Add 'org.criu.config' annotation documentation

Signed-off-by: Adrian Reber <[email protected]>

Author: adrianreber

docs/checkpoint-restore.md

@@ -0,0 +1,50 @@
+# Checkpoint and Restore #
+
+For a basic description about checkpointing and restoring containers with
+`runc` please see [runc-checkpoint(8)](../man/runc-checkpoint.8.md) and
+[runc-restore(8)](../man/runc-restore.8.md).
+
+## Checkpoint/Restore Annotations ##
+
+In addition to specifying options on the command-line like it is described
+in the man-pages (see above), it is also possible to influence CRIU's
+behaviour using CRIU configuration files. For details about CRIU's
+configuration file support please see [CRIU's wiki](https://criu.org/Configuration_files).
+
+In addition to CRIU's default configuration files `runc` tells CRIU to
+also evaluate the file `/etc/criu/runc.conf`. Using the annotation
+`org.criu.config` it is, however, possible to change this additional
+CRIU configuration file.
+
+If the annotation `org.criu.config` is set to an empty string `runc`
+will not pass any additional configuration file to CRIU. With an empty
+string it is therefore possible to disable the additional CRIU configuration
+file. This can be used to make sure that no additional configuration file
+changes CRIU's behaviour accidentally.
+
+If the annotation `org.criu.config` is set to a non-empty string `runc` will
+pass that string to CRIU to be evaluated as an additional configuration file.
+If CRIU cannot open this additional configuration file, it will ignore this
+file and continue.
+
+### Annotation Example to disable additional CRIU configuration file ###
+
+```
+{
+	"ociVersion": "1.0.0",
+	"annotations": {
+		"org.criu.config": ""
+	},
+	"process": {
+```
+
+### Annotation Example to set a specific CRIU configuration file ###
+
+```
+{
+	"ociVersion": "1.0.0",
+	"annotations": {
+		"org.criu.config": "/etc/special-runc-criu-options"
+	},
+	"process": {
+```