Improve container image startup parameters

.docker/entrypoint.sh

@@ -14,4 +14,4 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-java -jar /opt/copybara/copybara_deploy.jar $COPYBARA_OPTIONS $COPYBARA_SUBCOMMAND $COPYBARA_CONFIG $COPYBARA_WORKFLOW $COPYBARA_SOURCEREF
+exec java -jar /opt/copybara/copybara_deploy.jar "$@"

Dockerfile

@@ -23,9 +23,11 @@ RUN go install github.com/bazelbuild/buildtools/buildifier@latest
 FROM openjdk:11-jre-slim
 COPY --from=build /home/ubuntu/bazel-bin/java/com/google/copybara/copybara_deploy.jar /opt/copybara/
 COPY --from=buildtools /go/bin/buildozer /go/bin/buildifier /usr/bin/
-COPY .docker/entrypoint.sh /usr/local/bin/copybara
-RUN chmod +x /usr/local/bin/copybara
+COPY .docker/entrypoint.sh /entrypoint
+RUN chmod +x /entrypoint
 RUN apt-get update && apt-get install -y \
         git \
     && rm -rf /var/lib/apt/lists/*
 WORKDIR /usr/src/app
+ENTRYPOINT ["/entrypoint"]
+CMD ["migrate", "copy.bara.sky"]

README.md

@@ -167,27 +167,15 @@ Once this has finished building, you can run the image like so from the root of
 the code you are trying to use Copybara on:
 
 ```sh
-docker run -it -v "$(pwd)":/usr/src/app copybara copybara
+docker run -it -v "$(pwd)":/usr/src/app copybara
 ```
 
-A few environment variables exist to allow you to change how you run copybara:
-* `COPYBARA_CONFIG=copy.bara.sky`
-  * allows you to specify a path to a config file, defaults to root `copy.bara.sky`
-* `COPYBARA_SUBCOMMAND=migrate`
-  * allows you to change the command run, defaults to `migrate`
-* `COPYBARA_OPTIONS=''`
-  * allows you to specify options for copybara, defaults to none
-* `COPYBARA_WORKFLOW=default`
-  * allows you to specify the workflow to run, defaults to `default`
-* `COPYBARA_SOURCEREF=''`
-  * allows you to specify the sourceref, defaults to none
-
 ```sh
 docker run \
     -e COPYBARA_CONFIG='other.config.sky' \
     -e COPYBARA_SUBCOMMAND='validate' \
     -v "$(pwd)":/usr/src/app \
-    -it copybara copybara
+    -it copybara
 ```
 
 #### Git Config and Credentials
@@ -200,7 +188,7 @@ docker run \
     -v ~/.ssh:/root/.ssh \
     -v ~/.gitconfig:/root/.gitconfig \
     -v "$(pwd)":/usr/src/app \
-    -it copybara copybara
+    -it copybara
 ```
 
 ## Documentation