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doc: mgmtd: update mgmtd conversion doc to be current.
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Also change `be_client_xpaths` to `be_client_config_xpaths` referred in the doc
to make much clearer it's use (since there's a separate `be_client_oper_xpaths`.

Signed-off-by: Christian Hopps <[email protected]>
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choppsv1 committed Jan 13, 2024
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194 changes: 110 additions & 84 deletions doc/developer/mgmtd-dev.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -37,11 +37,10 @@ easily be added as *front-ends* to mgmtd to support those protocols as well.
Converting A Daemon to MGMTD
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

A daemon must first be transitioned to the new *northbound* interface if that
has not already been done (see `this northbound conversion documentation
<https://github.com/opensourcerouting/frr/wiki/Retrofitting-Configuration-Commands>`_
for how to do this). Once this is done a few simple steps are all that is
required move the daemon over to ``mgmtd`` control.
A daemon must first be transitioned to the new :ref:`northbound` interface if that
has not already been done (see :ref:`nb-retrofit` for how to do this). Once this
is done a few simple steps are all that is required move the daemon over to
``mgmtd`` control.

Overview of Changes
-------------------
Expand All @@ -52,16 +51,27 @@ requires enabling *frontend* (CLI and YANG) and *backend* (YANG) support.

Front-End Interface:

1. Add YANG module file to ``mgmtd/subdir.am`` (e.g., ``yang/frr-staticd.c``)
2. Add YANG module description into array defined in ``mgmtd/mgmt_main.c``
3. Add CLI handler file[s] to ``mgmtd/subdir.am`` (e.g., ``staticd/static_vty.c``)
4. [if needed] Exclude (#ifndef) non-configuration CLI handlers from CLI source
file (e.g., inside ``staticd/static_vty.c``)
1. Add YANG module file to ``mgmtd/subdir.am`` (e.g., ``yang/frr-staticd.yang.c``).
2. Add CLI handler file[s] to ``mgmtd/subdir.am`` (e.g., ``staticd/static_vty.c``).
3. [if needed] Exclude (#ifndef) non-configuration CLI handlers from CLI source
file (e.g., inside ``staticd/static_vty.c``).
4. [otherwise] Remove CLI handler file from SOURCES in daemon (e.g in :file:`staticd/subdir.am`)
5. Add YANG module description into array defined in ``mgmtd/mgmt_main.c`` (see :ref:`mgmtd-config-write`).
6. Initialize the CLI handlers inside :code:`mgmt_vty_init` in :file:`mgmtd/mgmt_vty.c`.
7. Direct ``vtysh`` to send CLI commands to ``mgmtd`` by modifying
``vtysh/vtysh.h``. At the top of this file each daemon has a bit
``#define``'d (e.g., ``#define VTYSH_STATICD 0x08000``) below this there are
groupings, replace all the uses of the daemons bit with ``VTYSH_MGMTD``
instead so that the CLI commands get properly routed to ``mgmtd`` rather than
the daemon now.

Back-End Interface:

5. Add XPATHs mappings to a couple arrays to direct ``mgmtd`` at your daemon in
``mgmtd/mgmt_be_adapter.c``
8. In ``mgmtd/mgmt_be_adapter.c`` add xpath prefix mappings to a one or both
mapping arrays (``be_client_config_xpaths`` and ``be_client_oper_xpaths``) to
direct ``mgmtd`` to send config and oper-state requests to your daemon. NOTE:
make sure to include library supported xpaths prefixes as well (e.g.,
"/frr-interface:lib").


Add YANG and CLI into MGMTD
Expand All @@ -72,44 +82,48 @@ As an example here is the addition made to ``mgmtd/subdir.am`` for adding

.. code-block:: make
if STATICD
nodist_mgmtd_mgmtd_SOURCES += \
if STATICD
nodist_mgmtd_mgmtd_SOURCES += \
yang/frr-staticd.yang.c \
yang/frr-bfdd.yang.c \
# end
nodist_mgmtd_libmgmt_be_nb_la_SOURCES += staticd/static_vty.c
endif
nodist_mgmtd_libmgmt_be_nb_la_SOURCES += staticd/static_vty.c
endif
An here is the addition to the modules array in ``mgmtd/mgmt_main.c``:

.. code-block:: c
static const struct frr_yang_module_info *const mgmt_yang_modules[] = {
#ifdef HAVE_STATICD
extern const struct frr_yang_module_info frr_staticd_info;
#endif
static const struct frr_yang_module_info *const mgmt_yang_modules[] = {
&frr_filter_info,
...
#ifdef HAVE_STATICD
&(struct frr_yang_module_info){.name = "frr-staticd",
.ignore_cfg_cbs = true},
#endif
}
#ifdef HAVE_STATICD
&frr_staticd_info,
#endif
}
CLI Handlers
------------
CLI Config and Show Handlers
----------------------------

The daemon's CLI handlers for configuration (which having been converted to
*northbound* now simply generate YANG changes) will be linked directly into
The daemon's CLI handlers for configuration (which having been converted to the
:ref:`northbound` now simply generate YANG changes) will be linked directly into
``mgmtd``.

If the operational and debug CLI commands are kept in files separate from the
daemon's configuration CLI commands then no extra work is required. Otherwise some
CPP #ifndef's will be required.

Currently ``mgmtd`` supports configuration CLI but not operational
state so if both types of CLI handlers are present in a single file (e.g. a
``xxx_vty.c`` or ``xxx_cli.c`` file ) then #ifndef will be used to exclude these
non-configuration CLI handlers from ``mgmtd``. The same goes for *debug* CLI
handlers. For example:
``mgmtd`` supports both config and operational state. However, many
daemons have not had their operational state CLI commands converted over to the
new YANG based methods. If that is the case and if both types of CLI handlers
are present in a single file (e.g. a ``xxx_vty.c`` or ``xxx_cli.c`` file) then
:code:`#ifndef` will need to be used to exclude the non-config CLI handlers from
``mgmtd``. The same goes for unconverted *debug* CLI handlers. For example:

.. code-block:: c
Expand All @@ -121,7 +135,7 @@ handlers. For example:
}
#ifndef INCLUDE_MGMTD_CMDDEFS_ONLY
DEFPY(daemon_show_oepr, daemon_show_oepr_cmd,
DEFPY(daemon_show_oper, daemon_show_oper_cmd,
"show daemon oper [all]"
...
{
Expand All @@ -140,67 +154,79 @@ handlers. For example:
}
.. _mgmtd-config-write:

Add Back-End XPATH mappings
---------------------------
CLI Config Write Handlers (:code:`cli_show`)
--------------------------------------------

To support writing out the CLI configuration file the northbound API defines a
2 callbacks (:code:`cli_show` and :code:`cli_show_end`). Pointers to these
callbacks used to live side-by-side in a daemons :code:`struct frr_yang_module_info`,
with the daemons back-end configuration and operational state callbacks
(normally in a file named `<daemon>_nb.c`).

However, these 2 functionalities need to be split up now. The *frontend* config
writing callbacks (:code:`cli_show`) should now be linked into ``mgmtd`` while
the *backend* config and oper-state callbacks (e.g., :code:`create`,
:code:`modify`, etc) should continue to be linked into the daemon.

So you will need to define 2 :code:`struct frr_yang_module_info` arrays.

1. The existing array remains in the same place in the daemon, but with all the
:code:`cli_show` handlers removed.

2. The removed :code:`cli_show` handlers should be added to a new
:code:`struct frr_yang_module_info` array. This second array should be
included in the same file that includes that actual function pointed to by
the the :code:`cli_show` callbacks (i.e., the file is compiled into
``mgmtd``).

This new :code:`struct frr_yang_module_info` array is the one to be included
in mgmtd in `mgmt_yang_modules` inside ``mgmtd/mgmt_main.c``.

Back-End XPATH mappings
-----------------------

In order for ``mgmtd`` to direct configuration to your daemon you need to add
some XPATH mappings to ``mgmtd/mgmt_be_adapter.c``. These XPATHs determine which
configuration changes get sent over the *back-end* interface to your daemon.
There are 2 arrays to update the first for config support and the second for
operational state.

Below are the strings added for staticd support:
Below are the strings added for staticd config support:

.. code-block:: c
static const struct mgmt_be_xpath_map_init mgmt_xpath_map_init[] = {
{
.xpath_regexp = "/frr-vrf:lib/*",
.subscr_info =
{
#if HAVE_STATICD
[MGMTD_BE_CLIENT_ID_STATICD] =
MGMT_SUBSCR_VALIDATE_CFG |
MGMT_SUBSCR_NOTIFY_CFG,
#endif
},
},
...
{
.xpath_regexp =
"/frr-routing:routing/control-plane-protocols/control-plane-protocol/frr-staticd:staticd/*",
.subscr_info =
{
#if HAVE_STATICD
[MGMTD_BE_CLIENT_ID_STATICD] =
MGMT_SUBSCR_VALIDATE_CFG |
MGMT_SUBSCR_NOTIFY_CFG,
#endif
},
},
};
#if HAVE_STATICD
static struct mgmt_be_client_xpath staticd_xpaths[] = {
{
.xpath = "/frr-vrf:lib/*",
.subscribed = MGMT_SUBSCR_VALIDATE_CFG | MGMT_SUBSCR_NOTIFY_CFG,
},
...
{
.xpath =
"/frr-routing:routing/control-plane-protocols/control-plane-protocol/frr-staticd:staticd/*",
.subscribed = MGMT_SUBSCR_VALIDATE_CFG | MGMT_SUBSCR_NOTIFY_CFG,
},
};
#endif
static struct mgmt_be_client_xpath_map
mgmt_client_xpaths[MGMTD_BE_CLIENT_ID_MAX] = {
#ifdef HAVE_STATICD
[MGMTD_BE_CLIENT_ID_STATICD] = {staticd_xpaths,
array_size(staticd_xpaths)},
#endif
};
#if HAVE_STATICD
static const char *const staticd_xpaths[] = {
"/frr-vrf:lib",
"/frr-interface:lib",
"/frr-routing:routing/control-plane-protocols/control-plane-protocol/frr-staticd:staticd",
NULL,
};
#endif
static const char *const *be_client_xpaths[MGMTD_BE_CLIENT_ID_MAX] = {
#ifdef HAVE_STATICD
[MGMTD_BE_CLIENT_ID_STATICD] = staticd_xpaths,
#endif
};
Below are the strings added for zebra operational state support (note zebra is
not conditionalized b/c it should always be present):

.. code-block:: c
static const char *const zebra_oper_xpaths[] = {
"/frr-interface:lib/interface",
"/frr-vrf:lib/vrf/frr-zebra:zebra",
"/frr-zebra:zebra",
NULL,
};
static const char *const *be_client_oper_xpaths[MGMTD_BE_CLIENT_ID_MAX] = {
[MGMTD_BE_CLIENT_ID_ZEBRA] = zebra_oper_xpaths,
};
MGMTD Internals
Expand Down
3 changes: 3 additions & 0 deletions doc/developer/northbound/retrofitting-configuration-commands.rst
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@@ -1,3 +1,6 @@

.. _nb-retrofit:

Retrofitting Configuration Commands
-----------------------------------

Expand Down
12 changes: 6 additions & 6 deletions mgmtd/mgmt_be_adapter.c
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Original file line number Diff line number Diff line change
Expand Up @@ -59,18 +59,17 @@ struct mgmt_be_xpath_map {
* above map as well.
*/
#if HAVE_STATICD
static const char *const staticd_xpaths[] = {
static const char *const staticd_config_xpaths[] = {
"/frr-vrf:lib",
"/frr-interface:lib",
"/frr-routing:routing/control-plane-protocols/control-plane-protocol/frr-staticd:staticd",
NULL,
};
#endif

static const char *const *be_client_xpaths[MGMTD_BE_CLIENT_ID_MAX] = {

static const char *const *be_client_config_xpaths[MGMTD_BE_CLIENT_ID_MAX] = {
#ifdef HAVE_STATICD
[MGMTD_BE_CLIENT_ID_STATICD] = staticd_xpaths,
[MGMTD_BE_CLIENT_ID_STATICD] = staticd_config_xpaths,
#endif
};

Expand Down Expand Up @@ -190,7 +189,7 @@ static void mgmt_be_xpath_map_init(void)

FOREACH_MGMTD_BE_CLIENT_ID (id) {
/* Initialize the common config init map */
for (init = be_client_xpaths[id]; init && *init; init++) {
for (init = be_client_config_xpaths[id]; init && *init; init++) {
MGMTD_BE_ADAPTER_DBG(" - CFG XPATH: '%s'", *init);
mgmt_register_client_xpath(id, *init, true);
}
Expand Down Expand Up @@ -843,7 +842,8 @@ static bool be_is_client_interested(const char *xpath,
MGMTD_BE_ADAPTER_DBG("Checking client: %s for xpath: '%s'",
mgmt_be_client_id2name(id), xpath);

xpaths = config ? be_client_xpaths[id] : be_client_oper_xpaths[id];
xpaths = config ? be_client_config_xpaths[id]
: be_client_oper_xpaths[id];
if (xpaths) {
for (; *xpaths; xpaths++) {
if (mgmt_be_xpath_prefix(*xpaths, xpath)) {
Expand Down

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