https://github.com/segmentio/topicctl

Tool for declarative management of Kafka topics
https://github.com/segmentio/topicctl

Last synced: 3 months ago
JSON representation

Tool for declarative management of Kafka topics

• Host: GitHub
• URL: https://github.com/segmentio/topicctl
• Owner: segmentio
• License: mit
• Created: 2020-07-21T19:52:19.000Z (over 4 years ago)
• Default Branch: master
• Last Pushed: 2024-07-15T20:58:12.000Z (6 months ago)
• Last Synced: 2024-08-01T16:27:06.935Z (6 months ago)
• Language: Go
• Size: 564 KB
• Stars: 583
• Watchers: 11
• Forks: 54
• Open Issues: 22
• Metadata Files:
  • Readme: README.md
  • License: LICENSE
  • Codeowners: CODEOWNERS

Awesome Lists containing this project

• awesome-ccamel - segmentio/topicctl - Tool for declarative management of Kafka topics (Go)
• awesome-kafka - topicctl - A tool for easy, declarative management of Kafka topics. Includes the ability to "apply" topic changes from YAML as well as a repl for interactive exploration of brokers, topics, consumer groups, messages, and more. (Libraries / Kafka)

README

        
![GitHub Actions](https://github.com/segmentio/topicctl/actions/workflows/ci.yml/badge.svg)

[![Go Report Card](https://goreportcard.com/badge/github.com/segmentio/topicctl)](https://goreportcard.com/report/github.com/segmentio/topicctl)

# topicctl

A tool for easy, declarative management of Kafka topics. Includes the ability to "apply" topic

changes from YAML as well as a repl for interactive exploration of brokers, topics, consumer groups,

messages, and more.



## Motivation

Managing Kafka topics via the standard tooling can be tedious and error-prone; there is no

standard, declarative way to define topics (e.g., YAML files that can be checked-in to git),

and understanding the state of a cluster at any given point in time requires knowing

and using multiple, different commands with different interfaces.

We created `topicctl` to make the management of our Kafka topics more transparent and

user-friendly. The project was inspired by `kubectl` and other tools that we've used in

non-Kafka-related contexts.

See [this blog post](https://segment.com/blog/easier-management-of-Kafka-topics-with-topicctl/) for

more details.

## 🆕 Upgrading from v0

We recently revamped `topicctl` to support ZooKeeper-less cluster access as well as some

additional security options (TLS/SSL and SASL)! See

[this blog post](https://segment.com/blog/topicctl-v1/) to learn more about why and how we did

this.

All changes should be backwards compatible, but you'll need to update your cluster configs if you

want to take advantage of these new features; see the [clusters section below](#clusters) for more

details on the latest config format.

The code for the old version has been preserved in the

[v0 branch](https://github.com/segmentio/topicctl/tree/v0) if you run into problems and need to

revert.

## Related projects

Check out the [data-digger](https://github.com/segmentio/data-digger) for a command-line tool

that makes it easy to tail and summarize structured data in Kafka.

## Getting started

### Installation

Either:

1. Run `go install github.com/segmentio/topicctl/cmd/topicctl@latest`

2. Clone this repo and run `make install` in the repo root

3. Use the Docker image: `docker pull segment/topicctl`

If you use (1) or (2), the binary will be placed in `$GOPATH/bin`.

If you use Docker, you can run the tool via

`docker run -ti --rm segment/topicctl [subcommand] [flags]`. Depending on your Docker setup and

what you're trying to do, you may also need to run in the host network via `--net=host` and/or

mount local volumes with `-v`.

### Quick tour

1. Start up a 6 node Kafka cluster locally:

```

docker-compose up -d

```

2. Run the net alias script to make the broker addresses available on localhost:

```

./scripts/set_up_net_alias.sh

```

3. Apply the topic configs in [`examples/local-cluster/topics`](/examples/local-cluster/topics):

```

topicctl apply --skip-confirm examples/local-cluster/topics/*yaml

```

4. Send some test messages to the `topic-default` topic:

```

topicctl tester --broker-addr=localhost:9092 --topic=topic-default

```

5. Open up the repl (while keeping the tester running in a separate terminal):

```

topicctl repl --cluster-config=examples/local-cluster/cluster.yaml

```

6. Run some test commands:

```

get brokers

get topics

get partitions

get partitions topic-default

get offsets topic-default

tail topic-default

```

7. Increase the number of partitions in the `topic-default` topic by changing the `partitions: ...`

value in

[topic-default.yaml](https://github.com/segmentio/topicctl/blob/master/examples/local-cluster/topics/topic-default.yaml#L10) to `9` and re-applying:

```

topicctl apply examples/local-cluster/topics/topic-default.yaml

```

8. Bring down the local cluster:

```

docker-compose down

```

## Usage

### Subcommands

#### apply

```

topicctl apply [path(s) to topic config(s)]

```

The `apply` subcommand ensures that the actual state of a topic in the cluster

matches the desired state in its config. If the topic doesn't exist, the tool will

create it. If the topic already exists but its cluster state is out-of-sync,

then the tool will initiate the necessary changes to bring it into compliance.

See the [Config formats](#config-formats) section below for more information on the

expected file formats.

#### bootstrap

```

topicctl [flags] bootstrap

```

The `bootstrap` subcommand creates apply topic configs from the existing topics in a

cluster. This can be used to "import" topics not created or previously managed by topicctl.

The output can be sent to either a directory (if the `--output` flag is set) or `stdout`.

By default, this does not include internal topics such as `__consumer_offsets`.

If you would like to have these topics included,

pass the `--allow-internal-topics` flag.

#### check

```

topicctl check [path(s) to topic config(s)]

```

The `check` command validates that each topic config has the correct fields set and is

consistent with the associated cluster config. Unless `--validate-only` is set, it then

checks the topic config against the state of the topic in the corresponding cluster.

#### create

```

topicctl create [flags] [command]

```

The `create` command creates resources in the cluster from a configuration file. 

Currently, only ACLs are supported. The create command is separate from the apply

command as it is intended for usage with immutable resources managed by topicctl.

#### delete

```

topicctl delete [flags] [operation]

```

The `delete` subcommand deletes a particular resource type in the cluster.

Currently, the following operations are supported:

| Subcommand      | Description |

| --------- | ----------- |

| `delete acls [flags]` | Deletes ACL(s) in the cluster matching the provided flags |

#### get

```

topicctl get [flags] [operation]

```

The `get` subcommand lists out the instances and/or details of a particular

resource type in the cluster. Currently, the following operations are supported:

| Subcommand      | Description |

| --------- | ----------- |

| `get balance [optional topic]` | Number of replicas per broker position for topic or cluster as a whole |

| `get brokers` | All brokers in the cluster |

| `get config [broker or topic]` | Config key/value pairs for a broker or topic |

| `get groups` | All consumer groups in the cluster |

| `get lags [topic] [group]` | Lag for each topic partition for a consumer group |

| `get members [group]` | Details of each member in a consumer group |

| `get partitions [optional: topics]` | Get all partitions for topics |

| `get offsets [topic]` | Number of messages per partition along with start and end times |

| `get topics` | All topics in the cluster |

| `get acls [flags]` | Describe access control levels (ACLs) in the cluster |

| `get users` | All users in the cluster |

#### rebalance

```

topicctl rebalance [flags]

```

The `apply` subcommand can be used with flag `--rebalance` rebalances a specified topics across a cluster.

The `rebalance` subcommand, on the other hand, performs a rebalance for **all** the topics defined at a given topic prefix path.

See the [rebalancing](#rebalancing) section below for more information on rebalancing.

#### repl

```

topicctl repl [flags]

```

The `repl` subcommand starts up a shell that allows running the `get` and `tail`

subcommands interactively.

#### reset-offsets

```

topicctl reset-offsets [topic] [group] [flags]

```

The `reset-offsets` subcommand allows resetting the offsets for a consumer group in a topic. There are 2 main approaches for setting the offsets:

1. Use a combination of `--partitions`, `--offset`, `--to-earliest` and `--to-latest` flags. `--partitions` flag specifies a list of partitions to be reset e.g. `1,2,3 ...`. If not used, the command defaults to resetting consumer group offsets for ALL of the partitions. `--offset` flag indicates the specific value that all desired consumer group partitions will be set to. If not set, it will default to -2. Finally, `--to-earliest` flag resets offsets of consumer group members to earliest offsets of partitions while `--to-latest` resets offsets of consumer group members to latest offsets of partitions. However, only one of the `--to-earliest`, `--to-latest` and `--offset` flags can be used at a time. This approach is easy to use but lacks the ability for detailed offset configuration.

2. Use `--partition-offset-map` flag to specify a detailed offset configuration for individual partitions. For example, `1=5,2=10,7=12,...` means that the consumer group offset for partition 1 must be set to 5, partition 2 to offset 10, partition 7 to offset 12 and so on. This approach provides greater flexibility and fine-grained control for this operation. Note that `--partition-offset-map` flag is standalone and cannot be coupled with any of the previous flags.

#### tail

```

topicctl tail [flags] [topic]

```

The `tail` subcommand tails and logs out topic messages using the APIs exposed in

[kafka-go](https://github.com/segmentio/kafka-go). It doesn't have the full functionality

of `kafkacat` (yet), but the output is prettier and it may be easier to use in some cases.

#### tester

```

topicctl tester [flags]

```

The `tester` command reads or writes test messages in a topic. For testing/demonstration purposes

only.

### Specifying the target cluster

There are three ways to specify a target cluster in the `topicctl` subcommands:

1. `--cluster-config=[path]`, where the refererenced path is a cluster configuration

  in the format expected by the `apply` command described above,

2. `--zk-addr=[zookeeper address]` and `--zk-prefix=[optional prefix for cluster in zookeeper]`, *or*

3. `--broker-addr=[bootstrap broker address]`

All subcommands support the `cluster-config` pattern. The last two are also supported

by the `get`, `repl`, `reset-offsets`, and `tail` subcommands since these can be run

independently of an `apply` workflow.

### Version compatibility

We've tested `topicctl` on Kafka clusters with versions between `0.10.1` and `2.7.1`, inclusive.

Note, however, that clusters at versions prior to `2.4.0` cannot use broker APIs for applying and

thus also require ZooKeeper API access for full functionality. See the

[cluster access details](#cluster-access-details) section below for more details.

If you run into any unexpected compatibility issues, please file a bug.

## Config formats

`topicctl` uses structured, YAML-formatted configs for clusters and topics. These are

typically source-controlled so that changes can be reviewed before being applied.

### Clusters

Each cluster associated with a managed topic must have a config. These configs can also be used

with the `get`, `repl`, `reset-offsets`, and `tail` subcommands instead of specifying a broker or

ZooKeeper address.

The following shows an annotated example:

```yaml

meta:

  name: my-cluster                      # Name of the cluster

  environment: stage                    # Cluster environment

  region: us-west-2                     # Cloud region of the cluster

  shard: 1                              # Shard index of this cluster, if it is sharded.

  description: |                        # A free-text description of the cluster (optional)

    Test cluster for topicctl.

spec:

  bootstrapAddrs:                       # One or more broker bootstrap addresses

    - my-cluster.example.com:9092

  clusterID: abc-123-xyz                # Expected cluster ID for cluster (optional,

                                        # used as safety check only)

  # ZooKeeper access settings (only required for pre-v2 clusters; leave off to force exclusive use

  # of broker APIs)

  zkAddrs:                              # One or more cluster zookeeper addresses; if these are

    - zk.example.com:2181               # omitted, then the cluster will only be accessed via

                                        # broker APIs; see the section below on cluster access for

                                        # more details.

  zkPrefix: my-cluster                  # Prefix for zookeeper nodes if using zookeeper access

  zkLockPath: /topicctl/locks           # Path used for apply locks (optional)

  # TLS/SSL settings (optional, not supported if using ZooKeeper)

  tls:

    enabled: true                       # Whether TLS is enabled

    caCertPath: path/to/ca.crt          # Path to CA cert to be used (optional)

    certPath: path/to/client.crt        # Path to client cert to be used (optional)

    keyPath: path/to/client.key         # Path to client key to be used (optional)

  # SASL settings (optional, not supported if using ZooKeeper)

  sasl:

    enabled: true                       # Whether SASL is enabled

    mechanism: SCRAM-SHA-512            # Mechanism to use; choices are AWS-MSK-IAM, PLAIN,

                                        # SCRAM-SHA-256, and SCRAM-SHA-512

    username: my-username               # SASL username; ignored for AWS-MSK-IAM

    password: my-password               # SASL password; ignored for AWS-MSK-IAM

```

Note that the `name`, `environment`, `region`, and `description` fields are used

for description/identification only, and don't appear in any API calls. They can

be set arbitrarily, provided that they match up with the values set in the

associated topic configs.

If the tool is run with the `--expand-env` option, then the cluster config will be prepreocessed

using [`os.ExpandEnv`](https://pkg.go.dev/os#ExpandEnv) at load time. The latter will replace

references of the form `$ENV_VAR_NAME` or `${ENV_VAR_NAME}` with the associated values from the

environment.

Additionally, the Amazon Resource Name (ARN) of a secret in AWS Secrets Manager can be provided

instead of the username and password. Topicctl will then retrieve the secret value from Secrets 

Manager and use it as the credentials. The secret in Secrets Manager must have a value in the format 

shown below, identical to what [AWS MSK requires](https://docs.aws.amazon.com/msk/latest/developerguide/msk-password.html#msk-password-tutorial).

```json

{

  "username": "alice",

  "password": "alice-secret"

}

```

An example of secrets manager being used can be seen below. Be sure to include the [6Random-Characters

AWS Secrets Manager tacks on to the end of a secrets ARN](https://docs.aws.amazon.com/secretsmanager/latest/userguide/getting-started.html).

```yaml

sasl:

    enabled: true

    mechanism: SCRAM-SHA-512

    secretsManagerArn: arn:aws:secretsmanager:::secret:SecretName-6RandomCharacters

```

### Topics

Each topic is configured in a YAML file. The following is an

annotated example:

```yaml

meta:

  name: topics-test                     # Name of the topic

  cluster: my-cluster                   # Name of the cluster

  environment: stage                    # Environment of the cluster

  region: us-west-2                     # Region of the cluster

  description: |                        # Free-text description of the topic (optional)

    Test topic in my-cluster.

  labels:                               # Custom key-value pairs purposed for topic bookkeeping (optional)

    key1: value1

    key2: value2

spec:

  partitions: 9                         # Number of topic partitions

  replicationFactor: 3                  # Replication factor per partition

  retentionMinutes: 360                 # Number of minutes to retain messages (optional)

  placement:

    strategy: in-zone                   # Placement strategy, see info below

    picker: randomized                  # Picker method, see info below (optional)

  settings:                             # Miscellaneous other config settings (optional)

    cleanup.policy: delete

    max.message.bytes: 5242880

```

The `cluster`, `environment`, and `region` fields are used for matching

against a cluster config and double-checking that the cluster we're applying

in is correct; they don't appear in any API calls.

See the [Kafka documentation](https://kafka.apache.org/documentation/#topicconfigs)

for more details on the parameters that can be set in the `settings` field. Note

that retention time can be set in either this section or via `retentionMinutes` but

not in both places. The latter is easier, so it's recommended.

Multiple topics can be included in the same file, separated by `---` lines, provided

that they reference the same cluster.

#### Placement strategies

The tool supports the following per-partition, replica placement strategies:

| Strategy     | Description |

| --------- | ----------- |

| `any` | Allow any replica placement |

| `balanced-leaders` | Ensure that the leaders of each partition are evenly distributed across the broker racks  |

| `in-rack` | Ensure that the followers for each partition are in the same rack as the leader; generally this is done when the leaders are already balanced, but this isn't required |

| `cross-rack` | Ensure that the replicas for each partition are all in different racks; generally this is done when the leaders are already balanced, but this isn't required |

| `static` | Specify the placement manually, via an extra `staticAssignments` field. ([example](examples/local-cluster/topics/topic-static.yaml)) |

| `static-in-rack` | Specify the rack placement per partition manually, via an extra `staticRackAssignments` field ([example](examples/local-cluster/topics/topic-static-in-rack.yaml))|

#### Picker methods

There are often multiple options to pick from when updating a replica. For instance, with an

`in-rack` strategy, we can pick any replica in the target rack that isn't already used in the

partition.

Currently, `topicctl` supports the following methods for this replica "picking" process:

| Method     | Description |

| --------- | ----------- |

| `cluster-use` | Pick based on broker frequency in the topic, then break ties by looking at the frequency of each broker across all topics in the cluster |

| `lowest-index` | Pick based on broker frequency in the topic, then break ties by choosing the lowest-index broker |

| `randomized` | Pick based on broker frequency in the topic, then break ties randomly. The underlying random generator uses a consistent seed (generated from the topic name, partition, and index), so the choice won't vary between apply runs.|

If no picking method is set in the topic config, then `randomized` is used by default.

Note that these all try to achieve in-topic balance, and only vary in the case of ties.

Thus, the placements won't be significantly different in most cases.

In the future, we may add pickers that allow for some in-topic imbalance, e.g. to correct a

cluster-wide broker imbalance.

#### Rebalancing

If `apply` is run with the `--rebalance` flag, then `topicctl` will rebalance specified topics

after the usual apply steps. This process will check the balance of the brokers for each index

position (i.e., first, second, third, etc.) for each partition and make replacements if there

are any brokers that are significantly over- or under-represented.

The rebalance process can optionally remove brokers from a topic. To use this feature, set the

`--to-remove` flag. Note that this flag has no effect unless `--rebalance` is also set.

Rebalancing is not done by default on all apply runs because it can be fairly disruptive and

generally shouldn't be necessary unless the topic started off in an imbalanced state or there

has been a change in the number of brokers.

To rebalance **all** topics in a cluster, use the `rebalance` subcommand, which will perform the `apply --rebalance`

function on all qualifying topics. It will inventory all topic configs found at  `--path-prefix` for a cluster

specified by `--cluster-config`.

This subcommand will not rebalance a topic if:

1. the topic config is inconsistent with the cluster config (name, region, environment etc...)

1. the partition count of a topic in the kafka cluster does not match the topic partition setting in the topic config

1. a topic's `retention.ms` in the kafka cluster does not match the topic's `retentionMinutes` setting in the topic config

1. a topic does not exist in the kafka cluster

### ACLs

Sets of ACLs can be configured in a YAML file. The following is an

annotated example:

```yaml

meta:

  name: acls-test                       # Name of the group of ACLs

  cluster: my-cluster                   # Name of the cluster

  environment: stage                    # Environment of the cluster

  region: us-west-2                     # Region of the cluster

  description: |                        # Free-text description of the topic (optional)

    Test topic in my-cluster.

  labels:                               # Custom key-value pairs purposed for ACL bookkeeping (optional)

    key1: value1

    key2: value2

spec:

  acls:

    - resource:

        type: topic                     # Type of resource (topic, group, cluster, etc.)

        name: test-topic                # Name of the resource to apply an ACL to

        patternType: literal            # Type of pattern (literal, prefixed, etc.)

        principal: User:my-user         # Principal to apply the ACL to

        host: *                         # Host to apply the ACL to

        permission: allow			    # Permission to apply (allow, deny)

      operations:                       # List of operations to use for the ACLs

        - read

        - describe

```

The `cluster`, `environment`, and `region` fields are used for matching

against a cluster config and double-checking that the cluster we're applying

in is correct; they don't appear in any API calls.

See the [Kafka documentation](https://kafka.apache.org/documentation/#security_authz_primitives)

for more details on the parameters that can be set in the `acls` field.

Multiple groups of ACLs can be included in the same file, separated by `---` lines, provided

that they reference the same cluster.

## Tool safety

The `bootstrap`, `get`, `repl`, and `tail` subcommands are read-only and should never make

any changes in the cluster.

The `apply` subcommand can make changes, but under the following conditions:

1. A user confirmation is required for any mutation to the cluster

2. Topics are never deleted

3. Partitions can be added but are never removed

4. All apply runs are interruptable and idempotent (see sections below for more details)

5. Partition changes in apply runs are locked on a per-cluster basis

6. Leader changes in apply runs are locked on a per-topic basis

7. Partition replica migrations are protected via

  ["throttles"](https://kafka.apache.org/0101/documentation.html#rep-throttle)

  to prevent the cluster network from getting overwhelmed

8. Before applying, the tool checks the cluster ID against the expected value in the

  cluster config. This can help prevent errors around applying in the wrong cluster when multiple

  clusters are accessed through the same address, e.g `localhost:2181`.

The `reset-offsets` command can also make changes in the cluster and should be used carefully.

The `create` command can be used to create new resources in the cluster. It cannot be used with

mutable resources.

### Idempotency

Apply runs are designed to be idemponent- the effects should be the same no matter how many

times they are run, assuming everything else in the cluster remains constant (e.g., the number of

brokers, each broker's rack, etc.). An exception is replica rebalance operations, which can be

non-deterministic. Changes in other topics should generally not effect idempotency, unless,

possibly, if the topic is configured to use the `cluster-use` picker.

### Interruptibility

If an apply run is interrupted, then any in-progress broker migrations or leader elections

will continue and any applied throttles will be kept in-place. The next time the topic is applied,

the process should continue from where it left off.

## Cluster access details

### ZooKeeper vs. broker APIs

`topicctl` can interact with a cluster through either ZooKeeper or by hitting broker APIs

directly.

Broker APIs are used exclusively if the tool is run with either of the following flags:

1. `--broker-addr` *or*

2. `--cluster-config` and the cluster config doesn't specify any ZK addresses

We recommend using this "broker only" access mode for all clusters running Kafka versions >= 2.4.

In all other cases, i.e. if `--zk-addr` is specified or the cluster config has ZK addresses, then

ZooKeeper will be used for most interactions. A few operations that are not possible via ZK

will still use broker APIs, however, including:

1. Group-related `get` commands: `get groups`, `get lags`, `get members`

2. `get offsets`

3. `reset-offsets`

4. `tail`

5. `apply` with topic creation

This "mixed" mode is required for clusters running Kafka versions < 2.0.

### Limitations of broker-only access mode

There are a few limitations in the tool when using the broker APIs exclusively:

1. Only newer versions of Kafka are supported. In particular:

    - v2.0 or greater is required for read-only operations (`get brokers`, `get topics`, etc.)

    - v2.4 or greater is required for applying topic changes

2. Apply locking is not yet implemented; please be careful when applying to ensure that someone

  else isn't applying changes in the same topic at the same time.

3. The values of some dynamic broker properties, e.g. `leader.replication.throttled.rate`, are

  marked as "sensitive" and not returned via the API; `topicctl` will show the value as

  `SENSITIVE`. This appears to be fixed in v2.6.

4. Broker timestamps are not returned by the metadata API. These will be blank in the results

  of `get brokers`.

5. Applying is not fully compatible with clusters provisioned in Confluent Cloud. It appears

  that Confluent prevents arbitrary partition reassignments, among other restrictions. Read-only

  operations seem to work.

### TLS

TLS (referred to by the older name "SSL" in the Kafka documentation) is supported when running

`topicctl` in the exclusive broker API mode. To use this, either set `--tls-enabled` in the

command-line or, if using a cluster config, set `enabled: true` in the `TLS` section of

the latter.

In addition to standard TLS, the tool also supports mutual TLS using custom certs, keys, and CA

certs (in PEM format). As with the enabling of TLS, these can be configured either on the

command-line or in a cluster config. See [this config](examples/auth/cluster.yaml) for an example.

### SASL

`topicctl` supports SASL authentication when running in the exclusive broker API mode. To use this,

either set the `--sasl-mechanism` and other appropriate `--sasl-*` flags on the command line or

fill out the `SASL` section of the cluster config.

The following mechanisms can be used:

1. `AWS-MSK-IAM`

2. `PLAIN`

3. `SCRAM-SHA-256`

4. `SCRAM-SHA-512`

If using `AWS-MSK-IAM`, then `topicctl` will attempt to discover your AWS credentials in the

locations and order described [here](https://docs.aws.amazon.com/sdk-for-go/api/aws/session/).

The other mechanisms require a username and password to be set in either the cluster config

or on the command-line. See the cluster configs in the [examples/auth](/examples/auth) and

[examples/msk](/examples/msk) directories for some specific examples.

Note that SASL can be run either with or without TLS, although the former is generally more

secure.

## Development

#### Run tests

First, set up docker-compose and the associated network alias:

```

docker-compose up -d

./scripts/set_up_net_alias.sh

```

This will create a 6 node, 3 rack cluster locally with the brokers

accessible on `169.254.123.123`.

Then, run:

```

make test

```

You can change the Kafka version of the local cluster by setting the

`KAFKA_IMAGE_TAG` environment variable when running `docker-compose up -d`. See the

[`bitnami/kafka` dockerhub page](https://hub.docker.com/r/bitnami/kafka/tags) for more

details on the available versions.

#### Run against local cluster

To run the `get`, `repl`, and `tail` subcommands against the local cluster,

set `--zk-addr=localhost:2181` and leave the `--zk-prefix` flag unset.

To test out `apply`, you can use the configs in `examples/local-cluster/`. For example,

to create all topics defined for that cluster:

```

topicctl apply examples/local-cluster/topics/*.yaml

```