DEV Community: Tarcisio Freitas

Updating Apache Tomcat on RHEL via AppStream: Challenges and Solutions

Tarcisio Freitas — Tue, 08 Jul 2025 05:40:17 +0000

This guide details the process of updating Apache Tomcat to the latest version (9.0.87) in a Red Hat Enterprise Linux (RHEL) 9.4 (Plow) environment, covering specific challenges encountered in July 2025. The motivation for this article arose from memory failures in the survivor area of the JVM, affecting critical Java applications and causing crashes even with a small number of active users.

We chose Tomcat to host ORDS/APEX and other Java-based applications. Despite initial efforts such as upgrading from Java 8 to Java 21 and constant monitoring using jstat, the memory leak persisted. Red Hat support recommended upgrading Tomcat to a version maintained via the AppStream repositories.

1. Prerequisites

Before starting, ensure the following:

Operating system: RHEL 9.4 with AppStream repositories configured (use of dnf is recommended).
Superuser privileges (sudo).
JDK installed and updated, compatible with the target Tomcat version (minimum Java 8 for Tomcat 9).

2. Preparing the Environment

2.1. Backup Current Installation

Perform a full backup of your existing Tomcat installation, preserving permissions, symbolic links, and metadata:

sudo systemctl stop tomcat
sudo cp -rp --preserve=all /opt/tomcat /backup_path/tomcat -v

Note: The --preserve=all option ensures symbolic links, ownerships, groups, and permissions are retained.

2.2. Remove Old Versions

In order to avoid future errors or conflicts, rmove any residual Tomcat packages and service files:

sudo dnf remove 'tomcat*' -y
sudo rm -f /etc/systemd/system/tomcat.service
sudo rm -rf /opt/tomcat

Confirm the removal:

rpm -qa -v | grep -i tomcat
sudo ls -lha /opt/tomcat
sudo ls -lha /usr/share/tomcat/

3. Installing Tomcat 9 via AppStream

3.1. Update and Install

Update the system and install Tomcat and its modules:

sudo dnf update -y
sudo dnf install tomcat tomcat-webapps tomcat-admin-webapps -y

3.2. Enable the Service

Start and enable the Tomcat service:

sudo systemctl enable --now tomcat
sudo systemctl daemon-reload

3.3. Configure Firewall

Open port 8080 if necessary:

sudo firewall-cmd --permanent --add-port=8080/tcp
sudo firewall-cmd --reload

4. Directory Structure

The following table compares the directory paths used by Tomcat when installed via AppStream vs. a traditional installation:

Category	AppStream (RHEL) Path	Traditional Path
Configuration	`/etc/tomcat`	`[TOMCAT_HOME]/conf`
Applications	`/var/lib/tomcat/webapps`	`[TOMCAT_HOME]/webapps`
Logs	`/var/log/tomcat`	`[TOMCAT_HOME]/logs`
Binaries	`/usr/share/tomcat`	`[TOMCAT_HOME]/bin`

5. Configuration and Application Deployment

5.1. Restore Configuration

Back up the default configuration and restore from your previous installation:

sudo mv /etc/tomcat/tomcat-users.xml /etc/tomcat/tomcat-users.xml.bkp
sudo cp /backup_path/tomcat/conf/tomcat-users.xml /etc/tomcat/tomcat-users.xml
sudo cp /backup_path/tomcat/webapps/manager/META-INF/context.xml /usr/share/tomcat/webapps/manager/META-INF/context.xml

5.2. Deploy Applications

Copy .war files and context configuration from backup:

sudo cp /backup_path/tomcat/webapps/*.war /usr/share/tomcat/webapps/
sudo cp /backup_path/tomcat/conf/Catalina/localhost/*.xml /etc/tomcat/Catalina/localhost/
sudo chown root:tomcat /usr/share/tomcat/webapps/*.war
sudo chmod 644 /usr/share/tomcat/webapps/*.war
sudo chown root:tomcat /etc/tomcat/Catalina/localhost/*.xml
sudo chmod 644 /etc/tomcat/Catalina/localhost/*.xml

5.3. Restart Tomcat

Reload the configuration and restart the service:

sudo systemctl daemon-reload
sudo systemctl restart tomcat

6. Memory Configuration (`CATALINA_OPTS`)

6.1. Initial Recommendations

Red Hat offers a JVM Configuration Calculator that helps generate optimal memory and GC settings:

Red Hat JVM Configuration Calculator

Also, this article provides excellent insights on JVM memory allocation:

How the JVM Uses and Allocates Memory

6.2. Configure Systemd

Edit Tomcat’s override configuration:

sudo systemctl edit tomcat

Insert the following content:

[Service]
Environment="CATALINA_OPTS=\
-Xms20G -Xmx20G -server \
-XX:+UseG1GC \
-XX:+ExplicitGCInvokesConcurrent \
-XX:MaxGCPauseMillis=500 \
-Xlog:gc*:file=/var/log/tomcat/gc.log:time,uptime,level,tags:filecount=5,filesize=10M \
-XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/tmp/"

Or use a single-line version for compatibility:

[Service]
Environment="CATALINA_OPTS=-Xms20G -Xmx20G -server -XX:+UseG1GC -XX:+ExplicitGCInvokesConcurrent -XX:MaxGCPauseMillis=500 -Xlog:gc*:file=/var/log/tomcat/gc.log:time,uptime,level,tags:filecount=5,filesize=10M -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/tmp/"

Note: If formatting issues prevent the service from starting, use the single-line version.

6.3. Set Log Permissions

sudo chown -R tomcat:tomcat /var/log/tomcat
sudo chmod 750 /var/log/tomcat

6.4. Restart and Validate

sudo systemctl restart tomcat
sudo systemctl status tomcat --no-pager
sudo systemctl show tomcat | grep CATALINA_OPTS

Why use --no-pager?

Displays full output directly in the terminal.

Easier to pipe or redirect in automation scripts.

Prevents hangs in automated tools that rely on systemctl.

6.5. Garbage Collector Selection

Avoid using multiple collectors simultaneously. Choose one:

For G1GC (recommended for modern JVMs):

-XX:+UseG1GC

For ParallelGC:

-XX:+UseParallelGC

6.6. Configure tomcat-users.xml to enable Web Mannager

Copy your configuration (if exists) of you

backup_tomcat_path/tomcat-users.xml

/etc/tomcat/tomcat-users.xml

7. Issues with Missing Libraries (commons-dbcp)

7.1. Problem Context

Some applications failed to deploy due to missing commons-dbcp. Red Hat’s minimal Tomcat packaging excludes legacy libraries like commons-dbcp 1.4.

Check availability:

sudo dnf search dbcp

7.2. Solution: Manual Installation

Step 1: Create Temporary Directory

mkdir -p ~/downloads/missing_libs_dnf_tomcat/
cd ~/downloads/missing_libs_dnf_tomcat/

Step 2: Download the Libraries

wget https://archive.apache.org/dist/commons/dbcp/binaries/commons-dbcp-1.4-bin.zip
wget https://archive.apache.org/dist/commons/pool/binaries/commons-pool-1.6-bin.zip

Step 3: Unzip and Copy to Tomcat’s `lib`

unzip commons-dbcp-1.4-bin.zip
unzip commons-pool-1.6-bin.zip
sudo cp commons-dbcp-1.4/commons-dbcp-1.4.jar /usr/share/tomcat/lib/
sudo cp commons-pool-1.6/commons-pool-1.6.jar /usr/share/tomcat/lib/

Step 4: Adjust `catalina.properties` (Optional)

If JNDI-related errors persist, comment out the DataSource.Factory line:

sudo vi /etc/tomcat/tomcat.conf

Comment the following:

#javax.sql.DataSource.Factory=org.apache.commons.dbcp.BasicDataSourceFactory

Step 5: Restart Tomcat

sudo systemctl restart tomcat

Conclusion

This guide documents how we solved JVM memory issues in a RHEL 9.4 environment by upgrading Java and Tomcat 9 via AppStream. The process involved backing up the existing setup, removing old versions, performing a clean install, fine-tuning JVM settings, and resolving missing library issues. We hope this article, written in July 2025, provides helpful guidance to other professionals facing similar challenges.

By Tarcisio Freitas

Oracle APEX Architect, Senior APEX Developer, Senior Oracle DBA

portuguese version:
https://dev.to/tarcisiogf/atualizando-o-apache-tomcat-no-rhel-9-via-appstream-e-seus-desafios-4g74

Header image credit: https://www.novoshore.com/2025/01/28/ords-24-4-http-removal

Atualizando o Apache Tomcat no RHEL 9 via AppStream e seus desafios

Tarcisio Freitas — Tue, 08 Jul 2025 05:29:23 +0000

Este guia detalha o processo de atualização do Apache Tomcat para ultima versão (9.0.87) em um ambiente Red Hat Enterprise Linux (RHEL) 9.4 (Plow), abordando desafios específicos encontrados em julho de 2025. A motivação para este artigo surgiu de falhas de memória na área survival da JVM em aplicações Java críticas, que causavam travamentos mesmo com poucos usuários conectados.
Escolhemos o Tomcat para hospedar o ORDS/APEX e outras aplicações em java.
Após algumas inciativas como atualização do Java 8 para o Java 21 e monitoramento constante via jstat, o memory leak persistia. O suporte da Red Hat recomendou atualizar o Tomcat para uma versão mantida nos repositórios AppStream.

1. Pré-requisitos

Antes de iniciar, verifique as seguintes condições:

Sistema operacional: RHEL 9.4 com repositórios AppStream configurados (recomenda-se o uso do dnf).
Permissões de superusuário (sudo).
JDK instalado e atualizado, compatível com a versão do Tomcat (mínimo Java 8 para Tomcat 9).

2. Preparação do Ambiente

2.1. Backup da Instalação Atual

Realize um backup completo da instalação do Tomcat, preservando permissões, links simbólicos e metadados:

sudo cp -rp --preserve=all /opt/tomcat /backup_path/tomcat/ -v

Nota: A opção --preserve=all mantém links simbólicos, proprietários, grupos e permissões.

2.2. Remoção de Versões Antigas

Remova pacotes e arquivos residuais do Tomcat:

sudo dnf remove 'tomcat*' -y
sudo rm -f /etc/systemd/system/tomcat.service

Confirme a remoção completa:

rpm -ql tomcat | less
sudo ls -lha /etc/tomcat/
sudo ls -lha /usr/share/tomcat/

3. Instalação do Tomcat 9 via AppStream

3.1. Atualização e Instalação

Atualize o sistema e instale o Tomcat e seus módulos:

sudo dnf update -y
sudo dnf install tomcat tomcat-webapps tomcat-admin-webapps -y

3.2. Ativação do Serviço

Habilite e inicie o serviço do Tomcat:

sudo systemctl enable --now tomcat
sudo systemctl daemon-reload

3.3. Configuração do Firewall

Libere a porta 8080, se necessário:

sudo firewall-cmd --permanent --add-port=8080/tcp
sudo firewall-cmd --reload

4. Estrutura de Diretórios

A tabela abaixo compara os caminhos do Tomcat instalado via AppStream com a instalação clássica:

Categoria	Caminho (AppStream - RHEL)	Caminho (Clássico)
Configuração	`/etc/tomcat`	`[TOMCAT_HOME]/conf`
Aplicações	`/var/lib/tomcat/webapps`	`[TOMCAT_HOME]/webapps`
Logs	`/var/log/tomcat`	`[TOMCAT_HOME]/logs`
Binários	`/usr/share/tomcat`	`[TOMCAT_HOME]/bin`

5. Configurações e Deploy de Aplicações

5.1. Restauração de Configurações

Faça backup do arquivo de configuração padrão e restaure configurações anteriores:

sudo mv /etc/tomcat/tomcat-users.xml /etc/tomcat/tomcat-users.xml.bkp
sudo cp /backup_path/tomcat/conf/tomcat-users.xml /etc/tomcat/tomcat-users.xml
sudo cp /backup_path/tomcat/webapps/manager/META-INF/context.xml /usr/share/tomcat/webapps/manager/META-INF/context.xml

5.2. Deploy de Aplicações

Copie os arquivos .war e configurações de contexto do backup:

sudo cp /backup_path/tomcat/webapps/*.war /usr/share/tomcat/webapps/
sudo cp /backup_path/tomcat/conf/Catalina/localhost/*.xml /etc/tomcat/Catalina/localhost/
sudo chown root:tomcat /usr/share/tomcat/webapps/*.war
sudo chmod 644 /usr/share/tomcat/webapps/*.war
sudo chown root:tomcat /etc/tomcat/Catalina/localhost/*.xml
sudo chmod 644 /etc/tomcat/Catalina/localhost/*.xml

5.3. Reiniciar o Tomcat

Atualize e reinicie o serviço:

sudo systemctl daemon-reload
sudo systemctl restart tomcat

6. Ajustes de Memória (CATALINA_OPTS)

6.1. Recomendações Iniciais

Existe uma calculadora que a Redhat oferta para o auxilio da configuração dos parâmetros da JVM muito interessante:

Este aplicativo permite especificar vários parâmetros para o ambiente e a JVM específicos, gerando opções otimizadas para a JVM. Ele também explica por que cada opção é gerada e fornece um link para a base de conhecimento da Red Hat para problemas e soluções conhecidos.

Calculadora de Configuração da JVM

E neste artigo há um bom conteúdo para a compressão da alocação de Memória da JVM

How the JVM Uses and Allocates Memory

6.2. Configuração do Systemd

Edite o override do serviço Tomcat:

sudo systemctl edit tomcat

Adicione o seguinte conteúdo:

[Service]
Environment="CATALINA_OPTS=
-Xms20G -Xmx20G -server \
-XX:+UseG1GC \
-XX:+ExplicitGCInvokesConcurrent \
-XX:MaxGCPauseMillis=500 \
-Xlog:gc*:file=/var/log/tomcat/gc.log:time,uptime,level,tags:filecount=5,filesize=10M \
-XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/tmp/"

ou assim

[Service]
Environment="CATALINA_OPTS=-Xms20G -Xmx20G -server -XX:+UseG1GC -XX:+ExplicitGCInvokesConcurrent -XX:MaxGCPauseMillis=500 -Xlog:gc*:file=/var/log/tomcat/gc.log:time,uptime,level,tags:filecount=5,filesize=10M -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/tmp/"

Nota: Se houver problemas com o formato (ocorre na hora do start do tomcat), dependendo da sua paciencia em acertar a diagramação correta, escolha a segunda opção.

6.3. Permissões de Logs

Ajuste as permissões do diretório de logs:

sudo chown -R tomcat:tomcat /var/log/tomcat
sudo chmod 750 /var/log/tomcat

6.4. Reiniciar e Validar

Reinicie e verifique o serviço:

sudo systemctl restart tomcat
sudo systemctl status tomcat --no-pager
sudo systemctl show tomcat | grep CATALINA_OPTS

Por que usar --no-pager?

Exibe a saída completa no terminal.

Facilita redirecionamento ou processamento por outros comandos.

Evita travamentos em scripts automatizados.

6.5. Escolha do Garbage Collector

Evite conflitos entre coletores de lixo. Escolha apenas um:

Para G1GC (recomendado para Java recente):

-XX:+UseG1GC

Para ParallelGC:

-XX:+UseParallelGC

7. Problemas com Bibliotecas (commons-dbcp)

7.1. Contexto do Problema

Algumas aplicações falharam no deploy devido à ausência da biblioteca commons-dbcp. A Red Hat empacota o Tomcat de forma minimalista, excluindo bibliotecas legadas como commons-dbcp 1.4.

Confirme a indisponibilidade:

sudo dnf search dbcp

7.2. Solução: Instalação Manual

Passo 1: Criar Diretório Temporário

mkdir -p ~/downloads/missing_libs_dnf_tomcat/
cd ~/downloads/missing_libs_dnf_tomcat/

Passo 2: Baixar Bibliotecas

wget https://archive.apache.org/dist/commons/dbcp/binaries/commons-dbcp-1.4-bin.zip
wget https://archive.apache.org/dist/commons/pool/binaries/commons-pool-1.6-bin.zip

Passo 3: Descompactar e Copiar

unzip commons-dbcp-1.4-bin.zip
unzip commons-pool-1.6-bin.zip
sudo cp commons-dbcp-1.4/commons-dbcp-1.4.jar /usr/share/tomcat/lib/
sudo cp commons-pool-1.6/commons-pool-1.6.jar /usr/share/tomcat/lib/

Passo 4: Ajustar `catalina.properties` (Opcional)

Se houver erros de JNDI, comente a linha referente ao DataSource.Factory:

sudo vi /etc/tomcat/catalina.properties

Localize e comente:

#javax.sql.DataSource.Factory=org.apache.commons.dbcp.BasicDataSourceFactory

Passo 5: Reiniciar o Tomcat

sudo systemctl restart tomcat

Conclusão

Este guia documenta a solução para falhas de memória na JVM em um ambiente RHEL 9.4, resolvidas pela atualização do Java e do Tomcat 9 via AppStream. O processo incluiu backup, remoção de versões antigas, instalação, configuração de memória e resolução de problemas com bibliotecas legadas. Esperamos que este conteúdo, registrado em julho de 2025, auxilie outros profissionais enfrentando desafios semelhantes.

Por Tarcisio Freitas
Oracle DBA, Oracle APEX Architect, Senior APEX Developer.

English version:
https://dev.to/tarcisiogf/updating-apache-tomcat-on-rhel-via-appstream-challenges-and-solutions-28d0

header_image/credit:https://www.novoshore.com/2025/01/28/ords-24-4-http-removal

Complete Tutorial: Setting up email sending on OCI Free Tier with Oracle APEX on Autonomous Database

Tarcisio Freitas — Wed, 21 Aug 2024 20:43:26 +0000

Cover Image credit: Imagem de creativeart no Freepik

First: What is OCI Email Delivery?

Oracle Cloud Infrastructure (OCI) Email Delivery is a service designed for sending transactional and high-volume emails securely and reliably. This article will guide you through the process of configuring OCI Email Delivery to send emails directly from your Oracle APEX Autonomous Database.

Objective

Configure OCI Email Delivery.
Integrate the service with Oracle APEX.
Test email delivery.
Troubleshoot sending issues

Before you Start

Ensure you have:

A free-tier Oracle Cloud Infrastructure (OCI) account.
Administrator privileges.
An active Oracle APEX service.

Notice

OCI often updates the names, order, and placement of services in the menu. As a result, the paths described in this article might differ slightly by the time you read it. However, a quick search in the service search bar should help you find the configuration options you need.

Let´s get start:

1. Create or Select a Domain

Once you’re logged into OCI with your administrator account.

If you haven’t added a domain yet, do so now. If multiple domains are available, select the one currently in use.

Go to: Menu > Identity and Security > Domains

If no information is displayed, verify that a valid compartment is selected.

2. Create a User Group

Go to: Menu > Identity and Security > Domains > Oracle Identity Cloud Service > Domain > Groups > Create Group

For example: Create a group named My-Email-Group.

3. Create a user and add them to the group (one step)

Go to: Menu > Identity and Security > Domains > Oracle Identity Cloud Service > Domain

4. Create an Email Policy

Go to: Menu > Identity and Security > Policies and associate it with the user group you've created

5. Create credentials for your SMTP service

Go to: Menu > Identity > Domains > your domain > Users > SMTP
Copy the user and password and store them securely, as you'll need them soon.

6. Create an email domain

Don’t confuse this with a regular domain.

Go to: Menu > Developer Services > Email Delivery

Click on Create Email Domain.

7. Create a user to approve your emails

Go to: Menu > Developer Services > Email Delivery

An Approved Sender is the email address used in the "From:" header of the emails you send. Each sender email address must be registered to use it for Email Delivery.

Example: noreply@yourdomain.com or sender_email@yourdomain.com

8. Obtain SMTP parameters

Oracle Message:
For optimal sending reputation, configure DKIM for this email domain. This is an important step to help ensure email delivery and reach the inbox.

Do not skip this step unless you're in a development environment, in a hurry, or you are not very concerned about security.

A suggestion: Why don't you keep going with the setup, test it out, send a test email? If it works, come back and finish the DKIM part.

Go to: Menu > Developer Services > Email Delivery > Configuration

In the SMTP sending information (not the first HTTPS sending information), copy:

Public endpoint
Port

Stay calm. Long configurations can be tedious, but we’re almost done!

9. Configure the SMTP Service in Autonomous

Execute the following command in:

Oracle Apex / SQL Workshop / SQL Commands or
SQL Developer
Or any environment that has admin permission and access to the autonomous.

It is now time to paste the SMTP credentials that you got in steps 5 and 9:



BEGIN
    APEX_INSTANCE_ADMIN.SET_PARAMETER('SMTP_HOST_ADDRESS', 'paste_your_smtp_endpoint_here');
    APEX_INSTANCE_ADMIN.SET_PARAMETER('SMTP_USERNAME', 'enter_your_username_here');
    APEX_INSTANCE_ADMIN.SET_PARAMETER('SMTP_PASSWORD', 'enter_your_password_here');
    COMMIT;
END;

10. Testing Email Delivery

Now it’s time to test. If everything is set up correctly, your email should be sent.

As in the previous step, choose your preferred location for sending the test:



BEGIN
    APEX_MAIL.SEND (
        P_To    => 'any@gmail.com',
        P_Cc    => 'another@gmail.com',
        P_From  => 'your_approved_sender@your_email_domain',
        P_Subj  => 'OCI Notification Test via Apex',
        P_Body  => 'Worked'
    );
    COMMIT;
    APEX_MAIL.PUSH_QUEUE;
END;


 APEX_MAIL.PUSH_QUEUE:

This instruction queues email messages for sending. It processes emails that have been configured but not yet sent, allowing you to manage and dispatch email communications from your APEX application.

Some people manage to set up the configuration correctly and send the email, but the message doesn’t reach the recipient. As a result, the developer might believe there is a problem with the environment, configuration, or execution of the command.

And in some cases, it's actually just the email that was sent to the queue and not executed immediately.

11. Checking Sending Issues

To check for sending issues...

Go to: Menu > Manage Instance > Mail Queue

If the email does not appear in the queue or is not sent, check the following:

Ensure APEX_MAIL.PUSH_QUEUE was executed.
Verify if there are errors in the sender's name.

Try another curious test.

If the recipient (entity that will receive the message) does not exist,
the email will not show sending errors. Only a failure in the sender’s name will generate a sending error.

When you press "Force Send All Mail" button, if the queue is empty, it means the email was successfully sent, as it was already ready for dispatch and waiting in the queue.

12. Important Queries for Analysis

You can also check complete details of all messagees using the administrative views:

To view the live status of the queue:



SELECT * FROM APEX_MAIL_QUEUE;

If no records were found, that's good. It means that nothing is stuck in the queue.

The most important.
To view the processing of all sent or unsent emails:



SELECT * FROM APEX_MAIL_LOG;

13. OCI Email Deliver Dashboard

After sending several messages, you can check more details in the Email Deliverability and Reputation Governance Dashboard in OCI.

Go to: Menu > Developer Services > Email Delivery

If all cards show zero activity, change the 'Filter by time' setting. Refreshing the page could display some data

14. Sending from you Oracle APEX app

if you are writing a process in Oracle APEX to send an email, using a template or PL/SQL code, enable the option to send immediately so that the message doesn’t get stuck in the queue.
Option Send Immediately: Active.

Actually, the image below shows all the settings you need to send a standardized email from any Oracle Apex page. Just click any button and you're good to go! It's the simplest and fastest way to do it. Don't forget to add a button to your page that triggers the send_mail_without_PLSQL process.

An alert...

The email queue serves several purposes. If every application sent emails immediately, it could lead to performance issues. So, it might be a good idea to understand the company culture or to establish one.

One way to do this is by talking to your database administrator, the person in charge of infrastructure, or a colleague who has been with the company longer, to figure out the best strategy for each environment (development, production, or staging).

Conclusion

Congratulations! You have successfully configured OCI Email Delivery and integrated it with Oracle APEX. To ensure effective and secure email delivery, consider configuring DKIM and monitoring your sending reputation.

If you encounter issues or need further support, consult Oracle’s official documentation or contact technical support.

Thanks for reading and for you time!

DEV Community: Tarcisio Freitas

Updating Apache Tomcat on RHEL via AppStream: Challenges and Solutions

1. Prerequisites

2. Preparing the Environment

2.1. Backup Current Installation

2.2. Remove Old Versions

3. Installing Tomcat 9 via AppStream

3.1. Update and Install

3.2. Enable the Service

3.3. Configure Firewall

4. Directory Structure

5. Configuration and Application Deployment

5.1. Restore Configuration

5.2. Deploy Applications

5.3. Restart Tomcat

6. Memory Configuration (CATALINA_OPTS)

6.1. Initial Recommendations

6.2. Configure Systemd

6.3. Set Log Permissions

6.4. Restart and Validate

6.5. Garbage Collector Selection

6.6. Configure tomcat-users.xml to enable Web Mannager

7. Issues with Missing Libraries (commons-dbcp)

7.1. Problem Context

7.2. Solution: Manual Installation

Step 1: Create Temporary Directory

Step 2: Download the Libraries

Step 3: Unzip and Copy to Tomcat’s lib

Step 4: Adjust catalina.properties (Optional)

Step 5: Restart Tomcat

Conclusion

Atualizando o Apache Tomcat no RHEL 9 via AppStream e seus desafios

1. Pré-requisitos

2. Preparação do Ambiente

2.1. Backup da Instalação Atual

2.2. Remoção de Versões Antigas

3. Instalação do Tomcat 9 via AppStream

3.1. Atualização e Instalação

3.2. Ativação do Serviço

3.3. Configuração do Firewall

4. Estrutura de Diretórios

5. Configurações e Deploy de Aplicações

5.1. Restauração de Configurações

5.2. Deploy de Aplicações

5.3. Reiniciar o Tomcat

6. Ajustes de Memória (CATALINA_OPTS)

6.1. Recomendações Iniciais

6.2. Configuração do Systemd

6.3. Permissões de Logs

6.4. Reiniciar e Validar

6.5. Escolha do Garbage Collector

7. Problemas com Bibliotecas (commons-dbcp)

7.1. Contexto do Problema

7.2. Solução: Instalação Manual

Passo 1: Criar Diretório Temporário

Passo 2: Baixar Bibliotecas

Passo 3: Descompactar e Copiar

Passo 4: Ajustar catalina.properties (Opcional)

Passo 5: Reiniciar o Tomcat

Conclusão

Complete Tutorial: Setting up email sending on OCI Free Tier with Oracle APEX on Autonomous Database

Cover Image credit: Imagem de creativeart no Freepik

First: What is OCI Email Delivery?

Objective

Before you Start

Notice

1. Create or Select a Domain

2. Create a User Group

3. Create a user and add them to the group (one step)

4. Create an Email Policy

5. Create credentials for your SMTP service

6. Create an email domain

7. Create a user to approve your emails

8. Obtain SMTP parameters

9. Configure the SMTP Service in Autonomous

10. Testing Email Delivery

11. Checking Sending Issues

12. Important Queries for Analysis

13. OCI Email Deliver Dashboard

14. Sending from you Oracle APEX app

6. Memory Configuration (`CATALINA_OPTS`)

Step 3: Unzip and Copy to Tomcat’s `lib`

Step 4: Adjust `catalina.properties` (Optional)

Passo 4: Ajustar `catalina.properties` (Opcional)