github.com/containers/libpod@v1.9.4-0.20220419124438-4284fd425507/README.md (about)

     1  ![PODMAN logo](logo/podman-logo-source.svg)
     2  
     3  # Library and tool for running OCI-based containers in Pods
     4  
     5  Libpod provides a library for applications looking to use the Container Pod concept,
     6  popularized by Kubernetes.  Libpod also contains the Pod Manager tool `(Podman)`. Podman manages pods, containers, container images, and container volumes.
     7  
     8  * [Latest Version: 1.8.2](https://github.com/containers/libpod/releases/latest)
     9  * [Continuous Integration:](contrib/cirrus/README.md) [![Build Status](https://api.cirrus-ci.com/github/containers/libpod.svg)](https://cirrus-ci.com/github/containers/libpod/master)
    10  * [GoDoc: ![GoDoc](https://godoc.org/github.com/containers/libpod/libpod?status.svg)](https://godoc.org/github.com/containers/libpod/libpod)
    11  * Automated continuous release downloads (including remote-client):
    12    * [Latest remote client for Windows](https://storage.googleapis.com/libpod-master-releases/podman-remote-latest-master-windows-amd64.msi)
    13    * [Latest remote client for MacOS](https://storage.googleapis.com/libpod-master-releases/podman-remote-latest-master-darwin-amd64.zip)
    14    * [Latest Snap package](https://snapcraft.io/podman)
    15  
    16  ## Overview and scope
    17  
    18  At a high level, the scope of libpod and Podman is the following:
    19  
    20  * Support multiple image formats including the OCI and Docker image formats.
    21  * Support for multiple means to download images including trust & image verification.
    22  * Container image management (managing image layers, overlay filesystems, etc).
    23  * Full management of container lifecycle.
    24  * Support for pods to manage groups of containers together.
    25  * Resource isolation of containers and pods.
    26  * Support for a Docker-compatible CLI interface through Podman.
    27  * Integration with CRI-O to share containers and backend code.
    28  
    29  This project tests all builds against each supported version of Fedora, the latest released version of Red Hat Enterprise Linux, and the latest Ubuntu Long Term Support release. The community has also reported success with other Linux flavors.
    30  
    31  ## Roadmap
    32  
    33  1. Integrate libpod into CRI-O to replace its existing container management backend
    34  1. Further work on the podman pod command
    35  1. Further improvements on rootless containers
    36  
    37  ## Communications
    38  
    39  If you think you've identified a security issue in the project, please *DO NOT* report the issue publicly via the Github issue tracker, mailing list, or IRC.
    40  Instead, send an email with as many details as possible to `security@lists.podman.io`. This is a private mailing list for the core maintainers.
    41  
    42  For general questions and discussion, please use the
    43  IRC `#podman` channel on `irc.freenode.net`.
    44  
    45  For discussions around issues/bugs and features, you can use the GitHub
    46  [issues](https://github.com/containers/libpod/issues)
    47  and
    48  [PRs](https://github.com/containers/libpod/pulls)
    49  tracking system.
    50  
    51  There is also a [mailing list](https://lists.podman.io/archives/) at `lists.podman.io`.
    52  You can subscribe by sending a message to `podman-join@lists.podman.io` with the subject `subscribe`.
    53  
    54  ## Rootless
    55  Podman can be easily run as a normal user, without requiring a setuid binary.
    56  When run without root, Podman containers use user namespaces to set root in the container to the user running Podman.
    57  Rootless Podman runs locked-down containers with no privileges that the user running the container does not have.
    58  Some of these restrictions can be lifted (via `--privileged`, for example), but rootless containers will never have more privileges than the user that launched them.
    59  If you run Podman as your user and mount in `/etc/passwd` from the host, you still won't be able to change it, since your user doesn't have permission to do so.
    60  
    61  Almost all normal Podman functionality is available, though there are some [shortcomings](https://github.com/containers/libpod/blob/master/rootless.md).
    62  Any recent Podman release should be able to run rootless without any additional configuration, though your operating system may require some additional configuration detailed in the [install guide](https://github.com/containers/libpod/blob/master/install.md).
    63  
    64  A little configuration by an administrator is required before rootless Podman can be used, the necessary setup is documented [here](https://github.com/containers/libpod/blob/master/docs/tutorials/rootless_tutorial.md).
    65  
    66  ## Out of scope
    67  
    68  * Specializing in signing and pushing images to various storage backends.
    69    See [Skopeo](https://github.com/containers/skopeo/) for those tasks.
    70  * Container runtimes daemons for working with the Kubernetes CRI interface.
    71    [CRI-O](https://github.com/cri-o/cri-o) specializes in that.
    72  * Supporting `docker-compose`.  We believe that Kubernetes is the defacto
    73    standard for composing Pods and for orchestrating containers, making
    74    Kubernetes YAML a defacto standard file format. Hence, Podman allows the
    75    creation and execution of Pods from a Kubernetes YAML file (see
    76    [podman-play-kube](https://github.com/containers/libpod/blob/master/docs/source/markdown/podman-play-kube.1.md)).
    77    Podman can also generate Kubernetes YAML based on a container or Pod (see
    78    [podman-generate-kube](https://github.com/containers/libpod/blob/master/docs/source/markdown/podman-generate-kube.1.md)),
    79    which allows for an easy transition from a local development environment
    80    to a production Kubernetes cluster. If Kubernetes does not fit your requirements,
    81    there are other third-party tools that support the docker-compose format such as
    82    [kompose](https://github.com/kubernetes/kompose/) and
    83    [podman-compose](https://github.com/muayyad-alsadi/podman-compose)
    84    that might be appropriate for your environment.
    85  
    86  ## OCI Projects Plans
    87  
    88  The plan is to use OCI projects and best of breed libraries for different aspects:
    89  - Runtime: [runc](https://github.com/opencontainers/runc) (or any OCI compliant runtime) and [OCI runtime tools](https://github.com/opencontainers/runtime-tools) to generate the spec
    90  - Images: Image management using [containers/image](https://github.com/containers/image)
    91  - Storage: Container and image storage is managed by [containers/storage](https://github.com/containers/storage)
    92  - Networking: Networking support through use of [CNI](https://github.com/containernetworking/cni)
    93  - Builds: Builds are supported via [Buildah](https://github.com/containers/buildah).
    94  - Conmon: [Conmon](https://github.com/containers/conmon) is a tool for monitoring OCI runtimes.
    95  
    96  ## Podman Information for Developers
    97  
    98  For blogs, release announcements and more, please checkout the [podman.io](https://podman.io) website!
    99  
   100  **[Installation notes](install.md)**
   101  Information on how to install Podman in your environment.
   102  
   103  **[OCI Hooks Support](pkg/hooks/README.md)**
   104  Information on how Podman configures [OCI Hooks][spec-hooks] to run when launching a container.
   105  
   106  **[Podman API](API.md)**
   107  Documentation on the Podman API using [Varlink](https://www.varlink.org/).
   108  
   109  **[Podman Commands](https://podman.readthedocs.io/en/latest/Commands.html)**
   110  A list of the Podman commands with links to their man pages and in many cases videos
   111  showing the commands in use.
   112  
   113  **[Podman Troubleshooting Guide](troubleshooting.md)**
   114  A list of common issues and solutions for Podman.
   115  
   116  **[Podman Usage Transfer](transfer.md)**
   117  Useful information for ops and dev transfer as it relates to infrastructure that utilizes Podman.  This page
   118  includes tables showing Docker commands and their Podman equivalent commands.
   119  
   120  **[Tutorials](docs/tutorials)**
   121  Tutorials on using Podman.
   122  
   123  **[Remote Client](https://github.com/containers/libpod/blob/master/docs/tutorials/remote_client.md)**
   124  A brief how-to on using the Podman remote-client.
   125  
   126  **[Basic Setup and Use of Podman in a Rootless environment](https://github.com/containers/libpod/blob/master/docs/tutorials/rootless_tutorial.md)**
   127  A tutorial showing the setup and configuration necessary to run Rootless Podman.
   128  
   129  **[Release Notes](RELEASE_NOTES.md)**
   130  Release notes for recent Podman versions
   131  
   132  **[Contributing](CONTRIBUTING.md)**
   133  Information about contributing to this project.
   134  
   135  [spec-hooks]: https://github.com/opencontainers/runtime-spec/blob/v2.0.1/config.md#posix-platform-hooks
   136  
   137  ## Buildah and Podman relationship
   138  
   139  Buildah and Podman are two complementary open-source projects that are
   140  available on most Linux platforms and both projects reside at
   141  [GitHub.com](https://github.com) with Buildah
   142  [here](https://github.com/containers/buildah) and Podman
   143  [here](https://github.com/containers/libpod).  Both, Buildah and Podman are
   144  command line tools that work on Open Container Initiative (OCI) images and
   145  containers.  The two projects differentiate in their specialization.
   146  
   147  Buildah specializes in building OCI images.  Buildah's commands replicate all
   148  of the commands that are found in a Dockerfile.  This allows building images
   149  with and without Dockerfiles while not requiring any root privileges.
   150  Buildah’s ultimate goal is to provide a lower-level coreutils interface to
   151  build images.  The flexibility of building images without Dockerfiles allows
   152  for the integration of other scripting languages into the build process.
   153  Buildah follows a simple fork-exec model and does not run as a daemon
   154  but it is based on a comprehensive API in golang, which can be vendored
   155  into other tools.
   156  
   157  Podman specializes in all of the commands and functions that help you to maintain and modify
   158  OCI images, such as pulling and tagging.  It also allows you to create, run, and maintain those containers
   159  created from those images.  For building container images via Dockerfiles, Podman uses Buildah's
   160  golang API and can be installed independently from Buildah.
   161  
   162  A major difference between Podman and Buildah is their concept of a container.  Podman
   163  allows users to create "traditional containers" where the intent of these containers is
   164  to be long lived.  While Buildah containers are really just created to allow content
   165  to be added back to the container image.  An easy way to think of it is the
   166  `buildah run` command emulates the RUN command in a Dockerfile while the `podman run`
   167  command emulates the `docker run` command in functionality.  Because of this and their underlying
   168  storage differences, you can not see Podman containers from within Buildah or vice versa.
   169  
   170  In short, Buildah is an efficient way to create OCI images while Podman allows
   171  you to manage and maintain those images and containers in a production environment using
   172  familiar container cli commands.  For more details, see the
   173  [Container Tools Guide](https://github.com/containers/buildah/tree/master/docs/containertools).