Bash functions for dealing with Docker containers in an unknown state (starting, stopping, removing, checking if they exist, etc)

docker-functions.sh

# Helper functions for dealing with Docker containers

# Returns "missing", "stopped" or "running"
get_container_state() {
    local CONTAINER_NAME=$1

    # Faster check to see if the container *might* exist
    CONTAINER_MISSING=$(container_does_not_exist "$CONTAINER_NAME")
    if [[ $CONTAINER_MISSING = "true" ]]; then
        echo -n "missing"
        return
    fi

    # Returns "true" if running, "false" if stopped, or neither if non-existent
    local CONTAINER_STATE=$(docker inspect -f {{.State.Running}} "$CONTAINER_NAME" 2>&1)
    if [[ $CONTAINER_STATE = "true" ]]; then
        echo -n "running"
        return
    elif [[ $CONTAINER_STATE = "false" ]]; then
        echo -n "stopped"
        return
    fi

    echo -n "missing"
    return
}

# This method can quickly determine if the container DOES NOT exist, but
# since it matches CONTAINER_NAME as a substring, it can't prove that the
# container DOES exist.
# Returns "true" if definitely missing, "false" if it *could* exist
container_does_not_exist() {
    local CONTAINER_ID=$(docker ps -q -f status=running -f name=$CONTAINER_NAME 2>&1)

    if [[ -z $CONTAINER_ID ]]; then
        echo -n "true"
        return
    fi

    echo -n "false"
}

stop_container() {
    local CONTAINER_NAME=$1
    echo -n "Stopping container: "
    docker stop "$CONTAINER_NAME"
}

remove_container() {
    local CONTAINER_NAME=$1
    echo -n "Removing container: "
    docker rm -vf "$CONTAINER_NAME"
}

remove_container_if_exists() {
    local CONTAINER_NAME=$1
    local CONTAINER_STATE=$(get_container_state "$CONTAINER_NAME")

    if [[ $CONTAINER_STATE = "missing" ]]; then
        return
    fi

    if [[ $CONTAINER_STATE = "running" ]]; then
        stop_container "$CONTAINER_NAME"
        CONTAINER_STATE="stopped"
    fi

    if [[ $CONTAINER_STATE = "stopped" ]]; then
        remove_container "$CONTAINER_NAME"
    fi
}