Enabling sbt plugins from the command line in any sbt project

demo.sh

% sbtx dependencyGraph
... blah blah ...
[info] *** Welcome to the sbt build definition for Scala! ***
[info] Check README.md for more information.
[error] Not a valid command: dependencyGraph
[error] Not a valid project ID: dependencyGraph


% sbtx -Dplugins=graph dependencyGraph
... blah blah ...
[info]                                    +---------------+
[info]                                    |    scalap     |
[info]                                    |org.scala-lang |
[info]                                    |2.12.0-SNAPSHOT|
[info]                                    +---------------+
[info]                                             |
[info]                                             v
[info]                                   +------------------+
[info]                                   |scala-compiler [S]|
[info]                                   |  org.scala-lang  |
[info]                                   | 2.12.0-SNAPSHOT  |
[info]                                   +------------------+
[info]                                       |   |   |   |
[info]                      ------------------   |   |   --------------------------
[info]                      |                    |   |                            |
[info]                      v                    |   |                            |
[info]              +--------------+             |   |                            |
[info]              |     ant      |             |   |                            |
[info]              |org.apache.ant|             |   |                            |
[info]              |    1.9.4     |             |   |                            |
[info]              +--------------+             |   |                            |
[info]                      |     ----------------   |                            |
[info]          -------------     |                  |                            |
[info]          |                 |                  |                            |
[info]          v                 v                  v                            v
[info]  +--------------+ +-----------------+ +----------------------+ +----------------------+
[info]  | ant-launcher | |scala-reflect [S]| |      scala-asm       | | scala-xml_2.12.0-M5  |
[info]  |org.apache.ant| | org.scala-lang  | |org.scala-lang.modules| |org.scala-lang.modules|
[info]  |    1.9.4     | | 2.12.0-SNAPSHOT | |    5.1.0-scala-1     | |        1.0.5         |
[info]  +--------------+ +-----------------+ +----------------------+ +----------------------+


% sbtx -Dplugins=graph,coursier dependencyGraph
... blah blah ...
https://repo1.maven.org/maven2/com/typesafe/mima-reporter_2.10/0.1.8/mima-reporter_2.10-0.1.8.pom
  100.0% [##########] 2.3 KiB (3.2 KiB / s)
https://repo1.maven.org/maven2/biz/aQute/bnd/biz.aQute.bnd/2.4.1/biz.aQute.bnd-2.4.1.pom
  100.0% [##########] 1.5 KiB (1.7 KiB / s)
https://repo1.maven.org/maven2/org/pantsbuild/jarjar/1.6.3/jarjar-1.6.3.pom
  100.0% [##########] 2.1 KiB (2.1 KiB / s)
https://repo.scala-sbt.org/scalasbt/sbt-plugin-releases/org.apache.ant/ant/1.9.6/ivys/ivy.xml.sha1
         [          ] 0 B (0 B / s)
https://repo.scala-sbt.org/scalasbt/sbt-plugin-releases/org.apache.ant/ant/1.9.6/ivys/ivy.xml
         [          ] 0 B (0 B / s)
https://repo.scala-sbt.org/scalasbt/sbt-plugin-releases/org.scala-lang/scala-swing/2.10.6/ivys/ivy.x…
         [          ] 0 B (0 B / s)
https://repo.scala-sbt.org/scalasbt/sbt-plugin-releases/org.scala-lang/scala-actors/2.10.6/ivys/ivy.…
         [          ] 0 B (0 B / s)

plugins.sbt

// This file is at $HOME/.sbt/0.13/plugins/plugins.sbt
lazy val isEnabled: Set[String] = sys.props.getOrElse("plugins", "").split(",").map(_.trim).toSet

def maybeEnable(pair: (String, ModuleID)): Seq[Setting[_]] =
  if (isEnabled(pair._1)) addSbtPlugin(pair._2) else Seq()

Seq[(String, ModuleID)](
  "aether"    -> "no.arktekk.sbt"     %  "aether-deploy"           % "0.17",
  "coursier"  -> "io.get-coursier"    %  "sbt-coursier"            % "1.0.0-M12",
  "graph"     -> "net.virtual-void"   %  "sbt-dependency-graph"    % "0.8.2",
  "impact"    -> "com.updateimpact"   %  "updateimpact-sbt-plugin" % "2.1.1",
  "jmh"       -> "pl.project13.scala" %  "sbt-jmh"                 % "0.2.10",
  "pgp"       -> "com.jsuereth"       %  "sbt-pgp"                 % "1.0.0",
  "psp"       -> "org.improving"      %  "sbt-psp"                 % "61521d8859be70ba566f5e776d6e68f06d062cec",
  "scalafmt"  -> "com.geirsson"       %% "sbt-scalafmt"            % "0.2.5",
  "scoverage" -> "org.scoverage"      %  "sbt-scoverage"           % "1.3.5",
  "sonatype"  -> "org.xerial.sbt"     %  "sbt-sonatype"            % "1.1",
  "unused"    -> "com.hanhuy.sbt"     %  "sbt-unused"              % "0.1",
  "updates"   -> "com.timushev.sbt"   %  "sbt-updates"             % "0.2.0"
).flatMap(maybeEnable)