log4j-jakarta-smtp/src/main/java/org/apache/logging/log4j/smtp/appender/SmtpAppender.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to you under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.logging.log4j.smtp.appender;

import org.apache.logging.log4j.core.Appender;
import org.apache.logging.log4j.core.Filter;
import org.apache.logging.log4j.core.Layout;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.appender.AbstractAppender;
import org.apache.logging.log4j.core.config.Property;
import org.apache.logging.log4j.core.filter.ThresholdFilter;
import org.apache.logging.log4j.core.layout.HtmlLayout;
import org.apache.logging.log4j.core.net.ssl.SslConfiguration;
import org.apache.logging.log4j.plugins.Configurable;
import org.apache.logging.log4j.plugins.Plugin;
import org.apache.logging.log4j.plugins.PluginAttribute;
import org.apache.logging.log4j.plugins.PluginElement;
import org.apache.logging.log4j.plugins.PluginFactory;
import org.apache.logging.log4j.plugins.validation.constraints.ValidPort;

/**
 * Send an e-mail when a specific logging event occurs, typically on errors or
 * fatal errors.
 *
 * <p>
 * The number of logging events delivered in this e-mail depend on the value of
 * <b>BufferSize</b> option. The <code>SmtpAppender</code> keeps only the last
 * <code>BufferSize</code> logging events in its cyclic buffer. This keeps
 * memory requirements at a reasonable level while still delivering useful
 * application context.
 *
 * By default, an email message will be formatted as HTML. This can be modified by
 * setting a layout for the appender.
 *
 * By default, an email message will be sent when an ERROR or higher severity
 * message is appended. This can be modified by setting a filter for the
 * appender.
 */
@Configurable(elementType = Appender.ELEMENT_TYPE, printObject = true)
@Plugin("SMTP")
public final class SmtpAppender extends AbstractAppender {

    private static final int DEFAULT_BUFFER_SIZE = 512;

    /** The SMTP Manager */
    private final SmtpManager manager;

    private SmtpAppender(
            final String name,
            final Filter filter,
            final Layout layout,
            final boolean ignoreExceptions,
            Property[] properties,
            final SmtpManager manager) {
        super(name, filter, layout, ignoreExceptions, properties);
        this.manager = manager;
    }

    /**
     * @since 2.13.2
     */
    public static class Builder extends AbstractAppender.Builder<Builder>
            implements org.apache.logging.log4j.plugins.util.Builder<SmtpAppender> {
        @PluginAttribute
        private String to;

        @PluginAttribute
        private String cc;

        @PluginAttribute
        private String bcc;

        @PluginAttribute
        private String from;

        @PluginAttribute
        private String replyTo;

        @PluginAttribute
        private String subject;

        @PluginAttribute
        private String smtpProtocol = "smtp";

        @PluginAttribute
        private String smtpHost;

        @PluginAttribute
        @ValidPort
        private int smtpPort;

        @PluginAttribute
        private String smtpUsername;

        @PluginAttribute(sensitive = true)
        private String smtpPassword;

        @PluginAttribute
        private boolean smtpDebug;

        @PluginAttribute
        private int bufferSize = DEFAULT_BUFFER_SIZE;

        @PluginElement("SSL")
        private SslConfiguration sslConfiguration;

        /**
         * Comma-separated list of recipient email addresses.
         */
        public Builder setTo(final String to) {
            this.to = to;
            return this;
        }

        /**
         * Comma-separated list of CC email addresses.
         */
        public Builder setCc(final String cc) {
            this.cc = cc;
            return this;
        }

        /**
         * Comma-separated list of BCC email addresses.
         */
        public Builder setBcc(final String bcc) {
            this.bcc = bcc;
            return this;
        }

        /**
         * Email address of the sender.
         */
        public Builder setFrom(final String from) {
            this.from = from;
            return this;
        }

        /**
         * Comma-separated list of Reply-To email addresses.
         */
        public Builder setReplyTo(final String replyTo) {
            this.replyTo = replyTo;
            return this;
        }

        /**
         * Subject template for the email messages.
         * @see org.apache.logging.log4j.core.layout.PatternLayout
         */
        public Builder setSubject(final String subject) {
            this.subject = subject;
            return this;
        }

        /**
         * Transport protocol to use for SMTP such as "smtp" or "smtps". Defaults to "smtp".
         */
        public Builder setSmtpProtocol(final String smtpProtocol) {
            this.smtpProtocol = smtpProtocol;
            return this;
        }

        /**
         * Host name of SMTP server to send messages through.
         */
        public Builder setSmtpHost(final String smtpHost) {
            this.smtpHost = smtpHost;
            return this;
        }

        /**
         * Port number of SMTP server to send messages through.
         */
        public Builder setSmtpPort(final int smtpPort) {
            this.smtpPort = smtpPort;
            return this;
        }

        /**
         * Username to authenticate with SMTP server.
         */
        public Builder setSmtpUsername(final String smtpUsername) {
            this.smtpUsername = smtpUsername;
            return this;
        }

        /**
         * Password to authenticate with SMTP server.
         */
        public Builder setSmtpPassword(final String smtpPassword) {
            this.smtpPassword = smtpPassword;
            return this;
        }

        /**
         * Enables or disables mail session debugging on STDOUT. Disabled by default.
         */
        public Builder setSmtpDebug(final boolean smtpDebug) {
            this.smtpDebug = smtpDebug;
            return this;
        }

        /**
         * Number of log events to buffer before sending an email. Defaults to {@value #DEFAULT_BUFFER_SIZE}.
         */
        public Builder setBufferSize(final int bufferSize) {
            this.bufferSize = bufferSize;
            return this;
        }

        /**
         * Specifies an SSL configuration for smtps connections.
         */
        public Builder setSslConfiguration(final SslConfiguration sslConfiguration) {
            this.sslConfiguration = sslConfiguration;
            return this;
        }

        @Override
        public SmtpAppender build() {
            if (getLayout() == null) {
                setLayout(HtmlLayout.newBuilder()
                        .setConfiguration(getConfiguration())
                        .build());
            }
            if (getFilter() == null) {
                setFilter(ThresholdFilter.createFilter(null, null, null));
            }
            final SmtpManager smtpManager = SmtpManager.getSmtpManager(
                    getConfiguration(),
                    to,
                    cc,
                    bcc,
                    from,
                    replyTo,
                    subject,
                    smtpProtocol,
                    smtpHost,
                    smtpPort,
                    smtpUsername,
                    smtpPassword,
                    smtpDebug,
                    getFilter().toString(),
                    bufferSize,
                    sslConfiguration);
            return new SmtpAppender(
                    getName(), getFilter(), getLayout(), isIgnoreExceptions(), getPropertyArray(), smtpManager);
        }
    }

    /**
     * @since 2.13.2
     */
    @PluginFactory
    public static Builder newBuilder() {
        return new Builder();
    }

    /**
     * Capture all events in CyclicBuffer.
     * @param event The Log event.
     * @return true if the event should be filtered.
     */
    @Override
    public boolean isFiltered(final LogEvent event) {
        final boolean filtered = super.isFiltered(event);
        if (filtered) {
            manager.add(event);
        }
        return filtered;
    }

    /**
     * Perform SmtpAppender specific appending actions, mainly adding the event
     * to a cyclic buffer and checking if the event triggers an e-mail to be
     * sent.
     * @param event The Log event.
     */
    @Override
    public void append(final LogEvent event) {
        manager.sendEvents(getLayout(), event);
    }
}