How do I install grails in a Docker image?

Question

I'm working on containerizing an existing application built on grails. I've been able to successfully build the project within a debian:stretch image (yes, I know that's old, but the project was originally built with old versions of just about everything) with gradle, maven, and default-jdk installed. However I'm unsure if that means I don't need grails. When I try grails --version from a command line prompt within the container it says "bash: grails: command not found".

There does not appear to be a separate package for grails that I can install using apt and all references seem to say to install grails via sdkman.

I'm not at all familiar with grails or groovy so I'm unsure of how to proceed. Any advice on how to install (or maybe verify installation?) of grails? If it's needed, how did the build succeed without it?

Answer 1

This is what we use in our environments:

docker-compose.yml

version: '3.7'

services:
  db:
    image: postgres:12.3
    environment:
      - POSTGRES_DB=databasename
      - POSTGRES_USER=postgres
      - POSTGRES_PASSWORD=postgres
    ports:
      - 5432:5432
    networks:
      - mynetwork

  backend:
    build:
      context: .
      target: development
    ports:
      - 8080:8080
      - 8083:8443
      - 5006:5005
    environment:
      - DB_HOST=db
      - DB_NAME=databasename
      - DB_PORT=5432
      - DB_USERNAME=postgres
      - DB_PASSWORD=postgres
    volumes:
      - grails-volume:/root/.m2
      - grails-volume:/root/.gradle
      - grails-volume:/root/.grails
      - ./grails-app:/app/grails-app
      - ./src:/app/src
      - ./version.txt:/version.txt
    entrypoint: ["sh", "-c", "./wait-for-it.sh db:5432 -t 30 -- grails run-app"]
    command: [""]
    depends_on:
      - db
    networks:
      - mynetwork

volumes:
  grails-volume:

networks:
  mynetwork:

Dockerfile:

# Image to start project and initialize dependencies.
FROM openjdk:8 AS initializer
ENV GRAILS_VERSION 4.0.3
# Install Grails
WORKDIR /usr/lib/jvm
RUN ls -l
RUN wget https://github.com/grails/grails-core/releases/download/v$GRAILS_VERSION/grails-$GRAILS_VERSION.zip && \
    unzip grails-$GRAILS_VERSION.zip && \
    rm -rf grails-$GRAILS_VERSION.zip && \
    ln -s grails-$GRAILS_VERSION grails
# Setup Grails path.
ENV GRAILS_HOME /usr/lib/jvm/grails
ENV PATH $GRAILS_HOME/bin:$PATH
ENV GRADLE_USER_HOME /app/.gradle
# Create minimal structure to trigger grails build with specified profile.
RUN mkdir /app \
    && mkdir /app/grails-app \
    && mkdir /app/grails-app/conf \
    && echo "grails.profile: rest-api" > /app/grails-app/conf/application.yml
# Set Workdir
WORKDIR /app
# Copy minimun files to trigger grails download of wrapper and dependencies.
COPY gradle.properties build.gradle /app/
# Trigger gradle build
RUN [ "grails", "stats" ]

# Implemented to improve cache in CI
FROM initializer as development
# Add wait-for-it ro wait for database
COPY wait-for-it.sh .
RUN ["chmod", "+x", "./wait-for-it.sh"]
# Copy source code
COPY grails-app /app/grails-app
COPY src /app/src
# Set Default Behavior
ENTRYPOINT ["./wait-for-it.sh", "db:5432", "-t", "30", "--", "grails", "run-app", "--debug-jvm"]
CMD [ "" ]

# Image used to build prod war
FROM development AS builder
# Build project
RUN [ "grails", "prod", "war" ]
RUN ls -l /app/build/libs

# Production image
FROM openjdk:8-jdk AS production
# Set correct timezone
ENV TZ=America/Argentina/Cordoba
RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone
# Add wait-for-it ro wait for database
COPY wait-for-it.sh .
RUN ["chmod", "+x", "/wait-for-it.sh"]
# Copy war inside container
COPY --from=builder /app/build/libs/app-*.war app.war
# Expose default port
EXPOSE 8080
# Wait for database to be available
ENTRYPOINT ["/wait-for-it.sh", "db-service:5432", "-t", "30", "--"]
# War runs directly. (Uses urandom as entropy source for faster startup time)
CMD ["java","-Djava.security.egd=file:/dev/./urandom","-jar","/app.war"]

wait-for-it.sh:

#!/usr/bin/env bash
#   Use this script to test if a given TCP host/port are available

WAITFORIT_cmdname=${0##*/}

echoerr() { if [[ $WAITFORIT_QUIET -ne 1 ]]; then echo "$@" 1>&2; fi }

usage()
{
    cat << USAGE >&2
Usage:
    $WAITFORIT_cmdname host:port [-s] [-t timeout] [-- command args]
    -h HOST | --host=HOST       Host or IP under test
    -p PORT | --port=PORT       TCP port under test
                                Alternatively, you specify the host and port as host:port
    -s | --strict               Only execute subcommand if the test succeeds
    -q | --quiet                Don't output any status messages
    -t TIMEOUT | --timeout=TIMEOUT
                                Timeout in seconds, zero for no timeout
    -- COMMAND ARGS             Execute command with args after the test finishes
USAGE
    exit 1
}

wait_for()
{
    if [[ $WAITFORIT_TIMEOUT -gt 0 ]]; then
        echoerr "$WAITFORIT_cmdname: waiting $WAITFORIT_TIMEOUT seconds for $WAITFORIT_HOST:$WAITFORIT_PORT"
    else
        echoerr "$WAITFORIT_cmdname: waiting for $WAITFORIT_HOST:$WAITFORIT_PORT without a timeout"
    fi
    WAITFORIT_start_ts=$(date +%s)
    while :
    do
        if [[ $WAITFORIT_ISBUSY -eq 1 ]]; then
            nc -z $WAITFORIT_HOST $WAITFORIT_PORT
            WAITFORIT_result=$?
        else
            (echo > /dev/tcp/$WAITFORIT_HOST/$WAITFORIT_PORT) >/dev/null 2>&1
            WAITFORIT_result=$?
        fi
        if [[ $WAITFORIT_result -eq 0 ]]; then
            WAITFORIT_end_ts=$(date +%s)
            echoerr "$WAITFORIT_cmdname: $WAITFORIT_HOST:$WAITFORIT_PORT is available after $((WAITFORIT_end_ts - WAITFORIT_start_ts)) seconds"
            break
        fi
        sleep 1
    done
    return $WAITFORIT_result
}

wait_for_wrapper()
{
    # In order to support SIGINT during timeout: http://unix.stackexchange.com/a/57692
    if [[ $WAITFORIT_QUIET -eq 1 ]]; then
        timeout $WAITFORIT_BUSYTIMEFLAG $WAITFORIT_TIMEOUT $0 --quiet --child --host=$WAITFORIT_HOST --port=$WAITFORIT_PORT --timeout=$WAITFORIT_TIMEOUT &
    else
        timeout $WAITFORIT_BUSYTIMEFLAG $WAITFORIT_TIMEOUT $0 --child --host=$WAITFORIT_HOST --port=$WAITFORIT_PORT --timeout=$WAITFORIT_TIMEOUT &
    fi
    WAITFORIT_PID=$!
    trap "kill -INT -$WAITFORIT_PID" INT
    wait $WAITFORIT_PID
    WAITFORIT_RESULT=$?
    if [[ $WAITFORIT_RESULT -ne 0 ]]; then
        echoerr "$WAITFORIT_cmdname: timeout occurred after waiting $WAITFORIT_TIMEOUT seconds for $WAITFORIT_HOST:$WAITFORIT_PORT"
    fi
    return $WAITFORIT_RESULT
}

# process arguments
while [[ $# -gt 0 ]]
do
    case "$1" in
        *:* )
        WAITFORIT_hostport=(${1//:/ })
        WAITFORIT_HOST=${WAITFORIT_hostport[0]}
        WAITFORIT_PORT=${WAITFORIT_hostport[1]}
        shift 1
        ;;
        --child)
        WAITFORIT_CHILD=1
        shift 1
        ;;
        -q | --quiet)
        WAITFORIT_QUIET=1
        shift 1
        ;;
        -s | --strict)
        WAITFORIT_STRICT=1
        shift 1
        ;;
        -h)
        WAITFORIT_HOST="$2"
        if [[ $WAITFORIT_HOST == "" ]]; then break; fi
        shift 2
        ;;
        --host=*)
        WAITFORIT_HOST="${1#*=}"
        shift 1
        ;;
        -p)
        WAITFORIT_PORT="$2"
        if [[ $WAITFORIT_PORT == "" ]]; then break; fi
        shift 2
        ;;
        --port=*)
        WAITFORIT_PORT="${1#*=}"
        shift 1
        ;;
        -t)
        WAITFORIT_TIMEOUT="$2"
        if [[ $WAITFORIT_TIMEOUT == "" ]]; then break; fi
        shift 2
        ;;
        --timeout=*)
        WAITFORIT_TIMEOUT="${1#*=}"
        shift 1
        ;;
        --)
        shift
        WAITFORIT_CLI=("$@")
        break
        ;;
        --help)
        usage
        ;;
        *)
        echoerr "Unknown argument: $1"
        usage
        ;;
    esac
done

if [[ "$WAITFORIT_HOST" == "" || "$WAITFORIT_PORT" == "" ]]; then
    echoerr "Error: you need to provide a host and port to test."
    usage
fi

WAITFORIT_TIMEOUT=${WAITFORIT_TIMEOUT:-15}
WAITFORIT_STRICT=${WAITFORIT_STRICT:-0}
WAITFORIT_CHILD=${WAITFORIT_CHILD:-0}
WAITFORIT_QUIET=${WAITFORIT_QUIET:-0}

# check to see if timeout is from busybox?
WAITFORIT_TIMEOUT_PATH=$(type -p timeout)
WAITFORIT_TIMEOUT_PATH=$(realpath $WAITFORIT_TIMEOUT_PATH 2>/dev/null || readlink -f $WAITFORIT_TIMEOUT_PATH)
if [[ $WAITFORIT_TIMEOUT_PATH =~ "busybox" ]]; then
        WAITFORIT_ISBUSY=1
        WAITFORIT_BUSYTIMEFLAG="-t"

else
        WAITFORIT_ISBUSY=0
        WAITFORIT_BUSYTIMEFLAG=""
fi

if [[ $WAITFORIT_CHILD -gt 0 ]]; then
    wait_for
    WAITFORIT_RESULT=$?
    exit $WAITFORIT_RESULT
else
    if [[ $WAITFORIT_TIMEOUT -gt 0 ]]; then
        wait_for_wrapper
        WAITFORIT_RESULT=$?
    else
        wait_for
        WAITFORIT_RESULT=$?
    fi
fi

if [[ $WAITFORIT_CLI != "" ]]; then
    if [[ $WAITFORIT_RESULT -ne 0 && $WAITFORIT_STRICT -eq 1 ]]; then
        echoerr "$WAITFORIT_cmdname: strict mode, refusing to execute subprocess"
        exit $WAITFORIT_RESULT
    fi
    exec "${WAITFORIT_CLI[@]}"
else
    exit $WAITFORIT_RESULT
fi

application.yml

#...Omitted code...
environments:
    development:
        dataSource:
            driverClassName: org.postgresql.Driver
            dialect: org.hibernate.dialect.PostgreSQLDialect
            # dbCreate: create-drop
            dbCreate: update
            url: jdbc:postgresql://${DB_HOST}:${DB_PORT}/${DB_NAME}
    test:
        dataSource:
            dbCreate: update
            url: jdbc:h2:mem:testDb;MVCC=TRUE;LOCK_TIMEOUT=10000;DB_CLOSE_ON_EXIT=FALSE
    production:
        dataSource:
            driverClassName: org.postgresql.Driver
            dialect: org.hibernate.dialect.PostgreSQLDialect
            dbCreate: update
            url: jdbc:postgresql://${DB_HOST}:${DB_PORT}/${DB_NAME}

In development you would use the docker-compose file to run the image (note that it has some volumes in order to avoid the need to restart the app when you change it): docker-compose up -d backend

To generate an image for production: docker build -t yourdockerhubuser/yourproject:versionnumber .

The wait-for-it.sh file is not needed to generate a Docker image. But it is useful to us in order to make the grails service to wait some seconds until the database service is ready to accept connections...

If you take a look at the Dockerfile you would note that is a multistage file. That means that has like several stages on it. The first ones has grails tools on it. The last one is the one used on production and has only the jdk8 (and probably the jre would be enough). That way you don't pollute the production image resulting in a smaller image.