This is a tool and library for converting old (spec v1-v2.x.0) Ignition configs to the new v3.x.0 format, and from v3.x.0 back to v2.x.0. See Upgrading Configs for details on the changes.
Ignition Spec 3 will mount filesystems at the mountpoint specified by path when running. Filesystems no longer have the name field and files, links, and directories no longer specify the filesystem by name. This means to translate filesystems (with the exception of root), you must also provide a mapping of filesystem name to absolute path, e.g.
map[string]string{"var": "/var"}
If you do not, and have a filesystem with the name "var", the translation will fail.
Conversely, when you translate from spec 3 down to spec 2, we generate names on the fly based on the path. If no path is specified, it is simply named by an incrementing integer. This information is not currently being stored, which means to translate from 3 -> 2 -> 3, you will have to manually provide the filesystem mapping that we generate.
- Save the generated filesystem mapping, so we can translate seamlessly from 3 -> 2 -> 3
- Revisit translated spec versions
The old spec versions have bugs that allow specifying configs that don't make sense. For example, it is valid for a v2.1+ config to specify that a path should be both a directory and a file. The behavior there is defined by Ignition's implementation instead of the spec and, in certain edge cases, by the contents of the filesystem Ignition is operating on.
This means Ignition can't be guaranteed to automatically translate an old config to an equivalent new config; it can fail at conversion. Since Ignition internally translates old configs to the latest config, this would mean old Ignition configs could stop working on newer versions of whatever OS included Ignition. Additionally, due to the change in how filesystems are handled (new configs require specifying the path relative to the sysroot that Ignition should mount the filesystem at), some configs require extra information to convert from the old versions to the new versions.
This tool exists to allow mechanical translation of old configs to new configs. If you are also switching operating systems, other changes may be necessary.
Most of the problems in old configs stem from specifying illogical things. Make sure you don't have any duplicate entries. Do not rely on the order in which files, directories, or links are created. Most configs should be translatable without problems.