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https://github.com/NixOS/nixpkgs.git
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b7fd022677
We were setting the systemd pre-start script through the systemd.services.<name>.preStart NixOS option. This option uses a string containing the pre-start script as input. In some scenarios, you want to extend this script to perform some additional actions before launching a container. At the moment, your only option is to mkForce the pre-start string and rewrite a preStart script from scratch. Potentially vendoring the Nixpkgs pre-start script in your custom pre-start script. (you can also create a new service unit in charge of running the custom pre-start and create a dependency link between the units, but that's also sub-optimal). The systemd.services.<name>.serviceConfig.ExecStartPre NixOS option gives us a better way to extend a pre-start script. Instead of being a simple script, this option can be a list of scripts. The NixOS module system then merges the multiple list declarations instead of overriding them. Meaning that if we use this ExecStartPre option, we can trivially extend the exec-start script: just add the custom script in the systemd service override and you're done. ExecStartPre behaves a tiny bit differently from preStart. Instead of expecting a string containing a script, it expects a path pointing to a script. We take advantage of this API change to check the pre-start script with shellCheck via the pkgs.writeShellApplication function.
367 lines
13 KiB
Nix
367 lines
13 KiB
Nix
{ config, options, lib, pkgs, ... }:
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with lib;
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let
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cfg = config.virtualisation.oci-containers;
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proxy_env = config.networking.proxy.envVars;
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defaultBackend = options.virtualisation.oci-containers.backend.default;
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containerOptions =
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{ ... }: {
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options = {
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image = mkOption {
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type = with types; str;
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description = lib.mdDoc "OCI image to run.";
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example = "library/hello-world";
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};
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imageFile = mkOption {
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type = with types; nullOr package;
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default = null;
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description = lib.mdDoc ''
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Path to an image file to load before running the image. This can
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be used to bypass pulling the image from the registry.
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The `image` attribute must match the name and
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tag of the image contained in this file, as they will be used to
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run the container with that image. If they do not match, the
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image will be pulled from the registry as usual.
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'';
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example = literalExpression "pkgs.dockerTools.buildImage {...};";
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};
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login = {
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username = mkOption {
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type = with types; nullOr str;
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default = null;
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description = lib.mdDoc "Username for login.";
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};
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passwordFile = mkOption {
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type = with types; nullOr str;
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default = null;
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description = lib.mdDoc "Path to file containing password.";
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example = "/etc/nixos/dockerhub-password.txt";
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};
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registry = mkOption {
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type = with types; nullOr str;
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default = null;
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description = lib.mdDoc "Registry where to login to.";
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example = "https://docker.pkg.github.com";
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};
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};
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cmd = mkOption {
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type = with types; listOf str;
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default = [];
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description = lib.mdDoc "Commandline arguments to pass to the image's entrypoint.";
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example = literalExpression ''
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["--port=9000"]
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'';
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};
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entrypoint = mkOption {
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type = with types; nullOr str;
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description = lib.mdDoc "Override the default entrypoint of the image.";
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default = null;
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example = "/bin/my-app";
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};
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environment = mkOption {
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type = with types; attrsOf str;
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default = {};
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description = lib.mdDoc "Environment variables to set for this container.";
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example = literalExpression ''
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{
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DATABASE_HOST = "db.example.com";
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DATABASE_PORT = "3306";
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}
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'';
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};
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environmentFiles = mkOption {
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type = with types; listOf path;
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default = [];
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description = lib.mdDoc "Environment files for this container.";
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example = literalExpression ''
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[
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/path/to/.env
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/path/to/.env.secret
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]
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'';
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};
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log-driver = mkOption {
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type = types.str;
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default = "journald";
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description = lib.mdDoc ''
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Logging driver for the container. The default of
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`"journald"` means that the container's logs will be
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handled as part of the systemd unit.
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For more details and a full list of logging drivers, refer to respective backends documentation.
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For Docker:
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[Docker engine documentation](https://docs.docker.com/engine/reference/run/#logging-drivers---log-driver)
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For Podman:
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Refer to the docker-run(1) man page.
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'';
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};
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ports = mkOption {
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type = with types; listOf str;
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default = [];
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description = lib.mdDoc ''
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Network ports to publish from the container to the outer host.
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Valid formats:
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- `<ip>:<hostPort>:<containerPort>`
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- `<ip>::<containerPort>`
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- `<hostPort>:<containerPort>`
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- `<containerPort>`
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Both `hostPort` and `containerPort` can be specified as a range of
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ports. When specifying ranges for both, the number of container
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ports in the range must match the number of host ports in the
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range. Example: `1234-1236:1234-1236/tcp`
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When specifying a range for `hostPort` only, the `containerPort`
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must *not* be a range. In this case, the container port is published
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somewhere within the specified `hostPort` range.
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Example: `1234-1236:1234/tcp`
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Refer to the
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[Docker engine documentation](https://docs.docker.com/engine/reference/run/#expose-incoming-ports) for full details.
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'';
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example = literalExpression ''
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[
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"8080:9000"
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]
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'';
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};
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user = mkOption {
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type = with types; nullOr str;
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default = null;
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description = lib.mdDoc ''
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Override the username or UID (and optionally groupname or GID) used
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in the container.
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'';
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example = "nobody:nogroup";
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};
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volumes = mkOption {
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type = with types; listOf str;
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default = [];
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description = lib.mdDoc ''
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List of volumes to attach to this container.
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Note that this is a list of `"src:dst"` strings to
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allow for `src` to refer to `/nix/store` paths, which
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would be difficult with an attribute set. There are
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also a variety of mount options available as a third
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field; please refer to the
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[docker engine documentation](https://docs.docker.com/engine/reference/run/#volume-shared-filesystems) for details.
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'';
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example = literalExpression ''
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[
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"volume_name:/path/inside/container"
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"/path/on/host:/path/inside/container"
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]
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'';
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};
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workdir = mkOption {
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type = with types; nullOr str;
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default = null;
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description = lib.mdDoc "Override the default working directory for the container.";
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example = "/var/lib/hello_world";
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};
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dependsOn = mkOption {
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type = with types; listOf str;
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default = [];
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description = lib.mdDoc ''
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Define which other containers this one depends on. They will be added to both After and Requires for the unit.
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Use the same name as the attribute under `virtualisation.oci-containers.containers`.
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'';
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example = literalExpression ''
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virtualisation.oci-containers.containers = {
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node1 = {};
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node2 = {
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dependsOn = [ "node1" ];
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}
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}
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'';
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};
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extraOptions = mkOption {
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type = with types; listOf str;
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default = [];
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description = lib.mdDoc "Extra options for {command}`${defaultBackend} run`.";
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example = literalExpression ''
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["--network=host"]
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'';
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};
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autoStart = mkOption {
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type = types.bool;
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default = true;
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description = lib.mdDoc ''
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When enabled, the container is automatically started on boot.
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If this option is set to false, the container has to be started on-demand via its service.
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'';
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};
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};
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};
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isValidLogin = login: login.username != null && login.passwordFile != null && login.registry != null;
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mkService = name: container: let
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dependsOn = map (x: "${cfg.backend}-${x}.service") container.dependsOn;
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escapedName = escapeShellArg name;
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preStartScript = pkgs.writeShellApplication {
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name = "pre-start";
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runtimeInputs = [ ];
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text = ''
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${cfg.backend} rm -f ${name} || true
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${optionalString (isValidLogin container.login) ''
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cat ${container.login.passwordFile} | \
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${cfg.backend} login \
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${container.login.registry} \
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--username ${container.login.username} \
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--password-stdin
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''}
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${optionalString (container.imageFile != null) ''
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${cfg.backend} load -i ${container.imageFile}
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''}
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${optionalString (cfg.backend == "podman") ''
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rm -f /run/podman-${escapedName}.ctr-id
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''}
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'';
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};
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in {
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wantedBy = [] ++ optional (container.autoStart) "multi-user.target";
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after = lib.optionals (cfg.backend == "docker") [ "docker.service" "docker.socket" ]
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# if imageFile is not set, the service needs the network to download the image from the registry
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++ lib.optionals (container.imageFile == null) [ "network-online.target" ]
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++ dependsOn;
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requires = dependsOn;
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environment = proxy_env;
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path =
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if cfg.backend == "docker" then [ config.virtualisation.docker.package ]
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else if cfg.backend == "podman" then [ config.virtualisation.podman.package ]
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else throw "Unhandled backend: ${cfg.backend}";
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script = concatStringsSep " \\\n " ([
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"exec ${cfg.backend} run"
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"--rm"
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"--name=${escapedName}"
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"--log-driver=${container.log-driver}"
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] ++ optional (container.entrypoint != null)
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"--entrypoint=${escapeShellArg container.entrypoint}"
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++ lib.optionals (cfg.backend == "podman") [
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"--cidfile=/run/podman-${escapedName}.ctr-id"
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"--cgroups=no-conmon"
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"--sdnotify=conmon"
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"-d"
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"--replace"
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] ++ (mapAttrsToList (k: v: "-e ${escapeShellArg k}=${escapeShellArg v}") container.environment)
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++ map (f: "--env-file ${escapeShellArg f}") container.environmentFiles
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++ map (p: "-p ${escapeShellArg p}") container.ports
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++ optional (container.user != null) "-u ${escapeShellArg container.user}"
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++ map (v: "-v ${escapeShellArg v}") container.volumes
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++ optional (container.workdir != null) "-w ${escapeShellArg container.workdir}"
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++ map escapeShellArg container.extraOptions
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++ [container.image]
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++ map escapeShellArg container.cmd
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);
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preStop = if cfg.backend == "podman"
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then "[ $SERVICE_RESULT = success ] || podman stop --ignore --cidfile=/run/podman-${escapedName}.ctr-id"
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else "[ $SERVICE_RESULT = success ] || ${cfg.backend} stop ${name}";
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postStop = if cfg.backend == "podman"
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then "podman rm -f --ignore --cidfile=/run/podman-${escapedName}.ctr-id"
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else "${cfg.backend} rm -f ${name} || true";
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serviceConfig = {
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### There is no generalized way of supporting `reload` for docker
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### containers. Some containers may respond well to SIGHUP sent to their
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### init process, but it is not guaranteed; some apps have other reload
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### mechanisms, some don't have a reload signal at all, and some docker
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### images just have broken signal handling. The best compromise in this
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### case is probably to leave ExecReload undefined, so `systemctl reload`
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### will at least result in an error instead of potentially undefined
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### behaviour.
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###
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### Advanced users can still override this part of the unit to implement
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### a custom reload handler, since the result of all this is a normal
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### systemd service from the perspective of the NixOS module system.
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###
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# ExecReload = ...;
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###
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ExecStartPre = [ "${preStartScript}/bin/pre-start" ];
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TimeoutStartSec = 0;
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TimeoutStopSec = 120;
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Restart = "always";
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} // optionalAttrs (cfg.backend == "podman") {
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Environment="PODMAN_SYSTEMD_UNIT=podman-${name}.service";
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Type="notify";
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NotifyAccess="all";
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};
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};
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in {
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imports = [
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(
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lib.mkChangedOptionModule
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[ "docker-containers" ]
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[ "virtualisation" "oci-containers" ]
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(oldcfg: {
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backend = "docker";
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containers = lib.mapAttrs (n: v: builtins.removeAttrs (v // {
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extraOptions = v.extraDockerOptions or [];
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}) [ "extraDockerOptions" ]) oldcfg.docker-containers;
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})
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)
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];
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options.virtualisation.oci-containers = {
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backend = mkOption {
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type = types.enum [ "podman" "docker" ];
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default = if versionAtLeast config.system.stateVersion "22.05" then "podman" else "docker";
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description = lib.mdDoc "The underlying Docker implementation to use.";
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};
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containers = mkOption {
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default = {};
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type = types.attrsOf (types.submodule containerOptions);
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description = lib.mdDoc "OCI (Docker) containers to run as systemd services.";
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};
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};
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config = lib.mkIf (cfg.containers != {}) (lib.mkMerge [
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{
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systemd.services = mapAttrs' (n: v: nameValuePair "${cfg.backend}-${n}" (mkService n v)) cfg.containers;
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}
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(lib.mkIf (cfg.backend == "podman") {
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virtualisation.podman.enable = true;
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})
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(lib.mkIf (cfg.backend == "docker") {
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virtualisation.docker.enable = true;
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})
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]);
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}
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