1.12.0

• Break: HandlerInterface::isHandling now receives a partial record containing only a level key. This was always the intent and does not break any Monolog handler but is strictly speaking a BC break and you should check if you relied on any other field in your own handlers.
• Added PsrHandler to forward records to another PSR-3 logger
• Added SamplingHandler to wrap around a handler and include only every Nth record
• Added MongoDBFormatter to support better storage with MongoDBHandler (it must be enabled manually for now)
• Added exception codes in the output of most formatters
• Added LineFormatter::includeStacktraces to enable exception stack traces in logs (uses more than one line)
• Added $useShortAttachment to SlackHandler to minify attachment size and $includeExtra to append extra data
• Added $host to HipChatHandler for users of private instances
• Added $transactionName to NewRelicHandler and support for a transaction_name context value
• Fixed MandrillHandler to avoid outputing API call responses
• Fixed some non-standard behaviors in SyslogUdpHandler

1.11.0

• Break: The NewRelicHandler extra and context data are now prefixed with extra_ and context_ to avoid clashes. Watch out if you have scripts reading those from the API and rely on names
• Added WhatFailureGroupHandler to suppress any exception coming from the wrapped handlers and avoid chain failures if a logging service fails
• Added MandrillHandler to send emails via the Mandrillapp.com API
• Added SlackHandler to log records to a Slack.com account
• Added FleepHookHandler to log records to a Fleep.io account
• Added LogglyHandler::addTag to allow adding tags to an existing handler
• Added $ignoreEmptyContextAndExtra to LineFormatter to avoid empty [] at the end
• Added $useLocking to StreamHandler and RotatingFileHandler to enable flock() while writing
• Added support for PhpAmqpLib in the AmqpHandler
• Added FingersCrossedHandler::clear and BufferHandler::clear to reset them between batches in long running jobs
• Added support for adding extra fields from $_SERVER in the WebProcessor
• Fixed support for non-string values in PrsLogMessageProcessor
• Fixed SwiftMailer messages being sent with the wrong date in long running scripts
• Fixed minor PHP 5.6 compatibility issues
• Fixed BufferHandler::close being called twice

1.10.0

• Added Logger::getHandlers() and Logger::getProcessors() methods
• Added $passthruLevel argument to FingersCrossedHandler to let it always pass some records through even if the trigger level is not reached
• Added support for extra data in NewRelicHandler
• Added $expandNewlines flag to the ErrorLogHandler to create multiple log entries when a message has multiple lines

1.9.1

• Fixed regression in RotatingFileHandler file permissions
• Fixed initialization of the BufferHandler to make sure it gets flushed after receiving records
• Fixed ChromePHPHandler and FirePHPHandler's activation strategies to be more conservative

1.9.0

• Added LogEntriesHandler to send logs to a LogEntries account
• Added $filePermissions to tweak file mode on StreamHandler and RotatingFileHandler
• Added $useFormatting flag to MemoryProcessor to make it send raw data in bytes
• Added support for table formatting in FirePHPHandler via the table context key
• Added a TagProcessor to add tags to records, and support for tags in RavenHandler
• Added $appendNewline flag to the JsonFormatter to enable using it when logging to files
• Added sound support to the PushoverHandler
• Fixed multi-threading support in StreamHandler
• Fixed empty headers issue when ChromePHPHandler received no records
• Fixed default format of the ErrorLogHandler

1.8.0

• Break: the LineFormatter now strips newlines by default because this was a bug, set $allowInlineLineBreaks to true if you need them
• Added BrowserConsoleHandler to send logs to any browser's console via console.log() injection in the output
• Added FilterHandler to filter records and only allow those of a given list of levels through to the wrapped handler
• Added FlowdockHandler to send logs to a Flowdock account
• Added RollbarHandler to send logs to a Rollbar account
• Added HtmlFormatter to send prettier log emails with colors for each log level
• Added GitProcessor to add the current branch/commit to extra record data
• Added a Monolog\Registry class to allow easier global access to pre-configured loggers
• Added support for the new official graylog2/gelf-php lib for GelfHandler, upgrade if you can by replacing the mlehner/gelf-php requirement
• Added support for HHVM
• Added support for Loggly batch uploads
• Added support for tweaking the content type and encoding in NativeMailerHandler
• Added $skipClassesPartials to tweak the ignored classes in the IntrospectionProcessor
• Fixed batch request support in GelfHandler

1.7.0

• Added ElasticSearchHandler to send logs to an Elastic Search server
• Added DynamoDbHandler and ScalarFormatter to send logs to Amazon's Dynamo DB
• Added SyslogUdpHandler to send logs to a remote syslogd server
• Added LogglyHandler to send logs to a Loggly account
• Added $level to IntrospectionProcessor so it only adds backtraces when needed
• Added $version to LogstashFormatter to allow using the new v1 Logstash format
• Added $appName to NewRelicHandler
• Added configuration of Pushover notification retries/expiry
• Added $maxColumnWidth to NativeMailerHandler to change the 70 chars default
• Added chainability to most setters for all handlers
• Fixed RavenHandler batch processing so it takes the message from the record with highest priority
• Fixed HipChatHandler batch processing so it sends all messages at once
• Fixed issues with eAccelerator
• Fixed and improved many small things

1.6.0

• Added HipChatHandler to send logs to a HipChat chat room
• Added ErrorLogHandler to send logs to PHP's error_log function
• Added NewRelicHandler to send logs to NewRelic's service
• Added Monolog\ErrorHandler helper class to register a Logger as exception/error/fatal handler
• Added ChannelLevelActivationStrategy for the FingersCrossedHandler to customize levels by channel
• Added stack traces output when normalizing exceptions (json output & co)
• Added Monolog\Logger::API constant (currently 1)
• Added support for ChromePHP's v4.0 extension
• Added support for message priorities in PushoverHandler, see $highPriorityLevel and $emergencyLevel
• Added support for sending messages to multiple users at once with the PushoverHandler
• Fixed RavenHandler's support for batch sending of messages (when behind a Buffer or FingersCrossedHandler)
• Fixed normalization of Traversables with very large data sets, only the first 1000 items are shown now
• Fixed issue in RotatingFileHandler when an open_basedir restriction is active
• Fixed minor issues in RavenHandler and bumped the API to Raven 0.5.0
• Fixed SyslogHandler issue when many were used concurrently with different facilities

1.5.0

• Added ProcessIdProcessor to inject the PID in log records
• Added UidProcessor to inject a unique identifier to all log records of one request/run
• Added support for previous exceptions in the LineFormatter exception serialization
• Added Monolog\Logger::getLevels() to get all available levels
• Fixed ChromePHPHandler so it avoids sending headers larger than Chrome can handle