Red Hat

Running an Embedded WildFly Host Controller in the CLI

WildFly supports running a standalone server in Offline mode as an embedded server. An analogous capability has been added for domain mode in the form of running an offline host controller. This article discusses some of the details and possible applications of this feature.

Introduction

For those not familiar with the existing embedded standalone server, see: Offline mode Running an Embedded WildFly 9 Server in the CLI · WildFly. One of the major use cases of this feature was to allow local administration of a WIldFly / JBoss EAP instance without requiring a socket based connection, or opening any local ports but still enabling configuration and administration operations. The embedded approach also allows for a fast boot that will allow multiple concurrent running instances to co-exist without configuring any additional socket offsets or interfaces to avoid port conflicts etc.

Using jboss-cli.sh and the embed-host-controller command enables a fast and flexible means of configuring host controller instances and servers.

Embedded Host Controller

In a similar way to the standalone embed-server command, the embed-host-controller command is provided, to start an embedded host controller running in the CLI. This host controller is started in admin-only mode, and no servers are started. [See below for more details on admin-only restrictions].

Starting an embedded Host Controller:

$ ./bin/jboss-cli.sh

You are disconnected at the moment. Type 'connect' to connect to the server or 'help' for the list of supported commands.
[disconnected /] embed-host-controller --std-out=echo
11:07:46,723 INFO  [org.jboss.modules] (AeshProcess: 1) JBoss Modules version 1.6.0.Final
11:07:46,825 INFO  [org.jboss.msc] (AeshProcess: 1) JBoss MSC version 1.2.7.SP1
11:07:46,870 INFO  [org.jboss.as] (MSC service thread 1-7) WFLYSRV0049: WildFly Full 11.0.0 (WildFly Core 3.0.1.Final) starting
[ Note: some startup output omitted for brevity. ]
11:07:48,845 INFO  [org.jboss.as] (Controller Boot Thread) WFLYSRV0025: WildFly Full 11.0.0 (WildFly Core 3.0.1.Final) (Host Controller) started in 2105ms - Started 56 of 61 services (18 services are lazy, passive or on-demand)

[domain@embedded /] ls -l
ATTRIBUTE                VALUE           TYPE
domain-organization      undefined       STRING
launch-type              EMBEDDED        STRING
local-host-name          master          STRING
management-major-version 5               INT
management-micro-version 0               INT
management-minor-version 0               INT
name                     Unnamed Domain  STRING
namespaces               []              OBJECT
process-type             Host Controller STRING
product-name             WildFly Full    STRING
product-version          11.0.0          STRING
release-codename         Kenny           STRING
release-version          3.0.1.Final     STRING
schema-locations         []              OBJECT

CHILD                     MIN-OCCURS MAX-OCCURS
core-service              n/a        n/a
deployment                n/a        n/a
deployment-overlay        n/a        n/a
extension                 n/a        n/a
host                      n/a        n/a
host-exclude              n/a        n/a
interface                 n/a        n/a
management-client-content n/a        n/a
path                      n/a        n/a
profile                   n/a        n/a
server-group              n/a        n/a
socket-binding-group      n/a        n/a
system-property           n/a        n/a

The non-modular client may also be used from the bin/client WildFly distribution:

$ java -jar bin/client/jboss-cli-client.jar
You are disconnected at the moment. Type 'connect' to connect to the server or 'help' for the list of supported commands.
[disconnected /] embed-host-controller --jboss-home=/wildfly-11.0.0
Warning! The CLI is running in a non-modular environment and cannot load commands from management extensions.
[domain@embedded /] cd /host=master/server-config=server-one
[domain@embedded server-config=server-one] ls -l
ATTRIBUTE                            VALUE             TYPE
auto-start                           true              BOOLEAN
cpu-affinity                         undefined         STRING
group                                main-server-group STRING
name                                 server-one        STRING
priority                             undefined         INT
socket-binding-default-interface     undefined         STRING
socket-binding-group                 undefined         STRING
socket-binding-port-offset           0                 INT
status                               STOPPED           STRING
update-auto-start-with-server-status false             BOOLEAN

CHILD           MIN-OCCURS MAX-OCCURS
interface       n/a        n/a
jvm             n/a        n/a
path            n/a        n/a
ssl             n/a        n/a
system-property n/a        n/a
[domain@embedded server-config=server-one]

See Modular vs Non-Modular Classloading and JBOSS_HOME in the original embedded server news article for details.

Executing commands:

[domain@embedded /]  /host=master/interface=public:write-attribute(name=inet-address, value=127.0.0.1)
{
    "outcome" => "success",
    "result" => undefined,
    "server-groups" => undefined,
    "response-headers" => {"process-state" => "reload-required"}
}

Reloading:

[domain@embedded /] reload --host=master --admin-only=true
11:17:20,092 INFO  [org.jboss.as] (Controller Boot Thread) WFLYSRV0025: WildFly Full 11.0.0 (WildFly Core 3.0.1.Final) (Host Controller) started in 279ms - Started 56 of 61 services (18 services are lazy, passive or on-demand)
[domain@embedded /]

Note that currently, the embedded host controller may only be started / reloaded in admin-only mode. In domain mode, servers are started and stopped via use of the process controller which is not currently supported as part of embedded mode.

Stopping:

[domain@embedded /] stop-embedded-host-controller
11:08:29,925 INFO  [org.jboss.as] (MSC service thread 1-7) WFLYSRV0050: WildFly Full 11.0.0 (WildFly Core 3.0.1.Final) stopped in 13ms

Command usage:

The embed-host-controller command has several options that behave in the same way as the previously mentioned standalone embedded server, which will not be discussed again here. The relevant embed-host-controller parameters are:

-c                - Name of the domain configuration file to use
                     (default is "domain.xml")
                     (Same as --domain-config)

--domain-config   - Name of the domain configuration file to use
                     (default is "domain.xml")
                     (Same as -c)

--host-config     - Name of the host configuration file to use
                     (default is "host.xml")

As mentioned above, --jboss-home, --std-out and --timeout may also be provided and function in the same manner as the embed-server command. The configuration files mentioned above (domain.xml, host.xml) above should be located in the $JBOSS_HOME/domain/configuration directory (or under the location pointed to by the system property jboss.domain.config.dir.) [See Command Line Properties for additional details on those properties.]

For example, to start an embedded host controller with configuration files contained in the otherdomain/configuration directory:

[wildfly-11]$ ./bin/jboss-cli.sh -Djboss.domain.config.dir=/wildfly-11/otherdomain/configuration
You are disconnected at the moment. Type 'connect' to connect to the server or 'help' for the list of supported commands.
[disconnected /] embed-host-controller --std-out=echo
11:26:44,122 INFO  [org.jboss.as] (Controller Boot Thread) WFLYSRV0025: WildFly Full 11.0.0 (WildFly Core 3.0.1.Final) (Host Controller) started in 1894ms - Started 56 of 61 services (18 services are lazy, passive or on-demand)
[domain@embedded /]

Configuration may then proceed and will be persisted to the otherdomain/configuration directory. This directory must already exist and contain base copies of the required configuration files (host.xml, domain.xml etc.).

Scripted configuration

The embedded host controller may be useful for configuration from a prepared file of scripted CLI commands. For example:

$ cat commands.cli
embed-host-controller
/server-group=main-server-group:write-attribute(name=socket-binding-port-offset, value=100)
/host=master/server-config=server-one:write-attribute(name=auto-start, value=false)
deploy --all-server-groups test.war
stop-embedded-host-controller

$ ./bin/jboss-cli.sh --file=commands.cli
{
    "outcome" => "success",
    "result" => undefined,
    "server-groups" => undefined
}

This approach may be used for a variety of setup and configuration tasks, for example setting up unit or integration tests quickly using the embedded host controller, then restarting in domain mode using domain.sh may require less time than starting the host controller normally using domain.sh, performing configuration and deployment etc, then restarting.

Other examples

Set server socket-binding-port-offset

In order to allow more than one running instance on the same host, a common configuration for testing (or any scenario needing to run a domain controller and a slave host controller (with servers) on the same host), a socket-binding-port-offset is commonly used. The slave host is configured to have a port offset so that the ports already in use by the domain controller’s servers do not conflict with those of the slave.

[domain@embedded /] /server-group=main-server-group:write-attribute(name=socket-binding-port-offset, value=100)
{
    "outcome" => "success",
    "result" => undefined,
    "server-groups" => undefined
}

Configure connection to remote domain controller

When configuring a slave host controller, configure the connection to the domain controller.

[domain@embedded /] /host=master:write-remote-domain-controller(host=remotedc.somedomain.tld, security-realm=ManagementRealm)
{
    "outcome" => "success",
    "result" => undefined,
    "server-groups" => undefined,
    "response-headers" => {"process-state" => "reload-required"}
}

System property

This can be useful as an initial configuration step before the host controller is started with domain.sh:

[domain@embedded /] /server-group=main-server-group/system-property=foo:add(value=bar)
{
    "outcome" => "success",
    "result" => undefined,
    "server-groups" => undefined
}

Future Direction

In the future we’d like to allow for starting the embedded host controller with some additional features, such as empty configurations in host and domain configuration files (similar to standalone embedded), and also re-examine the meaning and usage of --admin-only in the context of the embedded host controller.

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