Common Development Environment

This repository contains the code for a development environment that can be used across teams and projects. It is designed to allow collections of applications to be loaded from a separate configuration repository, and maximising consistency between them.

It provides several hooks for applications to take advantage of, including:

• Docker container creation and launching via docker-compose
• Automatic creation of commodity systems such as Postgres or Elasticsearch (with further hooks to allow for initial provisoning such as running SQL, Alembic DB upgrades or Elasticsearch index creation)

Getting started

Prerequisites

Recommended setup

• Docker and Docker Compose. Exactly what toolset you use depends on your OS and personal preferences, but recommended are:
  • Docker For Mac
  • Docker for Windows 10 (See the wiki for more information on getting a working Windows environment set up)
  • Docker CE for Linux
• Git
• Ruby 2.3+

Alternative setup

• Vagrant (v1.9.5+)
• VirtualBox (v5.1+)

A Vagrantfile is provided so vagrant up will result in a virtual machine containing all the prerequisites from the Recommended setup above. From there, just vagrant ssh in and use the dev-env as you would natively.

Git/SSH

You must ensure the shell you are starting the dev-env from can access all the necessary Git repositories - namely the config repo and the application repos it specifies. If they are to be accessed via SSH, this wiki page has some proven techniques for generating keys and making them available to the shell.

Controlling the dev-env

To begin:

1. Start Docker.
2. Using Git, clone this repository into a directory of your choice.
3. Open a terminal in that directory, and run source run.sh up
4. If this is the first time you are launching the machine you will be prompted for the url of a configuration repository (both SSH or HTTP(S) Git formats will work). Paste it in and press enter.

TIP: You can add a # onto the end of the configuration repository location followed by a branch, tag or commit you want to check out, if the default branch is not good enough.

Other run.sh parameters are:

• halt - stops all containers
• reload - stops all containers then rebuilds and restarts them (including running any commodity fragments)
• destroy - stops/removes all containers, removes all built images (i.e. leaving any pulled from Docker Hub) and resets all dev-env configuration files.
• repair - sets the Docker-compose configuration to use the fragments from applications in this dev-env instance (in case you are switching between several)

Usage guide

Configuration Repository

This is a Git repository that must contain a single file - configuration.yml. The configuration file lists the applications that will be running in the dev-env, and specifies the URL of their Git repository (the repo key) plus which branch/tag/commit should be initially checked out (the ref key). The name of the application should match the repository name so that things dependent on the directory structure like volume mappings in the app's docker-compose-fragment.yml will work correctly.

The application repositories will be pulled and updated on each up or reload, unless the current checked out branch does not match the one in the configuration. This allows you to create and work in feature branches while remaining in full control of updates and merges.

If you are creating a new app that doesn't have a remote Git repository to clone from yet, you can manually put a directory into /apps/ and add it to the configuration with the repo key set to none and no ref key.

Example

Application support

For an application repository to leverage the full power of the dev-env...

Docker containers are used to run all apps. So some files are needed to support that.

/fragments/docker-compose-fragment.yml

This is used by the environment to construct an application container and then launch it. Standard Compose file structure applies - and all apps must use the same Compose file version (which must be 2) - but some recommendations are:

• Container name and service name should match
• Any ports that need to be accessed from the host machine (as opposed to from other containers) should be mapped
• A volumes entry should map the path of the app folder to wherever the image expects source files to be (if they are to be accessed dynamically, and not copied in at image build time)
• If the provided log collator is to be used, then a syslog logging driver needs to be present, forwarding to logstash:25826.
• If you wish to run the container as the host user so you have full access to any files created by the container (this is only a problem on Linux and Windows), environment variables OUTSIDE_UID and OUTSIDE_GID are provided for use in the fragment as build args (which can then be used in the Dockerfile to create a matching user and set them as the container-executor).

Although generally an application should only have itself in it's compose fragment, there is no reason why other containers based on other Docker images cannot also be listed in this file, if they are not provided already by the dev-env.

Note that when including directives such as a Dockerfile build location or host volume mapping for the source code, the Compose context root . is considered to be the dev-env's /apps/ folder, not the location of the fragment. Ensure relative paths are set accordingly.

Example

/fragments/docker-compose-fragment.3.7.yml

An optional variant of docker-compose-fragment.yml with a version of 3.7. The development environment will select the highest compose file version supplied by all applications in the environment. If all applications supply a docker-compose-fragment.3.7.yml, then the environment will use the 3.7 files, otherwise it falls back to the version 2 compose files.

Compose 3.7 support requires Docker engine version 18.06.0 or later.

If the environment cannot identify a universal compose file version, then provisioning will fail.

Example

/Dockerfile

This is a file that defines the application's Docker image. The Compose fragment may point to this file. Extend an existing image and install/set whatever is needed to ensure that containers created from the image will run. See the Dockerfile reference for more information.

Example - Python/Flask

Example - Java

/configuration.yml

This file specifies which commodities the dev-env should create and launch for the application to use. If the commodity must be started before your application, ensure that it is also present in the appropriate section of the docker-compose-fragment file (e.g. depends_on).

The list of allowable commodity values is:

1. postgres
2. postgres-9.6
3. db2 (Warning: source image no longer available on Docker Hub; use db2_community instead)
4. db2_devc (Warning: source image deprecated by IBM; use db2_community instead)
5. db2_community
6. elasticsearch
7. elasticsearch5
8. nginx
9. rabbitmq
10. redis
11. swagger
12. wiremock
13. squid

• The file may optionally also indicate that one or more services are resource intensive when starting up. The dev env will start those containers seperately - 3 at a time - and wait until each are declared healthy before starting any more. This requires a healthcheck command specified here or in the Dockerfile/docker-compose-fragment (in which case just use 'docker' in this file).
  • If one of these expensive services prefers another one to be considered "healthy" before a startup attempt is made (such as a database, to ensure immediate connectivity and no expensive restarts) then the dependent service can be specified here, with a healthcheck command following the same rules as above.

Example

Commodities

Individual commodities may require further files in order to set them up correctly even after being specified in the application's configuration.yml, these are detailed below. Note that unless specified, any fragment files will only be run once. This is controlled by a generated .commodities.yml file in the root of the this repository, which you can change to allow the files to be read again - useful if you've had to delete and recreate a commodity container.

PostgreSQL

/fragments/postgres-init-fragment.sql

This file contains any one-off SQL to run in Postgres - at the minimum it will normally be creating a database and an application-specific user.

Example

If you want to spatially enable your database see the following example:

Example - Spatial

The default Postgres port 5432 will be available for connections from other containers and on the host. Postgres 9.6 will be exposed on port 5433.

/manage.py

This is a standard Alembic management file - if it exists, then a database migration will be run on every up or reload.

DB2

db2_community (DB2 Community Edition 11.5) is recommended over db2_devc (DB2 Developer C 11.0) or db2 (DB2 Express 10.5)

Note that DB2 Developer C is exposed on the host ports 50001/55001 and DB2 Community on 50002/55002 to avoid port clashes.

/fragments/db2-init-fragment.sql /fragments/db2-devc-init-fragment.sql /fragments/db2-community-init-fragment.sql

This file contains any one-off SQL to run in DB2 - at the minimum it will normally be creating a database.

Example

ElasticSearch

/fragments/elasticsearch-fragment.sh /fragments/elasticsearch5-fragment.sh

This file is a shell script that contains curl commands to do any setup the app needs in elasticsearch - creating indexes etc. It will be passed a single argument, the host and port, which can be accessed in the script using $1.

The ports 9200/9300 and 9202/9302 are exposed on the host for Elasticsearch versions 2 and 5 respectively.

Example

Nginx

/fragments/nginx-fragment.conf

This file forms part of an NGINX configration file. It will be merged into the server directive of the main configuration file.

Important - if your app is adding itself as a proxied location{} behind NGINX, NGINX must start AFTER your app, otherwise it will error with a host not found. So your app's docker-compose-fragment.yml must actually specify NGINX as a service and set the depends_on variable with your app's name. Compose will automatically merge this with the dev-env's own NGINX fragment. See the end of the example Compose fragment for the exact code.

Example

RabbitMQ

There are no fragments needed when using this. The Management Console will be available on http://localhost:45672 (guest/guest).

Redis

There are no fragments needed when using this. Redis will be available at http://localhost:16379 on the host and at http://redis:6379 inside the Docker network.

You can monitor Redis activity using the CLI:

bashin redis
redis-cli monitor

Squid

There are no fragments needed when using this. An HTTP proxy will be made available to all containers at runtime, at hostname squid and port 3128. It will be available on the host on port 30128.

It also supports HTTPS, however you will need to ensure the self signed root CA is loaded into wherever it needs to go, depending on what is using the proxy (Java cacerts etc). This is best to do in your Dockerfile, alongside setting any variables needed to point to use the proxy itself.

Other files

/fragments/custom-provision.sh

This file contains anything you want - for example, initial data load. It will be executed on the host, not in the container. It is only ever run once (during the first run.sh up), and the file .custom_provision.yml is used by the dev-env to keep track of whether they have been run or not. Like .commodities.yml, this can be manually modified to trigger another run.

/fragments/custom-provision-always.sh

This works the same way as custom-provision.sh except it is executed on every run.sh up.

/fragments/host-fragments.yml

This file contains details of hosts to be forwarded on the host; if it exists then requests to the second address shall be forwarded to the first address.

Example

/fragments/docker-compose-<any value>-fragment.yml

This file can be used to override the default settings for a docker container such as environment variables. It will not be loaded by default but can be applied using the add-to-docker-compose alias.

Logging

Any messages that get forwarded to the logstash* container on TCP port 25826 will be output both in the logstash container's own stdout (so livelogs logstash can be used to monitor all apps) and in ./logs/log.txt.

* Note that it is not really logstash, but we kept the container name that for backwards compatibility purposes.

If you want to make use of this functionality, ensure that logstash is also present in the appropriate section of the docker-compose-fragment file (e.g. depends_on).

Hints and Tips

• Ensure that you give Docker enough CPU and memory to run all your apps.
• The run.sh destroy command should be a last resort, as you will have to rebuild all images from scratch. Try the fullreset alias as that will just remove your app containers and recreate them. They are most likely to be the source of any corruption. Remember to alter .commodities.yml and .custom_provision.yml if you need to, and run.sh reload.

Useful commands

If you hate typing long commands then the commands below have been added to the dev-env for you:

status                                           -     view the status of all running containers
stop <name of container>                         -     stop a container
start <name of container>                        -     start a container
restart <name of container>                      -     restart a container
logs <name of container>                         -     view the logs of a container (from the past)
livelogs <name of container>                     -     view the logs of a container (as they happen)
ex <name of container> <command to execute>      -     execute a command in a running container
run <options> <name of container> <command>      -     creates a new container and runs the command in it.
remove <name of container>                       -     remove a container
fullreset <name of container>                    -     Performs stop, remove then rebuild. Useful if a container (like a database) needs to be wiped. Remember to reset .commodities if you do though to ensure init fragments get rerun
rebuild <name of container>                      -     checks if a container needs rebuilding and rebuilds/recreates/restarts it if so, otherwise does nothing. Useful if a file has changed that the Dockerfile copies into the image.
bashin <name of container>                       -     bash in to a container
unit-test <name of container>                    -     run the unit tests for an application (this expects there to a be a Makefile with a unittest command). If you add -r it will output reports to the test-output folder.
integration-test <name of container>             -     run the integration tests for an application (this expects there to a be a Makefile with a integrationtest command).
acceptance-test | acctest                        -     run the acceptance tests run_tests.sh script inside the given container. If using the skeleton, any further parameters will be passed to cucumber.
          <name of container> <cucumber args>
acceptance-lint | acclint                        -     run the acceptance tests run_linting.sh script inside the given container.
          <name of container>
psql[96] <name of database>                      -     run psql in the postgres/posrgres-96 container
db2[c][co]                                       -     run db2 command line in the db2/db2_devc/db2_community container
manage <name of container> <command>             -     run manage.py commands in a container
alembic <name of container> <command>            -     run an alembic db command in a container, with the appropriate environment variables preset
add-to-docker-compose
  <name of new compose fragment>                 -     looks in fragments folder of loaded apps to search for a new docker-compose-fragment including the provided parameter eg docker-compose-syt2-fragment then runs docker-compose up

If you prefer using docker or docker-compose directly then below is list of useful commands (note: if you leave out <name of container> then all containers will be affected):

docker-compose run --rm <name of container> <command>    -    spin up a temporary container and run a command in it
docker-compose rm -v -f <name of container>              -    remove a container
docker-compose down --rmi all -v --remove-orphans        -    stops and removes all containers, data, and images created by up. Don't use `--rmi all` if you want to keep the images.
docker-compose stop|start|restart <name of container>    -    (aliases: stop/start/restart) starts, stops or restarts a container (it must already be built and created)
docker exec -it <name of container> bash                 -    (alias: bashin) gets you into a bash terminal inside a running container (useful for then running psql etc)

For those who get bored typing docker-compose you can use the alias dc instead. For example "dc ps" rather than "docker-compose ps".

Adding Breakpoints to Applications Running in Containers

In order to interact with breakpoints that you add to your applications you need to run the container in the foreground and attach to the container terminal. You do that like so:

docker-compose stop <name of container>
docker-compose run --rm --service-ports <name of container>

Versioning

We use SemVer for versioning. For the versions available and the changelog, see the releases page.

Authors

• Simon Chapman (GitHub)
• Ian Harvey (GitHub)

See also the list of contributors who participated in this project.

License

This project is licensed under the MIT License - see the LICENSE file for details

Acknowledgments

• Matthew Pease (GitHub) - for helping create the original internal version