> For the complete documentation index, see [llms.txt](https://docs.catalyx.solutions/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.catalyx.solutions/catalyx-blockchain-manager/hyperledger-fabric/version-2.4/network-and-node-management/chaincode-management.md).
# Chaincode Management
## What is Chaincode?
Chaincode is the smart contract of Hyperledger Fabric that handles the business logic of a particular application. It programmatically accesses two distinct pieces of the ledger — a blockchain that immutably records the history of all transactions, and a world state that holds a cache of the current value of these states.
Catalyst Blockchain Manager supports JavaScript, Golang, and Java for smart contract development.
### Key Concepts
**Endorsement:** Any transaction generated by the chaincode must be approved by specific organizations as defined by the endorsement policy.
**Valid Transactions:** Each peer completes validation in two phases:
1. Ensuring all parties mentioned in the endorsement policy have signed the transaction
2. Checking authenticity by matching the world state at signing time against the current state
**External Chaincodes:** With Hyperledger Fabric v2.0, chaincode can be added externally through a Docker image. Catalyst Blockchain Manager supports this — you simply reference your Docker image in an online repository.
***
## Chaincodes Lifecycle
Catalyst Blockchain Manager supports Hyperledger Fabric v2.0 capabilities with the following [chaincode lifecycle](https://hyperledger-fabric.readthedocs.io/en/release-2.2/chaincode_lifecycle.html#fabric-chaincode-lifecycle):
{% stepper %}
{% step %}
#### Add Chaincode Template
Create a Docker image and provide a link to the Docker repository when adding a chaincode template in Catalyst Blockchain Manager.
{% hint style="danger" %}
You need to add the required environment variables (`CHAINCODE_ID` and `CHAINCODE_ADDRESS`) to run chaincode in Catalyst Blockchain Manager. See [Create Your Application](file:///7571772/getting-started/create-your-application.md).
{% endhint %}
{% endstep %}
{% step %}
#### Install the Chaincode on Your Peers
Every organization that will use the chaincode to endorse a transaction or query the ledger needs to complete this step.
{% endstep %}
{% step %}
#### Approve a Chaincode Definition
Every organization that will use the chaincode needs to complete this step. The chaincode definition needs to be approved by a sufficient number of organizations to satisfy the channel's Lifecycle Endorsement policy.
{% endstep %}
{% step %}
#### Commit the Chaincode Definition
Once all necessary approvals are received, commit the definition to the channel.
{% endstep %}
{% endstepper %}
Organizations can also [upgrade](#how-to-upgrade-a-chaincode) and [delete](#how-to-remove-a-chaincode) a chaincode.
***
## How to Add a Chaincode in Catalyst Blockchain Manager?
Go to the **Chaincode** tab and click **Add chaincode**.
Provide:
* **Chaincode name**
* **Number of replicas** — Chaincode replicas to deploy
* **Image** — Link to your chaincode Docker container at the public Docker repository
{% hint style="info" %}
For private repositories, specify an `imagePullSecret`. Create one in your Kubernetes cluster with the label `"app.kubernetes.io/name": "image-pull-secret"`.
{% endhint %}
* **Resources:** Requested CPU, CPU limit, Requested memory, Memory limit
* **Version**
* **Indexes** (optional, CouchDB only):
* Chaincode index
* Private index (for [private data collections](https://hyperledger-fabric.readthedocs.io/en/release-2.2/private-data/private-data.html))
{% hint style="info" %}
Indexes can only be applied to CouchDB. LevelDB does not support indexes.
{% endhint %}
Click **Save** to add the chaincode template.
Chaincode statuses
| Status | Description |
| ----------- | ------------------------------------------------------- |
| **Pending** | Ready to be installed on a peer |
| **Running** | Chaincode pod is running; can be committed to a channel |
| **Failed** | All chaincode pods have failed status |
| **Deleted** | The chaincode was deleted |
***
## How to Install Chaincode on a Peer?
Go to the **Peer** tab, click on a specific peer with **Running** status, go to the **Chaincodes** tab, and click **Install chaincode**.
Select the chaincode from the dropdown menu showing all chaincode templates added to the platform.
After installation, the chaincode container(s) will launch. It may take a few minutes to start.
***
## How to Approve Chaincode on a Channel?
{% stepper %}
{% step %}
#### Go to the Channels tab
Open the specific channel where you need to approve the chaincode.
{% endstep %}
{% step %}
#### Click "Approve chaincode"
Under the **Chaincodes** section, click the **Approve chaincode** button.
Fill in:
* **Peer** — A peer where the chaincode was installed
* **Chaincode** — Select from the dropdown
* **Endorsers** — Organizations that need to execute and validate transactions
* **Policy** — ANY, MAJORITY, or ALL
* **Sequence** — Automatically specified (increases every time chaincode is upgraded)
* **Package ID** — Auto-specified when you choose a peer
* **Init required** — If checked, ensures the Init function is invoked before any other function and only once
* **Private collection** (optional) — For private data between specific organizations
{% endstep %}
{% endstepper %}
{% hint style="danger" %}
Each Endorser organization needs to approve the **same chaincode definition** to commit it on a channel. Only the peer and Package ID differ per organization.
You cannot approve a chaincode definition twice. If you see an error, check if it was already approved.
{% endhint %}
After approval, you can see the chaincode commitment status at the Chaincodes tab. When all approvals per the channel policy are received, you can commit.
***
## How to Commit a Chaincode?
Go to the **Channels** tab, open the specific channel, and click **Commit chaincode** under the Chaincodes section. Select a peer and the chaincode, then click **Save**.
{% hint style="info" %}
Only an organization with endorser rights on the channel who approved this chaincode definition earlier can commit it.
{% endhint %}
{% hint style="info" %}
Sometimes you cannot commit a chaincode even after all endorser approvals. This can be caused by no anchor peer specified for some organizations — without an anchor peer, the organization's peers won't be returned in a discovery service request.
{% endhint %}
After successful commitment, you can test the chaincode using the **Query** and **Invoke** buttons.
***
## How to Upgrade a Chaincode?
{% stepper %}
{% step %}
#### Add a new chaincode version
Add the same chaincode name with a new version. See [How to Add a Chaincode](#how-to-add-a-chaincode-in-catalyst-blockchain-manager).
{% endstep %}
{% step %}
#### Install the new chaincode on your peers
{% endstep %}
{% step %}
#### Approve the new chaincode definition
{% endstep %}
{% step %}
#### Commit the definition to the channel
{% endstep %}
{% endstepper %}
{% hint style="info" %}
To only update the chaincode policies (without changing binaries), skip steps 1 and 2 — just approve and commit the same chaincode with a new policy.
{% endhint %}
See [Upgrading a Chaincode](https://hyperledger-fabric.readthedocs.io/en/release-2.0/chaincode_lifecycle.html?highlight=lifecycle%20chaincode#upgrade-a-chaincode) in the Hyperledger Fabric documentation.
***
## How to Remove a Chaincode?
Click the **Remove** button in the Actions column of the Chaincodes table.
{% hint style="danger" %}
Removing a chaincode will delete all chaincode deployments. Do not remove a chaincode if you want it to remain running, committed to a channel, and used by business applications.
{% endhint %}
---
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