Apache Storm offers a range of configuration options when trying to secure your cluster. By default all authentication and authorization is disabled but can be turned on as needed. Many of these features only became available in Storm-0.10.

You can still have a secure storm cluster without turning on formal Authentication and Authorization. But to do so usually requires configuring your Operating System to restrict the operations that can be done. This is generally a good idea even if you plan on running your cluster with Auth.

The exact details of how to setup these precautions varies a lot and is beyond the scope of this document.

It is generally a good idea to enable a firewall and restrict incoming network connections to only those originating from the cluster itself and from trusted hosts and services. Towards this end, a complete list of ports storm uses are below.

If the data your cluster is processing is sensitive it might be best to set up IPsec to encrypt all traffic being sent between the hosts in the cluster.

Note that the Worker Processes ports above are just the default ones, the actual ports for your setup may vary.

The UI and logviewer processes provide a way to not only see what a cluster is doing, but also manipulate running topologies. In general these processes should not be exposed except to users of the cluster.

Some form of Authentication is typically required; e.g., by using java servlet filters

ui.filter: "filter.class"
ui.filter.params: "param1":"value1"

or by restricting the UI/log-viewers ports to only accept connections from localhost, and then front them with another web server, like Apache httpd, that can authenticate/authorize incoming connections and proxy the connection to the storm process. To make this work the ui process must have logviewer.port set to the port of the proxy in its storm.yaml, while the logviewers must have it set to the actual port that they are going to bind to.

The servlet filters are preferred because they allow individual topologies to specify who is (and who is not) allowed to access the pages associated with each topology.

The Storm UI can be configured to use AuthenticationFilter from hadoop-auth.

ui.filter: "org.apache.hadoop.security.authentication.server.AuthenticationFilter"
ui.filter.params:
   "type": "kerberos"
   "kerberos.principal": "HTTP/nimbus.witzend.com"
   "kerberos.keytab": "/vagrant/keytabs/http.keytab"
   "kerberos.name.rules": "RULE:[2:$1@$0]([jt]t@.*EXAMPLE.COM)s/.*/$MAPRED_USER/ RULE:[2:$1@$0]([nd]n@.*EXAMPLE.COM)s/.*/$HDFS_USER/DEFAULT"

make sure to create a principal HTTP/{hostname} (here hostname should be the host where the UI daemon runs).

Once configured, you must do kinit before accessing the UI.

Here's an example of accessing Storm's API after the setup above:

curl  -i --negotiate -u:anyUser  -b ~/cookiejar.txt -c ~/cookiejar.txt  http://storm-ui-hostname:8080/api/v1/cluster/summary

1. Firefox: Go to about:config and search for network.negotiate-auth.trusted-uris double-click to add value "http://storm-ui-hostname:8080"
2. Google-chrome: start from command line with: google-chrome --auth-server-whitelist="*storm-ui-hostname" --auth-negotiate-delegate-whitelist="*storm-ui-hostname"
3. IE: Configure trusted websites to include "storm-ui-hostname" and allow negotiation for that website

Caution: In AD MIT Kerberos setup, the key size is bigger than the default UI jetty server request header size. So make sure you set ui.header.buffer.bytes to 65536 in storm.yaml. More details are in STORM-633

Both UI and DRPC allow users to configure ssl.

For UI, set the following config in storm.yaml. Generating keystores with proper keys and certs should be taken care of by the user before this step.

1. ui.https.port
2. ui.https.keystore.type (example "jks")
3. ui.https.keystore.path (example "/etc/ssl/storm_keystore.jks")
4. ui.https.keystore.password (keystore password)
5. ui.https.key.password (private key password)

Optional config:

1. ui.https.truststore.path (example "/etc/ssl/storm_truststore.jks")
2. ui.https.truststore.password (truststore password)
3. ui.https.truststore.type (example "jks")

To set up 2-way authentication:

1. ui.https.want.client.auth (If this set to true, server requests for client certificate authentication, but keeps the connection even if no authentication is provided)
2. ui.https.need.client.auth (If this set to true, server requires the client to provide authentication)

Similarly to the UI configuration above, set the following config to configure SSL for DRPC:

1. drpc.https.port
2. drpc.https.keystore.type (example "jks")
3. drpc.https.keystore.path (example "/etc/ssl/storm_keystore.jks")
4. drpc.https.keystore.password (keystore password)
5. drpc.https.key.password (private key password)

Optional config:

1. drpc.https.truststore.path (example "/etc/ssl/storm_truststore.jks")
2. drpc.https.truststore.password (truststore password)
3. drpc.https.truststore.type (example "jks")

To set up 2-way authentication:

1. drpc.https.want.client.auth (If this set to true, server requests for client certificate authentication, but keeps the connection even if no authentication is provided)
2. drpc.https.need.client.auth (If this set to true, server requires the client to provide authentication)

Storm offers pluggable authentication support through thrift and SASL. This example only goes off of Kerberos as it is a common setup for most big data projects.

Setting up a KDC and configuring kerberos on each node is beyond the scope of this document and it is assumed that you have done that already.

Each ZooKeeper Server, Nimbus, and DRPC server will need a service principal, which, by convention, includes the FQDN of the host it will run on. Be aware that the ZooKeeper user MUST be zookeeper. The supervisors and UI also need a principal to run as, but because they are outgoing connections they do not need to be service principals. The following is an example of how to set up kerberos principals, but the details may vary depending on your KDC and OS.

# ZooKeeper (Will need one of these for each box in the ZK ensemble)
sudo kadmin.local -q 'addprinc zookeeper/zk1.example.com@STORM.EXAMPLE.COM'
sudo kadmin.local -q "ktadd -k /tmp/zk.keytab  zookeeper/zk1.example.com@STORM.EXAMPLE.COM"
# Nimbus and DRPC
sudo kadmin.local -q 'addprinc storm/storm.example.com@STORM.EXAMPLE.COM'
sudo kadmin.local -q "ktadd -k /tmp/storm.keytab storm/storm.example.com@STORM.EXAMPLE.COM"
# All UI logviewer and Supervisors
sudo kadmin.local -q 'addprinc storm@STORM.EXAMPLE.COM'
sudo kadmin.local -q "ktadd -k /tmp/storm.keytab storm@STORM.EXAMPLE.COM"

be sure to distribute the keytab(s) to the appropriate boxes and set the FS permissions so that only the headless user running ZK, or storm, has access to them.

Both storm and ZooKeeper use jaas configuration files to log the user in. Each jaas file may have multiple sections for different interfaces being used.

To enable Kerberos authentication in storm you need to set the following storm.yaml configs

storm.thrift.transport: "backtype.storm.security.auth.kerberos.KerberosSaslTransportPlugin"
java.security.auth.login.config: "/path/to/jaas.conf"

Nimbus and the supervisor processes will also connect to ZooKeeper (ZK) and we want to configure them to use Kerberos for authentication with ZK. To do this append

-Djava.security.auth.login.config=/path/to/jaas.conf

to the childopts of nimbus, ui, and supervisor. Here is an example given the default childopts settings at the time of this doc's writing:

nimbus.childopts: "-Xmx1024m -Djava.security.auth.login.config=/path/to/jaas.conf"
ui.childopts: "-Xmx768m -Djava.security.auth.login.config=/path/to/jaas.conf"
supervisor.childopts: "-Xmx256m -Djava.security.auth.login.config=/path/to/jaas.conf"

The jaas.conf file should look something like the following for the storm nodes. The StormServer section is used by nimbus and the DRPC nodes. It does not need to be included on supervisor nodes. The StormClient section is used by all storm clients that want to talk to nimbus, including the ui, logviewer, and supervisor. We will use this section on the gateways as well, but the structure of that will be a bit different. The Client section is used by processes wanting to talk to ZooKeeper and really only needs to be included with nimbus and the supervisors. The Server section is used by the ZooKeeper servers. Having unused sections in the jaas is not a problem.

StormServer {
   com.sun.security.auth.module.Krb5LoginModule required
   useKeyTab=true
   keyTab="$keytab"
   storeKey=true
   useTicketCache=false
   principal="$principal";
};
StormClient {
   com.sun.security.auth.module.Krb5LoginModule required
   useKeyTab=true
   keyTab="$keytab"
   storeKey=true
   useTicketCache=false
   serviceName="$nimbus_user"
   principal="$principal";
};
Client {
   com.sun.security.auth.module.Krb5LoginModule required
   useKeyTab=true
   keyTab="$keytab"
   storeKey=true
   useTicketCache=false
   serviceName="zookeeper"
   principal="$principal";
};
Server {
   com.sun.security.auth.module.Krb5LoginModule required
   useKeyTab=true
   keyTab="$keytab"
   storeKey=true
   useTicketCache=false
   principal="$principal";
};

The following is an example based off of the keytabs generated

StormServer {
   com.sun.security.auth.module.Krb5LoginModule required
   useKeyTab=true
   keyTab="/keytabs/storm.keytab"
   storeKey=true
   useTicketCache=false
   principal="storm/storm.example.com@STORM.EXAMPLE.COM";
};
StormClient {
   com.sun.security.auth.module.Krb5LoginModule required
   useKeyTab=true
   keyTab="/keytabs/storm.keytab"
   storeKey=true
   useTicketCache=false
   serviceName="storm"
   principal="storm@STORM.EXAMPLE.COM";
};
Client {
   com.sun.security.auth.module.Krb5LoginModule required
   useKeyTab=true
   keyTab="/keytabs/storm.keytab"
   storeKey=true
   useTicketCache=false
   serviceName="zookeeper"
   principal="storm@STORM.EXAMPLE.COM";
};
Server {
   com.sun.security.auth.module.Krb5LoginModule required
   useKeyTab=true
   keyTab="/keytabs/zk.keytab"
   storeKey=true
   useTicketCache=false
   serviceName="zookeeper"
   principal="zookeeper/zk1.example.com@STORM.EXAMPLE.COM";
};

Nimbus also will translate the principal into a local user name, so that other services can use this name. To configure this for Kerberos authentication set

storm.principal.tolocal: "backtype.storm.security.auth.KerberosPrincipalToLocal"

This only needs to be done on nimbus, but it will not hurt on any node. We also need to inform the topology who the supervisor daemon and the nimbus daemon are running as, from a ZooKeeper perspective.

storm.zookeeper.superACL: "sasl:${nimbus-user}"

Here nimbus-user is the Kerberos user that nimbus uses to authenticate with ZooKeeper. If ZooKeeeper is stripping host and realm then this needs to have host and realm stripped too.

Complete details of how to setup a secure ZK are beyond the scope of this document. But in general you want to enable SASL authentication on each server, and optionally strip off host and realm

authProvider.1 = org.apache.zookeeper.server.auth.SASLAuthenticationProvider
kerberos.removeHostFromPrincipal = true
kerberos.removeRealmFromPrincipal = true

And you want to include the jaas.conf on the command line when launching the server so it can use it can find the keytab.

-Djava.security.auth.login.config=/jaas/zk_jaas.conf

Ideally the end user will only need to run kinit before interacting with storm. To make this happen seamlessly we need the default jaas.conf on the gateways to be something like

StormClient {
   com.sun.security.auth.module.Krb5LoginModule required
   doNotPrompt=false
   useTicketCache=true
   serviceName="$nimbus_user";
};

The end user can override this if they have a headless user that has a keytab.

Authentication does the job of verifying who the user is, but we also need authorization to do the job of enforcing what each user can do.

The preferred authorization plug-in for nimbus is The SimpleACLAuthorizer. To use the SimpleACLAuthorizer, set the following:

nimbus.authorizer: "backtype.storm.security.auth.authorizer.SimpleACLAuthorizer"

DRPC has a separate authorizer configuration for it. Do not use SimpleACLAuthorizer for DRPC.

The SimpleACLAuthorizer plug-in needs to know who the supervisor users are, and it needs to know about all of the administrator users, including the user running the ui daemon.

These are set through nimbus.supervisor.users and nimbus.admins respectively. Each can either be a full Kerberos principal name, or the name of the user with host and realm stripped off.

The Log servers have their own authorization configurations. These are set through logs.users and logs.groups. These should be set to the admin users or groups for all of the nodes in the cluster.

When a topology is submitted, the submitting user can specify users in this list as well. The users and groups specified (in addition to the users in the cluster-wide setting) will be granted access to the submitted topology's worker logs in the logviewers.

To ensure isolation of users in multi-tenancy, the supervisors must run under a headless user and unique group:

1. Add your chosen "headless user" to all supervisor hosts.
2. Create unique group and make it the primary group for the headless user on the supervisor nodes.
3. Then set following properties on storm for these supervisor nodes.

To support multi-tenancy better we have written a new scheduler. To enable this scheduler set:

storm.scheduler: "backtype.storm.scheduler.multitenant.MultitenantScheduler"

Be aware that many of the features of this scheduler rely on storm authentication. Without storm authentication, the scheduler will not know what the user is, and thus will not isolate topologies properly.

The goal of the multi-tenant scheduler is to provide a way to isolate topologies from one another, but it also allows you to limit the total resources that an individual user can have in the cluster.

The scheduler config can be set either through storm.yaml or through a separate config file called multitenant-scheduler.yaml (which should be placed in the same directory as storm.yaml). Though it is preferable to use multitenant-scheduler.yaml, because it can be updated without needing to restart nimbus.

There is currently only one config option:

• multitenant.scheduler.user.pools: a map from the user name to the maximum number of nodes that the user is guaranteed to be able to use for their topologies.

For example:

multitenant.scheduler.user.pools:
    "evans": 10
    "derek": 10

By default storm runs workers as the user that is running the supervisor. This is not ideal for security. To make storm run the topologies as the user that launched them set.

supervisor.run.worker.as.user: true

There are several files that go along with this that need to be configured properly to make storm secure.

The worker-launcher executable is a special program that allows the supervisor to launch workers as different users. For this to work, worker-launcher needs to be owned by root, but with the group set to be a group that only the supervisor headless user is a part of. worker-launcher also needs to have 6550 octal permissions. There is also a worker-launcher.cfg file, usually located under /etc/, that should look something like the following:

storm.worker-launcher.group=$(worker_launcher_group)
min.user.id=$(min_user_id)

where worker_launcher_group is the same group the supervisor user is a part of, and min.user.id is set to the first real user id on the system. This config file also needs to be owned by root and not have world nor group write permissions.

A storm client may submit requests on behalf of another user. For example, if a userX submits an oozie workflow and as part of workflow execution if user oozie wants to submit a topology on behalf of userX it can do so by leveraging the impersonation feature. In order to submit a topology as some other user, you can use the StormSubmitter.submitTopologyAs API. Alternatively you can use NimbusClient.getConfiguredClientAs to get a nimbus client as some other user and perform any nimbus action (i.e., kill/rebalance/activate/deactivate) using this client.

To ensure only authorized users can perform impersonation, you should start nimbus with nimbus.impersonation.authorizer set to backtype.storm.security.auth.authorizer.ImpersonationAuthorizer. The ImpersonationAuthorizer uses nimbus.impersonation.acl as the acl to authorize users. Following is a sample nimbus config for supporting impersonation:

nimbus.impersonation.authorizer: backtype.storm.security.auth.authorizer.ImpersonationAuthorizer
nimbus.impersonation.acl:
    impersonating_user1:
        hosts:
            [comma separated list of hosts from which impersonating_user1 is allowed to impersonate other users]
        groups:
            [comma separated list of groups whose users impersonating_user1 is allowed to impersonate]
    impersonating_user2:
        hosts:
            [comma separated list of hosts from which impersonating_user2 is allowed to impersonate other users]
        groups:
            [comma separated list of groups whose users impersonating_user2 is allowed to impersonate]

To support the oozie use-case, the following config can be supplied:

nimbus.impersonation.acl:
    oozie:
        hosts:
            [oozie-host1, oozie-host2, 127.0.0.1]
        groups:
            [some-group-that-userX-is-part-of]

Individual topologies have the ability to push credentials (tickets and tokens) to workers so that they can access secure services. Exposing this to all of the users can be a pain for them. To hide this from them, in the common case plugins can be used to populate the credentials, unpack them on the other side into a java Subject, and also allow Nimbus to renew the credentials if needed. These are controlled by the following configs:

• topology.auto-credentials: a list of java plugins, all of which must implement IAutoCredentials interface, that populate the credentials on gateway and unpack them on the worker side. On a kerberos secure cluster they should be set by default to point to backtype.storm.security.auth.kerberos.AutoTGT. nimbus.credential.renewers.classes should also be set to this value so that nimbus can periodically renew the TGT on behalf of the user.
• nimbus.credential.renewers.freq.secs: controls how often the renewer will poll to see if anything needs to be renewed, but the default should be fine.

In addition Nimbus itself can be used to get credentials on behalf of the user submitting topologies. This can be configures using:

• nimbus.autocredential.plugins.classes: a list of fully qualified class names, all of which must implement INimbusCredentialPlugin. Nimbus will invoke the populateCredentials method of all the configured implementation as part of topology submission. You should use this config with topology.auto-credentials and nimbus.credential.renewers.classes so the credentials can be populated on the worker side and nimbus can automatically renew them. Currently there are 2 examples of using this config: AutoHDFS and AutoHBase, which auto-populate hdfs and hbase delegation tokens for topology submitter so they don't have to distribute keytabs on all possible worker hosts.

By default storm allows any sized topology to be submitted. But ZooKeeper and other components have limitations on how big a topology can actually be. The following configs allow you to limit the maximum size a topology can be.

The Logviewer daemon now is also responsible for cleaning up old log files for dead topologies.

With SimpleACLAuthorizer any user with a valid kerberos ticket can deploy a topology or do further operations such as activate, deactivate, access cluster information, etc. One can restrict this access by specifying nimbus.users or nimbus.groups in storm.yaml. If nimbus.users is configured then only the users in the list can deploy a topology or access the cluster. Similarly nimbus.groups restrict storm cluster access to users who belong to those groups.

E.g.:

nimbus.users:
   - "testuser"

or

nimbus.groups:
   - "storm"

Hopefully more on this soon