Migrating components using a directory with flow definition JSON files as input

Learn how to use the Cloudera Flow Management Migration Tool to migrate components from flow definition JSON files.

Example flows for migrating components

The input directory contains the following flow definition files:

TCP_Listener_flow_definition.json
This file contains the TCP Listener process group (ID: b41940d7-0194-1000-42fc-458834630567)
Elastic_flow_definition.json
This file contains process group Elastic (ID: b42881c7-0194-1000-3cdf-1bd453a0ed0f)

TCP Listener Process Group

This process group contains the following simple flow:

The process group defines a variable called TCP Listener Port, which is referenced by the ListenTCPRecord processor.

Elastic Process Group

This process group also contains a simple flow:

The process group defines a variable called Elasticsearch Index, which is referenced in the PutElasticsearchJson processor’s Index property.

Your goal is to migrate the components used in Cloudera Flow Management 2.1.7.2000 powered by NiFi 1 to parameters used in Cloudera Flow Management 4.10.0 powered by NiFi 2.

The example guides you through component migration one flow definition at a time, simplifying the process and maintaining a clear activity log. Although the example uses simple flow definitions, the step-by-step approach can be applied to more complex scenarios. In real-world scenarios, Cloudera recommends defining a migration strategy based on your flow’s structure.

Make a backup of the output folder (/etc/migration-tool-output/components) before running the next migration step.

note

This step is crucial because the same output folder is used as in the previous migration, and its contents will be overwritten. To retain a record of changes made at each stage, it is better to create a backup.
Copy the migrated_TCP_Listener.json and migrated_Elastic.json files to the Migration Tool’s input folder (/etc/migration-tool-input).
Rename the file, overwriting the existing ones, to TCP_Listener_flow_definition.json and Elastic_flow_definition.json for clarity.
Run Stage 1 component migration using the following command.
```
bin/migration.sh nifi migrate-components \
-i /etc/migration-tool-input \
-od /etc/migration-tool-output/components \
--sourceCompatibleOutput
```
This generates a sourceVersion folder that contains the output files of the Stage 1 migration.
```
components
└──sourceVersion
    ├── activity_log.json
    └── migrated_output
        ├── migrated_Elastic.json
        └── migrated_TCP_Listener.json
```
activity_log.json
- The log describes all the actions that were performed for this stage of the process group migration.
- Log of all actions performed during this stage of the process group migration.
note

One activity log file will be created for the entire command.
migrated_TCP_Listener.json
- A modified NiFi 1 flow, which is not compatible with NiFi 2 yet.
- It contains everything the original flow did, except the TCP Listener process group was modified as described in the Activity Log.
migrated_Elastic.json
- A modified NiFi 1 flow definition which is not compatible with NiFi 2 yet.
- It contains everything the original flow definition did, except the Elastic process group was modified with the actions described in the Activity Log.
Validate the Stage 1 component migration output for TCP_Listener_flow_definition.json.
1. Load the migrated_TCP_Listener.json into a NiFi 1 instance and check the flow.
2. Review the activity_log.json file and check for any manual-change-requests or manual-validation-requests. If none are present, proceed to the next step.
  In this example, you can see the following information in the Activity Log:
```
{
	"sequence" : 2,
	"type" : "change-info",
	"subject" : "b41966ad-0194-1000-a08d-a92489457356",
	"message" : "Component [org.apache.nifi.processors.standard.ListenTCPRecord] has been deprecated (NIFI-13509)",
	"context" : {
  	"rule" : "36227b60-75f0-40dc-8caf-a2ec577aa54c"
}
```
  1. Open the targetVersion/migrated_TCP_Listener.json file and search for the "subject" ID, b41966ad-0194-1000-a08d-a92489457356. This ID refers to the ListenTCPRecord processor.
  2. Search for the value of the identifier as “subject” element in NiFi’s search box.
    
    You are directed to the ListenTCPRecord processor. No manual modifications are needed at this stage. However, it is important to note that the ListenTCPRecord processor is deprecated and is not available in NiFi 2. Once the full component migration (Stage 1 and Stage 2) is complete, instructions will be provided on how to handle this deprecation.
3. If manual changes are necessary, update the migrated_TCP_Listener.json on the NiFi canvas after loading it. Once the flow is validated and meets expectations, continue with the next step.
Validate the Stage 1 component migration output for Elastic_flow_definition.json.
1. Load the migrated_Elastic.json into a NiFi 1 instance and check the flow.
2. Review the activity_log.json file. It contains a change-info entry that informs you of changes to a NiFi 2 processor, identified by the subject ID.
```
{
	"sequence" : 2,
	"type" : "change-info",
	"subject" : "b428aad6-0194-1000-d73d-9f2332a59f04",
	"message" : "Property [Max JSON Field String Length] has been added (NIFI-12343); Property [put-es-json-not_found-is-error] has been renamed to [put-es-not_found-is-error] (NIFI-12255); Property [put-es-json-error-documents] has been removed (NIFI-12255); Relationships [success] has been renamed to [original]; Relationship [successful] has been added (NIFI-12255);",
	"context" : {
  	"rule" : "6501a693-b524-4d1a-b11e-69747c2651e8"
}
```
  1. Open the targetVersion/migrated_output/migrated_Elastic.json file and search for the "subject" ID, b428aad6-0194-1000-d73d-9f2332a59f04. This ID refers to the PutElasticsearchJson processor.
  2. To identify the processor affected by these changes, search for the identifier value of the “subject” element in NiFi’s search box.You are directed to the PutElasticsearchJson processor. No manual modifications are needed at this stage. However, it is important to note that changes will be applied to the PutElasticsearchJson processor during Stage 2 of the migration. Once the full component migration (Stage 1 and Stage 2) is complete, instructions will be provided on how to handle this change.
At this stage, you have completed Stage 1 of both variable and component migration for your flow definition files. After reviewing the logs, you confirmed that no manual changes were needed. You can proceed with a full component migration using the /etc/migration-tool-input from Step 5.
Run full component migration (Stage 1 and 2).
1. Make a backup of the output folder (/etc/migration-tool-output/components) before running the next migration step.
  
  note
  
  This step is crucial because the same output folder is used as in the previous migration, and its contents will be overwritten. To retain a record of changes made at each stage, it is better to create a backup.
2. Run the full component migration using the following command.
```
bin/migration.sh nifi migrate-components \
-i /etc/migration-tool-input \
-od /etc/migration-tool-output/components
```
  This generates the following output:
```
components
├──sourceVersion
│    ├── activity_log.json
│    └── migrated_output
│        ├── migrated_Elastic.json
│        └── migrated_TCP_Listener.json
└──sourceVersion
    ├── activity_log.json
    └── migrated_output
        ├── migrated_Elastic.json
        └── migrated_TCP_Listener.json
```
  The contents of the previously generated sourceVersion folder will be overwritten. The contents represent the NiFi 1 compatible version of the migrated flow definition. Since you already performed Stage 1 component migration, the activity log will only include the same entries as those in Steps 2 and 4.
  
  Additionally, a targetVersion directory is created, containing the output files of the Stage 2 part of the migration:
  migrated_TCP_Listener.json
  NiFi 2-compatible flow definition
  
  You can load it into NiFi 2 and validate it
  migrated_Elastic.json
  NiFi 2-compatible flow definition
  
  You can load it into NiFi 2 and validate it
  activity_log.json
  List of all actions performed during this stage of the migration, and any manual steps that you need to perform.
Validate the Stage 2 component migration output for TCP_Listener_flow_definition.json.
1. Load the targetVersion/migrated_output/migrated_TCP_Listener.json into a NiFi 2 instance and check the flow.
2. Review the targetVersion/activity_log.json file.
  In this example, you can see the following manual-change-request entry.
```
{
	"sequence" : 6,
	"type" : "manual-change-request",
	"subject" : "b41966ad-0194-1000-a08d-a92489457356",
	"message" : "The component has been deprecated. It is suggested to replace it with a combination of [org.apache.nifi.processors.standard.ListenTCP] and [org.apache.nifi.processors.standard.ConvertRecord] processors",
	"context" : {
  	"rule" : "36227b60-75f0-40dc-8caf-a2ec577aa54c"
}
```
  1. Open the targetVersion/migrated_TCP_Listener.json file and search for the "subject" ID b41966ad-0194-1000-a08d-a92489457356. This ID refers to the ListenTCPRecord processor.
  2. To identify the processor affected by these changes, search for the identifier value of the “subject” element in NiFi’s search box. It refers to the ListenTCPRecord processor. Open the TCP Listener process group. You can see that the processor is marked with dashed borders and its version number still shows that of the NiFi 1 instance. It means that it is a "ghost processor", not available in NiFi 2. The log message suggests replacing it with a combination of ListenTCP and ConvertRecord processors.
    
    Instantiate and configure the ListenTCP and ConvertRecord processors, connect them appropriately, and then remove the ghost processor.
    
    Besides these changes there are no further manual-change-requests or manual-validation-requests in the Activity Log.
3. Download the flow definition and you have the fully NiFi 2 compatible TCP_Listener_flow_definition.json.
Validate the Stage 2 component migration output for Elastic_definition.json.
1. Load the targetVersion/migrated_output/migrated_Elastic.json into a NiFi 2 instance and check the flow.
2. Review the targetVersion/activity_log.json file.
  In this example, you can see the following manual-change-request entry.
```
{
	"sequence" : 3,
	"type" : "manual-change-request",
	"subject" : "b428aad6-0194-1000-d73d-9f2332a59f04",
	"message" : "New relationship [original] has been added, it has to be connected to a downstream processor or terminated.",
	"context" : {
  	"rule" : "6501a693-b524-4d1a-b11e-69747c2651e8"
}
```
  1. Open the targetVersion/migrated_Elastic.json file and search for the "subject" ID b428aad6-0194-1000-d73d-9f2332a59f04. This ID refers to the PutElasticsearchJson processor.
  2. To identify the processor affected by these changes, search for the identifier value of the “subject” element in NiFi’s search box. It refers to the PutElasticsearchJson processor. You will find an unbound "original" relationship that needs to be connected to a downstream processor or terminated. Make the necessary modifications manually. Once completed, this change request is resolved.
3. Download the flow definition and you have the fully NiFi 2 compatible Elastic_flow_definition.json.