# container-structure-test **Repository Path**: mirrors_benjaminp/container-structure-test ## Basic Information - **Project Name**: container-structure-test - **Description**: validate the structure of your container images - **Primary Language**: Unknown - **License**: Apache-2.0 - **Default Branch**: main - **Homepage**: None - **GVP Project**: No ## Statistics - **Stars**: 0 - **Forks**: 0 - **Created**: 2025-02-16 - **Last Updated**: 2025-11-01 ## Categories & Tags **Categories**: Uncategorized **Tags**: None ## README Container Structure Tests ==================== The Container Structure Tests provide a powerful framework to validate the structure of a container image. These tests can be used to check the output of commands in an image, as well as verify metadata and contents of the filesystem. Tests can be run either through a standalone binary, or through a Docker image. **Note: container-structure-test is not an officially supported Google project, and is currently in maintainence mode. Contributions are still welcome!** ## Installation ### OS X Install via [brew](https://brew.sh/): ```bash $ brew install container-structure-test ``` ```shell curl -LO https://github.com/GoogleContainerTools/container-structure-test/releases/latest/download/container-structure-test-darwin-arm64 && chmod +x container-structure-test-darwin-arm64 && sudo mv container-structure-test-darwin-arm64 /usr/local/bin/container-structure-test ``` ### Linux ```shell curl -LO https://github.com/GoogleContainerTools/container-structure-test/releases/latest/download/container-structure-test-linux-amd64 && chmod +x container-structure-test-linux-amd64 && sudo mv container-structure-test-linux-amd64 /usr/local/bin/container-structure-test ``` If you want to avoid using sudo: ```shell curl -LO https://github.com/GoogleContainerTools/container-structure-test/releases/latest/download/container-structure-test-linux-amd64 && chmod +x container-structure-test-linux-amd64 && mkdir -p $HOME/bin && export PATH=$PATH:$HOME/bin && mv container-structure-test-linux-amd64 $HOME/bin/container-structure-test ``` > [!warning] > Container builds are currently not updated with new releases Additionally, a container image for running tests through Google Cloud Builder can be found at `gcr.io/gcp-runtimes/container-structure-test:latest`. ## Setup To use container structure tests to validate your containers, you'll need the following: - The container structure test binary or docker image - A container image to test against - A test `.yaml` or `.json` file with user defined structure tests to run inside of the specified container image Note that the test framework looks for the provided image in the local Docker daemon (if it is not provided as a tar). The `--pull` flag can optionally be provided to force a pull of a remote image before running the tests. ## Example Run An example run of the test framework: ```shell container-structure-test test --image gcr.io/registry/image:latest \ --config config.yaml ``` Tests within this framework are specified through a YAML or JSON config file, which is provided to the test driver via a CLI flag. Multiple config files may be specified in a single test run. The config file will be loaded in by the test driver, which will execute the tests in order. Within this config file, four types of tests can be written: - Command Tests (testing output/error of a specific command issued) - File Existence Tests (making sure a file is, or isn't, present in the file system of the image) - File Content Tests (making sure files in the file system of the image contain, or do not contain, specific contents) - Metadata Test, *singular* (making sure certain container metadata is correct) ## Command Tests Command tests ensure that certain commands run properly in the target image. Regexes can be used to check for expected or excluded strings in both `stdout` and `stderr`. Additionally, any number of flags can be passed to the argument as normal. Each command in the setup section will run in a separate container and then commits a modified image to be the new base image for the test run. #### Supported Fields: **NOTE: `schemaVersion` must be specified in all container-structure-test yamls. The current version is `2.0.0`.** - Name (`string`, **required**): The name of the test - Setup (`[][]string`, *optional*): A list of commands (each with optional flags) to run before the actual command under test. - Teardown (`[][]string`, *optional*): A list of commands (each with optional flags) to run after the actual command under test. - Command (`string`, **required**): The command to run in the test. - Args (`[]string`, *optional*): The arguments to pass to the command. - EnvVars (`[]EnvVar`, *optional*): A list of environment variables to set for the individual test. See the **Environment Variables** section for more info. - Expected Output (`[]string`, *optional*): List of regexes that should match the stdout from running the command. - Excluded Output (`[]string`, *optional*): List of regexes that should **not** match the stdout from running the command. - Expected Error (`[]string`, *optional*): List of regexes that should match the stderr from running the command. - Excluded Error (`[]string`, *optional*): List of regexes that should **not** match the stderr from running the command. - Exit Code (`int`, *optional*): Exit code that the command should exit with. Example: ```yaml commandTests: - name: "gunicorn flask" setup: [["virtualenv", "/env"], ["pip", "install", "gunicorn", "flask"]] command: "which" args: ["gunicorn"] expectedOutput: ["/env/bin/gunicorn"] - name: "apt-get upgrade" command: "apt-get" args: ["-qqs", "upgrade"] excludedOutput: [".*Inst.*Security.* | .*Security.*Inst.*"] excludedError: [".*Inst.*Security.* | .*Security.*Inst.*"] ``` Depending on your command the argument section can get quite long. Thus, you can make use of YAML's list style option for separation of arguments and the literal style option to preserve newlines like so: ```shell commandTests: - name: "say hello world" command: "bash" args: - -c - | echo hello && echo world ``` ### Image Entrypoint To avoid unexpected behavior and output when running commands in the containers, **all entrypoints are overwritten by default.** If your entrypoint is necessary for the structure of your container, use the `setup` field to call any scripts or commands manually before running the tests. ```yaml commandTests: ... setup: [["my_image_entrypoint.sh"]] ... ``` ### Intermediate Artifacts Each command test run creates either a container (with the `docker` driver) or tar artifact (with the `tar` driver). By default, these are deleted after the test run finishes, but the `--save` flag can optionally be passed to keep these around. This would normally be used for debugging purposes. ## File Existence Tests File existence tests check to make sure a specific file (or directory) exist within the file system of the image. No contents of the files or directories are checked. These tests can also be used to ensure a file or directory is **not** present in the file system. #### Supported Fields: - Name (`string`, **required**): The name of the test - Path (`string`, **required**): Path to the file or directory under test - ShouldExist (`boolean`, **required**): Whether or not the specified file or directory should exist in the file system - Permissions (`string`, *optional*): The expected Unix permission string (e.g. drwxrwxrwx) of the files or directory. - Uid (`int`, *optional*): The expected Unix user ID of the owner of the file or directory. - Gid (`int`, *optional*): The expected Unix group ID of the owner of the file or directory. - IsExecutableBy (`string`, *optional*): Checks if file is executable by a given user. One of `owner`, `group`, `other` or `any` Example: ```yaml fileExistenceTests: - name: 'Root' path: '/' shouldExist: true permissions: '-rw-r--r--' uid: 1000 gid: 1000 isExecutableBy: 'group' ``` ## File Content Tests File content tests open a file on the file system and check its contents. These tests assume the specified file **is a file**, and that it **exists** (if unsure about either or these criteria, see the above **File Existence Tests** section). Regexes can again be used to check for expected or excluded content in the specified file. #### Supported Fields: - Name (`string`, **required**): The name of the test - Path (`string`, **required**): Path to the file under test - ExpectedContents (`string[]`, *optional*): List of regexes that should match the contents of the file - ExcludedContents (`string[]`, *optional*): List of regexes that should **not** match the contents of the file Example: ```yaml fileContentTests: - name: 'Debian Sources' path: '/etc/apt/sources.list' expectedContents: ['.*httpredir\.debian\.org.*'] excludedContents: ['.*gce_debian_mirror.*'] ``` ## Metadata Test The Metadata test ensures the container is configured correctly. All of these checks are optional. #### Supported Fields: - EnvVars (`[]EnvVar`): A list of environment variable key/value pairs that should be set in the container. isRegex (*optional*) interpretes the value as regex. - UnboundEnvVars (`[]EnvVar`): A list of environment variable keys that should **NOT** be set in the container. - Labels (`[]Label`): A list of image labels key/value pairs that should be set on the container. isRegex (*optional*) interpretes the value as regex. - Entrypoint (`[]string`): The entrypoint of the container. - Cmd (`[]string`): The CMD specified in the container. - Exposed Ports (`[]string`): The ports exposed in the container. - Unexposed Ports (`[]string`): The ports **NOT** exposed in the container. - Volumes (`[]string`): The volumes exposed in the container. - UnmountedVolumes (`[]string`): The volumes **NOT** exposed in the container. - Workdir (`string`): The default working directory of the container. - User (`user`): The default user of the container. Example: ```yaml metadataTest: envVars: - key: foo value: baz labels: - key: 'com.example.vendor' value: 'ACME Incorporated' - key: 'build-date' value: '^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}\.\d{6}$' isRegex: true exposedPorts: ["8080", "2345"] volumes: ["/test"] entrypoint: [] cmd: ["/bin/bash"] workdir: "/app" user: "luke" ``` ## License Tests License tests check a list of copyright files and makes sure all licenses are allowed at Google. By default it will look at where Debian lists all copyright files, but can also look at an arbitrary list of files. #### Supported Fields: - Debian (`bool`, **required**): If the image is based on Debian, check where Debian lists all licenses. - Files (`string[]`, *optional*): A list of other files to check. Example: ```yaml licenseTests: - debian: true files: ["/foo/bar", "/baz/bat"] ``` ### Environment Variables A list of environment variables can optionally be specified as part of the test setup. They can either be set up globally (for all test runs), or test-local as part of individual command test runs (see the **Command Tests** section above). Each environment variable is specified as a key-value pair. Unix-style environment variable substitution is supported. To specify, add a section like this to your config: ```yaml globalEnvVars: - key: "VIRTUAL_ENV" value: "/env" - key: "PATH" value: "/env/bin:$PATH" ``` ### Additional Options The following fields are used to control various options and flags that may be desirable to set for the running container used to perform a structure test against an image. This allows an image author to validate certain runtime behavior that cannot be modified in the image-under-test such as running a container with an alternative user/UID or mounting a volume. Note that these options are currently only supported with the `docker` driver. The following list of options are currently supported: ```yaml containerRunOptions: user: "root" # set the --user/-u flag privileged: true # set the --privileged flag (default: false) allocateTty: true # set the --tty flag (default: false) envFile: path/to/.env # load environment variables from file and pass to container (equivalent to --env-file) envVars: # if not empty, read each envVar from the environment and pass to test (equivalent to --env/e) - SECRET_KEY_FOO - OTHER_SECRET_BAR capabilities: # Add list of Linux capabilities (--cap-add) - NET_BIND_SERVICE bindMounts: # Bind mount a volume (--volume, -v) - /etc/example/dir:/etc/dir ``` ## Running Tests On [Google Cloud Build](https://cloud.google.com/cloud-build/docs/) This tool is released as a builder image, tagged as `gcr.io/gcp-runtimes/container-structure-test`, so you can specify tests in your `cloudbuild.yaml`: ```yaml steps: # Build an image. - name: 'gcr.io/cloud-builders/docker' args: ['build', '-t', 'gcr.io/$PROJECT_ID/image', '.'] # Test the image. - name: 'gcr.io/gcp-runtimes/container-structure-test' args: ['test', '--image', 'gcr.io/$PROJECT_ID/image', '--config', 'test_config.yaml'] # Push the image. images: ['gcr.io/$PROJECT_ID/image'] ``` ## Running File Tests Without Docker Container images can be represented in multiple formats, and the Docker image is just one of them. At their core, images are just a series of layers, each of which is a tarball, and so can be interacted with without a working Docker daemon. While running command tests currently requires a functioning Docker daemon on the host machine, File Existence/Content tests do not. This can be useful when dealing with images which have been `docker export`ed or saved in a different image format than the Docker format, or when you're simply trying to run structure tests in an environment where Docker can't be installed. To run tests without using a Docker daemon, users can specify a different "driver" to use in the tests, with the `--driver` flag. An example test run with a different driver looks like: ```shell container-structure-test test --driver tar --image gcr.io/registry/image:latest \ --config config.yaml ``` The currently supported drivers in the framework are: - `docker`: the default driver. Supports all tests, and uses the Docker daemon on the host to run them. You can set the runtime to use (by example `runsc` to run with gVisor) using `--runtime` flag. - `tar`: a tar driver, which extracts an image filesystem to wherever tests are running, and runs file/metadata tests against it. Does *not* support command tests. ### Running Structure Tests Through Bazel Structure tests can also be run through `bazel`. With Bazel 6 and bzlmod, just see https://registry.bazel.build/modules/container_structure_test. Otherwise, load the rule and its dependencies in your `WORKSPACE`, see bazel/test/WORKSPACE.bazel in this repo. Load the rule definition in your BUILD file and declare a `container_structure_test` target, passing in your image and config file as parameters: ```bazel load("@container_structure_test//:defs.bzl", "container_structure_test") container_structure_test( name = "hello_test", configs = ["testdata/hello.yaml"], image = ":hello", ) ``` ### Flags: `container-structure-test test -h` ``` -c, --config stringArray test config files --default-image-tag string default image tag to used when loading images to the daemon. required when --image-from-oci-layout refers to a oci layout lacking the reference annotation. -d, --driver string driver to use when running tests (default "docker") -f, --force force run of host driver (without user prompt) -h, --help help for test -i, --image string path to test image --image-from-oci-layout string path to the oci layout to test against --metadata string path to image metadata file --no-color no color in the output -o, --output string output format for the test report (available format: text, json, junit) (default "text") --platform string Set platform if host is multi-platform capable (default "linux/amd64") --pull force a pull of the image before running tests -q, --quiet flag to suppress output --runtime string runtime to use with docker driver --save preserve created containers after test run --test-report string generate test report and write it to specified file (supported format: json, junit; default: json) ``` See this [example repo](https://github.com/nkubala/structure-test-examples) for a full working example. ## Output formats Reports are generated using one of the following output formats: `text`, `json` or `junit`. Formats like `json` and `junit` can also be used to write a report to a specified file using the `--test-report`. ### Output samples #### Text ```text ==================================== ====== Test file: config.yaml ====== ==================================== === RUN: File Existence Test: whoami --- PASS duration: 0s === RUN: Metadata Test --- PASS duration: 0s ===================================== ============== RESULTS ============== ===================================== Passes: 2 Failures: 0 Duration: 0s Total tests: 2 PASS ``` #### JSON The following sample has been formatted. ```json { "Pass": 2, "Fail": 0, "Total": 2, "Duration": 0, "Results": [ { "Name": "File Existence Test: whoami", "Pass": true, "Duration": 0 }, { "Name": "Metadata Test", "Pass": true, "Duration": 0 } ] } ``` ### JUnit The following sample has been formatted. ```xml ```