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Log Courier Configuration

Table of Contents generated with DocToc

Overview

The Log Courier configuration file is in YAML format. It can also be in JSON format is desired.

When loading a configuration file, the format is determined by the file extension. If the file extension is not recognised, Log Courier reports an error.

  • .yaml - YAML
  • .json - JSON
  • .conf - JSON

YAML Format

YAML format is the preferred format for Log Courier configuration files as it tends to be easier to read and write than most other formats, such as JSON. It is also easier to manage by scripts as it is line-based.

Entries start with their name followed by a colon. A value then follows it, with optional quoting, on the same line, or a block of names and values follow it on the next line with indentation.

Lists can be specified by starting each line with -. To place a block in a list, prefix the first name and value pair with - and then indent the rest accordingly.

It is best explained with an example:

network:
  servers:
    - "10.0.0.1:12345"
    - "10.0.0.2:12345"
  transport: tcp
files:
  - paths: [ "/var/log/nginx/access.log", "/var/log/nginx/error.log" ]
    fields:
      type: nginx_logs

JSON Format

If in doubt, it is best to use YAML configuration as it tends to be easier to read and write than JSON format.

Blocks are wrapped in { and } and within those is a comma-separate list of name and value pairs. Names are always double-quoted strings (e.g. "hello world") and the values can be numbers, double-quoted strings, another block, or a list of something. Lists are comma-separated lists of these and are wrapped in [ and ]. The configuration file is formed by a single block, as shown below.

{
  "network": {
    "servers": [ "10.0.0.1:12345", "10.0.0.2:12345" ],
    "transport": "tcp"
  },
  "files": [ {
    "paths": [ "/var/log/nginx/access.log", "/var/log/nginx/error.log" ]
  } ]
}

End-of-line comments start with a pound sign outside of a string, and cause all characters until the end of the line to be ignored. Block comments start with a forwarder slash and an asterisk and cause all characters, including new lines, to be ignored until an asterisk followed by a forwarder slash is encountered.

{
    "general": {
        # General configuration here
    },
    "network": {
        # Network configuration here
    }, # (these are end-of-line comments)
    "files": [
        /* File configuration here
        (this is a block comment) */
    ]
}

Examples

Several configuration examples are available for perusal in the examples folder. Examples use the preferred format of YAML.

An example JSON configuration is also available that follows a single log file.

The configuration is documented in full below.

Reloading

Log Courier can reload its configuration without the need for a restart. It will do this upon receiving the SIGHUP signal. To send this signal, run the following command replacing 1234 with the Process ID of Log Courier.

kill -HUP 1234

Log Courier will reopen its own log file if one has been configured, allowing native log rotation to take place.

Please note that files Log Courier has already started harvesting will continue to be harvested after the reload with their original configuration; the reload process will only affect new files. Additionally, harvested log files will not be reopened. Log rotations are detected automatically. To control when a harvested log file is closed you can adjust the dead time option.

In the case of a network configuration change, Log Courier will disconnect and reconnect as required at the earliest opportunity.

Configuration reload is not currently available on Windows builds of Log Courier.

Field Types

String, Number, Boolean, Array, Dictionary

These are JSON types and follow the same rules. Strings within double quotes, arrays of fields within square brackets separated by commas, and dictionaries of key value pairs within curly braces and each entry, in the form key": value, separated by a comma.

Duration

This can be either a number or a string describing the duration. A number will always be interpreted in seconds.

  • 5 = 5 seconds
  • 300 = 5 minutes (which is 300 seconds)
  • 5s = 5 seconds
  • 15m = 15 minutes

Fileglob

A fileglob is a string representing a file pattern.

The pattern format used is detailed at http://golang.org/pkg/path/filepath/#Match and is shown below for reference:

term:
    '*'         matches any sequence of non-Separator characters
    '?'         matches any single non-Separator character
    '[' [ '^' ] { character-range } ']'
                            character class (must be non-empty)
    c           matches character c (c != '*', '?', '\\', '[')
    '\\' c      matches character c

character-range:
    c           matches character c (c != '\\', '-', ']')
    '\\' c      matches character c
    lo '-' hi   matches character c for lo <= c <= hi
  • /var/log/*.log
  • /var/log/program/log_????.log
  • /var/log/httpd/access.log
  • /var/log/httpd/access.log.[0-9]

Stream Configuration

Stream Configuration parameters can be specified for file groups within files and also for stdin. They customise the log entries produced by passing, for example, by passing them through a codec and adding extra fields.

add host field

Boolean. Optional. Default: true

Adds an automatic "host" field to generated events that contains the host value from the general configuration section.

add offset field

Boolean. Optional. Default: true

Adds an automatic "offset" field to generated events that contains the current offset in the current data stream.

Beware that this value will reset when a file rotates or is truncated and is generally not useful. It will be kept configurable to allow full compatibility with Logstash Forwarder's traditional behaviour, and from version 2 the default will be changed to false.

add path field

Boolean. Optional. Default: true

Adds an automatic "path" field to generated events that contains the path to the current data stream. For stdin, this field is set to a hyphen, "-".

add timezone field

Boolean. Optional. Default: false

Adds an automatic "timezone" field to generated events that contains the local machine's local timezone in the format, "-0700 MST".

codecs

Codec configuration. Optional. Default: Single plain codec
Configuration reload will only affect new or resumed files

Depending on how log-courier was built, some codecs may not be available. Run log-courier -list-supported to see the list of codecs available in a specific build of log-courier.

The specified codecs will receive the lines read from the log stream and perform any decoding necessary to generate events. The plain codec does nothing and simply ships the events unchanged.

When multiple codecs are specified, the first codec will receive events, and the second codec will receive the output from the first codec. This allows versatile configurations, such as combining events into multiline events and then filtering those that aren't required.

All configurations are an array of dictionaries with at least a "name" key. Additional options can be provided if the specified codec allows.

  • [ { "name": "codec-name" } ]
  • [ { "name": "codec-name", "option1": "value", "option2": "42" } ]
  • [ { "name": "first-name" }, { "name": "second-name" } ]

Aside from "plain", the following codecs are available at this time.

dead time

Duration. Optional. Default: "1h"
Configuration reload will only affect new or resumed files

If a log file has not been modified in this time period, it will be closed and Log Courier will simply watch it for modifications. If the file is modified it will be reopened.

If a log file that is being harvested is deleted, it will remain on disk until Log Courier closes it. Therefore it is important to keep this value sensible to ensure old log files are not kept open preventing deletion.

fields

Dictionary. Optional
Configuration reload will only affect new or resumed files

Extra fields to attach to events prior to shipping. These can be simple strings, numbers or even arrays and dictionaries.

Examples:

  • { "type": "syslog" }
  • { "type": "apache", "server_names": [ "example.com", "www.example.com" ] }
  • { "type": "program", "program": { "exec": "program.py", "args": [ "--run", "--daemon" ] } }

admin

The admin configuration enables or disabled the REST interface within Log Courier and allows you to configure the interface to listen on.

enabled

Boolean. Optional. Default: false
Requires restart

Enables the REST interface. The lc-admin utility can be used to connect to this.

listen address

String. Required when enabled is true.
Default: tcp:127.0.0.1:1234
RPM/DEB Package Default: unix:/var/run/log-courier/admin.socket

The address the REST interface should listen on must be in the format transport:address.

Allowed transports are "tcp", "tcp4", "tcp6" (Windows and *nix) and "unix" (*nix only). For the tcp transports the address format is host:port. For the unix transport the address should specify a filename to use when creating the unix domain socket. If no transport name is specified, "tcp" is assumed.

Examples:

127.0.0.1:1234
tcp:127.0.0.1:1234
unix:/var/run/log-courier/admin.socket

files

The files configuration lists the file groups that contain the logs you wish to ship. It is an array of file group configurations.

    [
        {
            # First file group
        },
        {
            # Second file group
        }
    ]

In addition to the configuration parameters specified below, each file group may also have Stream Configuration parameters specified.

paths

Array of Fileglobs. Required

At least one Fileglob must be specified and all matching files for all provided globs will be monitored.

If the log file is rotated, Log Courier will detect this and automatically start harvesting the new file. It will also keep the old file open to catch any delayed writes that a still-reloading application has not yet written. You can configure the time period before this old log file is closed using the dead time option.

See above for a description of the Fileglob field type.

To read from stdin, see the -stdin command line argument.

Examples:

  • [ "/var/log/*.log" ]
  • [ "/var/log/program/log_????.log" ]
  • [ "/var/log/httpd/access.log", "/var/log/httpd/access.log.[0-9]" ]

general

The general configuration affects the general behaviour of Log Courier, such as where to store its persistence data or how often to scan for the appearence of new log files.

log file

Filepath. Optional
Requires restart

A log file to save Log Courier's internal log into. May be used in conjunction with log stdout and log syslog.

global fields

Dictionary. Optional
Configuration reload will only affect new or resumed files

Extra fields to attach to events prior to shipping. This is identical in behaviour to the fields Stream Configuration and applies globally to the stdin section and to all files listed in the files section.

host

String. Optional. Default: System FQDN.
Configuration reload will only affect new or resumed files

Every event has an automatic field, "host", that contains the current system FQDN. Using this option allows a custom value to be given to the "host" field instead of the system FQDN.

log level

String. Optional. Default: "info".
Available values: "critical", "error", "warning", "notice", "info", "debug"
Requires restart

The minimum level of detail to produce in Log Courier's internal log.

log stdout

Boolean. Optional. Default: true
Requires restart

Enables sending of Log Courier's internal log to the console (stdout). May be used in conjunction with log syslog and log file.

log syslog

Boolean. Optional. Default: false
Requires restart

Enables sending of Log Courier's internal log to syslog. May be used in conjunction with log stdout and log file.

This option is ignored by Windows builds.

line buffer bytes

Number. Optional. Default: 16384

The size of the line buffer used when reading files.

If max line bytes is greater than this value, any lines that exceed this size will trigger additional memory allocations. This value should be set to a value just above the 90th percentile (or average) line length.

max line bytes

Number. Optional. Default: 1048576

The maxmimum line length to process. If a line exceeds this length, it will be split across multiple events. Each split line will have a "tag" field added containing the tag "splitline". The final part of the line will not have a "tag" field added.

If the fields configuration already contained a "tags" entry, and it is an array, it will be appended to. Otherwise, the "tag" field will be left as is.

This setting can not be greater than the spool max bytes setting.

persist directory

String. Required
RPM/DEB Package Default: /var/lib/log-courier Requires restart

The directory that Log Courier should store its persistence data in.

At the time of writing, the only file saved here is .log-courier that contains the offset in the file that Log Courier needs to resume from after a graceful restart or crash. The offset is only updated when the remote endpoint acknowledges receipt of the events.

prospect interval

Duration. Optional. Default: 10

How often Log Courier should check for changes on the filesystem, such as the appearance of new log files, rotations and deletions.

spool max bytes

Number. Optional. Default: 10485760

The maximum size of an event spool, before compression. If an incomplete spool does not have enough room for the next event, it will be flushed immediately.

If this value is modified, the receiving end should also be configured with the new limit. For the Logstash plugin, this is the max_packet_size setting.

The maximum value for this setting is 2147483648 (2 GiB).

spool size

Number. Optional. Default: 1024

How many events to spool together and flush at once. This improves efficiency when processing large numbers of events by submitting them for processing in bulk.

Internal benchmarks have shown that increasing to 5120, for example, can give around a 25% boost of events per second, at the expense of more memory usage.

For most installations you should leave this at the default as it can easily cope with over 10,000 events a second and uses little memory. It is useful only in very specific circumstances.

spool timeout

Duration. Optional. Default: 5

The maximum amount of time to wait for a full spool. If an incomplete spool is not filled within this time limit, the spool will be flushed immediately.

includes

Array of Fileglobs. Optional

Includes should be an array of additional file group configuration files to read. Each configuration file should follow the format of the files section.

"includes": [ "/etc/log-courier/conf.d/*.conf" ]

A file at /etc/log-courier/conf.d/apache.conf could then contain the following.

[ {
    "paths": [ "/var/log/httpd/access.log" ],
    "fields": { "type": "access_log" }
} ]

network

The network configuration tells Log Courier where to ship the logs, and also what transport and security to use.

failure backoff

Duration. Optional. Default: 0

Pause this long before allowing a failed endpoint to be used again. On each consecutive failure, the pause is exponentially increased.

When set to 0, there is no backoff after the first failure. The second failure then pauses for 1 second and begins to exponentially increase on each consecutive failure.

(This is distinct from reconnect backoff in that it handles all failures, and is available for all transports. For example, if a remote endpoint keeps failing almost immediately after a successful connection, this backoff would prevent it from being used again immediately and slowing down the entire pipeline.)

failure backoff max

Duration. Optional. Default: 300s

The maximum time to wait before using a failed endpoint again. This prevents the exponential increase of failure backoff from becoming too high.

max pending payloads

Number. Optional. Default: 4

The maximum number of spools that can be in transit to a single endpoint at any one time. Each spool will be kept in memory until the remote endpoint acknowledges it.

If Log Courier has sent this many spools to a remote endpoint, and has not yet received acknowledgement responses for them (either because the remote endpoint is busy or because the link has high latency), it will pause and wait before sending anymore.

For most installations you should leave this at the default as it is high enough to maintain throughput even on high latency links and low enough not to cause excessive memory usage.

method

String. Optional. Default: "random" Available values: "random", "failover", "loadbalance"

Specified the method to use when managing multiple servers.

random: Connect to a random endpoint on startup. If the connected endpoint fails, close that connection and reconnect to another random endpoint. Protection is added such that during reconnection, a different endpoint to the one that just failed is guaranteed. This is the same behaviour as Log Courier 1.x.

failover: The endpoint list acts as a preference list with the first endpoint in the list the preferred endpoint, and every one after that the next preferred endpoints in the order given. The preferred endpoint is connected to initially, and only when that connection fails is another less preferred endpoint connected to. Log Courier will continually attempt to connect to more preferred endpoints in the background, failing back to the most preferred endpoint if one becomes available and closing any connections to less preferred endpoints.

loadbalance: Connect to all endpoints and load balance events between them. Faster endpoints will receive more events than slower endpoints. The strategy for load balancing is dynamic based on the acknowledgement latency of the available endpoints.

reconnect backoff

Duration. Optional. Default: 0
Available when transport is one of: tcp, tls

Pause this long before reconnecting to a endpoint. If the remote endpoint is completely down, this slows down the rate of reconnection attempts. On each consecutive failure, the pause is exponentially increased.

When set to 0, the initial reconnect attempt is made immediately. The second attempt then pauses for 1 second and begins to exponentially increase on each consecutive failure.

reconnect backoff max

Duration. Optional. Default: 300s
Available when transport is one of: tcp, tls

The maximum time to wait between reconnect attempts. This prevents the exponential increase of reconnect backoff from becoming too high.

rfc 2782 srv

Boolean. Optional. Default: true

When performing SRV DNS lookups for entries in the servers list, use RFC 2782 style lookups of the form _service._proto.example.com.

rfc 2782 service

String. Optional. Default: "courier"

Specifies the service to request when using RFC 2782 style SRV lookups. Using the default, "courier", an "@example.com" endpoint entry would result in a lookup for _courier._tcp.example.com.

servers

Array of Strings. Required

Sets the list of endpoints to send logs to. Accepted formats for each endpoint entry are:

  • ipaddress:port
  • hostname:port (A DNS lookup is performed)
  • @hostname (A SRV DNS lookup is performed, with further DNS lookups if required)

How multiple endpoints are managed is defined by the method configuration.

ssl ca

Filepath. Required
Available when transport is one of: tls

Path to a PEM encoded certificate file to use to verify the connected endpoint.

ssl certificate

Filepath. Optional
Available when transport is one of: tls

Path to a PEM encoded certificate file to use as the client certificate.

ssl key

Filepath. Required with ssl certificate
Available when transport is one of: tls

Path to a PEM encoded private key to use with the client certificate.

timeout

Duration. Optional. Default: 15

This is the maximum time Log Courier will wait for a endpoint to respond to a request after logs were send to it. If the endpoint does not respond within this time period the connection will be closed and reset.

transport

String. Optional. Default: "tls"
Available values: "tcp", "tls"

Sets the transport to use when sending logs to the endpoints. "tls" is recommended for most users.

"tcp" is an insecure equivalent to "tls" that does not encrypt traffic or authenticate the identity of endpoints. This should only be used on trusted internal networks. If in doubt, use the secure authenticating transport "tls".

stdin

The stdin configuration contains the Stream Configuration parameters that should be used when Log Courier is set to read log data from stdin using the -stdin command line entry.