On 7/9/24 09:14, jm...@redhat.com wrote:
> From: Jakob Meng <c...@jakobmeng.de>
>
> For monitoring systems such as Prometheus it would be beneficial if
> OVS would expose statistics in a machine-readable format.
>
> This patch introduces support for different output formats to
> ovs-appctl. It gains a global option '-f,--format' which changes it to
> print a JSON document instead of plain-text for humans. For example, a
> later patch implements support for
> 'ovs-appctl --format json dpif/show'. By default, the output format
> is plain-text as before.
>
> A new 'set-options' command has been added to lib/unixctl.c which
> allows to change the output format of the commands executed afterwards
> on the same socket connection. It is supposed to be run by ovs-appctl
> transparently for the user when a specific output format has been
> requested.
> For example, when a user calls 'ovs-appctl --format json dpif/show',
> then ovs-appctl will call 'set-options' to set the output format as
> requested by the user and afterwards it will call the actual command
> 'dpif/show'.
> This ovs-appctl behaviour has been implemented in a backward compatible
> way. One can use an updated client (ovs-appctl) with an old server
> (ovs-vswitchd) and vice versa. Of course, JSON output only works when
> both sides have been updated.
>
> Two access functions unixctl_command_{get,set}_output_format() and a
> unixctl_command_reply_json function have been added to lib/unixctl.h:
> unixctl_command_get_output_format() is supposed to be used in commands
> like 'dpif/show' to query the requested output format. When JSON output
> has been selected, the unixctl_command_reply_json() function can be
> used to return JSON objects to the client (ovs-appctl) instead of
> plain-text with the unixctl_command_reply{,_error}() functions.
>
> When JSON has been requested but a command has not implemented JSON
> output the plain-text output will be wrapped in a provisional JSON
> document with the following structure:
>
> {"reply":"$PLAIN_TEXT_HERE","reply-format":"plain"}
>
> Thus commands which have been executed successfully will not fail when
> they try to render the output at a later stage.
>
> A test for the 'version' command has been implemented which shows how
> the provisional JSON document looks like in practice. For a cleaner
> JSON document, the trailing newline has been moved from the program
> version string to function ovs_print_version(). This way, the
> plain-text output of the 'version' command has not changed.
>
> Output formatting has been moved from unixctl_client_transact() in
> lib/unixctl.c to utilities/ovs-appctl.c. The former merely returns the
> JSON objects returned from the server and the latter is now responsible
> for printing it properly.
>
> In popular tools like kubectl the option for output control is usually
> called '-o|--output' instead of '-f,--format'. But ovs-appctl already
> has an short option '-o' which prints the available ovs-appctl options
> ('--option'). The now chosen name also better aligns with ovsdb-client
> where '-f,--format' controls output formatting.
>
> Reported-at: https://bugzilla.redhat.com/1824861
> Signed-off-by: Jakob Meng <c...@jakobmeng.de>
> ---
> Documentation/ref/ovs-appctl.8.rst | 12 ++
> NEWS | 3 +
> lib/unixctl.c | 180 ++++++++++++++++++++++-------
> lib/unixctl.h | 17 ++-
> lib/util.c | 6 +-
> python/ovs/unixctl/server.py | 3 -
> tests/appctl.py | 5 +
> tests/ovs-vswitchd.at | 12 ++
> utilities/ovs-appctl.c | 135 +++++++++++++++++++---
> 9 files changed, 305 insertions(+), 68 deletions(-)
Recheck-request: github-robot
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