How to Compose an Infinispan Docker Image

In a previous post, we showed how to manipulate the Infinispan Docker container configuration at both runtime and boot time.

Before diving into multi-host Docker usage, in this post, we'll explore how to create multi-container Docker applications involving Infinispan with the help of Docker Compose.

For this, we'll look at a typical scenario of an Infinispan server backed by an Oracle database as a cache store.

All the code for this sample can be found on GitHub.

Using Infinispan With the Oracle JDBC Cache Store

In order to have a cache with persistence with Oracle, we need to do some configuration: configure the driver in the server, create the data source associated with the driver, and configure the cache itself with JDBC persistence.

Let's take a look at each of those steps.

Obtaining and Configuring the Driver

The driver (ojdbc6.jar) should be downloaded and placed in the Driver folder of the sample project.

The module.xml declaration used to make it available on the server is as follows:

<?xml version="1.0" encoding="UTF-8"?>

<module xmlns="urn:jboss:module:1.0" name="com.oracle.jdbc.driver">
    <resources>
        <resource-root path="ojdbc6.jar"/>
    </resources>

    <dependencies>
      <module name="javax.api"/>
       <module name="javax.transaction.api"/>
    </dependencies>
</module>

Configuring the Data Source

The data source is configured in the datasource element of the server configuration file as shown below:

<datasource enabled="true" jndi-name="java:jboss/datasources/OracleDS" pool-name="oracle">
          <connection-url>jdbc:oracle:thin:@oracle:1521:xe</connection-url>
          <connection-property name="oracle.net.encryption_client">accepted</connection-property>
          <connection-property name="oracle.net.encryption_types_client">AES128</connection-property>
          <connection-property name="oracle.jdbc.ReadTimeout">120000</connection-property>
          <driver>oracle</driver>
          <security>
            <user-name>SYSTEM</user-name>
            <password>oracle</password>
          </security>
          <pool>
            <min-pool-size>1</min-pool-size>
            <max-pool-size>50</max-pool-size>
            <prefill>true</prefill>
            <flush-strategy>EntirePool</flush-strategy>
          </pool>
          <validation>
            <validate-on-match>true</validate-on-match>
            <valid-connection-checker class-name="org.jboss.jca.adapters.jdbc.extensions.oracle.OracleValidConnectionChecker"/>
            <use-fast-fail>true</use-fast-fail>
            <stale-connection-checker class-name="org.jboss.jca.adapters.jdbc.extensions.oracle.OracleStaleConnectionChecker"/>
            <exception-sorter class-name="org.jboss.jca.adapters.jdbc.extensions.oracle.OracleExceptionSorter"/>
          </validation>
          <timeout>
            <blocking-timeout-millis>60000</blocking-timeout-millis>
            <allocation-retry>100</allocation-retry>
            <allocation-retry-wait-millis>10000</allocation-retry-wait-millis>
            <idle-timeout-minutes>10</idle-timeout-minutes>
            <query-timeout>30000</query-timeout>
          </timeout>
          <statement>
            <share-prepared-statements>false</share-prepared-statements>
          </statement>
        </datasource>

Inside the datasource/drivers element, we need to declare the driver:

<driver module="com.oracle.jdbc.driver" name="oracle">
            <xa-datasource-class>oracle.jdbc.xa.client.OracleXADataSource</xa-datasource-class>
          </driver>

Creating the Cache

The last piece is to define a cache with the proper JDBC Store:

        <replicated-cache name="docker-compose-demo" mode="ASYNC" start="EAGER">
          <expiration interval="300000" lifespan="525600000000"/>
          <transaction mode="NONE"/>
          <string-keyed-jdbc-store datasource="java:jboss/datasources/OracleDS" passivation="false" preload="true" purge="false" shared="true">
            <property name="databaseType">ORACLE</property>
            <string-keyed-table prefix="ISPN">
              <id-column name="id" type="VARCHAR(256)"/>
              <data-column name="datum" type="BLOB"/>
              <timestamp-column name="version" type="NUMBER"/>
            </string-keyed-table>
            <property name="skipLoad">true</property>
            <property name="startupTimeout">30000</property>
            <write-behind modification-queue-size="209715200" shutdown-timeout="25000" flush-lock-timeout="15000" thread-pool-size="5"/>
          </string-keyed-jdbc-store>
        </replicated-cache>

Putting It All Together

From now on, without using Docker, we'll be ready to download and install Oracle following the specific instructions for your OS, then download the Infinispan Server, edit the configuration files, copy over the driver jar, and figure out how to launch the database and server, taking care not to have any port conflicts.

If it sounds too much work, it's because it really is. Wouldn't it be nice to have all these wired together and launched with a simple command line? Let's take a look at the Docker way next.

Enter Docker Compose

Docker Compose is a tool part of the Docker stack to facilitate the configuration, execution, and management of related Docker containers.

By describing the application aspects in a single YAML file, it allows centralized control of the containers, including custom configuration and parameters, and it also allows runtime interactions with each of the exposed services.

Composing Infinispan

Our Docker Compose file to assemble the application is given below:

version: '2'

services:
  oracle:
    image: wnameless/oracle-xe-11g
    environment:
      - ORACLE_ALLOW_REMOTE=true
  infinispan:
    image: jboss/infinispan-server:8.2.5.Final
    command: custom/clustered-docker
    depends_on:
      - oracle
    volumes:
      - $PWD/driver:/opt/jboss/infinispan-server/modules/com/oracle/jdbc/driver/main/
      - $PWD/custom:/opt/jboss/infinispan-server/standalone/configuration/custom

It contains two services:

• Oracle: Uses the wnameless/oracle-xe-11g Docker image with an environment variable to allow remote connections.
• Infinispan: Uses Version 8.2.5 Final of the Infinispan Server image. It is launched with a custom command pointing to the changed configuration file and it also mounts two volumes in the container: one for the driver and its module.xml and another for the folder holding our server XML configuration.

Launching

To start the application, just execute:

docker-compose up -d

To inspect the status of the containers, use:

$ docker-compose ps

         Name                        Command               State                                           Ports                                         
--------------------------------------------------------------------------------------------------------------------------------------------------------
infinispan_infinispan_1   docker-entrypoint.sh custo ...   Up      11211/tcp, 11222/tcp, 57600/tcp, 7600/tcp, 0.0.0.0:8080->8080/tcp, 8181/tcp, 9990/tcp 
infinispan_oracle_1       /bin/sh -c /usr/sbin/start ...   Up      0.0.0.0:1521->1521/tcp, 22/tcp, 8080/tcp                                       

To follow the Infinispan server logs, use:

docker-compose logs -f infinispan

Infinispan usually starts faster than the database, and since the server waits until the database is ready (more on that later), keep an eye on the log output for "Infinispan Server 8.2.5.Final (WildFly Core 2.0.10.Final) started." After that, both Infinispan and Oracle are properly initialized.

Testing It

Let's insert a value using the Rest endpoint from Infinispan and verify it was saved to the Oracle database:

IP=$(docker-compose exec infinispan hostname -i | tr -d '\r')

curl -v -X PUT  -H "Content-Type: text/plain" --data "value" http://${IP}:8080/rest/docker-compose-demo/hello

To check the Oracle database, we can attach to the container and use Sqlplus:

$ docker-compose exec oracle bash

root@9212b18ea641:/# sqlplus SYSTEM/oracle

SQL*Plus: Release 11.2.0.2.0 Production on Tue Nov 29 17:29:32 2016

Copyright (c) 1982, 2011, Oracle.  All rights reserved.

Connected to:
Oracle Database 11g Express Edition Release 11.2.0.2.0 - 64bit Production

SQL> select id from "ISPN_docker_compose_demo";

ID
--------------------------------------------------------------------------------
hello 

Other Operations

It's also possible to increase and decrease the number of containers for each of the services:

docker-compose scale infinispan=2

A Thing or Two About Startup Order

When dealing with dependent containers in Docker-based environments, it's highly recommended to make the connection obtention between parties robust enough so that the fact that one dependency is not totally initialized doesn't cause the whole application to fail when starting.

Although Compose does have a depends_on instruction, it simply starts the containers in the declared order but it has no means to detected when a certain container is fully initialized and ready to serve requests before launching a dependent one.

One may be tempted to simply write some glue script to detect if a certain port is open, but that does work in practice; the network socket may be opened, but the background service could still be in a transient initialization state.

The recommended solution for this it to make whoever depends on a service to retry periodically until the dependency is ready. On the Infinispan plus Oracle case, we specifically configured the data source with retries to avoid failing at once if the database is not ready:

          <timeout>
            <blocking-timeout-millis>60000</blocking-timeout-millis>
            <allocation-retry>100</allocation-retry>
            <allocation-retry-wait-millis>10000</allocation-retry-wait-millis>
            <idle-timeout-minutes>10</idle-timeout-minutes>
            <query-timeout>30000</query-timeout>
          </timeout>

When starting the application via Compose you'll notice that Infinispan print some WARN with connection exceptions until Oracle is available. Don't panic; this is expected!

Conclusion

Docker Compose is a powerful and easy to use tool to launch applications involving multiple containers. In this post, it's allowed the start of Infinispan plus Oracle with custom configurations with a single command.

It's also a handy tool to have during development and testing phase of a project, especially when using and evaluating Infinispan with its many possible integrations.

Be sure to check other examples of using Docker Compose involving Infinispan, such as the Infinispan+Spark Twitter demo, and the Infinispan+Apache Flink demo.