Is it possible to create NiFi workflows using REST API or any other thing?

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I'm wondering is it possible to create NiFi workflows with the existing processors using REST Api or CLI instead of creating workflows in GUI. Is REST Api can be used to create workflows or only to modify and schedule workflows. If we can create workflows using REST api or CLI, any articles or blogs to look into it?

Let's say I want to create a workflow which simply takes file form local and put it to hdfs. This can be possible by drag and drop the processors in GUI but Is it possible to do the same using REST API or CLI or any other thing which we can do programatically? It would be a great help if you guide me regarding this.

Thanks a lot.

Apache NiFi

MattWhoAnswer

Titanium ⭐️⭐️⭐️

@girish6

Anything you can do through the NiFi UI can also be accomplished via the NiFi rest-api.

Within NiFi you can go to the global menu in the upper right corner and then select "Help".
On the left side of the Help UI you will see and option in the list for the NiFi rest-api docs for the release you are running.

However, it is easier to get use to NiFi rest-api through the developer tools available in your browser.
You can open the developer tools while you are in the NiFi UI and see the rest-api calls as they are made when you perform an action on the GUI (like adding a processor component). You can even right click on the rest-api call in the developers tool window and copy as curl to get the exact rest-api call you could make from a command line prompt.

Hope this helps you,

Matt

MattWhoAnswer

Titanium ⭐️⭐️⭐️

@girish6

Anything you can do through the NiFi UI can also be accomplished via the NiFi rest-api.

Within NiFi you can go to the global menu in the upper right corner and then select "Help".
On the left side of the Help UI you will see and option in the list for the NiFi rest-api docs for the release you are running.

However, it is easier to get use to NiFi rest-api through the developer tools available in your browser.
You can open the developer tools while you are in the NiFi UI and see the rest-api calls as they are made when you perform an action on the GUI (like adding a processor component). You can even right click on the rest-api call in the developers tool window and copy as curl to get the exact rest-api call you could make from a command line prompt.

Hope this helps you,

Matt

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girish6Author

Silver ⭐️⭐️

Thank you so much @MattWho

But another question popped up here. Is there any possibility to execute the xml file somewhere (not on GUI) where it can reflects in the GUI same as curl command.
Through REST API calls we can create and modify workflows, thats totally fine. In the same way, can we create and modify workflows in the xml file and executing somewhere reflects in the GUI?

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MattWho

Titanium ⭐️⭐️⭐️

@girish6

By xml file, I am assuming you are referring to the flow.xml.gz file?

NiFi will only read the flow.xml.gz file during NiFi startup. While NiFi is running the flow.xml resides completely in JVM heap memory and updates made via the UI or rest-api calls are pushed to flow.xml.gz only.

It can be very dangerous manually editing the flow.xml.gz file and is not recommended. Your queued FlowFiles are tightly coupled to specific connection uuids. While the NiFI UI/rest-api would block you from removing a connection which has queued FlowFiles, the flow.xml.gz would not offer such protections. This could result in data loss if someone where to manually edit the flow.xml.gz file and restart NiFi.

Also keep in mind that in a multi-node NiFi cluster each node runs with its own copy of the flow.xml.gz loaded in to memory and the UI and rest-api calls are replicated to all nodes to make sure these files stay synced across your cluster.

Hope this helps,

Matt

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