Add CRIU configuration file support

Dockerfile

@@ -45,10 +45,14 @@ RUN cd /tmp \
     && rm -rf /tmp/bats
 
 # install criu
+# For CRIU 3.11 one patch is needed for the test 'checkpoint and restore with container specific CRIU config'
+# This should be no longer necessary with CRIU 3.12
+# See https://github.com/opencontainers/runc/pull/1933
 ENV CRIU_VERSION v3.11
 RUN mkdir -p /usr/src/criu \
     && curl -sSL https://github.com/checkpoint-restore/criu/archive/${CRIU_VERSION}.tar.gz | tar -v -C /usr/src/criu/ -xz --strip-components=1 \
     && cd /usr/src/criu \
+    && curl https://github.com/checkpoint-restore/criu/commit/bb0b2f2635d71e549851b7c626a1464e42a3b5c7.patch | patch -p1 \
     && make install-criu \
     && rm -rf /usr/src/criu
 

libcontainer/container_linux.go

@@ -875,6 +875,32 @@ func waitForCriuLazyServer(r *os.File, status string) error {
 	return nil
 }
 
+func (c *linuxContainer) handleCriuConfigurationFile(rpcOpts *criurpc.CriuOpts) {
+	// CRIU will evaluate a configuration starting with release 3.11.
+	// Settings in the configuration file will overwrite RPC settings.
+	// Look for annotations. The annotation 'org.criu.config'
+	// specifies if CRIU should use a different, container specific
+	// configuration file.
+	_, annotations := utils.Annotations(c.config.Labels)
+	configFile, exists := annotations["org.criu.config"]
+	if exists {
+		// If the annotation 'org.criu.config' exists and is set
+		// to a non-empty string, tell CRIU to use that as a
+		// configuration file. If the file does not exist, CRIU
+		// will just ignore it.
+		if configFile != "" {
+			rpcOpts.ConfigFile = proto.String(configFile)
+		}
+		// If 'org.criu.config' exists and is set to an empty
+		// string, a runc specific CRIU configuration file will
+		// be not set at all.
+	} else {
+		// If the mentioned annotation has not been found, specify
+		// a default CRIU configuration file.
+		rpcOpts.ConfigFile = proto.String("/etc/criu/runc.conf")
+	}
+}
+
 func (c *linuxContainer) Checkpoint(criuOpts *CriuOpts) error {
 	c.m.Lock()
 	defer c.m.Unlock()
@@ -940,6 +966,8 @@ func (c *linuxContainer) Checkpoint(criuOpts *CriuOpts) error {
 		LazyPages:       proto.Bool(criuOpts.LazyPages),
 	}
 
+	c.handleCriuConfigurationFile(&rpcOpts)
+
 	// If the container is running in a network namespace and has
 	// a path to the network namespace configured, we will dump
 	// that network namespace as an external namespace and we
@@ -1190,6 +1218,8 @@ func (c *linuxContainer) Restore(process *Process, criuOpts *CriuOpts) error {
 		},
 	}
 
+	c.handleCriuConfigurationFile(req.Opts)
+
 	// Same as during checkpointing. If the container has a specific network namespace
 	// assigned to it, this now expects that the checkpoint will be restored in a
 	// already created network namespace.