger) through the Configuration, Conditions, and Pipeline Input steps.
* [Test the trigger](#test-the-trigger) by pushing a new chart version, and [enable or disable](#enable-or-disable-a-trigger) it.

***

### Before you begin <a href="#before-you-begin" id="before-you-begin"></a>

Before you create a Helm chart trigger, ensure you have the following:

* **A Harness CD pipeline for Helm charts**: An existing pipeline that deploys a Helm chart. Go to the [Helm chart deployment tutorial](/continuous-delivery/use-continuous-delivery/deploy-services-on-different-platforms/helm/helm-cd-quickstart.md) for more information on building one.

***

### How Helm chart triggers work <a href="#how-helm-chart-triggers-work" id="how-helm-chart-triggers-work"></a>

When you add a Helm chart trigger to a pipeline, you tell Harness which Helm chart to listen on for changes. When a new version of the Helm chart is added in its repo, Harness initiates the trigger and the pipeline is executed.

Typically, you add a Helm chart trigger to a pipeline that deploys the same Helm chart. The Helm chart is added to the CD stage in the pipeline, as part of the Harness Service **Manifest**, and the same Helm chart is added to the trigger. However, the Helm chart you specify in the trigger does not have to be used in the pipeline:

* A change in a Helm chart can trigger any pipeline, even one that does not deploy a Helm chart.
* A change in a Helm chart can trigger a pipeline that deploys a different Helm chart.

#### Chart polling <a href="#chart-polling" id="chart-polling"></a>

After you create a trigger to listen for new Helm chart versions, Harness polls for new charts continuously. Polling is immediate because Harness uses a perpetual task framework that constantly monitors for new versions.

Harness looks at what has changed in the repo to determine if a new chart version has been added. If Harness detects a change, it initiates the trigger.

#### Chart versions in artifacts <a href="#chart-versions-in-artifacts" id="chart-versions-in-artifacts"></a>

When you add the Helm chart to Harness as a manifest, you have different options for the **Chart Version**.

<figure><img src="/files/LCuzTgB9C6Ga8YKUhlgA" alt=""><figcaption><p>Click to view full size image</p></figcaption></figure>

* **Fixed Value**: If you use a [fixed value](/harness-platform/use-harness-platform/variables-and-expressions/runtime-inputs.md) for **Chart Version** (for example, `0.1.4`), Helm chart triggers work, but Harness does not select the latest chart version. Instead, Harness selects the hardcoded chart version in **Chart Version** (`0.1.4`).
* **Runtime Input**: If you use a [runtime input](/harness-platform/use-harness-platform/variables-and-expressions/runtime-inputs.md) for **Chart Version**, you can enter the version to use in your trigger as part of the **Trigger Pipeline Inputs**. Go to [Pipeline Input](#pipeline-input) below.
* **Expression**: If you use an [expression](/harness-platform/use-harness-platform/variables-and-expressions/runtime-inputs.md) for **Chart Version**, you can:
  * Use a [Harness variable expression](/harness-platform/use-harness-platform/variables-and-expressions/harness-variables.md), such as a Service variable.
  * Use the expression `<+trigger.manifest.version>` to pass in the new chart version that initiated the trigger as the version to deploy.

{% hint style="info" %}
Harness variable expressions are not supported in triggers for pipeline or stage variables.
{% endhint %}

***

### Create a Helm chart trigger <a href="#create-a-helm-chart-trigger" id="create-a-helm-chart-trigger"></a>

Typically, you add a Helm chart trigger to a pipeline that deploys a Helm chart, where the Helm chart is added to the CD stage as part of the Harness Service **Manifest**. The trigger wizard walks you through three steps in order: **Configuration**, **Conditions**, and **Pipeline Input**.

To open the trigger:

1. Select a Harness pipeline that includes a Helm chart in the stage's **Service Definition**.

   <figure><img src="/files/gYko6DBHTvLxTJxPLjWy" alt=""><figcaption><p>Click to view full size image</p></figcaption></figure>

   Go to the [Helm chart deployment tutorial](/continuous-delivery/use-continuous-delivery/deploy-services-on-different-platforms/helm/helm-cd-quickstart.md) for more information on adding Helm charts to a stage's **Service Definition**.
2. Select **Triggers**.
3. Click **New Trigger**.
4. Select the **Helm Chart** trigger listed under **Manifest**. The **On New Manifest** trigger opens on the **Configuration** step.

#### Configuration <a href="#configuration" id="configuration"></a>

1. Enter a **Name** for the trigger. **Description** and **Tags** are optional.
2. In **Listen on New Manifest**, select **Define Manifest Source**.
3. In **Specify Helm Chart Store**, select the store type:

   * **HTTP Helm**: Go to the [HTTP Helm repo connector settings reference](/harness-platform/use-harness-platform/connectors/code-repositories/ref-source-repo-provider/http-helm-repo-connector-settings-reference.md) for more information on HTTP Helm connectors.
   * **S3**: Go to the [AWS connector settings reference](/harness-platform/use-harness-platform/connectors/cloud-providers/ref-cloud-providers/aws-connector-settings-reference.md) for more information on AWS connectors.
   * **Google Cloud Storage**: Go to the [Google Cloud Platform (GCP) connector settings reference](/harness-platform/use-harness-platform/connectors/cloud-providers/ref-cloud-providers/gcs-connector-settings-reference.md) for more information on GCS connectors.

   <div data-gb-custom-block data-tag="hint" data-style="info" class="hint hint-info"><p>You cannot use <a href="/pages/odjnwzskMFglDpaw1VSJ">OCI Helm registries</a> with Helm chart triggers.</p></div>
4. Create or select a connector for the store, and then click **Continue**.
5. In **Manifest Details**, enter the name of the Helm chart to listen on in **Chart Name**, for example, `nginx` or `etcd`. The exact **Manifest Details** fields depend on the Helm chart store you selected.
6. In **Helm Version**, select the version of Helm your repo uses.

   <figure><img src="/files/HZOIRUNOTQVzAGw7kqIW" alt=""><figcaption><p>Click to view full size image</p></figcaption></figure>
7. Click **Submit** to add the Helm chart to the trigger. Harness now polls that Helm chart for changes.
8. Click **Continue** to move to the **Conditions** step.

#### Conditions (optional) <a href="#conditions-optional" id="conditions-optional"></a>

The **Conditions** step is optional. Specify the conditions for running the pipeline, for example, when the manifest version matches a value or pattern.

1. To add a condition, set the **Manifest/Package Version**: select an operator and enter a value to match.
2. Click **Continue** to move to the **Pipeline Input** step.

**Regex and wildcards**

You can use wildcards in the condition's value, and you can select **Regex**.

For example, if the build is `todolist-v2.0`:

* With Regex not selected, both `todolist*` or `*olist*` match.
* With Regex selected, the regex `todolist-v\d.\d` matches.

If the regex expression does not result in a match, Harness ignores the value.

Harness supports standard Java regex. For example, if Regex is enabled and the intent is to match a filename, the wildcard should be `.*` instead of simply a wildcard `*`. To match all of the files that end in `-DEV.tgz`, enter `.*-DEV\.tgz`.

#### Pipeline Input <a href="#pipeline-input" id="pipeline-input"></a>

1. Select the **Pipeline Stages** to run, and provide values for any runtime inputs. If your pipeline uses [runtime inputs](/harness-platform/use-harness-platform/variables-and-expressions/runtime-inputs.md) or [input sets](/harness-platform/use-harness-platform/pipelines/input-sets.md), you can select the inputs to use when the trigger executes the pipeline.

   <figure><img src="/files/Gfh9a8ToWWzd0EWADZso" alt=""><figcaption><p>Click to view full size image</p></figcaption></figure>
2. Click **Create Trigger**. The new trigger is listed.

***

### Test the trigger <a href="#test-the-trigger" id="test-the-trigger"></a>

After the trigger is created and the pipeline runs using it, in **Deployments**, you can see the trigger and the user who initiated the deployment.

<figure><img src="/files/2AT1G81pKSeuD7ATZkVx" alt=""><figcaption><p>Click to view full size image</p></figcaption></figure>

If you look at the trigger in your pipeline again, you can see its activation records, which are also available in the trigger details.

You can test the trigger by pushing a new chart version to your Helm chart registry. You can use [Harness CI](/continuous-integration/new-to-harness-ci/overview.md) to build and push to your registry.

The following is a simple cURL example using a Nexus repo that works as a Helm chart HTTP server.

Add the repo:

```
helm repo \
add nexus_http \
https://nexus3.dev.example.io/repository/<repo_name>/ \
--username '<username>' --password '<password>'
```

Fetch the chart:

```
helm fetch nexus_http/<chart_name>
```

Next, update the version in your chart.

Package the chart:

```
helm package <filename>
```

Push the new version to the Helm HTTP server:

```
curl -u <username>:<password> \
https://nexus3.dev.example.io/repository/<repo_name>/ \
--upload-file <chart_name>-<chart_version>.tgz \
-v
```

Your Helm chart HTTP server now has the new version of the Helm chart.

***

### Enable or disable a trigger <a href="#enable-or-disable-a-trigger" id="enable-or-disable-a-trigger"></a>

Use the **Enabled** toggle at the top of the trigger to enable or disable it.

***

### Reuse trigger YAML to create new triggers <a href="#reuse-trigger-yaml-to-create-new-triggers" id="reuse-trigger-yaml-to-create-new-triggers"></a>

Reuse triggers by copying and pasting trigger YAML. This is helpful when you have advanced conditions you do not want to set up each time.

<figure><img src="/files/sXkXEjrwDRym8hB3K34P" alt=""><figcaption><p>Click to view full size image</p></figcaption></figure>

{% hint style="info" %}
Trigger manifest expressions used in a pipeline are resolved when you rerun a pipeline that was activated by a trigger.
{% endhint %}

***

### Related articles <a href="#related-articles" id="related-articles"></a>

* [Schedule pipelines using triggers](/harness-platform/use-harness-platform/triggers/schedule-pipelines-using-cron-triggers.md): Schedule pipeline executions with cron triggers.
* [Trigger pipelines using Git events](/harness-platform/use-harness-platform/triggers/triggering-pipelines.md): Run pipelines in response to Git events.