Converting older formats to advanced

First of all, converting of older formats is not strictly necessary. All formats can be mixed and matched and play well together.

There are stil a number of reasons to convert older formats:

  • existing simple constructs need to be enhanced and become more complex
  • aid future extensions
  • ensure no side-effects accidently occur
  • unify rsyslog.conf language

Do not overdo conversion

Note: simple facility and severity based filters which trigger writing to files can actually be very well expressd in basic. So if you have something like:   /var/log/maillog

We suggest you leave it as-is without conversion. Equally, in our opion it is also fine to add new rules like the above. If you still want to convert, the line may look as follows (completely in new format):

if prifilt("") then {
     action(type="omfile" file="/var/log/maillog")

More compact, this can also be written like:

if prifilt("") then action(type="omfile" file="/var/log/maillog")

The older-selector-style filter is well-known, so this may also write it as: action(type="omfile" file="/var/log/maillog")

There are ample additional possibilities. We suggest to keep things consistent.

Converting Actions

In general, you have lines like:

filter action

where filter is any of the filters and action is … the action to be carried out. As could be seen above, the filter does not necessarily need to be changed in order to convert the action. All filters also work with all config formats. It often is best to keep existing filters, at least while working on the conversion (do not change too many things at once).

The following table lists traditional action syntax and how it can be converted to new-style action() objects. The link will bring you to detail documentation. In these detail documentations all parameters are given. It is also specified which obsolete legacy directives map to advanced properties. This table is not conclusive but covers the most commonly used actions.

basic advanced
file path (/var/log/…) action(type=”omfile” file=”/var/log…/” …)
UDP forwarding (@remote) action(type=”omfwd” target=”remote” protocol=”udp” …)
TCP forwarding (@remote) action(type=”omfwd” target=”remote” protocol=”tcp” …)
user notify (:omusrmsg:user) action(type=”omusrmsg” users=”user” …)
module name (:omxxx:..) action(type=”omxxx” …)

Some concrete examples:

OLD: :hostname, contains, "remote-sender" @@central
NEW: :hostname, contains, "remote-sender" action(type="omfwd" target="central" protocol="tcp")

OLD: if $msg contains "error" then @central
NEW: if $msg contains "error" then action(type="omfwd" target="central" protocol="udp")

OLD: *.emerg :omusrmsg:*
NEW: *.emerg action(type="omusrmsg" users="*")

NOTE: Some actions do not have a basic configuration line. They may only be called via the action() syntax. Similarly, some very few actions, mostly contributed, do not support action() syntax and thus can only be configured via basic and obsolete legacy. See module doc for details.

Converting Action Chains

Actions can be chained via the ampersand character (‘&’). In advanced format this has been replaced by blocks. For example:

*.error /var/log/errorlog
&       @remote


*.error {
        action(type="omfile" file="/var/log/errorlog")
        action(type="omfwd" target="remote" protocol="udp")

The latter is much easier to understand and less error-prone when extended.

A common construct is to send messages to a remote host based on some message content and then not further process it. This involves the stop statement (or it’s very old-time equivalent tilde (‘~’). It may be specfied as such:

:msg, contains, "error" @remote
& ~

which is equavalent to:

:msg, contains, "error" @remote
& stop

This format is often found in more modern distro’s rsyslog.conf. It again is fully equivalent to:

:msg, contains, "error" {
        action(type="omfwd" target="remote" protocol="udp")

And, just to prove the point, this is also exactly the same like:

if $msg contains "error" then {
        action(type="omfwd" target="remote" protocol="udp")

See also

Help with configuring/using Rsyslog:

  • Mailing list - best route for general questions
  • GitHub: rsyslog source project - detailed questions, reporting issues that are believed to be bugs with Rsyslog
  • Stack Exchange (View, Ask) - experimental support from rsyslog community

See also

Contributing to Rsyslog:

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