| Message ID | 9aa6160b2664a52ff778fad67c366d67d3a0f8ab.1651285313.git.ehem+xen@m5p.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Allow use of JSON in domain configuration files | expand |
On Tue, Apr 19, 2022 at 06:23:41PM -0700, Elliott Mitchell wrote: > JSON is currently used when saving domains to mass storage. Being able > to use JSON as the normal input to `xl create` has potential to be > valuable. Add the functionality. > > Move the memset() earlier so to allow use of the structure sooner. > > Signed-off-by: Elliott Mitchell <ehem+xen@m5p.com> So, I gave this a try and creating a guest from a json config, and that fails very early with "Unknown guest type". Have you actually tried to create a guest from config file written in json? Also, this would need documentation about the new option, about the format. The man page need to be edited. An example of a config file written in json would be nice as well. Thanks,
On Fri, May 20, 2022 at 03:12:46PM +0100, Anthony PERARD wrote: > On Tue, Apr 19, 2022 at 06:23:41PM -0700, Elliott Mitchell wrote: > > JSON is currently used when saving domains to mass storage. Being able > > to use JSON as the normal input to `xl create` has potential to be > > valuable. Add the functionality. > > > > Move the memset() earlier so to allow use of the structure sooner. > > > > Signed-off-by: Elliott Mitchell <ehem+xen@m5p.com> > > So, I gave this a try and creating a guest from a json config, and that > fails very early with "Unknown guest type". > > Have you actually tried to create a guest from config file written in > json? > > Also, this would need documentation about the new option, about the > format. The man page need to be edited. > > An example of a config file written in json would be nice as well. I'll be trying for these at some point, but no timeframe yet. This was an idea which occurred to me when looking at things. I'm wavering on whether this is the way to go... Real goal is I would like to generate a replacement for the `xendomains` init script. While functional the script is woefully inadaquate for anything other than the tiniest installation. Notably there can be ordering constraints for start/shutdown (worse, those could be distinct). One might also wish different strategies for different domains (some get saved to disk on reboot, some might get shutdown/restarted). For some of the configuration for this, adding to domain.cfg files makes sense. This though ends up with the issue of what should the extra data look like? I'm oscillating between adding a section in something libxl's parser takes as a comment, versus adding a configuration option to domain.cfg (libxl's parser ignores unknown sections which is not entirely good!). JSON's structure would be good for an addition, but JSON comes with its own downsides. Most likely such a thing would be implemented in Python. Needs a bit more math than shell is good for.
On Tue, May 31, 2022 at 06:25:13PM -0700, Elliott Mitchell wrote: > On Fri, May 20, 2022 at 03:12:46PM +0100, Anthony PERARD wrote: > > On Tue, Apr 19, 2022 at 06:23:41PM -0700, Elliott Mitchell wrote: > > > JSON is currently used when saving domains to mass storage. Being able > > > to use JSON as the normal input to `xl create` has potential to be > > > valuable. Add the functionality. > > > > > > Move the memset() earlier so to allow use of the structure sooner. > > > > > > Signed-off-by: Elliott Mitchell <ehem+xen@m5p.com> > > > > So, I gave this a try and creating a guest from a json config, and that > > fails very early with "Unknown guest type". > > > > Have you actually tried to create a guest from config file written in > > json? > > > > Also, this would need documentation about the new option, about the > > format. The man page need to be edited. > > > > An example of a config file written in json would be nice as well. > > I'll be trying for these at some point, but no timeframe yet. This was > an idea which occurred to me when looking at things. I'm wavering on > whether this is the way to go... > > Real goal is I would like to generate a replacement for the `xendomains` > init script. While functional the script is woefully inadaquate for > anything other than the tiniest installation. > > Notably there can be ordering constraints for start/shutdown (worse, > those could be distinct). One might also wish different strategies for > different domains (some get saved to disk on reboot, some might get > shutdown/restarted). Is this that something like `libvirt` or some other toolstacks could help with? Or maybe you are looking for something that as a small footprint on the system and just run once at boot and at shutdown. > For some of the configuration for this, adding to domain.cfg files makes > sense. This though ends up with the issue of what should the extra data > look like? Maybe `xl` could be taught to ignore some options that have a prefix like "xendomain_", even if at the moment it ignore everything it doesn't know I think. > I'm oscillating between adding a section in something libxl's parser > takes as a comment, versus adding a configuration option to domain.cfg A comment section could work too I guess, like there's one for `sysv` init system which describe dependency as comments. > (libxl's parser ignores unknown sections which is not entirely good!). > JSON's structure would be good for an addition, but JSON comes with its > own downsides. > > Most likely such a thing would be implemented in Python. Needs a bit > more math than shell is good for. If you plan to convert the `xendomains` init script to python, I don't think that would be a good idea, as it is probably better to not add a dependency for a init script that has been a shell script for a while. But introducing a new utility in python or other language might be fine. Cheers,
diff --git a/tools/xl/xl.h b/tools/xl/xl.h index 72538d6a81..4b0828431f 100644 --- a/tools/xl/xl.h +++ b/tools/xl/xl.h @@ -48,6 +48,11 @@ struct domain_create { int migrate_fd; /* -1 means none */ int send_back_fd; /* -1 means none */ char **migration_domname_r; /* from malloc */ + enum { + CONFIG_FORMAT_DEFAULT, + CONFIG_FORMAT_JSON, + CONFIG_FORMAT_LEGACY, + } config_format; /* format specified for configuration */ }; int create_domain(struct domain_create *dom_info); diff --git a/tools/xl/xl_cmdtable.c b/tools/xl/xl_cmdtable.c index 35182ca196..8a791d8c49 100644 --- a/tools/xl/xl_cmdtable.c +++ b/tools/xl/xl_cmdtable.c @@ -30,6 +30,8 @@ const struct cmd_spec cmd_table[] = { "-F Run in foreground until death of the domain.\n" "-f FILE, --defconfig=FILE\n Use the given configuration file.\n" "-h Print this help.\n" + "-j, --json Interpret configuration file as JSON format\n" + "-J Use traditional configuration file format (current default)\n" "-n, --dryrun Dry run - prints the resulting configuration\n" " (deprecated in favour of global -N option).\n" "-p Leave the domain paused after it is created.\n" diff --git a/tools/xl/xl_vmcontrol.c b/tools/xl/xl_vmcontrol.c index 4bf041fb01..dd8b3f81a6 100644 --- a/tools/xl/xl_vmcontrol.c +++ b/tools/xl/xl_vmcontrol.c @@ -789,7 +789,7 @@ int create_domain(struct domain_create *dom_info) extra_config); } config_source=config_file; - config_in_json = false; + config_in_json = dom_info->config_format == CONFIG_FORMAT_JSON; } else { if (!config_data) { fprintf(stderr, "Config file not specified and" @@ -1167,6 +1167,7 @@ int main_create(int argc, char **argv) struct domain_create dom_info = { /* Command-line options */ .config_file = NULL, + .config_format = CONFIG_FORMAT_DEFAULT, .console_autoconnect = 0, .debug = 0, .daemonize = 1, @@ -1189,6 +1190,7 @@ int main_create(int argc, char **argv) {"defconfig", 1, 0, 'f'}, {"dryrun", 0, 0, 'n'}, {"ignore-global-affinity-masks", 0, 0, 'i'}, + {"json", 0, 0, 'j'}, {"quiet", 0, 0, 'q'}, {"vncviewer", 0, 0, 'V'}, {"vncviewer-autopass", 0, 0, 'A'}, @@ -1200,13 +1202,16 @@ int main_create(int argc, char **argv) argc--; argv++; } - SWITCH_FOREACH_OPT(opt, "AFVcdef:inpq", opts, "create", 0) { + SWITCH_FOREACH_OPT(opt, "AFJVcdef:ijnpq", opts, "create", 0) { case 'A': dom_info.vnc = dom_info.vncautopass = 1; break; case 'F': dom_info.daemonize = 0; break; + case 'J': + dom_info.config_format = CONFIG_FORMAT_LEGACY; + break; case 'V': dom_info.vnc = 1; break; @@ -1226,6 +1231,9 @@ int main_create(int argc, char **argv) case 'i': dom_info.ignore_global_affinity_masks = 1; break; + case 'j': + dom_info.config_format = CONFIG_FORMAT_JSON; + break; case 'n': dryrun_only = 1; break;
JSON is currently used when saving domains to mass storage. Being able to use JSON as the normal input to `xl create` has potential to be valuable. Add the functionality. Move the memset() earlier so to allow use of the structure sooner. Signed-off-by: Elliott Mitchell <ehem+xen@m5p.com> --- v2: Removing the UUOC situation. Correct the comparison to match the correct variable type. Rename to "config_format" from "format". Rename everything from "format" to "config_format". --- tools/xl/xl.h | 5 +++++ tools/xl/xl_cmdtable.c | 2 ++ tools/xl/xl_vmcontrol.c | 12 ++++++++++-- 3 files changed, 17 insertions(+), 2 deletions(-)