dnsmasq: add dnsmasq.d entries for lxc and libvirt

A while ago changes were merged to meta-openembedded to make
/etc/dnsmasq.d (and specifically the files it contains) referenced
when the main instance of dnsmasq is run (see dnsmasq.service and
commit ba665493a0dd [dnsmasq: allow for dnsmasq instances to reuse
default dnsmasq.conf]).

We, however, continued to modify the global configuration
(/etc/dnsmasq.conf) to keep the main instance of dnsmasq from
attaching to virbr0 and lxcbr0, by using 'bind-dynamic'. This approach
is problematic, since it is common that other instances of dnsmasq
will make use of the global configuration file and may have
incompatible options. We see this for example when attempting to start
lxc-net which will attempt to use 'bind-interface' which is
incompatible with 'bind-dynamic' that we were adding to the global
configuration.

Here we remove our change to the global configuration (leaving it
mostly empty as it should be) and instead have lxc and libvirt
packages instruct the global instance not to bind to virbr0 and lxcbr0
by adding configuration files to /etc/dnsmasq.d (setting
except-interface).

The added benefit to this approach is that if lxc or libvirt are not
part of an image the global configuration will not be modified in such
a way as to expect that they are present.

Signed-off-by: Mark Asselstine <mark.asselstine@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@windriver.com>

2 files changed, 8 insertions, 0 deletions

diff --git a/recipes-containers/lxc/files/dnsmasq.conf b/recipes-containers/lxc/files/dnsmasq.conf
new file mode 100644
index 00000000..124f7ebe
--- /dev/null
+++ b/recipes-containers/lxc/files/dnsmasq.conf
@@ -0,0 +1,2 @@
+bind-interfaces
+except-interface=lxcbr0
diff --git a/recipes-containers/lxc/lxc_2.0.8.bb b/recipes-containers/lxc/lxc_2.0.8.bb
index c9ce5f06..b616e947 100644
--- a/recipes-containers/lxc/lxc_2.0.8.bb
+++ b/recipes-containers/lxc/lxc_2.0.8.bb
@@ -36,6 +36,7 @@ SRC_URI = "http://linuxcontainers.org/downloads/${BPN}-${PV}.tar.gz \
         file://lxc-doc-upgrade-to-use-docbook-3.1-DTD.patch \
         file://logs-optionally-use-base-filenames-to-report-src-fil.patch \
         file://cgroups-work-around-issue-in-gcc-7.patch \
+        file://dnsmasq.conf \
         "
 
 SRC_URI[md5sum] = "7bfd95280522d7936c0979dfea92cdb5"
@@ -134,6 +135,11 @@ do_install_append() {
             if [ -d ${D}${exec_prefix}/lib/python* ]; then mv ${D}${exec_prefix}/lib/python* ${D}${libdir}/; fi
             rmdir --ignore-fail-on-non-empty ${D}${exec_prefix}/lib
         fi
+
+        # Force the main dnsmasq instance to bind only to specified interfaces and
+        # to not bind to virbr0. Libvirt will run its own instance on this interface.
+        install -d ${D}/${sysconfdir}/dnsmasq.d
+        install -m 644 ${WORKDIR}/dnsmasq.conf ${D}/${sysconfdir}/dnsmasq.d/lxc
 }
 
 EXTRA_OEMAKE += "TEST_DIR=${D}${PTEST_PATH}/src/tests"