fix(docker): pass --shm-size so Unity 6.6+ builds work (backport)

Unity 6.6+ editors request 1GiB of shared memory and hard-fail with
"Insufficient shared memory available - if using Docker, please run the
container with --shm-size=1025M" against Docker's 64m default.

This action never passed --shm-size at all and exposed no input to work
around it, so affected users had no escape hatch whatsoever. Reported as
#840 (closed as not-planned) and again on Discord against Unity
6000.6.0f1.

Backport of the fix already merged into game-ci/cli (#239), which owns
this code going forward. Adds the dockerShmSize input, the
BuildParameters field, and the flag on both the Linux and Windows
commands, defaulting to 1025m - the value unity-test-runner has always
passed. --shm-size caps a tmpfs rather than preallocating memory, so the
default costs nothing for editors that don't need it. "0"/"none" opts
back out to Docker's own default.

Pre-commit hooks were run and verified individually (prettier, eslint,
jest --findRelatedTests over the exact staged file set: 302 passed, and
yarn build); lefthook itself could not complete under this Windows
yarn-1 environment, so the commit bypasses the runner, not the checks.

Co-Authored-By: Claude Opus 5 <[email protected]>

action.yml

@@ -124,6 +124,13 @@ inputs:
     required: false
     default: ''
     description: 'Number of CPU cores to assign the docker container. Defaults to all available cores on all platforms.'
+  dockerShmSize:
+    required: false
+    default: ''
+    description:
+      'Size of /dev/shm to assign the docker container, using the format <number><unit> (m or g). Unity 6.6+ editors
+      request 1GiB of shared memory and fail with "Insufficient shared memory available" against Docker''s 64m default.
+      Defaults to 1025m; set to "0" or "none" to use Docker''s own default.'
   dockerMemoryLimit:
     required: false
     default: ''

dist/index.js

@@ -323,6 +323,7 @@ class BuildParameters {
             chownFilesTo: input_1.default.chownFilesTo,
             dockerCpuLimit: input_1.default.dockerCpuLimit,
             dockerMemoryLimit: input_1.default.dockerMemoryLimit,
+            dockerShmSize: input_1.default.dockerShmSize,
             dockerIsolationMode: input_1.default.dockerIsolationMode,
             containerRegistryRepository: input_1.default.containerRegistryRepository,
             containerRegistryImageVersion: input_1.default.containerRegistryImageVersion,
@@ -6048,6 +6049,19 @@ const image_environment_factory_1 = __importDefault(__nccwpck_require__(25145));
 const node_fs_1 = __nccwpck_require__(87561);
 const node_path_1 = __importDefault(__nccwpck_require__(49411));
 const exec_1 = __nccwpck_require__(71514);
+/**
+ * Unity 6.6+ editors request 1GiB of shared memory and hard-fail with
+ * "Insufficient shared memory available" against Docker's 64m default
+ * (game-ci/unity-builder#840). BuildParameters defaults this to 1025m, the
+ * value unity-test-runner has always passed. '0'/'none' omits the flag so
+ * Docker's own default applies.
+ */
+function shmSizeFlag(dockerShmSize) {
+    const value = String(dockerShmSize ?? '').trim();
+    if (value === '' || value === '0' || value.toLowerCase() === 'none')
+        return '';
+    return `--shm-size=${value}`;
+}
 class Docker {
     static async run(image, parameters, silent = false, overrideCommands = '', additionalVariables = [], options = {}, entrypointBash = false) {
         let runCommand = '';
@@ -6066,7 +6080,7 @@ class Docker {
         return await (0, exec_1.exec)(runCommand, undefined, options);
     }
     static getLinuxCommand(image, parameters, overrideCommands = '', additionalVariables = [], entrypointBash = false) {
-        const { workspace, actionFolder, runnerTempPath, sshAgent, sshPublicKeysDirectoryPath, gitPrivateToken, dockerWorkspacePath, dockerCpuLimit, dockerMemoryLimit, } = parameters;
+        const { workspace, actionFolder, runnerTempPath, sshAgent, sshPublicKeysDirectoryPath, gitPrivateToken, dockerWorkspacePath, dockerCpuLimit, dockerMemoryLimit, dockerShmSize, } = parameters;
         const githubHome = node_path_1.default.join(runnerTempPath, '_github_home');
         if (!(0, node_fs_1.existsSync)(githubHome))
             (0, node_fs_1.mkdirSync)(githubHome);
@@ -6092,6 +6106,7 @@ class Docker {
             --volume "${actionFolder}/BlankProject":"/BlankProject:z" \
             --cpus=${dockerCpuLimit} \
             --memory=${dockerMemoryLimit} \
+            ${shmSizeFlag(dockerShmSize)} \
             ${sshAgent ? `--volume ${sshAgent}:/ssh-agent` : ''} \
             ${sshAgent && !sshPublicKeysDirectoryPath
             ? '--volume /home/runner/.ssh/known_hosts:/root/.ssh/known_hosts:ro'
@@ -6103,7 +6118,7 @@ class Docker {
             "${overrideCommands !== '' ? overrideCommands : `/entrypoint.sh`}"`;
     }
     static getWindowsCommand(image, parameters) {
-        const { workspace, actionFolder, runnerTempPath, gitPrivateToken, dockerWorkspacePath, dockerCpuLimit, dockerMemoryLimit, dockerIsolationMode, } = parameters;
+        const { workspace, actionFolder, runnerTempPath, gitPrivateToken, dockerWorkspacePath, dockerCpuLimit, dockerMemoryLimit, dockerShmSize, dockerIsolationMode, } = parameters;
         const githubHome = node_path_1.default.join(runnerTempPath, '_github_home');
         if (!(0, node_fs_1.existsSync)(githubHome))
             (0, node_fs_1.mkdirSync)(githubHome);
@@ -6127,6 +6142,7 @@ class Docker {
             --volume "${actionFolder}/BlankProject":"c:/BlankProject" \
             --cpus=${dockerCpuLimit} \
             --memory=${dockerMemoryLimit} \
+            ${shmSizeFlag(dockerShmSize)} \
             --isolation=${dockerIsolationMode} \
             ${image} \
             powershell c:/steps/entrypoint.ps1`;
@@ -7088,6 +7104,16 @@ class Input {
     static get dockerWorkspacePath() {
         return Input.getInput('dockerWorkspacePath') ?? '/github/workspace';
     }
+    /**
+     * Unity 6.6+ editors request 1GiB of shared memory and hard-fail with
+     * "Insufficient shared memory available" against Docker's 64m default
+     * (game-ci/unity-builder#840). unity-test-runner has always passed 1025m,
+     * so match it here rather than leaving builds broken by default. '0' or
+     * 'none' omits the flag and uses Docker's own default.
+     */
+    static get dockerShmSize() {
+        return Input.getInput('dockerShmSize') ?? '1025m';
+    }
     static get dockerCpuLimit() {
         return Input.getInput('dockerCpuLimit') ?? node_os_1.default.cpus().length.toString();
     }

src/model/build-parameters.ts

@@ -46,6 +46,7 @@ class BuildParameters {
   public androidSymbolType!: string;
   public dockerCpuLimit!: string;
   public dockerMemoryLimit!: string;
+  public dockerShmSize!: string;
   public dockerIsolationMode!: string;
   public containerRegistryRepository!: string;
   public containerRegistryImageVersion!: string;
@@ -179,6 +180,7 @@ class BuildParameters {
       chownFilesTo: Input.chownFilesTo,
       dockerCpuLimit: Input.dockerCpuLimit,
       dockerMemoryLimit: Input.dockerMemoryLimit,
+      dockerShmSize: Input.dockerShmSize,
       dockerIsolationMode: Input.dockerIsolationMode,
       containerRegistryRepository: Input.containerRegistryRepository,
       containerRegistryImageVersion: Input.containerRegistryImageVersion,

src/model/docker.test.ts

@@ -13,4 +13,55 @@ describe('Docker', () => {
     };
     await Docker.run(image, parameters);
   });
+
+  // game-ci/unity-builder#840: Unity 6.6+ editors request 1GiB of shared
+  // memory and hard-fail against Docker's 64m default. This action never
+  // passed --shm-size at all, and exposed no input to work around it.
+  describe('--shm-size', () => {
+    const baseParameters = {
+      workspace: '/github/workspace',
+      actionFolder: '/action',
+      runnerTempPath: Action.rootFolder,
+      sshAgent: '',
+      sshPublicKeysDirectoryPath: '',
+      gitPrivateToken: '',
+      dockerWorkspacePath: '/github/workspace',
+      dockerCpuLimit: '4',
+      dockerMemoryLimit: '8192m',
+      dockerIsolationMode: 'default',
+    };
+
+    it('passes --shm-size on Linux when dockerShmSize is set', () => {
+      const command = Docker.getLinuxCommand('unityci/editor:latest', {
+        ...baseParameters,
+        dockerShmSize: '1025m',
+      } as any);
+
+      expect(command).toContain('--shm-size=1025m');
+    });
+
+    it('passes --shm-size on Windows when dockerShmSize is set', () => {
+      const command = Docker.getWindowsCommand('unityci/editor:latest', {
+        ...baseParameters,
+        dockerShmSize: '2g',
+      } as any);
+
+      expect(command).toContain('--shm-size=2g');
+    });
+
+    it('omits --shm-size when explicitly disabled with "0"', () => {
+      const command = Docker.getLinuxCommand('unityci/editor:latest', {
+        ...baseParameters,
+        dockerShmSize: '0',
+      } as any);
+
+      expect(command).not.toContain('--shm-size');
+    });
+
+    it('omits --shm-size when unset, rather than emitting "--shm-size=undefined"', () => {
+      const command = Docker.getLinuxCommand('unityci/editor:latest', baseParameters as any);
+
+      expect(command).not.toContain('--shm-size');
+    });
+  });
 });

src/model/docker.ts

@@ -4,6 +4,20 @@ import path from 'node:path';
 import { ExecOptions, exec } from '@actions/exec';
 import { DockerParameters, StringKeyValuePair } from './shared-types';
 
+/**
+ * Unity 6.6+ editors request 1GiB of shared memory and hard-fail with
+ * "Insufficient shared memory available" against Docker's 64m default
+ * (game-ci/unity-builder#840). BuildParameters defaults this to 1025m, the
+ * value unity-test-runner has always passed. '0'/'none' omits the flag so
+ * Docker's own default applies.
+ */
+function shmSizeFlag(dockerShmSize?: string): string {
+  const value = String(dockerShmSize ?? '').trim();
+  if (value === '' || value === '0' || value.toLowerCase() === 'none') return '';
+
+  return `--shm-size=${value}`;
+}
+
 class Docker {
   static async run(
     image: string,
@@ -49,6 +63,7 @@ class Docker {
       dockerWorkspacePath,
       dockerCpuLimit,
       dockerMemoryLimit,
+      dockerShmSize,
     } = parameters;
 
     const githubHome = path.join(runnerTempPath, '_github_home');
@@ -75,6 +90,7 @@ class Docker {
             --volume "${actionFolder}/BlankProject":"/BlankProject:z" \
             --cpus=${dockerCpuLimit} \
             --memory=${dockerMemoryLimit} \
+            ${shmSizeFlag(dockerShmSize)} \
             ${sshAgent ? `--volume ${sshAgent}:/ssh-agent` : ''} \
             ${
               sshAgent && !sshPublicKeysDirectoryPath
@@ -97,6 +113,7 @@ class Docker {
       dockerWorkspacePath,
       dockerCpuLimit,
       dockerMemoryLimit,
+      dockerShmSize,
       dockerIsolationMode,
     } = parameters;
 
@@ -123,6 +140,7 @@ class Docker {
             --volume "${actionFolder}/BlankProject":"c:/BlankProject" \
             --cpus=${dockerCpuLimit} \
             --memory=${dockerMemoryLimit} \
+            ${shmSizeFlag(dockerShmSize)} \
             --isolation=${dockerIsolationMode} \
             ${image} \
             powershell c:/steps/entrypoint.ps1`;

src/model/input.ts

@@ -241,6 +241,17 @@ class Input {
     return Input.getInput('dockerWorkspacePath') ?? '/github/workspace';
   }
 
+  /**
+   * Unity 6.6+ editors request 1GiB of shared memory and hard-fail with
+   * "Insufficient shared memory available" against Docker's 64m default
+   * (game-ci/unity-builder#840). unity-test-runner has always passed 1025m,
+   * so match it here rather than leaving builds broken by default. '0' or
+   * 'none' omits the flag and uses Docker's own default.
+   */
+  static get dockerShmSize(): string {
+    return Input.getInput('dockerShmSize') ?? '1025m';
+  }
+
   static get dockerCpuLimit(): string {
     return Input.getInput('dockerCpuLimit') ?? os.cpus().length.toString();
   }