Migration Guide#

Hello Gazebo community!!

In April 2022, it was announced that we’d be retiring the “Ignition” name in favor of “Gazebo”. This migration guide will serve you help you execute the necessary changes in your own packages, and luckily it won’t be as troublesome as the move from Gazebo Classic!

Overview#

Changes#

So what’s happening in practice? In summary:

  • Whenever the name Ignition or ign is used, the Gazebo counterpart (Gazebo or gz) is used instead, preserving case

  • ign-gazebo / Ignition Gazebo became gz-sim / Gazebo Sim

  • The Ignition logo has been replaced by the Gazebo logo.

These changes were made in:

  • Websites

  • GitHub organizations and repositories

  • Documentation

  • UIs

  • Namespaces, command line tools, shared libraries, directories, APIs, files

This means that a bulk of the migration effort on a user’s part will involve intelligent find-and-replaces of filenames, directories, and source code. You may also look at the tracking GitHub issue if you need to trace any changes made to support the migration in the core libraries.

Tick-tocks and Hard-tocks#

This section provides just an overview of the different changes made, for a more detailed listing of tick-tocks, see the migration file in each of the individual core libraries’ repositories:

Additionally the migration pointers in a later section of this migration guide should help you get your packages ready and working with Gazebo.

Generally speaking, you should still be able to use either the Ignition counterpart or Gazebo counterpart for most things if you are using Ionic, due to explicit tick-tocking logic written in the stack. Just note that using the Ignition counterpart will generally cause deprecation warnings to be emitted.

Tick-tocks#

Tick-tocks for the following are implemented, though not all of them will emit deprecation warnings. These tick-tocks are implemented either as aliases, or otherwise have some sort of redirection mechanism (e.g. symlinks, directory retargets, string replacements in source) to target the Gazebo counterpart instead.

Also, in the source code, most of these tick-tocks will have an associated comment calling out that they are deprecated, or have a GZ_DEPRECATED() macro call.

Namespaces

  • Python namespaces

    • e.g. ignition.math.XXX → gz.math.XXX

  • C++ namespaces

    • e.g. ignition::gazebo::XXX → gz::sim::XXX

  • Message namespaces and packages

    • e.g. ignition.msgs.XXX → gz.msgs.XXX, ignition/msgs/header.proto → gz/msgs/header.proto

Source

  • Class names, members, functions, and variables in public headers

    • e.g. IgnitionFormatter → GzFormatter

  • Public headers

    • e.g. include/ignition → include/gz

  • Plugins

    • e.g. ignition::gazebo::systems::LiftDrag → gz::sim::systems::LiftDrag

  • Shared libraries

    • e.g. libignition-gazebo-buoyancy-engine-system.so → libgz-sim-buoyancy-engine-system.so

    • You may remove the lib and .so prefix and suffixes!

      • e.g. libignition-gazebo-buoyancy-engine-system.so → gz-sim-buoyancy-engine-system

  • C++ Macros in public headers

    • e.g. IGN_PARTITION → GZ_PARTITION

CMake and Packaging

  • CMake macros/functions

    • e.g. ign_find_package() → gz_find_package()

  • CMake macro/function arguments

    • e.g. NO_IGNITION_PREFIX → NO_PROJECT_PREFIX

  • CMake variables*

    • e.g. IgnOGRE2_FOUND → GzOGRE2_FOUND

    • Not every CMake variable is tick-tocked, but most of the ones that are used in downstream libraries are

  • CMake packages found by gz_find_package()

    • e.g. gz_find_package(IgnCURL) → gz_find_package(GzCURL)

  • Debian packages

    • e.g. libignition-cmake3-dev → libgz-cmake3-dev

Misc.

  • Environment variables (names and values)

    • e.g. IGN_GAZEBO_RESOURCE_PATH → GZ_SIM_RESOURCE_PATH

  • Command line

    • e.g. ign → gz, ign gazebo → gz sim

  • GUI QML

    • e.g. IgnSpinBox → GzSpinBox

  • Topics* (typically in tests)

    • e.g. /ignition/XXX → /gz/XXX

    • Note: /gazebo is NOT migrated to /sim

  • GitHub organizations and repositories

    • e.g. ignitionrobotics → gazebosim , ign-cmake → gz-cmake

  • GitHub actions and workflows

    • e.g. ignition-tooling → gazebo-tooling

  • Websites

  • SDF and launch tags

    • e.g. <ignition-gui> → <gz-gui>

  • SDF namespaces

    • e.g. ignition:type

Hard-tocks#

There are some exceptions that have been hard-tocked instead, meaning that you MUST use the Gazebo counterpart. Using the Ignition counterpart will likely cause compilation or something else to break (unless it’s just a documentation change.)

Namespaces

  • Ruby namespaces

    • e.g. ignition/math → gz/math

Source

  • Install space

    • e.g. install/share/ignition → install/share/gz

CMake and Packaging

  • Most includeable CMake files in gz-cmake

    • e.g. IgnUtils.cmake → GzUtils.cmake

  • Gazebo library CMake project names

    • e.g. ignition-utils2 → gz-utils2

  • Internally used CMake variables

    • e.g. IGN_TRANSPORT_VER → GZ_TRANSPORT_VER

Misc.

  • Gazebo launchfiles and tags

    • e.g. sim.ign → sim.gzlaunch, <ign → <gz

  • Config and log paths (PENDING)

    • e.g. ~/.ignition/gui/log → ~/.gz/gui/log

    • Some config paths have been tick-tocked (e.g. ~/.ignition/gazebo/plugins)

  • Fuel URL (PENDING)

  • Fuel cache paths (ALSO PENDING)

    • e.g. ~/.ignition/fuel → ~/.gz/fuel

  • Library names in documentation and comments

    • e.g. Ignition Gazebo → Gazebo Sim

  • gz-launch Websocket server

    • e.g. ign.js → gz.js

Also, anything that is internal to the core Gazebo libraries and not used in downstream libraries (e.g. header guards, private headers or source, tests, documentation) is hard-tocked.

Untocks#

A very small selection of things have not been migrated, mostly for backwards compatibility reasons (e.g. supporting Fortress.)

Migration#

Overview#

The following migration guidelines are just that—guidelines and suggestions for how to get your package migrated, that should cover most general cases.

Just keep in mind the overarching goal of replacing every Ignition counterpart (IGN, Ign, Ignition, ign, ignition) to the Gazebo counterpart (GZ, Gz, gz).

Recommendations#

What might help greatly is to:

  • Make ample use of regex and sed

    • The migration guide will be giving suggestions for what regex expressions to use, but always review before executing the replace

  • Pay attention to case!!

  • Use an editor to review changes, and source control to allow for easy rollbacks

  • Pay attention to compilation warnings/errors, which usually (but not always) give suggestions for what to replace!

  • If in doubt, trace the change to changes listed in the tracking issue

Also, if you are building the Gazebo stack from source, you should do a clean, fresh rebuild and install. Delete your build and install directories, and run the build with --merge-install.

Gotchas#

Most of the migration effort you should do is mainly finding and replacing instances of Ignition-related terms with the Gazebo-related one.

However, here are a lot of edge cases that make it difficult to create a script to handle the migration (leading to errors or bugs), so before the migration steps are suggested, it would be good to know some of these cases.

  • Case-sensitivity not respected

    • e.g. IGNITION_ADD_PLUGIN → gz_ADD_PLUGIN

  • Greedy matches

    • e.g. Align → Algz, unsigned → unsgzed, signal → sgzal

  • Not migrating “gazebo” to “sim”

    • e.g. ign-gazebo → gz-gazebo (it should be gz-sim)

  • Matching ign before ignition

    • e.g. ignition-cmake3 → gzition-cmake3

  • Migrating a library that should not be migrated

    • e.g. ignition-cmake2 → gz-cmake2

  • Grammar

    • e.g. “an Ignition library” → “an Gazebo library”

Additionally, take note of the following behaviors:

  • Pre-existing config files do not get overwritten, so if you’d like to use your old configurations or have a config file in a custom location, you might need to manually migrate Ignition-counterpart references in your config files to get them to point to the appropriate counterpart

    • For example, a prior config file targeting gz-sim file could be using an ignition::gazebo::systems::Physics plugin. You might encounter deprecation warnings because that reference has not yet been migrated.

  • Because the install spaces have changed, if you have hard-coded locations involving ignition, you might need to migrate them to gz

Migration Steps#

It’s important to execute the steps within each of the individual sections in-order! The steps will typically go from specific to general.

Migrate Files and File References#

  1. In your package root, look for files and directories matching the (case-insensitive) pattern of ign(ition)?[_|-]gazebo, and migrate ign / ignition appropriately to gz, and gazebo to sim

  2. In your package root, look for files and directories with (case-insensitive) ign / ignition, and move them to gz, matching case

  3. Update all internal references to the migrated files and directories in (1) and (2) in your package

Migrate CMake#

In CMakeLists.txt files (and their references in your source files!):

Variables and macro/function calls

Find: IGN(ITION)?_GAZEBO
Replace: GZ_SIM

Find: ign(ition)?_gazebo
Replace: gz_sim

Find: IGN(ITION)?_
Replace: GZ_

Find: ign(ition)?_
Replace: gz_

Includes

Find: include\(Ign
Replace: include(Gz

Find: include\(ign
Replace: include(gz

Find: gz_find_package\(ign-
Replace: gz_find_package(gz-

Find: gz_find_package\(Ign(ition)?
Replace: gz_find_package(Gz-

Project Names

Find: ignition-gazebo
Replace: gz-sim

Find: ignition-
Replace: gz-

Note: Be wary that sometimes CMake arguments trickle down to the source files, so ensure you also migrate them appropriately

Migrate Macros and Environment Variables#

Migrate source macros and environment variables

Find: IGN(ITION)?_GAZEBO
Replace: GZ_SIM

Find: ign(ition)?_gazebo
Replace: gz_sim

Find: IGN(ITION)?_
Replace: GZ_

Find: ign(ition)?_
Replace: gz_

For environment variables, you can use the same approach as with macros, but pay attention to the values stored in the environment variables! (e.g. paths.)

Additionally, the logging macros have also been migrated! Migrate any uses!

  • ignerr -> gzerr

  • ignwarn -> gzwarn

  • ignmsg -> gzmsg

  • igndbg -> gzdbg

  • ignlog -> gzlog

  • ignLogInit -> gzLogInit

  • ignLogClose -> gzLogClose

  • ignLogDirectory -> gzLogDirectory

Migrate SDF#

In .sdf files:

Find: <ignition
Replace: <gz

Find: </ignition
Replace: </gz

Find: ignition:
Replace: gz:

Some examples:

  • <gz:odometer

  • <gz-gui

Migrate Plugins and Shared Libraries#

The plugin finder is able to find plugins even if their filenames are stripped of lib and .so.

In .sdf files and source files (e.g. .cc):

Find: (lib)?ign(ition)?-gazebo([^. ]*)\.so
Replace: gz-sim\3

Find: (lib)?ign(ition)?([^. ]*)\.so
Replace: gz\3

Find: ignition::gazebo
Replace: gz::sim

Find: ignition::
Replace: gz::

Migrate Bindings#

In Python files (e.g. .py)

Find: ignition.gazebo
Replace: gz.sim

Find: ignition.
Replace: gz.

In Ruby files (e.g. .i, .rb)

Find: ign(ition)?/
Replace: gz/

Migrate Messages#

In your message definitions

Find: ign(ition)?\.gazebo
Replace: gz.sim

Find: ign(ition)?/gazebo
Replace: gz/sim

Find: ign(ition)?\.
Replace: gz.

Find: ign(ition)?/
Replace: gz/

Migrate Headers and Sources#

Sweeping checks everywhere (pay special attention to reviewing these!)

Headers

Find: #include\s*([<"])ign(ition)?/gazebo
Replace: #include \1gz/sim

Find: #include\s*([<"])ign(ition)?/
Replace: #include \1gz/

// Note: You should be wary of the IGNITION GAZEBO case for the following
// and adjust accordingly
Find: #([^\s]*)\s+(.*)IGN(?:ITION)?_(.*)_(H+)_(.*)$
Replace: #$1 $2GZ_$3_$4_$5

Find: #endif\s*// GZ(.*)_H
Replace: #endif  // GZ$1_H

Namespaces

Find: namespace\s*ignition
Replace: namespace gz

Find: namespace\s*gazebo
Replace: namespace sim

Find: ignition::gazebo
Replace: gz::sim

Find: Ignition::Gazebo
Replace: Gz::Sim

Find: ignition::
Replace: gz::

Find: Ignition::
Replace: Gz::

Everything Else

You probably want to manually inspect:

  • Ign

  • ignition

And also be mindful that certain instances of gazebo (usually as part of an API) need to use sim instead.

Migrate Your CLI Usage#

Where you used to use:

ign gazebo shapes.sdf

Now you should use:

gz sim shapes.sdf

Notice that the gazebo verb is deprecated.

Helpful CLI Redirection#

In order to support side-by-side installs of Ionic and Fortress, the ign CLI executable (and the gazebo verb) will not be installed for Ionic. This means that unless Fortress is also installed alongside Ionic, CLI usage has to be migrated. Use gz instead of ign, and sim instead of gazebo.

You may add the following script to your ~/.bashrc file to redirect any ign calls to gz, so you won’t have to migrate all of your scripts (that are still using ign), though it is still recommended to make the migration.

ign() {
  if which ign &> /dev/null; then
    $(which ign) "$@"
  else
    if which gz &> /dev/null; then
      echo "[DEPRECATED] ign is deprecated! Please use gz instead!"
      if [ "$1" = "gazebo" ]; then
        echo "[DEPRECATED] The gazebo verb is deprecated! Please use sim instead!"
        shift
        $(which gz) sim "$@"
      else
        $(which gz) "$@"
      fi
    else
      echo "[ERROR] It seems like you don't have Gazebo installed!"
      return 1
    fi
  fi
}

Double-Check#

These might be useful to double-check if you have any lingering stuff, or erroneously migrated instances

You should match these case-insensitively.

Errors

  • gz-gazebo

  • gzition

  • an gz

Remaining Ign

  • \.ign(ition)?

  • ign(ition)?[-_]

Additional Packages#

This section details changes that have taken place in some other Gazebo related packages.

ros_gz#

ros_ign has been renamed to ros_gz. All internal references to ign or ignition that pre-Ionic versions of Gazebo don’t rely on have been migrated.

If you want to run ros_gz demos with custom sim version or sim args, use the gz_version and gz_args launch parameters. Using the ign_version launch parameter will also require you to explicitly set the ign_args launch parameters instead.

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