Merge pull request #1027 from praekelt/feature/issue-1027-docker-entr…

…ypoint

Add a Docker entrypoint script for easier process starting

docker/Dockerfile

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+FROM praekeltfoundation/python-base
+MAINTAINER Praekelt Foundation <dev@praekeltfoundation.org>
+
+ENV VUMI_VERSION "0.6.2"
+RUN pip install vumi==$VUMI_VERSION
+
+COPY ./vumi-entrypoint.sh /app/vumi-entrypoint.sh
+WORKDIR /app
+
+ENTRYPOINT ["eval-args.sh", "dinit", "/app/vumi-entrypoint.sh"]
+CMD []

docker/README.md

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+# Vumi Docker image
+Documentation for Vumi is available online at http://vumi.readthedocs.org/ and in the `docs` directory of the repository.
+
+## Usage
+The Docker image provides an entrypoint for Vumi that allows the configuration of Vumi workers via environment variables.
+
+### Environment variables
+#### Basic options:
+* `TWISTD_COMMAND`: the command to pass to `twistd` (default: `vumi_worker`)
+* `WORKER_CLASS`: the Vumi worker class to use
+* `CONFIG_FILE`: the path to the YAML configuration file to use
+* `SENTRY_DSN`: the Sentry DSN to use for reporting errors
+
+#### AMQP options:
+AMQP/RabbitMQ options can be set via environment variables. At a minimum, the `AMQP_HOST` variable must be set or else none of the other AMQP variables will take effect.
+* `AMQP_HOST`: the address for the RabbitMQ server
+* `AMQP_PORT`: the port for the RabbitMQ server (default: `5672`)
+* `AMQP_VHOST`: the name of the RabbitMQ vhost to use (default: `/`)
+* `AMQP_USERNAME`: the username to authenticate with RabbitMQ (default: `guest`)
+* `AMQP_PASSWORD`: the password to authenticate with RabbitMQ (default: `guest`)
+
+#### `VUMI_OPT_` options
+Additional options can be passed to Vumi via variables that start with `VUMI_OPT_`. These variables will be converted to `--set-option` CLI options. For example, the environment variable `VUMI_OPT_BUCKET=1` will result in the CLI option `--set-option=bucket:1`.
+
+### `/app` directory
+The `/app` directory is created and set as the current working directory. This is the directory where the files (e.g. YAML config) for your application should be put.
+
+### Examples
+Running a built-in worker class without a config file:
+```shell
+docker run --rm -it \
+  -e WORKER_CLASS=vumi.blinkenlights.MetricTimeBucket \
+  -e AMQP_HOST=rabbitmq.service.consul \
+  -e VUMI_OPT_BUCKETS=3 \
+  -e VUMI_OPT_BUCKET_SIZE=10 \
+  praekeltfoundation/vumi
+```
+
+Dockerfile for an image with an external worker class and a config file:
+```dockerfile
+FROM praekeltfoundation/vumi
+RUN pip install vumi-http-api
+COPY ./my-config.yaml /app/my-config.yaml
+ENV WORKER_CLASS="vumi_http_api.VumiApiWorker" \
+    CONFIG_FILE="my-config.yaml" \
+    AMQP_HOST="rabbitmq.service.consul"
+EXPOSE 8000
+```
+
+Dockerfile for an image with custom arguments:
+```dockerfile
+FROM praekeltfoundation/vumi
+RUN pip install go-metrics-api
+COPY ./my-config.yaml /app/my-config.yaml
+ENV TWISTD_COMMAND="cyclone"
+EXPOSE 8000
+CMD ["--app", "go_metrics.server.MetricsApi", \
+     "--port", "8000", \
+     "--app-opts", "my-config.yaml"]
+```

docker/vumi-entrypoint.sh

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+#!/bin/bash -e
+
+TWISTD_COMMAND="${TWISTD_COMMAND:-vumi_worker}"
+
+WORKER_CLASS_OPT=""
+if [ -n "$WORKER_CLASS" ]; then
+  WORKER_CLASS_OPT="--worker-class $WORKER_CLASS"
+fi
+
+CONFIG_OPT=""
+if [ -n "$CONFIG_FILE" ]; then
+  CONFIG_OPT="--config $CONFIG_FILE"
+fi
+
+AMQP_OPTS=""
+if [ -n "$AMQP_HOST" ]; then
+  AMQP_OPTS="--hostname $AMQP_HOST \
+    --port ${AMQP_PORT:-5672} \
+    --vhost ${AMQP_VHOST:-/} \
+    --username ${AMQP_USERNAME:-guest} \
+    --password ${AMQP_PASSWORD:-guest}"
+fi
+
+SENTRY_OPT=""
+if [ -n "$SENTRY_DSN" ]; then
+  SENTRY_OPT="--sentry $SENTRY_DSN"
+fi
+
+SET_OPTS=$(env | grep ^VUMI_OPT_ | sed -e 's/^VUMI_OPT_//' -e 's/=/ /' | awk '{printf("%s=%s:%s ", "--set-option", tolower($1), $2);}')
+
+exec twistd --nodaemon \
+  $TWISTD_COMMAND \
+  $WORKER_CLASS_OPT \
+  $CONFIG_OPT \
+  $AMQP_OPTS \
+  $SENTRY_OPT \
+  $SET_OPTS \
+  "$@"